penetrants testing

8/13/2019 Penetrants TESTING

http://slidepdf.com/reader/full/penetrants-testing 1/86

DYE PENETRANT TESTING SAIMIRA

CONSULTANTS

CONTENTS

1. INTRODUCTION 01

2. PRINCIPLES OF DYE PENETRANT TESTING 04

3. CLASSIFICATION OF DYE PENETRANT TESTING METHODS 10

4. FLOW CHART OF VARIOUS PROCESS COMBINATIONS 13

5. FLOW CHART FOR PROCESS SEQUENCE OF VISIBLE 14

DYE AND FLOURESCENT TYPE PENETRANTS,

. DUAL SENSITIVITY PENETRANTS PROCESS SEQUENCE 15

!. TYPES OF PENETRANTS 1!

". THE PROCESS OF EMULSIFICATION 23

#. DEVELOPERS 32

10. ULTRAVIOLET LIGHT 3"

11. CLEANING OF TEST SURFACE 40

12. STANDARD SPECIMEN 43

13. SYSTEM PERFORMANCE CHEC$ % $DM PANELS 44

14. EVALUATION 55

15. INSPECTION 51

1. TEST PROCESS 5

PREPARED BY S.MUTHUKUMAR, B.Tech ASNT NDT LEVELlll

1




CONSULTANTS

INTRODUCTION

LIQUID PENETRANT TESTING

Liquid penetrant test method enhances the isi!i"it# o$ sur$ace !rea%in&

$"a's such as crac%s( $issures( creices and pores) It can !e used er#

success$u""# re&ard"ess o$ component si*e and can to"erate comp"icated part

&eometr#) Liquid penetrants can seep into arious t#pes o$ minute sur$ace pores or

openin&s !# capi""ar# action( !ecause o$ this( the process is 'e"" suited $or detection

o$ a"" t#pes o$ sur$ace crac%s( "aps( porosit#( shrin%a&e areas( "aminations and simi"ar

t#pe o$ discontinuities) It is e+tensie"# used $or the inspection o$ cast and 'rou&ht

and 'e"ded products o$ !oth $errous and non $errous meta"s( po'der meta""ur&#

parts ( ceramics( p"astics( and &"ass o!,ects)

Penetrant testin& is used on meta"s such as a"uminium( ma&nesium( !rass(

copper( cast iron( stee"( stain"ess stee"( titanium and other common a""o#s) It can

a"so test other materia"s( inc"udin& &"a*ed ceramics( p"astics( mo"ded ru!!er(

po'dered meta" products and &"ass)

Some "imitations are( The discontinuit# to !e detected must !e open to

the sur$ace and the interior $ree $rom $orei&n materia"s) The test sur$ace shou"d

not !e porous) The materia" under test must not !e suscepti!"e to dama&e

$rom the "iquids used $or the e+amination The test process has temperature

"imitations - ./ to 01/ C 2) - usin& specia" materia"s( the ran&e is 3.0 to 1// / C

part temperatures 2) As Specia" requirements( Penetrant materia"s must !e

desi&ned 'ith a "o' su"$ur and ha"o&en content to aoid harm$u" e$$ects on

the test parts) Stain"ess stee"s are especia""# suscepti!"e to corrosion 'hen

e+posed to ch"orine and Car!on stee"s to su"$ur) Titanium is e+treme"#


2




CONSULTANTS

suscepti!"e to em!ritt"ement 'hen in contact 'ith ha"o&ens) 4i&h Nic%e" a""o#s

are a"so a$$ected !# su"pher and ha"o&ens) These harm$u" chemica"s can !e

$ound in penetrant materia"s !ut are "imited to .5 !# 'ei&ht o$ content)

Common penetrant materia"s attac% P6C( ma%in& it !ritt"e( 'hich "eads to

crac%in&) Liquid o+#&en compati!"e penetrant materia"s must !e used 'hen

testin& parts that 'i"" !e in contact 'ith either "iquid or &aseous o+#&en)

7ethod 8 A penetratin& "iquid is app"ied to the c"ean and dr# test sur$ace

and a""o'ed to enter the discontinuit# openin& oer a period o$ time) The "iquid

soa%s into materia" $"a's that are open at the test sur$ace)

A$ter a suita!"e penetration time( the e+cess sur$ace penetrant is remoed

and the test sur$ace is dried) A dee"oper is then app"ied in a thin uni$orm

coatin& 'hich acts as !"otter and dra's some o$ the entrapped penetrant out

o$ the discontinuities) The penetrant stains the dee"oper and the indication

!ecomes isi!"e) The sur$ace $"a' !ecomes increasin&"# isi!"e to the e#e(

!ecause the d#e spreads in the dee"oper and e$$ectie"# !roadens the trace)

The d#e indicator appears either red or !"ue on a 'hite !ac%&round $or

co"or contrast penetrants or appears 9e""o' : &reen or oran&e 3 red on a dar%

io"et !ac%&round( 'hen the sur$ace is i""uminated !# an u"traio"et "amp $or a

$"uorescent test process) The sensitiit# o$ the test depends on the si*e o$ the

discontinuit# openin& and not on the "en&th) Crac% 'idth is the more important

determinant o$ a penetrant;s a!i"it# to detect crac%s) Ti&ht narro' crac%s(

re&ard"ess o$ "en&th( are more di$$icu"t $or penetrants to $ind) <ati&ue crac%s

and $or&in& crac%s are ti&hter and require more ,udicious processin& and

hi&her sensitiit# penetrants to "ocate than castin& crac%s o$ the same "en&th)

The crac% "imit $or this inspection method is appro+imate"# /)0 =m crac% 'idth)

Detection o$ sur$ace $"a's depends on the &enera" condition and $inish o$the test sur$ace) The depth o$ the anticipated de$ect shou"d !e three times

deeper than the &enera" sur$ace rou&hness >a""e#> depth) De$ect detect3 a!i"it#

can !e $urther diminished !# norma""# accepta!"e sur$ace conditions such as


3




CONSULTANTS

too" mar%s( scratches( sca"e( ed&es( &rooes( notches( rou&h 'e"d sur$aces etc(

'here penetrant is trapped)

A"thou&h the d#e penetrant test is a er# eas# process( it is a"so er#

eas# to ma%e mista%es and ma%e the test ine$$ectie) Care must !e e+ercised

!# the operator in order to per$orm a"" the steps o$ the e+amination correct"#)

Sensitiit# : equa" or !etter than 7T : !etter than RT $or sur$ace discontinuities . ?m

+ ./ ?m + 0/ ?m can !e detected) App"ications : on a"" materia"s : meta"s@$errous

and non$errous

nonmeta"s @ru!!er (p"astic etc a"" t#pe o$ de$ects @open to sur$ace

Norma""# not app"ica!"e to porous materia"s @un$ired ceramics and po'der

meta""ur&ica" parts Present"# <i"tered partic"e penetrant $or porous materia"s has

!een dee"oped)

Rou&h sur$aces 3 B .10 ?m3!ac%&round poses pro!"em in usin& penetrant testin&)

4i&h"# co"oured @isi!"e or $"uorescent or&anic d#e "iquid 'hich is a"so sur$ace

actie in nature @ca""ed penetrants is app"ied on to the c"ean sur$ace o$ the

component and a""o'ed su$$icient time $or penetration into discontinuities) The

e+cess sur$ace penetrant on the component is remoed) This "eaes a c"ean sur$ace

o$ the component 'ith pentrant residin& in the discontinuities) At this point O$ time(

dee"opr( 'hich is hi&h"# a!sorptie in nature( is app"ied) The dee"oper !rin&s !ac%

or !"eeds out the penetrant there!# proidin& an indication in a contrastin&!ac%&round o$ 'hite co"our o$ dee"oper)

.)Preparation o$ part

1) App"ication o$ penetrant


4




CONSULTANTS

) Remoa" o$ e+cess sur$ace penetrant

) Dee"opment

0) Inspection and Ea"uation

) Post C"eanin&

Ph#sica" princip"es


I!"ec#$% &' I#e("(e#&#$%A""l$c&#$% %) 'e*el%"e(

Pee#(&# &""l$c&#$%

Fig.1. Principle of Penetrant Testing

Cle& !+()&ce %) C%"%e#

Re%*&l %) e-ce!! !+()&ce "ee#(&#A)#e( (e%*&l %) e-ce!! !+()&ce "ee#(&# &'

e)%(e &""l$c&#$% 'e*el%"e(

/




CONSULTANTS

"iquid penetrant inspection depends main"# on penetrant e$$ectie"# 'ettin& the

sur$ace o$ a so"id 'or% piece or specimen( $"o'in& oer that sur$ace to $orm a

continuous and reasona!"# uni$orm coatin& and the mi&ratin& into caities that are

open to the sur$ace)

So this a!i"it# o$ &ien penetrant to $"o' oer a sur$ace and enter sur$ace caities

depends principa""# on the $o""o'in&8

C"ean"iness o$ the sur$aces

Con$i&uration o$ the cait#

C"ean"iness o$ the cait# si*e o$ sur$ace openin& o$ the cait#

Sur$ace tension o$ the $"uid

A!i"it# o$ the "iquid to 'et the sur$ace

Contact an&"e o$ the "iquid

The cohesie $orces !et'een mo"ecu"es o$ "iquid causes the sur$ace tension( a !est

e+amp"e $or this phenomenon is tendenc# o$ "iquid oer the sur$ace such as drop"et

O$ 'ater( these contracts into sphere( in such drop"et( sur$ace tension is counter

!a"anced !# interna" h#drostatic pressure o$ the $"uid)

Fhen the "iquid comes into contact 'ith a so"id sur$ace( a cohesie $orces

responsi!"e $or sur$ace tension competes 'ith the adhesie $orces !et'een themo"ecu"es o$ the "iquid and so"id sur$aces(( these t'o $orces ,oint"# determines the

contact an&"e !et'een the "iquid and 'et sur$ace(! There are are three t#pes o$ "iquid

'ets the so"id sur$ace in re"ation to contact an&"e(

I$ contact an&"e is H/ de&rees "iquid hain& &ood 'ettin& a!i"it#

I$ contact an&"e is B H/ de&rees "iquid hain& poor 'ettin& a!i"it#

I$ contact an&"e is H/ de&rees "iquid hain& poor 'ettin& a!i"it#


0




CONSULTANTS

The propert# o$ a "iquid ca""ed capi""arit# is e+p"ained as the process o$ increase in

the meniscus or o$ the $"uid in a thin tu!e oer the 'ater "ee" 'hen this tu!e is

immersed in 'ater in container( this capi""ar# rise is a"so c"ose"# re"ated to 'ettin&

an&"e !et'een the "iquid that 'ets the tu!e and the inner sur$ace o$ the tu!e( Fettin&

an&"e !et'een capi""ar# tu!e And "iquid Less than H/ de&rees then meniscus o$ the

"iquid 'i"" !e concae and "iquid "ee" in the tu!e raises in the tu!e oer the "iquid

"ee" in a container : hain& &ood 'ettin& a!i"it#





CONSULTANTS

Physical principles

C&'())&*+ '*--*/

2T - θ

ρ

W66(7 &8()(6+ 9, '*, *-6

θ :#0; #0; < #0;

Fettin& an&"e !et'een capi""ar# tu!e And "iquid &reater than H/ de&rees then

meniscus o$ the "iquid 'i"" !e cone+ and "iquid "ee" in the tu!e reduces in the tu!e

oer the "iquid "ee" in a container : hain& poor 'ettin& a!i"it#

This is due to h#drostatic pressure immediate"# under the meniscus is reduced !#

the distri!ution o$ sur$ace tension in the concae sur$ace( and the "iquid is pushed up

!# the h#drau"ica""# transmitted pressure o$ the atmosphere at the $ree sur$ace o$ the

"iquid outside the capi""ar# tu!e)

The hei&ht to 'hich the "iquid rises is direct"# proportiona" to the sur$ace

tension o$ the "iquid and to the cosine an&"e o$ contact( and it is inerse"#

proportiona" to the densit# o$ the "iquid and the radius o$ the capi""ar# tu!e( This

a!oe e+p"ained simi"ar phenomena is app"ica!"e $or the penetrants enterin& the

discontinuit# and seepin& out 'hen dee"oper is app"ied)The term iscosit# is a"so

re"ated to rate at 'hich the "iquid 'i"" $"o' and it is hain& ne&"i&i!"e e$$ect in

penetratin& a!i"it#) hi&h"# iscous "iquids are not suita!"e $or not suita!"e $or

penetrants( since rate o$ $"o' is s"o'er one consequent"# requires "on&er time to

mi&rate into $ine $"a's)





CONSULTANTS

The princip"e o$ "iquid penetrant testin& is !ased on the a!i"it# o$ some

"iquids to enter a discontinuit# openin& and then re3emer&e $rom it 'hen the

e+cess penetrant is remoed $rom the sur$ace) Capi""ar# action is the means !#

)

A liquid drop on a ideally smooth,

clean surface at equilibrium

γ L

γ SL γ SG

'33* 466(75 θ<#0

G339 466(75 θ: #0 γ L

γ SL γ L COSθ γ SG

L 1 LIQUID= GAS, SG1 SOLID=GAS, SL1 LIQUID=SOLID FOR

GOOD SPREADING γ SG < γ SL

T &83> 9-2*('6(37 (- ?3* & )(@.(9 9*3' 37 & -3)(9 -.*?&2 &79 &83>6 )(@.(9 (- 5&-3.- 9(.

'hich a "iquid enters a discontinuit# openin&) This action is 'hat causes a

piece o$ spon&e to a!sor! "iquid

Capi""ar# action is a phenomenon in 'hich 'ater or other "iquids 'i"" rise

a!oe the norma" "iquid "ee" in a sma"" !ore or capi""ar# tu!e due to the

attraction o$ the mo"ecu"es in the "iquid $or each other and $or the 'a"" o$ the

tu!e - cohesion and adhesion 2)

Cohesion is interaction !et'een t'o sur$aces o$ the same materia" in

contact( ma%es them c"in& to&ether - 'ith t'o di$$erent materia"s the simi"ar

phenomenon is ca""ed adhesion 2) Accordin& to %inetic theor#( cohesion is

caused !# attraction !et'een partic"es at the atomic or mo"ecu"ar "ee") Sur$ace





CONSULTANTS

tension( 'hich causes "iquids to $orm spherica" drop"ets( is caused !#

cohesion)

The distance the "iquid 'i"" rise up the tu!e o$ a &ien diameter and

materia" is a $unction o$ three $actorsJ Sur$ace tension( Fettin& a!i"it#( Tu!e

open or c"ose at the top end) Liquid 'i"" rise "ess in a c"osed end tu!e)

The practica" circumstances( a penetrant encounters durin& testin& is more

comp"e+) Crac%s( $or e+amp"e are not capi""ar# tu!es( !ut simu"ate the !asic

interaction !et'een a "iquid and a so"id sur$ace( 'hich is responsi!"e $or the

mi&ration o$ penetrant into its open space) This same interaction acts a&ain

and penetrant emer&es $rom the discontinuit# 'hen the e+cess penetrant is

remoed $rom the sur$ace

Factors influencing Penetrant

infiltration into discontinuities

1. -*?&, 6,7-(7 ? 60, )(@(9 ',7,6*&76 2. 9(-76(7(6+ 7?(*&6(7 7-6&76

3. -*?&, &6(7- &79 76&A(7&76-

4. &99(6(>,- &79 76&A(7&76- (7 60, )(@(9',7,6*&76

5. A,0&7(&) 8-6*6(7-

. 6,A',*&6*, ? 60, 6,-6 8B,6

!. *07,-- ? 60, (76,*(* &))- ? 60,9(-76(7(6+

Norma""#( the penetrants need to hae a er# "o' contact an&"e and thecommercia" penetrants hae contact an&"es !et'een / :0)) Contact an&"e depends on

the so"id sur$ace to !e 'etted) Fater3&"ass has a contact an&"e o$ / de&) compared to

'ater3si"er 'hich is H/ de&


1




CONSULTANTS

Once the "iquid 'ets the sur$ace( the a!i"it# o$ the "iquid t Sur$ace tension Is

one o$ the most important properties 'hich determines the penetratin& a!i"it#

o$ a "iquid) Lo' sur$ace tension "iquids proide !etter penetration and spreads

'e"" on part sur$ace)

Fettin& a!i"it# is a"so determines the penetratin& a!i"it# o$ a "iquid) A!i"it#

to 'et or spread on the sur$ace is re"ated direct"# to the contact an&"e

!et'een the "iquid and the sur$ace at the point o$ contact) To hae a &ood

'ettin& a!i"it#( the contact an&"e must !e sma"") Penetrants used $or testin&

hae contact an&"e o$ 0/ or "ess)

Kri&htness The d#e in the penetrant shou"d !e hi&h"# sta!"e and !ri&ht

enou&h to !e isi!"e in er# thin $i"m) 6o"ati"it# is the speed 'ith 'hich a

"iquid eaporates)

Penetrant shou"d !e non o"ati"e to a""o' "on& penetration and inspection

time) The penetrant must not dr# durin& the e+amination period) <"ash point is

the temperature at 'hich $"amma!"e apor is &ien o$$) <or sa$et# purpose( a

penetrant shou"d hae hi&her or no $"ash point)

Chemica" Innertness is the a!i"it# o$ a materia" not to interact 'hen mi+ed

'ith or !rou&ht into contact 'ith other materia"s) Penetrant shou"d !e as inert

and non corrosie as possi!"e to'ards the materia"s to !e tested)

So"u!i"it# is the a!i"it# o$ a materia" to !e disso"ed into another materia")

Penetrant must !e so"u!"e in order to !e easi"# remoed $rom the sur$ace o$

the part !ein& e+amined) Creep is the a!i"it# o$ sma"" amounts o$ "iquid in

discontinuities to com !ac% out to $orm an indication)

To"erance $or Contamination is the a!i"it# to to"erate sma"" amounts o$

$orei&n su!stances and not a$$ect un$aora!"# the action o$ a penetrant) A

penetrant is a compound o$ seera" in&redients and a "itt"e 'ater( acids(deter&ents and de&reaser so"ents ma# upset the !a"ance and cause the

penetrant to "ose some or a"" o$ its important properties) To+icit#( S%in irritation

and odor No penetrant shou"d contain poisonous( corrosie or s%in irritatin&

materia" or hae an o$$ensie odor)


11




CONSULTANTS

Penetrant properties points to remem!er

.) Lo' sur$ace tension and contact an&"e( capa!"e o$ smooth"# and een"#

spread on the part sur$ace)

1) Lo' iscosit#( capa!"e o$ enterin& sma"" discontinuit# openin&s $aster)

) Non o"ati"e)

) Eas# remoa" $rom part sur$ace !ut not $rom the discontinuities) The

penetrant shou"d &et remoed 'ith no d#e precipitation)

0) Capa!"e o$ emer&in& $rom discontinuities a$ter e+cess penetrant is

remoed)

) 4i&h isi!i"it# and contrast in sma"" quantities and thin $i"ms on part

sur$ace)

) Does not corrode the test sur$ace)

M) 7ust !e Non To+ic

The rise in the capi""ar# or enter into the openin&s is determined !# sur$ace tension

@T

4ence the main properties o$ penetrant are T and ) The a!i"it# o$ the "iquid to

spread or 'et the so"id sur$ace is re"ated to the contact an&"e ( 'hich quanti$ies the

resu"tant adhesie and cohesie $orces( The contact an&"e is de$ined as the an&"e

!et'een the so"id sur$ace and the tan&ent dra'n to the "iquid at the point o$ contact)

It can !e seen that spreadin& a!i"it# and contact an&"e are inerse"# re"ated)

Co"our contrast ratio o$ isi!"e d#e is .8./ @The "i&ht re$"ected !# the 'hite

!ac%&round to !ri&ht red o$ the d#e) Co"our contrast ratio o$ the $"uorescent d#e is

.8.// @"i&ht emitted !# the indication to the "i&ht emitted !# the dar% !ac%&round

Kecause o$ this co"our contrast ratio( the indication is !etter seen in the case o$

$"uorescent indication ) The human e#e !rin&s an e$$ect ca""ed ha"ation e$$ect( the

a!i"it# to ma&ni$# the indication propert# o$ penetrant is d#e so"ou!"e capa!i"it# to

produce easi"# isi!"e indications($ina""# this penetrants must !e easi"# remoed !#

suita!"e so"ents or remoer or emu"si$ier 'ithout precipitatin& the d#e(


12




CONSULTANTS

The per$ormance o$ a penetrant is achieed !# a com!ination o$ contro""ed

ph#sica" and chemica" properties J

6iscosit# Is re"ated to the rate at 'hich a "iquid 'i"" $"o' under some

app"ied $orce) It a$$ects the speed o$ penetration throu&h the discontinuit#

openin&) A "o' iscosit# "iquid is used $or $aster penetration and a"so "ess

dra& out in immersion)

There are main"# three t#pes o$ penetrants name"#

Liquid Penetrant T9PE

∗ <"uorescent BBB T#pe @I J 6isi!"e BBB T#pe @II

∗

E+cess Penetrant Remoa" 7ethod

∗ Fater Fasha!"e 7ethod @A

∗ Post3Emu"si$ia!"e( Liphophi"ic 7ethod @K

∗ So"ent remoa!"e 7ethod @C

Post3Emu"si$ia!"e( 4#drophi"ic 7ethod @D

Dee"oper <orm

∗ Dr# Dee"oper BB <orm @a

∗ Fater3so"u!"e BB <orm @!

∗ Fater3suspended BB <orm @c

∗ Non3aqueous BB <orm @d

So"ents $or pre3c"eanin& CLASS

∗ ha"o&nated Non3<"amma!"e C"ass @.

∗ non3ha"o&nated <"amma!"e C"ass @1

App"ication o$ penetrant

Penetrant can !e app"ied !# immersion( dippin& (spra#in&( s'a!!in& and pourin&


13




CONSULTANTS

D'e"" time 8 The tota" time the penetrant is contact 'ith the test sur$ace inc"udin& the

time required $or app"ication and $or drain )

D'e"" time app"ication time drain time

Norma""# 03/ mts) Depends on the si*e and nature o$ discontinuit# and the materia"

and sur$ace condition o$ the materia" etc) The on"# requirement is that a thin "a#er o$

penetrant shou"d !e present $or the speci$ied time @d'e"" time on the sur$ace to !e

inspected

Remoa" o$ e+cess penetrant

The e+cess sur$ace penetrant on the sur$ace is care$u""# remoed 'ithout

a$$ectin& the penetrant that is residin& in the discontinuit#) In an# NDT method the

Si&na" to Noise ratio is important and this shou"d !e as hi&h as possi!"e S3 6o"ume o$

penetrant that has entered into the discontinuit# N3 Unremoed e+cess sur$ace

penetrant in the discontinuit#

This is an important step as the unremoed e+cess sur$ace penetrant 'i"" a$$ect

su!sequent"# !# a$$ectin& the contrast o$ the indication @e+cessie !ac%&round and

i$ an# penetrant in the discontinuit# is distur!ed the o"ume o$ the penetrant

indication 'i"" &et reduced @The o"ume o$ penetrant is a"read# er# sma""

It is o!ious that in PT to achiee a hi&h SN ratio( the e+cess penetrant on the

sur$ace shou"d !e remoed as comp"ete"# as possi!"e and the penetrant is the

discontinuit# shou"d not !e "ost !# oer'ashin&

Penetrant remoa" methods

Disso"e and remoe

.) Disperse @emu"si$# and remoe !# 'ater 'asha!"epost emu"si$ication

1) Simp"# 'ater 'ash i$ penetrant contains !ui"t in Emu"si$ier @FF

In each case( care need !e e+ercised so as to comp"ete"# remoe the e+cess

penetrant on the sur$ace comp"ete"# and at the same time the penetrant in thediscontinuit# is not a$$ected) Fash : dont oer 'ash )

In the case( 'e"ds( 'hen need !e inspected 'ithout $"ushin& the cro'n( the

sur$ace ou&hness poses pro!"ems &iin& !ac%&round co"ouration there!# a$$ectin&

the isi!i"it# o$ the ndication) 4ence So"ent remoa!"e and 'ater 'asha!"e


14




CONSULTANTS

ariations are norma""# emp"o#ed) 4ere oer'ashin& tendenc# o$ these methods(

ista%en to adanta&e( meanin&( the sur$ace is much $ree $rom the !ac%&round

co"ouration) O$ course( the sensitiit# su$$ers) Sensitiit# depends on the amount o$

retained penetrant in the discontinuit#

DE6ELOPING

A$ter the remoa" o$ the e+cess sur$ace penetrant ( in dee"opin& step( the

penetrant $rom the discontinuit# is !rou&ht to the sur$ace so as to $orm an isi!"e

indication)

Dee"oper $unctions) The dee"oper $unctions are

.)To assist the natura" seepa&e o$ the penetrant in the discontinuit# and e+tract or

!"ot out the penetrant so as to $orm an isua" indication @mechanism o$ isua"

indication

1) To proide a contrastin& !ase 'hich enhances the detection an indication) K"ue3

!"ac% to #e""o'ish &reen8 'hite to red

) To spread the penetrant so as to increase the apparent si*e o$ the indication

) To mas% some con$usin& indications

7echanism o$ dee"opin& action 8

Natura" seepa&e is assisted and the a!soptie dee"opers !"ot out more

penetrant $rom the discontinuit#) The thic%ness o$ the penetrant "a#er is increased to

the "ee"s a!oe the thresho"d isi!i"it# )@ Some $"uorescent penetrant indications

can !e seen 'ithout dee"opin& 'ith hi&h intensit# !"ac% "i&ht 3/// micro'attsq)cm

Dee"oper has t'o ariations8 Dr# and Fet) In the case o$ 'et( aqueous and non

aqueous)As the sensitiit# o$ 'et dee"opers are !etter than( dr# dee"opers and

since in 'e"d inspection( "ess sensitie methods name"# 'ater 'asha!"e and so"ent

remoa!"e are emp"o#ed ( it is !etter to use 'et dee"opers @most"# nonaqueous in'e"d inspection in spite sur$ace rou&hness) Norma""# $or hi&h sur$ace rou&hness( dr#

po'der is !etter suited )

<LOF C4ART ILLUSTRATES 6ARIOUS PROCESS CO7KINATIONS


1/




CONSULTANTS

6ISIKLE <LOURESCENTDUALSENSITI6IT9

FATERE7ULSI<IER SOL6ENT FATER SOL6ENT

FATER

FET DR9NONAQUEOUSFET

FATERSUSPENDEDPARTICLE

FATERSOLOUKLE

<LOF C4ART <OR PROCESS SEQUENCE O< 6ISIKLE D9E AND <LOURESCENT

T9PE PENETRANTS(


10




CONSULTANTS

FATERFAS4AKLE

POSTE7ULSI<IED

SOL6ENTRE7O6AL

APPL9PENETRANT

APPL9PENETRANT

APPL9PENETRANT

APPL9E7ULSI<IER

FATER FAS4SOL6ENTFIPE

DR9

APPL9FATERKASED FETDE6ELOPER

APPL9 DR9POFDERDE6ELOPER

APPL9 NONAQUEOUSFEDE6ELOPER

APPL9 DR9POFDERDE6ELOPER DR9

INSPECT

POST CLEAN


1




CONSULTANTS

DUAL SENSITI6IT9 PENETRANTS PROCESS SEQUENCE

DUALSENSITI6IT9PENETRANTSPROCESSSEQUENCE

PRECLEAN

APPL9PENETRANT

SOL6ENTFIPE

FATERFAS4

DR9

APPL9 DR9POFDERDE6ELOPER

APPL9 NONAQUEOUSFETDE6ELOPER

INSPECT

POSTCLEAN

Dee"opin& action at the end o$ dee"oper time reea"s an indication) In this

step the indications are interpreted as to the ori&in o$ the indication name"# 'hether

True or $a"se indications and i$ true indication 'hether re"eant or nonre"eant and i$


1




CONSULTANTS

re"eant as to the nature o$ discontinuities "inear or o"umetric)

Inspection enironement depends on the t#pe o$ d#e 3 6isi!"e or $"uorescent d#e

'hite "i&ht $or isi!"e and !"ac% "i&ht $or $"uoresecent)

T#pes o$ penetrants

Penetrants are &enera""# a chemica" so"ution o$ hi&h"# sta!"e d#es( either

isi!"e or $"uorescent( in a mi+ture o$ sur$ace actie a&ents 'ith a !"end o$

hi&h"# re$ined h#drocar!on disti""ate) The carrier "iquid is practica""# co"or"ess

and transparent) The d#e proides a hi&h contrast indication a&ainst the

!ac%&round)

Petro"eum disti""ates( 'hich are re"atie"# nono"ati"e and used to di"ute

!oth 'ater 'asha!"e and non 3 'ater 'asha!"e penetrants( contri!ute to

penetrant per$ormance in seera" 'a#s) As a di"uent( a "i&ht petro"eum disti""ate

disso"es "i&ht or&anic soi"s on sur$aces and in $"a's( and it assists crac%

penetration 'ith its "o' sur$ace tension and a$$init# $or meta" sur$aces) A"so(

petro"eum disti""ates natura""# $"uoresce a "i&ht !"ue co"or and( in a minor 'a#(

contri!ute to penetrant !ri&htness) Petro"eum disti""ates are source o$ ha"o&ens

and su"phur)

Fater !ased $"uorescent penetrants - usin& 'ater as di"uent 'hich

represents at "east 0/5 o$ a penetrant 2 hae !een dee"oped $or eas#

disposa"( preious"# used as non3certi$ied app"ications( are no' approed) Fater

!ased $"uorescent penetrants are restricted to 'ater 'asha!"e method and

aai"a!"e in sensitiit# "ee" . and 1) The penetrants are "iquid o+#&en

compati!"e( suita!"e $or use as a "ea% detector and $or inspection o$ p"astics)

The penetrants are compati!"e 'ith 'ater !ased prec"eaners( e)&)( hot a"%a"ine(

'hich $or enironmenta" reasons hae rep"aced petro"eum so"ents and apor

de&reasers) Kein& compati!"e 'ith the aqueous c"eaner( these penetrants hae

to"erance $or rinse 'ater carr# oer) A"so( $"a' entrapped 'ater is "ess "i%e"# to

impair the inspection process( such as 'ou"d happen 'hen $"a' entrapped

'ater repe""ed a petro"eum !ased penetrant)


1




CONSULTANTS

Fater in 'ater !ased penetrants 'i"" eaporate( and re&u"ar( testin& 'ith a

re$ractometer is necessar# to measure the "oss) Periodic 'ater additions are

part o$ the maintenance criteria $or these penetrants) Lon&er penetration time

- / mins 2 improes sensitiit# and dr# dee"opers are "ess suita!"e $or these

penetrants)

Se"ection o$ penetrant t#pe depends on(

• Sensitiit# required) - ti&htness o$ the openin& 2

• Num!er o$ artic"es to !e tested)

• Sur$ace condition o$ the part to !e tested)

• Con$i&uration o$ the test specimen)

• Aai"a!i"it# o$ 'ater( e"ectricit#( compressed air and other equipments)

• Suita!i"it# in enironment 'here the test 'i"" !e per$ormed)

• Cost o$ inspection)

In 'e"d inspection( "o'er sensitiit# methods(name"# 'ater Fasha!"e and

so"ent remoa!"e are emp"o#ed due to sur$ace rou&hness o$ the 'e"d) 4ence( use o$

hi&h sensitiit# penetrant name"# $"uorescent d#e penetrant ma# !e pre$erred)

6isi!"e D#e 8

6isi!"e d#e or co"or contrast penetrant inspection ma%es use o$ a d#e

that is isi!"e in ordinar# "i&ht) These penetrants contain a hi&h"# sta!"e !ri&ht

red or purp"e d#e( so that the indications produce a de$inite contrast 'ith the

'hite !ac%&round o$ the dee"oper po'der) The d#es are isi!"e in er# thin

$i"m) Co"or contrast penetrant can not achiee the "ee" o$ sensitiit# 'hich is

possi!"e 'ith the $"uorescent penetrants !ecause o$ hi&her iscosit# and

ina!i"it# to enter er# ti&ht crac%s)

As a &enera" ru"e o$ thum!( isi!"e penetrant e+amination is rou&h"#

equa" to $"uorescent penetrant e+amination o$ "ee" . sensitiit#) Discontinuities

in the ran&e o$ 0/ in NiCr pane"s are routine"# detected and under the ri&ht

conditions and processin& / discontinuities can !e hi&h"i&hted) The


2




CONSULTANTS

adanta&e o$ usin& a isi!"e penetrant is that it can !e used 'ith ordinar#

shop "i&htin& and $rom a sma"" porta!"e so"ent remoa!"e %it at an# "ocation)

The# are specia""# suita!"e $or $ie"d app"ications and 'here dar%enin& the

inspection area is impractica")


21




CONSULTANTS


Se!$#$*$#5 %) "ee#(&#!

All )l+%(e!ce# e#h%'! &(e %(e !e!$#$*e

#h& *$!$le '5e "ee#(&#

Pee#(&# T5"e

P(%"e(#$e!

V$!$!le '5e 6l+%(e!ce#

'5e

I'$c&#$% B($7h# (e'

c%l%+(

Yell%8$!h

7(ee9%

e-c$#&#$%:

B&c;7(%+' <h$#e c%l%+(

%) #he'e*el%"e(

D&(; 9,&-. 2

)#.c&'le!:

C%l%+( c%#(&!# (&#$% =1>14 =1>144V$!$$l$#59!ee&$l$#5: Me'$+, Ve(5 h$7h

H&l&#$%

e))ec#9&$l$#5 %) #he

e5e #% ,&7$)5 #he$'$c&#$%:

N%(,&l H$7h

Se!$#$*$#5 Me'$+, H$7hI 8el' $!"ec#$%, l%8e( !e!$#$*$#5 e#h%'!,

&el5 8&#e( <&!h&le &' !%l*e# (e%*&le &(e

e"l%5e' '+e #% !+()&ce (%+7he!! %) #he 8el'.

Hece, +!e %) h$7h !e!$#$*$#5 "ee#(&# &el5

)l+%(e!ce# '5e "ee#(&# &5 e "(e)e((e'.

22




CONSULTANTS

6isi!"e penetrants are "ess u"nera!"e to contamination $rom c"eanin& $"uid that

can si&ni$icant"# reduce the !ri&htness o$ a $"uorescent indication) 6isi!"e

penetrants are used in maintenance( repair and in manu$acturin& processes

'here a isi!"e indication he"ps in "ocatin& the area $or su!sequent repair

'or%( such as "ar&e rou&h castin&s) These penetrants are a"so used $or

throu&h "ea% testin& o$ heat e+chan&ers and tan%s( 'here penetrant is app"ied

to one side and dee"oper to the other)

E$$ect o$ Temperature8 Penetrants are norma""# dee"oped $or use $rom a!out

./ to 01/ C) 4o'eer the# can !e used as "o' as / C !ut penetration time

must !e increased !# 1 to times) At "o' temperature( penetrant !ecomes

hi&h"# iscous and s"u&&ish)

Idea" operatin& temperatures $or norma" use o$ penetrants "ie !et'een ./ /

C and M/ C) Penetrant testin& at hi&her part temperature has positie

adanta&e) The mo"ecu"ar moement o$ a "iquid is direct"# re"ated to the "iquid;s

a!so"ute temperature) The hi&her the temperature( the &reater the moement and

iscosit# decreases) Thus( a penetrant( in contact 'ith a heated part( 'i"" !e

"ess iscous and $ast penetrate into $"a's !# disp"acin& an# &as or "iquid $rom

the interior o$ the discontinuit#)

4eat apori*es discontinuit# entrapped so"ents and moisture( 'hich mi&ht

other'ise inter$ere 'ith penetration) 4eat "ique$ies hea# oi"s and 'a+es present

$rom preious processin&( $aci"itatin& penetrant disp"acement) Thus( a heated

penetrant 'i"" more e$$ectie"# $i"" a crac%) In addition( 'hen penetrants are

heated( d'e"" time ma# !e reduced !ecause o$ $aster penetration) Durin& the

d'e"" time( the part temperature 'i"" $a"" and the iscosit# o$ the penetrant 'i""

increase) This 'i"" resist oer remoa") Simi"ar"#( the dee"opin& step is a"so

$aster( penetrant mo"ecu"es are more readi"# a!sor!ed !# the dee"oper "a#er(and the dee"oper dries $aster) Fhen inspectin& heated sur$aces 'ith 'ater

'asha!"e penetrants( it 'ou"d !e prudent to 'ipe the sur$ace 'ith a so"ent or

c"eaner resistant to hi&h temperatures( since !oi"in& 'ater ma# not rinse e+cess

penetrant satis$actori"#) 4i&h temp certi$ied penetrant materia"s sha"" !e used)


23




CONSULTANTS

<"uorescent D#e - T#pe I 2 8 <"uorescent penetrant uses minera"s or chemica"

compounds 'hich emit isi!"e "i&ht 'hen e+posed to u"traio"et "i&ht)

<"uorescent penetrants response is ma+imum 'hen e+posed to 0 nm

'ae"en&th u"traio"et "i&ht)

The d#e a!sor!s this ener&# and emits !et'een 01/ nm to 1/ nm

'ae"en&ths 'hich is isi!"e as !ri""iant #e""o'3&reen) Oran&e 3 red t#pe

penetrants are a"so aai"a!"e) The e$$icienc# o$ $"uorescent d#es in conertin&

U6 "i&ht to isi!"e "i&ht ma# !e reduced !# pro"on&ed e+posure to U6 "i&ht)

E"eated temperature can reduce the $"uorescence o$ penetrant in open tan%s)<"uorescent penetrants are desi&ned $or di$$erent sensitiit# "ee"s J

Lee" .1 U"tra "o'( $or castin&s and rou&h sur$aces)

Lee" . Lo' sensitiit# 0/?m NiCr crac% pane"s)

Lee" 1 Norma" sensitiit# /?m( &enera" purpose use)

Lee" 4i&h sensitiit# 1/ 3 /?m)

Lee" U"tra hi&h sensitiit# ./?m e+treme"# critica" use)

The actua" certi$ications $or sensitiit# "ee" to ( ino"es the use o$ a

series o$ titanium and nic%e" a""o# pane"s containin& er# sma""( "a!orator#

&enerated $ati&ue crac%s) <"uorescent penetrants are more sensitie than isi!"e

d#e !ecause the# hae "o'er iscosit#( can penetrate sma""er openin&s( and


24




CONSULTANTS

hae e+ce""ent isi!i"it#) It is easier to detect somethin& &"o'in& in the dar%

than to o!sere a sma"" co"ored area on a 'hite !ac%&round) <"uorescent

indications are man# times !ri&hter than their dar% surroundin&s) The

!ri&htness o$ indications depends on the incident U6 3 "i&ht intensit# and

minimum ./// micro 'atts cm1 is required at the test sur$ace) Kac%&round

'hite "i&ht i""umination is to !e "imited to 1/ Lu+)

<"uorescent penetrants require a dee"oper 'ith "o'er partic"e

concentration( !ecause the 'hite !ac%&round proided !# the dee"oper is not

necessar#) Dee"oper is required on"# $or the !"ottin& action) <"uorescent

indications are isi!"e in er# thin $i"m) <or these penetrants( remoa" o$ e+cess

penetrant !# so"ent 'ipin& requires more care and is a pro!"em 'hen a "ar&e

sur$ace area is to !e c"eaned) Fater 'asha!"e t#pe 'i"" reduce this pro!"em)

<or $"uorescent penetrant testin&( it is er# important to ensure that the

part sur$ace is comp"ete"# $ree $rom nitric( su"phuric( chromic acids( a"%a"ine

perman&anate( acid chromate so"utions( acid $erric so"utions( pero+ides(

persu"phates etc) These common c"eaners a"" de&rade or %i"" the $"uorescence

comp"ete"#)

Dua" sensitiit# penetrants - T#pe III 2 8 These penetrant contains a

com!ination o$ red isi!"e d#e and oran&e $"uorescent d#e( such as K# Lu+

$rom Sher'in) The test o!,ect is $irst ie'ed under 'hite "i&ht $or red d#e

indications $o""o'ed !# u"traio"et "i&ht in a dar%ened area $or oran&e

indications) These penetrants proide t'o "ee"s o$ inspection sensitiit#) One

adanta&e is that $"a's "ocated durin& U6 e+amination are mar%ed !# isi!"e


2/




CONSULTANTS

indications $or repeat e+amination or repair 'or%)

Another adanta&e is that $"a's $ound in one mode can !e eri$ied in the

second mode) 4o'eer( the !ri&htness o$ the isi!"e red co"or and the

$"uorescent co"or are "ess than the indiidua" isi!"e d#e and $"uorescent

penetrants)

Important 8 <"uorescent penetrant shou"d neer !e used on sur$aces 'hich

hae !een processed preious"# 'ith co"or contrast penetrant) In man# cases

residues o$ d#es persist in a de$ect( the $"uorescent process su$$ers not on"#

$rom the residue reducin& the amount a!"e to &et into the de$ect( residues o$

co"or d#es 'i"" compete $or "i&ht and e$$ectie"# %i"" the $"uorescence o$ an#

entrapped $"uorescent penetrant in su!sequent tests) .5 isi!"e penetrant can

stop the $"uorescence) I$ $"uorescent inspection is required( then the part sha""

!e c"eaned thorou&h"# to remoe an# co"or penetrant residue $rom the interior

o$ the discontinuities) App"#in& a reersi!"e penetrant dee"oper( 'hich contains

a $"uorescent d#e( reacts 'ith(


20




CONSULTANTS

and thus is quenched !#( the red d#e) Fhen the sur$ace is ie'ed under U6

i""umination( the residua" spots o$ red d#e can !e detected( 'hich stands out

as dar% spots a&ainst a $"uorescent !ac%&round) Once the remoa" o$ red

penetrant d#e has !een comp"eted and eri$ied !# this procedure( the

dee"oper is remoed !# rinsin& 'ith 'ater)

<"uorescent Kri&htness 8 is the amount o$ isi!"e "i&ht &ien o$$ 'hen a

$"uorescent d#e is e+posed to U6 "i&ht) It depends on J

the thic%ness o$ the penetrant $i"m)

the intensit# o$ the U6 "i&ht)

amount o$ $"uorescent d#e and its capa!i"it# to a!sor! U6 "i&ht)

the e$$icienc# o$ the d#e in conertin& the re"eased e"ectrons to isi!"e"i&ht)

Penetrants 'ere e+amined !# p"acin& a drop o$ used and ne' penetrant ne+t

to each other on a paper to'e" $or a isua" comparison) 7ost penetrant

speci$ications require rep"acement 'hen the !ri&htness drops !# more than

./5) Under test situations( the human e#e ma# detect a chan&e o$ a!out .05

or more in !ri&htness) <"uorescent !ri&htness measurement can !e per$ormed

usin& a approed Photo $"uorometer

Note 8 The &enera" ru"e is to use the "o'est sensitiit# $"uorescent

penetrant that reea"s the discontinuities o$ interest)


2




CONSULTANTS

Post Emu"si$ication penetrants 8

These penetrants are not direct"# 'ater 'asha!"e and the dan&er o$ oer3

'ashin& the penetrant $rom the discontinuities is reduced) An emu"si$#in&

a&ent is used that ma%es the sur$ace penetrant so"u!"e in 'ater so that the

e+cess penetrant can !e remoed !# 'ater rinse and then a dee"oper can !e

app"ied) These penetrants hae !etter penetratin& a!i"it# than 'ater 'asha!"e

penetrants and can detect minute $"a's) These processes are 'ide"# used 'ith

$"uorescent penetrants !ut much "ess 'ith co"or contrast penetrant) Emu"si$iers

are "iquids used to render the e+cess penetrant 'ater 'asha!"e) The

manu$acturers care$u""# $ormu"ate the emu"si$iers dependin& upon the penetrant

to !e used) Penetrants and emu"si$iers are used as a s#stem( and emu"si$ier

$rom one manu$acturer ma# not per$orm adequate"# on a di$$erent

manu$acturers penetrant)

There are t'o t#pes o$ emu"si$iers used in the remoa" processes J The#

are Lipophi"ic emu"si$iers and 4#drophi"ic remoers - deter&ents 2 )Lipophi"ic

emu"si$iers - 7ethod K 2 are oi" !ased and contain !"ends o$ sur$actants( esters

and hi&h !oi"in& point h#drocar!on disti""ates) The# are co"ored other than

&reen to a""o' eas# identi$ication) These emu"si$iers are used as supp"ied( and

$unction !# mechanica" and chemica" action)

The commonest method $or app"ication o$ "ipophi"ic emu"si$iers is directimmersion $o""o'ed !# draina&e) A$ter the emu"si$ier has coated the sur$ace o$

the part( mechanica" action starts to remoes some o$ the e+cess penetrant as

the mi+ture drains $rom the part) Durin& the emu"si$ication time( the emu"si$ier

di$$uses into the remainin& penetrant $i"m on the sur$ace o$ the part and


2




CONSULTANTS

render it 'ater 'asha!"e) The emu"si$ier is $ast actin&( thus ma%in& the

emu"si$ication - or contact time 2 er# critica") The emu"si$ier continues to act as

"on& as it is in contact 'ith the penetrant( there$ore( the rinse operation shou"d

ta%e p"ace quic%"# to aoid oer 3 emu"si$ication) The component ma# !e

immersed rapid"# in a "ar&e o"ume o$ 'ater to stop the action o$ the

emu"si$#in& a&ent) On remoa" $rom the 'ater( the 'ash is comp"eted !# spra#

rinsin&)

Spra# app"ication $o""o'ed !# draina&e has a"so !een used success$u""#)

Krush app"ication o$ "ipophi"ic emu"si$iers is prohi!ited( !ecause this 'ou"d

mechanica""# mi+ the emu"si$ier into the penetrant resu"tin& in non uni$orm

emu"si$ication) <"o'in& the emu"si$ier on the component sur$ace is not

recommended !ecause it ma# not !e possi!"e to coer the component

sur$aces rapid"# enou&h to ensure uni$orm emu"si$ication) It is essentia" that

comp"e+ shaped components are rotated durin& the draina&e sta&e so that the

arious sur$aces receie simi"ar processin&)

The three properties o$ "ipophi"ic emu"si$iers that contro" the 'ashin&

characteristics are actiit#( iscosit#( and 'ater to"erance) Speci$ic contact

times $or "ipophi"ic emu"si$iers shou"d !e esta!"ished $or each app"ication) The

contact time can ar# !et'een / and .M/ seconds dependin& on the t#pe o$

the emu"si$#in& a&ent( the penetrant in use and the sur$ace condition o$ the

components) Lipophi"ic emu"si$iers are used at temperatures !et'een .0 and

10/ C) Lipoph#"ic emu"si$ier are misci!"e 'ith penetrants in a"" concentrations)

4o'eer( i$ the concentration o$ penetrant contamination in the emu"si$ier

!ecomes too &reat( the mi+ture 'i"" not $unction a$$ectie"# as a remoer) A

speci$ication requirement is that( "ipophi"ic emu"si$iers !e capa!"e o$ to"eratin&

1/5 penetrant contamination 'ithout a reduction in per$ormance) The emu"si$ieris to !e rep"aced 'hen its c"eanin& action is "ess than that o$ ne' materia")

Since "ipophi"ic emu"si$iers are oi" 3 !ased( the# hae a "imited to"erance $or

'ater) Fhen the to"erance "ee" is reached( the emu"si$ier starts to thic%en and

'i"" eentua""# $orm a &e" as more 'ater is added) Speci$ication requires that


2




CONSULTANTS

"ipophi"ic emu"si$iers !e $ormu"ated to $unction adequate"# 'ith at "east 05

'ater contamination and that "ipophi"ic emu"si$iers !e rep"aced 'hen the 'ater

concentration reaches the "imit)

Flow diagram for PE lipophilic

M,6039 D *,3>&) '*32,-- ASTM E 15

P* )&7 9*+ A'')+

'76*&76 9))

D(' (7

E)-(?(* T( (- *(6(&)

*(7-

9*+N7

A@-

9>)'* (7-'6

O$P-6)&7

*6


3




CONSULTANTS

4#drophi"ic remoers are app"ied !# immersion in an aqueous so"ution)

The concentration $or immersion aries !et'een the ran&e o$ 1)05 to ./5( 1/5

and up to / 5 dependin& on !rands and conditions o$ a&itation) Themanu$acturer o$ the emu"si$ier can proide the proper in$ormation concernin&

this concentration) Concentrations hi&her than recommended !# the emu"si$ier

manu$acturer or the qua"i$ied percenta&e is prohi!ited) The immersion time

aries $rom 1/ seconds to 0 minutes dependin& on the penetrant( emu"si$ier

concentration( sur$ace rou&hness and a&itation) The sur$ace actie a&ent in the

remoer com!ines 'ith a sma"" quantit# o$ penetrant $rom the sur$ace and

preents the penetrant $rom recom!inin& 'ith the remainin& sur$ace penetrant)

A s"i&ht a&itation is necessar# to remoe the co""oida" suspension o$ penetrant

: emu"si$ier $rom the sur$ace and to e+pose $resh penetrant) The pre$erred

method o$ a&itation is mechanica")

A&itation usin& compressed air can cause hea# $oamin& and ma# introduce


31




CONSULTANTS

contaminants) Fhen app"ication is !# immersion( h#drophi"ic emu"si$iers

ma"$unction as a resu"t o$ penetrant accumu"ation) Contamination increases

'hen part &eometr# inc"udes caities( or areas 'hich entrap penetrant to !e

carried oer to the emu"si$ier tan%) Emu"si$ier 'ith "o'er concentration &ets

contaminated $aster) The /5 concentration( i$ used( to"erates some three times

more penetrant contamination as the ./5 concentration does) Eer#thin& !ein&

equa"( a /5 concentration "asts three times "on&er than a ./5 concentration(

and is economica" !ecause o$ "ess $requent disposa"s) 4#drophi"ic emu"si$iers

are in$ested !# $un&us and a"&ae and the tan%s must remain coered 'hen

not in actie use) /5 concentration has more resistance to this in$estation)

4#drophi"ic remoer so"utions are a"so app"ied !# spra# or as $oam) The

concentration o$ the so"ution tend to !e much "o'er up to 05) 4o'eer( hi&her

concentration ma# !e used dependin& on the manu$acturers recommendation)

Immediate"# $o""o'in& the remoer spra#in&( a $resh'ater rinse o$ the entire

part is required to stop the action o$ an# remoer remainin& on the sur$ace o$

the part) 4#drophi"ic remoers minimi*e !ac%&round $"uorescence on part

sur$aces as 'e"" as !"eed out o$ e+cess penetrant $rom ho""o' parts)

The concentration o$ the deter&ent so"ution is critica" to the success o$

the process and must !e contro""ed) Fater "oss in h#drophi"ic emu"si$iers

resu"ts in more concentrated and more actie so"utions( a cause $or oer3

emu"si$ication 'ith resu"tant $ai"ure o$ the penetrant process) To monitor the

concentration( the re$ractie inde+ o$ the 'or%in& so"ution is &enera""#

measured and compared a&ainst &raphs &enerated !# measurin& the re$ractie

inde+ o$ so"utions o$ %no'n concentrations( usin& a Re$ractometer - an optica"

deice 'ith a readin& sca"e 2) A drop o$ the 'or%in& so"ution is p"aced on the

proper spot on the re$ractometer and a readin& is made on the sca"e and thenconerted into percenta&e !# usin& a ta!"e or a &raph app"ica!"e $or the

particu"ar remoer and supp"ied !# the emu"si$ier manu$acturer) The &raph ma#

!e &enerated in the 'or%station usin& prepared so"utions o$ the standard


32




CONSULTANTS

6o"ati"e a"iphatic a"coho"s)

The $"amma!"e c"eaners are potentia" $ire ha*ards !ut are $ree $rom

ha"o&ens( 'hi"e the non $"amma!"e c"eaners contain ha"o&ens( 'hich render

them unsuita!"e $or some app"ications) So"ent remoa!"e penetrant ma# !e

app"ied to the test sur$ace !# spra#in&( dippin&( $"oodin& or !rushin&) <or a

sma"" test area( !rushin& contro"s app"ied penetrant and remoa" o$ e+cess

penetrant is easier)

E+cess penetrant remoa" is per$ormed !# 'ipin& the part sur$ace in one

direction on"#( 'ith a c"ean and "int $ree c"oth or a!sor!ent paper) The proper

procedure is to ma%e a sin&"e pass( then $o"d the c"oth to e+pose a c"ean

sur$ace $or each succeedin& 'ipe) This 'i"" remoe most o$ the penetrant) The

remainin& traces are then remoed !# 'ipin& 'ith a ne' c"oth or paper "i&ht"#

'etted 'ith the so"ent remoer) A$ter each pass( the sur$ace o$ the c"oth is

e+amined) I$ there is more than a trace o$ penetrant on the c"oth( the c"oth is

$o"ded to e+pose a c"ean sur$ace( remoistened 'ith the so"ent( and the

sur$ace is 'iped a&ain) The process is repeated unti" there is "itt"e or no trace

o$ penetrant on the c"oth) C"eanin& shou"d !e done quic%"#( usin& a minimum

o$ c"eaner) I$ the operation is pro"on&ed or i$ e+cessie amount o$ the c"eaner

is used( some penetrant ma# !e remoed $rom discontinuities) The sur$ace is

then ie'ed under suita!"e "i&ht to ensure that the e+cess penetrant is

remoed) <or app"ication o$ dee"oper( the sur$ace is dried !# eaporation or

'ipin&)


34




CONSULTANTS

Non $"amma!"e( o"ati"e so"ents can !e used in the apor phase in

automatic processin& stations - "i%e apor de&reasin& 2) The so"ent shou"d !e

redisti""ed $requent"# to aoid hea# contamination 'ith penetrant( since the

penetrant 'i"" start to co3disti" 'ith the so"ent and cause hea# !ac%&round)

Note 8 The o"ati"e or&anic so"ents used $or penetrant remoa" are the

most a&&ressie and &reat care must !e ta%en in their use to preent oer3

remoa") <or manua" processin&( the so"ent remoer must !e used !# 'ipin&

'ith a c"oth) Use o$ a so"ent remoer !# spra#in& or $"oodin& 'i"" resu"ts in

oer 'ash or di"ution o$ the penetrant and the indications 'i"" !ecome di$$used

and 'ea%) The optimum sensitiit# is achieed 'hen the !ri&htest indications

appear a&ainst a thin dee"oper contrastin& !ac%&round)

Fhen norma" c"eanin& cannot su$$icient"# remoe penetrant $rom as3

'e"ded sur$aces( machined parts 'ith sharp inside corners( or parts 'ith

depressions or pits( such areas can !e $urther c"eaned 'ith a commercia""#

aai"a!"e cotton s'a! or 'ith a cotton s'a! on a toothpic% 'etted 'ith the

so"ent)


3/




CONSULTANTS

some hints

.) Due to sur$ace rou&hness o$ un$"ushed 'e"ds( it is !etter to use( 'ater

'asha!"e and so"ent remoa!"e methods to aoid undesira!"e !ac%&round)

1) In the case o$ So"ent remoa!"e pentrants( usua" precaution o$ 'ipin& 'ith

so"ent moistened "int $ree c"oth ma# not #ie"d the desired resu"ts !ecause o$

e+cessie !ac%&round) Sometimes( the so"ent is direct"# app"ied to the 'e"d

to oercome this di$$icu"t#) O$ course $ine crac%s ma# !e missed

) In the case o$ TIG and 7IG 'here !etter sur$ace is o!tained( it is !etter to &o

so"ent 'ipin& method

) Inspection 'ith mu"tip"e pass 'e"ds 'ith penetrants requires that each 'e"d

!ead is inspected prior to the ne+t pass to proide the ne+t the !est re"ia!i"it#)

C"eanin& a$ter each testin&

0) 0)Fater 'asha!"e $"uorescent penetrants can !e used on "ar&e pressureesse"s or other "ar&e structures !# 'ashin& 'ith a hose and air dr#in&)

Dee"opent 'ith so"ent suspended dee"oper can proide &ood sensitiit#

Fater 'asha!"e penetrants can !e 'ashed more readi"# $rom most 'e"d

) ) It is important to remoe a"" the o$ the s"a& $rom 'e"ds !e$ore penetrant

testin&) Grindin& o$$ the ripp"es on rou&h 'e"ds is desira!"e) Grindin&

shou"d not smear the meta"

) ) Kra*ed ,oints can discontinuities simi"ar to 'e"d !eads that can !e detected

!# PT) A !ra*e that does not 'et the sur$ace is indication o$ a poor ,oint)

Dee"opers 8

Norma""# a dee"oper is used to comp"ete the penetrant process)

Dee"opers are $ine 'hite po'ders app"ied as dr# or 'ith a "iquid carrier to


30




CONSULTANTS

$orm a thin uni$orm coatin& on the test sur$ace) Dee"oper acts "i%e a spon&e

'ith er# $ine random capi""ar# paths) Fhen the penetrant contacts the

dee"oper( it spreads throu&h these paths !# capi""ar# action - %no'n as !"ottin&

or reerse capi""ar# action 2) The penetrant &radua""# di$$uses into the dee"oper

and indications !ecome "ar&er than the discontinuit# openin&) The 'hite co"or

o$ the dee"oper proides contrast 'ith co"or contrast penetrants and a"so

proides a dar%er !ac%&round $or $"uorescent indications)

It shou"d !e noted that the dee"oper itse"$ does not produce indications

!ut simp"# a!sor!s the penetrant a"read# present !e"o' it and ma%es it more

isi!"e) Dee"oper shou"d !e app"ied as soon as possi!"e or 'ithin / minutes

a$ter the remoa" o$ the e+cess penetrant)

Dr# dee"opers - <orm A 2 8 - !"ends o$ chemica""# inert 'hite po'ders 2

Dr# dee"opers are a non to+ic $"u$$# a!sor!ent 'hite po'der that is used

most"# 'ith $"orescent penetrant process) These dr# po'ders do not norma""#

proide su$$icient 'hite !ac%&round $or contrast 'ith co"or contrast penetrants)

This ma# !e achieed !# use o$ e"ectrostatic spra# app"ication !ut is not

a"'a#s contro""ed easi"#) Dr# po'ders must !e used on dr# sur$ace on"#) Dr#

dee"opers are the "east sensitie)

The dr# po'ders shou"d !e used in a c"osed container or( i$ spra#ed(

inside a !ooth 'ith &ood e+traction) Fhere the throu&hput o$ components is

"o'( components can !e p"aced on a &rid in a tan% and po'der app"ied usin&

a scoop or $rom a pear shaped ru!!er pu$$er) E+cess po'der is then remoed

!# &ent"e air !"ast( sha%in& or tappin&) Dr# po'der ma# a"so !e app"ied !#

!rushin& on rou&h test sur$aces)

Dr# po'der is !est app"ied !# p"acin& the component in a dust storm

ca!inet 'hich ma# !e o$ the tunne" t#pe or top "oadin&) The ca!inet is sea"edto !e dust proo$) 7ost ca!inets 'or% on a preset c#c"e so that once started

the ca!inet cannot !e opened unti" the c#c"e is comp"ete) The dr# po'der

dee"oper is then a&itated 'ith dr# and oi" $ree compressed air( 'hich !"o's

the po'der into a c"oud around the component to coat the sur$ace) It is


3




CONSULTANTS

Dee"oper

properties

Good !"ottin& action) 7ust !e easi"# 'etted !# penetrant and dra' the

ma+imum amount o$ penetrant $rom the de$ect)

<ine &rained

Sho' indications $rom sma"" amount o$ penetrant)

7as% out inter$erin& penetrant and part sur$ace !ac%&round)

To $orm a thin and uni$orm coatin&)

Non $"uorescent)

Easi"# c"eaned $rom the sur$ace)

Non $"amma!"e)

Non to+ic and non corrosie)

Dee"oper se"ection 8

Se"ect 'et dee"oper in pre$erence to dr# on er# smooth test sur$aces)

Se"ect dr# dee"oper in pre$erence to 'et on er# rou&h test sur$aces)

C"eanin& and re inspectin& a rou&h sur$ace is di$$icu"t( i$ a 'et dee"oper

'as used $or a prior inspection)

Fet dee"opers can not !e used re"ia!"# 'here part con$i&uration

accumu"ates dee"oper at certain "ocations such as threads) E+cess

dee"oper can mas% out indications) Dr# dee"oper can !e used)

So"ent suspended dee"opers are er# e$$ectie $or $"a's 'ith narro'

openin&( !ut are not satis$actor# $or $indin& 'ide sha""o' de$ects)


3




CONSULTANTS

Aqueous - Fet 2 dee"opers 8

These dee"opers are used in penetrant inspection stations) Aqueous dee"oper

uses 'ater as the carrier o$ the dee"oper partic"es) The dee"oper is used as

a so"ution - <orm K 2 or as suspension - <orm C 2)

Fater !ased dee"oper inc"udes a 'ettin& a&ent( corrosion inhi!ition

s#stem and dispersin& medium) These dee"opers are app"ied direct"# on a

'ater 'ashed sur$ace and a$ter dr#in& a so"ent 'ashed sur$ace) Parts are

dried immediate"# a$ter e+cess dee"oper has drained $rom the component)

These dee"opers are "ess sensitie 'hen compared to non 3 aqueous

dee"opers)

Fater So"u!"e dee"opers - <orm K 2 8 - K"ends o$ 'hite cr#sta""ine po'ders to !e

disso"ed in 'ater 2

Supp"ied as so"u!"e 'hite po'ders to !e disso"ed in 'ater at a

concentration recommended !# the manu$acturer - / 3 / & "it 2 to prepare a

transparent 'or%in& so"ution) The prepared !ath is comp"ete"# so"u!"e and does

not require a&itation) I$ the so"utions are stored in open tan%s( precipitate ma#

$orm due to "oss o$ 'ater !# eaporation) The concentration o$ the so"ution is

monitored !# measurin& the speci$ic &rait# 'ith a h#drometer) Fater so"u!"e

dee"opers are not recommended $or use 'ith 'ater 'asha!"e penetrants

!ecause o$ the potentia" to 'ash the penetrant $rom 'ithin the $"a' un"ess the

dee"oper app"ication is er# care$u""# contro""ed)

Fater so"ution dee"opers can !e app"ied !# immersion $o""o'ed !#

draina&e in a stain"ess stee" tan%) The dee"oper ma# !e app"ied !# $"o'3on(

!rush or a 'et spra#) Fhen spra# app"ication is used( it is important( that the

spra# is 'et and the drop"ets coa"esce to $orm a continuous "a#er on the test

sur$ace) The part sur$ace must !e dried actie"# a$ter the dee"oper app"ication

to $orm an uni$orm "a#er) The dried dee"oper $i"m is 'ater so"u!"e and can !e

remoed a$ter inspection !# simp"e 'ater rinsin&)


4




CONSULTANTS

So"u!"e dee"opers contain inor&anic compounds 'hich ioni*es in the

so"ution)

Dippin& di$$erent meta"s in contact 'ith each other and use o$ uncoated

!as%et produce &a"anic corrosion) The contaminated dee"oper so"ution

!ecomes &ra# to dar% &ra# in co"or)

Fater Suspended dee"opers - <orm C 2 8 - K"ends o$ 'hite inert po'ders and

sur$actants $or suspension in 'ater 2

supp"ied as inso"u!"e 'hite po'ders to !e suspended in 'ater at a

concentration recommended !# the manu$acturer - around / & "it 2 to &ie a

'or%in& preparation) Fater suspension dee"opers ma# !e app"ied !# immersion

in an a&itated !ath or !# spra#in&) The immersion tan% shou"d !e o$ stain"ess

stee" 'ith mechanica" stirrer to preent sett"in&) Air a&itation shou"d !e aoided

since the dee"opers contain 'ettin& a&ents and corrosion inhi!itors 'hich

ma# !ecome de&raded !# chemica" reaction 'ith the o+#&en or car!on

dio+ide in the air) I$ the dee"oper is to !e app"ied !# spra#in&( the desi&n

and operation o$ the spra# apparatus must a""o' continuous a&itation o$ the

reseroir o$ dee"oper and the app"ication must a""o' the suspension to arrie

'et at the test sur$ace) <oamin& must !e aoided !ecause 'hen $oam !u!!"es!rea% the# "eae ho"es in the dee"oper coatin&)

The amount o$ po'der in suspension must !e care$u""# maintained) Too

much or too "itt"e dee"oper on the test sur$ace can serious"# a$$ect sensitiit#)

It is essentia" that the dee"oper !ath is monitored !# chec%in& the speci$ic

&rait# and the 'ettin& characteristics)

Fater suspension dee"oper is app"ied !e$ore dr#in&( the dee"opin& time

decreases !ecause the heat $rom the dr#in& operation he"ps penetrant !ac% to

the sur$ace openin& and the dee"oper $i"m !ein& a"read# in p"ace( the

dee"opin& action !e&ins at once)

Non Aqueous Suspension dee"opers - <orm D 2 8 - Chemica""# inert 'hite

pi&ments suspended in o"ati"e "iquid carriers 2


41




CONSULTANTS

These consist o$ dee"oper partic"es suspended in a o"ati"e or&anic

so"ent) The use o$ a quic% dr#in& so"ent as carrier ma%es non aqueous 'et

dee"oper the most sensitie $or detection o$ minute crac%s) The so"ent

com!ines 'ith the penetrant in the crac%s( and the resu"t is a "ess iscous

"iquid 'hich !"eeds into the dee"oper $air"# quic%"# as the so"ent eaporates)

Non aqueous suspension dee"opers must !e app"ied !# spra#in& on a

dried part sur$ace) Spra#in& ma# !e !# aeroso" can or conentiona" spra# &un)

Since o"ati"e so"ents are used in these dee"opers( e$$icient e+traction $aci"it#

must !e proided in the inspection area)

The suspended partic"es separate on standin& - sett"es to the !ottom o$

the container 2 and so must !e a&itated !e$ore use to an homo&eneous

mi+ture) Fhen aeroso" cans are used( this is done !# sha%in& the can) <or a

spra# &un app"ication( the reseroir must !e equipped 'ith an e$$icient a&itator)

A"ternatie methods o$ app"ication( such as immersion( $"o'3on or !rushin& on

'i"" cause "oss o$ sensitiit#)

A dee"oper coat 'hich is ,ust thic% enou&h to mas% the meta" sur$ace

is a!out ri&ht) I$ the coat is too thic%( the penetrant mi&ht not !"ot throu&h to

the sur$ace) I$ it is too thin( it mi&ht not !"ot 'e"" enou&h)

Spra#in& shou"d !e per$ormed $rom a distance o$ M to ./ inches $rom the

test sur$ace) 4o"din& the can too c"ose to the sur$ace 'i"" resu"t in e+cessie

dee"oper !ein& app"ied eer# time)


42




CONSULTANTS

U6 3 A - // 3 // nm 2 3 Lon& Fae)

U6 3 K - // 3 1M/ nm 2 3 7edium Fae)

U6 3 C - 1M/ 3 .M/ nm 2 3 Short Fae)

U"traio"et A is not considered harm$u" to the human e#e) U"traio"et K can

cause sun!urn as 'e"" as !e harm$u" to the e#es) U"traio"et C is used $or

&ermicida" purposes and is harm$u" to the e#es and the !od#) Da#"i&ht ie'in&

is considered to !e a ran&e o$ 0/ throu&h 0/ nm( 'ith the aera&e !ein& 000

nm)

The $"uorescent materia"s used in NDT $or !oth the ma&netic and

penetrant inspections are se"ected to proide ma+imum $"uorescent properties

'ith U6 3 A e+citation in the 0 nm 'ae"en&th) In $act these materia"snorma""# $"uoresce under e+citation o$ an# 'ae"en&th( $rom 1/ 3 // nm) The

$"uorescence( 'hich is re$"ected !ac% is in the ran&e o$ 0/ 3 1/ nm and is

isi!"e as #e""o'3&reen to the human e#e) An# e+cessie 'hite "i&ht in the

inspection area - especia""# those in the &reen #e""o' 'ae"en&ths 2 'i""

decrease the contrast o$ indication to !ac%&round( $or this reason( speci$ications

"imit the am!ient 'hite "i&ht "ee" to 1/ "u+ ma+imum)

K"ac% "i&ht sources are norma""# hi&h pressure mercur# arc !u"!s and

"o' pressure mercur# apor dischar&e tu!es) Lo' pressure mercur# apor "i&ht

sources hae a deep purp"e coatin& on the inside sur$ace o$ the !u"! to $i"ter

out undesired U6 'ae"en&ths and !"oc%s the isi!"e "i&ht &enerated !# the

!u"!) 7ercur# apor arc - 4ID 2 "amps used $or NDT hae on"# t'o "ines o$ U6 3

A ener&# in si&ni$icant intensities) One o$ these !ands is at 0 3 nanometer

'ae"en&th)

Ne' micro po'er &as dischar&e techno"o&# - 7PWL 2( is reco&ni*ed to

create a much hi&her contrast o$ $"uorescent indication to !ac%&round( thus

improin& the operator;s isua" acuit#) 7PWL spot "amps produce in e+cess o$

H/(/// micro 'atts cm 1 $rom .1 inch distance( and a""o' inspection to !e

per$ormed in areas 'here preious"# it 'ou"d hae !een impossi!"e)


44




CONSULTANTS

U"trasonic C"eanin& 8 is per$ormed on "ar&e num!er o$ sma"" parts !#

immersion or dippin& the part in a u"trasonic c"eanin& tan% 'ith a"most an#

%ind o$ c"eanin& so"ution) So"ents and a"coho" 'or% 'e"" 'ith u"trasonic

a&itation) It is the most e$$ectie method $or openin& up de$ects !# remoin&

contaminants im!edded in the discontinuit# cait#) U"trasonic c"eanin& has !een

$ound to !e e$$ectie in remoin& penetrant entrapped in discontinuities) Ti&ht

$"a's require 1 hours o$ c"eanin&) <or &eometrica""# comp"e+ components( hu&e

!ene$its resu"t $rom com!inin& the chemica" action o$ a so"ent 'ith u"trasonic

a&itation)

U"trasonic c"eanin& is !ased on the princip"e o$ producin& caitations in a

"iquid so"ent in 'hich the component to !e c"eaned is immersed) Lar&e

quantities o$ tin# !u!!"es are created in the so"ent - caitations 2 !# hi&h

intensit# compression 'aes) The co""apsin& pressure o$ the !u!!"es $orces

them into creices 'here the $"uid penetrates !et'een contamination and the

'or% piece sur$ace) This action $orces the contaminant o$$ the 'or% piece

"eain& it tota""# c"ean) The $requenc# o$ u"trasonic i!ration is / to /%4*

a"thou&h hi&her $requencies ma# sometimes !e used) C"eaners are aai"a!"e as

static so"ents or u"trasonic t#pes)

Etchin& 8 This process uses acids or a"%a"ine so"utions to disso"e smeared

meta" $rom the sur$ace) Etchin& is per$ormed a$ter an# operation that cou"d

mechanica""# remoe materia" $rom the sur$ace( such as sand !"astin&(machinin&( &rindin& or po'er !rushin&( to assure that the crac%s are opened to

the sur$ace) These mechanica" operations tend to smear and c"ose the

discontinuit# openin&s)


40




CONSULTANTS

Etchin& on stee" is accomp"ished usin& 0 to 1/5 o$ acid so"utions or 1/5

so"ution o$ ammonium per su"phate) The so"ution is app"ied $or a speci$ic

period o$ time( neutra"i*ed and rinsed) The etchin& time is depends on the

amount o$ materia" that is to !e remoed)

Etchin& usua""# requires a separate certi$ication !ecause o$ the inherent

dan&er to the test operator and the component !ein& used) Acid entrapment

$rom etchin& can hae disastrous e$$ects on the penetrant inspection) Sodium

h#dro+ide caustic o$ten used to etch a"uminum parts does not a$$ect

penetrants !ut can reduce the !ri&htness o$ indications) Care$u" c"eanin& o$

!oth acid and caustic etches !e$ore penetrant inspection is hi&h"#

recommended)

Dr#in& the Parts sur$ace 8 Components that require the use o$ c"eanin& a&ents

$or the pre c"eanin& process must !e dried comp"ete"# !e$ore penetrant

app"ication) Fhen 'ater !ased c"eaners are used durin& pre c"eanin&( the $ina"

step is a 'ash 'ith c"ean 'ater and the parts are thorou&h"# dried) Fater or

c"eanin& "iquid residue 'i"" hinder entrance o$ penetrant into discontinuities)

The norma" 'a# o$ remoin& 'ater $rom c"eaned parts !e$ore penetrant

app"ication is to heat them in a temperature contro""ed re 3 circu"atin& air oen

$or one hour at around .10/ C) An a"ternatie is to immerse the components in

a de'aterin& $"uid 'hich is then itse"$ remoed !# apor de&reasin&)

The Part sur$aces are to !e dried a&ain a$ter remoa" o$ e+cess penetrant

and the sta&e at 'hich sur$aces are dried depends on the t#pe o$ dee"oper

to !e used) Fhen dr# po'ders or non aqueous so"ent suspension dee"oper

is used( the sur$aces must !e comp"ete"# dr# !e$ore app"ication) Fhen 'ater

so"u!"e or 'ater suspended dee"oper is used( the parts are dried a$ter the

app"ication o$ the dee"oper) Dr#in& temperatures o$ / 3 M/XC - ./ 3 .X< 2 is norma" $or oen dr#in&)

Oens shou"d !e thermostatica""# contro""ed 'ith supp"# o$ c"ean dr# re 3

circu"atin& air and shou"d !e capa!"e o$ dr#in& the parts in ./ minutes) Care

shou"d !e ta%en so as not to raise the sur$ace temperature o$ the part a!oe


4




CONSULTANTS

// C) In an oen( dr#in& o$ sma"" and "ar&e parts to&ether is not recommended

!ecause o$ dissimi"ar dr#in& time) E+cessie dr#in& can dama&e the part as

'e"" as eaporation o$ the penetrant( 'hich can impair the sensitiit# o$ the

inspection)

Dr#in& components !e$ore penetrant app"ication ma# require heatin& them

to .1// C $or at "east . hour in an oen operatin& at am!ient pressure) The

component must coo" do'n to // C !e$ore the app"ication o$ the penetrant) A

acuum dr#in& oen can dr# the component 'ithin ./ minutes)

6acuum dr#in& oens can maintain a 'or%in& pressure as "o' as ./ mi""i

!ars a!so"ute and this can !e achieed 'ithin 1 minutes) At this pressure(

'ater !oi"s at a temperature !e"o'

0/ C) 4o'eer( atmospheric 'ater apor 'i"" condense on 'or% pieces

remoed $rom a dr#in& oen operatin& at this temperature) 6acuum dr#in&

oens equipped 'ith e+terna" heatin& e"ements in their !ase and 'a"" to

maintain a 'or%in& temperature at nomina"

// C can reduce dr#in& times to "ess than ./ minutes) The residua"

temperature o$ appro+imate"# // C is achieed a$ter dr#in&( 'hich is idea" $or

penetrant app"ication) The oens are sma""er in si*e and can accommodate a

sin&"e( re"atie"# "ar&e 'or% piece( or man# sma""er components)

Fith recommended care( the oen proides a "on& and e$$icient serice

enhancin& the dr#in& process a$ter prec"eanin&)

Standard Test samp"es 8

Quench crac%ed a"uminium !"oc% 8 These !"oc%s are made o$ AST7 K

1/H( SK 1.. or 1/1 3 T a"uminum appro+imate"# 1> 'ide W > "on& W M

thic% pieces) The !"oc%s are heated and quenched to produce an oera""

circu"ar crac% pattern) A &rooe is machined in the midd"e o$ the !"oc% to

separate the crac%s into t'o *ones) Since the crac%s are uncontro""ed( the

!"oc%s are used $or comparin& the per$ormance o$ penetrants on"# and not $or

a!so"ute ea"uations)


4




CONSULTANTS

At the center o$ the $ace( an area appro+imate"# . inch in diameter sha""

!e mar%ed 'ith H0/ / < temperature indicatin& cra#on or paint) The mar%ed area

sha"" !e heated 'ith a !"o' torch to a temperature !et'een H0/ / and H0 / <)

The area shou"d !e heated 'ithin minutes to produce a temperature

di$$erence 'ithin the !"oc%) The !"oc% is then immediate"# quenched in co"d

'ater 'hich produces a net'or% o$ re"atie"# ti&ht and uni$orm crac% pattern

on the $ace) The !"oc% sha"" then !e dried !# heatin& to appro+imate"# // / <)

It is !ecause o$ ti&ht crac% pattern( that co"or contrast penetrants are not

norma""# chec%ed 'ith this !"oc%) These penetrants are not as sensitie as

$"uorescent penetrants) The crac%in& 'i"" !e s#mmetrica" on either side o$ the

separation &rooe !ut the depth and the 'idth o$ the crac%s produced is

uncontro""ed and un%no'n)

<or the co"or contrast penetrants comparison on"#( the

H0/ / < crac%ed !"oc% is heated a second time to M// / < and quenched

a&ain to open the crac%s 'ider) Ne' and used penetrants or di$$erent !rands

o$ penetrants can !e processed and then compared side !# side)

A penetrant in use can !e chec%ed $or its crac% detection a!i"it# and

indicatin& !ri&htness a&ainst $resh penetrant samp"es) One ha"$ o$ the !"oc% is

processed 'ith the used penetrant and the other ha"$ 'ith the $resh penetrant)

The 'ho"e p"ate is then processed to comp"etion in the re"eant 'a#) The

indications $rom each ha"$ can !e tested under identica" i""umination on the

same a""o# 'ith the same sur$ace condition( resu"tin& in a true comparison o$

re"atie sensitiit#) The s"i&ht potentia" $or error 'ith this deice arises 'ith the

requirement that the discontinuities in !oth ha"es !e as identica" as possi!"e)

I$ crac%s detected on the used penetrant side is not as comp"ete as the $resh

penetrant side( the used penetrant is considered contaminated and shou"d !ediscarded) I$ the !ri&htness o$ the used penetrant indications appear to !e

!e"o' H/ 5 o$ the !ri&htness o$ the $resh penetrant indications( the used

penetrant is discarded)


4




CONSULTANTS

Use o$ penetrant outside their norma" operatin& temperature ran&e - . / to

01 / C 2 can !e qua"i$ied usin& these !"oc%s) T'o separate !"oc%s are

processed) One !"oc% is heated or coo"ed to the proposed e+amination

temperature and maintained at that temperature throu&hout the processin&

c#c"e) The other !"oc% is processed 'ithin the norma" operationa" temperature

o$ the penetrant) I$ the indications o!tained under the proposed conditions are

essentia""# the same as o!tained 'ith the norma" conditions( the proposed

technique sha"" !e considered to !e qua"i$ied $or use) These !"oc%s can !e

reused !# care$u" c"eanin&) A / minutes soa% in isoprop#" a"coho" c"ears the

induced crac%s o$ residua" penetrant)

S#stem per$ormance chec% YDS Pane"s 8

The t'o outer ed&es hae 10 mm 'ide strips o$ !ritt"e chrome p"atin& o$

/). mm thic%ness) <ie contro""ed induced crac%s o$ ar#in& dimensions are

produced in pairs) The sheet is sheared into t'o equa" sections and the# are

irtua" t'ins) Koth the sections are processed $or side !# side comparison)

S#stem per$ormance chec%s ino"e processin& a test specimen 'ith

%no'n de$ects to determine i$ the process 'i"" reea" discontinuities o$ the si*e

required) The purpose o$ the %no'n de$ect Standard is not to eri$# the

sensitiit# "ee" o$ the penterant( !ut to monitor the per$ormance o$ the entire

penetrant e+amination s#stem)

<urther( The specimen must !e processed $o""o'in& the same procedure

used to process production parts) A s#stem per$ormance chec% is t#pica""#

required dai"#( at the reactiation o$ a s#stem a$ter maintenance or repairs( or

an# time the s#stem is suspected o$ !ein& out o$ contro") As 'ith penetrant

inspection( resu"ts are direct"# dependent on the s%i"" o$ the operator( there$ore

each operator shou"d process a pane") Yno'n Discontinuit# Standards - YDS pane"s 2 8 The pane"s come in pairs

hain& %no'n discontinuities in %no'n "ocations) T'o YDS pane"s are produced

simu"taneous"# $rom a sin&"e sheet o$ stain"ess stee"( so the# are precise"#

matched as to p"atin& thic%ness( crac% si*e( and sur$ace rou&hness) The center


/




CONSULTANTS

section is &rit !"asted to speci$ication rou&hness) This rou&h section is used to

compare 'asha!i"it# o$ di$$erent t#pes o$ penetrant)

Standard Test samp"es 18

YDS pane"s permit the monitorin& o$ in use penetrants as 'e"" as side

!# side comparison to ne'( unused penetrant) The# are ru&&ed and can

'ithstand dai"# s#stem processin&) A simp"e / min soa% in isoprop#" a"coho"

c"ears the induced crac%s o$ residua" penetrant)

Crac%ed nic%e" chromium p"ated pane"s 8 The nic%e" chromium test pane"s

are idea" penetrant sensitiit# comparators) The pane"s are aai"a!"e 'ith crac%

o$ ./( 1/( /( 0/ microns and come in matched pairs) The si*e re$ers to the

depth o$ the nic%e" p"atin&) 7atched pairs ena!"es studies o$ the e$$ects o$


/1




CONSULTANTS

process chan&es as compared to a standard process or comparin& used

materia" s $resh materia")

A thic% !rass pane" measurin& .3.1> + >( p"ated 'ith !ritt"e nic%e"( on

one side) The nic%e" p"atin& is then p"ated 'ith a er# thin "a#er o$ chromium

$or protection) The pane" is stress "oaded on one side( 'hich produces $ine

"atera" crac%s throu&h the p"atin&) These crac%s are then used $or the penetrant

s#stem per$ormance chec%) T'o pane"s containin& identica" or near"# identica"

crac% patterns are used to per$orm the chec%s) The depth o$ the p"atin& can !e

contro""ed( and pane"s are aai"a!"e 'ith p"atin& thic%ness o$ ./=m - /)///> 2)

Nic%e" chromium pane"s hae !een sectioned and micro3photo&raphed) The

photo&raphs reea" crac% 'idth to !e .1/th o$ the depth) So( the 'idth o$ the

crac%s in the ./=m p"ated pane" 'ou"d !e /)0=m - /)////1> 2) Under "a!orator#

conditions( hi&h sensitiit# penetrants !oth 'ater 'asha!"e and non 'ater3

'asha!"e $ind the $"a' "ines in these ./=m pane"s) So( theoretica""#( the penetrant

that can sho' crac%s in a ./=m nic%e" chromium sensitiit# pane"( is e+pected

to $ind a $"a' measurin& /)0=m + /)0=m + ./=m)

Apart $rom "en&th( another measure o$ concern shou"d !e $"a' 'idth( since a

penetrant;s a!i"it# to enter a crac% depends more on a crac%s 'idth than its

"en&th) <or e+amp"e( crac%s in $or&in&s are inherent"# ti&hter and more di$$icu"t

to reea" than crac%s o$ equa" "en&th in castin&s or e+trusions) Crac%s under

compression( squee*ed ti&ht and hain& irtua""# no 'idth( are o$ten impossi!"e

to sho' 'ith penetrant inspection)

Limitations 8 A pro!"em 'ith test pieces is that once a penetrant process

has sho'n a"" the discontinuities in a test piece no other process can appear

more sensitie) Simi"ar"# i$ the discontinuities are di$$icu"t to sho' and can !e

$ound on"# !# use o$ the most sensitie process a"" other processes appearequa""# ine$$ectie) The si*e o$ the re$erence discontinuities itse"$ increase 'ith

use) The si*e o$ the indications must !e recorded - photo&raph trans$er

"acquer rep"ica 2 'hen the !"oc% is $irst used and compared 'ith the

indications o!tained 'ith su!sequent uses)


/2




CONSULTANTS

Important 8 Seera" precautions are necessar# 'hen usin& the penetrant

test pane"s) The pane"s must !e thorou&h"# c"eaned as quic%"# as possi!"e

a$ter each use) Penetrant residues 'hen "e$t in discontinuities !ecome er#

iscous and e+treme"# di$$icu"t to remoe) In cases o$ seere contamination !#

preious residues( the PS70 and NiCr test pane"s can !e !oi"ed in 0 to 1/5

deter&ent so"ution $or / minutes) This is $o""o'ed( a$ter coo"in&( !# a 'ater

rinse then a rinse 'ith acetone) In !et'een uses the# shou"d !e %ept in dr#

acetone - $"amma!"e 2 or .(.(.( trich"oroethane) I$ 'ater is a""o'ed to contaminate

either o$ the so"ents( the discontinuities can !ecome corroded) So"ents are

!est %ept dr# !# use o$ mo"ecu"ar siees or si"ica &e") Some speci$ications

"imit the num!er o$ times that a test pane" can !e reused)

The "e$t picture sho's crac% comparisions on Ni3Cr → pane"s and the

ri&ht sho's 'asha!i"it# test $or t'o di$$erent penetrants

Ea"uation is the process o$ decidin& the seerit# o$ the condition a$ter

the discontinuit# indications hae !een interpreted) Ea"uation "eads to the

decision as to 'hether the part must !e re,ected( to !e repaired or direct"#

accepted $or use)

In "iquid penetrant testin&( discontinuities are ,ud&ed on the si*e o$ the

indication and not on the actua" si*e o$ the discontinuit# openin& isi!"e at the

sur$ace) The indication en"ar&es 'ith time and it is !etter to ea"uate the

indications at the minimum dee"opment time a""o'ed !# the procedure)

Recommended dee"opment time as per AS7E Sec 6 is minimum to

ma+imum / minutes) Ea"uation shou"d !e&in 'ith an oer a"" e+amination o$

the test sur$ace to determine that the 'or% piece has !een proper"# processed

and is in satis$actor# condition $or inspection)

Usua""#( the indications are c"assi$ied as "inear or rounded)

Linear t#pe is an indication 'ith a "en&th &reater than three times the 'idth) It

'i"" appear as a continuous( strai&ht or ,a&&ed "ine) These indications

represents more harm$u" discontinuities) Crac%s( seams( deep scratch( undercut(


/3




CONSULTANTS

"ac% o$ $usion at sur$ace( ro""in& and $or&in& "aps( co"d shut etc produce "inear

indications) The same $"a's ma# sho' up as an intermittent "ine indicatin& that

the $"a' ma# !e partia""# c"osed at the sur$ace)

A rounded indication is de$ined as a circu"ar or e""iptica" and 'ith a "en&th o$

three times or "ess than its 'idth) Porosit# or a cait# at sur$ace produces

such indications)

Co"or contrast penetrant indications 8 Indications 'i"" appear in red a&ainst 'hite !ac%&round at the "ocations

o$ the discontinuities) Depth or si*e o$ the interna" cait# ma# !e co3re"ated

'ith the !ri&htness o$ co"or( speed o$ !"eedin& and d#e spread)

Usua""#( a crac%( deep scratch or simi"ar openin& 'i"" sho' up as a so"id

"ine) Ti&ht crac% or a "ap sho' as a !ro%en "ine) Gross porosit# 'i"" produce

"ar&e rounded indications) <ine porosit# is indicated !# red dots) Porous

materia" 'i"" produce random"# distri!uted tin# red dots) Crater crac% ma#

produce round indication !ecause the# tend to trap "ar&e amount o$ penetrant)

Indications 'ith a "i&ht pin% co"or ma# indicate e+cessie c"eanin&)

Di$$used or 'ea% indications are di$$icu"t to interpret and the part shou"d !e


/4




CONSULTANTS

reprocessed) In man# cases the# turn out to !e $a"se indications caused !#

improper processin&)

<"uorescent indications 8

These indications are ie'ed under u"traio"et "i&ht in a dar%ened area)

The indication &"o's !ri""iant #e""o' &reen or oran&e red a&ainst io"et

!ac%&round o$ the dee"oper)

Porosit# 'i"" sho' as &"o'in& spots) Crac%s 'i"" sho' as $"uorescent

"ines) Fhere a "ar&e discontinuit# has trapped a quantit# o$ penetrant( the

indication 'i"" spread 'ide on the sur$ace) E+perience in the use o$ this

method a""o's conc"usion to !e dra'n $rom the e+tent o$ this spread 'ith

respect to the re"atie si*e o$ the discontinuities) Poor"# processed part 'i""

hae !road $"uorescent patches)

Acceptance standard $or 'e"ds 8 AS7E Sec 6III Appendi+

a) re"eant indications 8 indications 'ith ma,or dimensions &reater than

. . in) - .) mm 2)

!) "inear indications 8 an indication hain& a "en&th &reater than three

times the 'idth)

c) rounded indications 8 an indication o$ circu"ar or e""iptica" shape 'ith

the "en&th equa" to or "ess than three times the 'idth)

An indication in e+cess o$ the "imits speci$ied !e"o' is not accepta!"e 8

a) Re"eant "inear indicationsJ

!) Re"eant rounded indications &reater than . in) - )M mm 2

c) <our or more re"eant rounded indications in a "ine separated !#

. . in) @.) mm or "ess - ed&e : to : ed&e 2


//




CONSULTANTS

Inspection 8

Dee"opment time 8

A$ter app"ication o$ the dee"oper( it must !e a""o'ed to 'or%) I$ the si*e

o$ the discontinuit# openin& is sma""( the penetrant !"eeds out s"o'"# into the

dee"oper)

Dr# po'der dee"oper re"# upon capi""ar# action( 'hich is s"o'er) Thedee"oper shou"d !e "e$t on the sur$ace $or a minimum o$ ten minutes

!e$ore inspection o$ indications)


/0




CONSULTANTS

A 'ater !ase - aqueous 2 dee"oper is to !e dried !# circu"atin& hot air or

heatin& in a temperature contro""ed oen) The minimum dee"opment time

is 0 minutes( a$ter the dee"oper "a#er !ecomes dr#)

A minimum o$ 0 minutes dee"opin& is a"so needed $or non aqueous

dee"oper) This time is ta%en $rom the point 'hen the dee"oper "a#er

appears to !e dr#)

Fatchin& the indication $orm immediate"# a$ter dee"oper app"ication and

a'areness o$ the t#pe o$ de$ects that ma# !e encountered !e$orehand is

e+treme"# he"p$u") The indication is not the same si*e as the discontinuit#

openin&( the dee"oper 'i"" ma&ni$# the discontinuit# si*e to ma%e it more

isi!"e to the e#e $or easier detection) Penetrants continue to !"eed out intothe dee"oper and indications !ecome "ar&er oer a period o$ time) Fise usa&e

o$ minimum and ma+imum dee"opment time is there$ore hi&h"# recommended)

Gross and "ar&e discontinuities 'i"" !e&in to $orm indication immediate"#) Ti&ht

and e+treme"# sma"" discontinuities 'i"" ta%e "on& time to $orm)

<or ea"uation o$ indications $or accept re,ect condition( a dee"opment

time o$ to / minutes is &enera""# used a$ter the dee"oper "a#er !ecomes

dr#)

Li&htin& 8 A"" penetrant e+aminations must !e per$ormed under

recommended "i&ht "ee"s( as 'ritten in the test procedure)

To see $aint indications 'ith co"or contrast penetrants( adequate 'hite

"i&ht is required) Inspection shou"d !e carried out in &ood 'hite "i&ht o$ at

"east 0// "u+ at the e+amination sur$ace) Inspection o$ $ine detai" ma# require

up to 1/// "u+) In natura" da#"i&ht( penetrant indications appear deep red a&ainst

the 'hite dee"oper !ac%&round) Under strip "i&ht - tu!e "amps 2( indications

appear some'hat dar%er than in the natura" da#"i&ht)

<or $"uorescent penetrant inspection the test sur$ace must !e e+amined

under u"traio"et - !"ac% "i&ht 2 o$ pea% 'ae"en&th around 0 nm and intensit#

o$ at "east ./// micro 'atts cm1 at the e+amination sur$ace 'ith a minimum

o$ inches distance !et'een the test sur$ace and the "i&ht source) Inspection


/




CONSULTANTS

must !e carried out in a dar%ened area 'here the am!ient 'hite "i&ht "ee"

shou"d not e+ceed 1/ "u+) The interior o$ the inspection !ooths shou"d !e

painted mat !"ac% to aoid distractin& re$"ections) Kri&htness o$ indication

depends on the intensit# o$ incident u"traio"et "i&ht and the dar%ness o$ the

surroundin&) I$ $"uorescent inspection is to !e per$ormed under norma" "i&htin&

condition( then the minimum intensit# shou"d !e /// micro 'atts cm 1 at the

e+amination sur$ace)

The output o$ U6 "amp $a""s 'ith time( the e$$ectie output a"so $a""s as

!u"!s( re$"ectors( or $i"ters !ecome dirt#) Once a 'ee% the optica" parts o$ the

"amp shou"d !e c"eaned 'ith a dr# c"oth 'hen the "amp is co"d) The U6 "i&ht

must !e chec%ed $or presence o$ crac%s in the $i"ter) A "amp 'ith crac%ed

$i"ter must not !e used) U6 "i&ht intensit# is to !e chec%ed 'hen $irst used

each da# $or required intensit# 'ith a ca"i!rated U6 "i&ht meter( in the

dar%ened room condition and a$ter a""o'in& a 0 minutes 'arm up period)

<"uorescent indications appear !ri""iant #e""o'3&reen or oran&e3red

dependin& on the t#pe o$ the d#e in the penetrant) The dar%er the area o$

inspection( the more !ri""iant"# the indications 'i"" &"o')

Dar% adaptation $or $"uorescent inspection 8

Fhen ea"uatin& $"uorescent indications( the e+aminers must a""o' their

e#es to ad,ust 'hen $irst enterin& the dar%ened inspection area) Norma""#( 0

minutes are enou&h time $or the e#es to adapt to the dar%ened condition)

Inspection shou"d not start unti" the e+aminer;s e#es hae adapted to the

dar%ened conditions) Dar% adaptation time can !e shortened !# 'earin&

suita!"e red e#e &"asses in 'hite "i&ht areas)

Note 8 Photosensitie e#e&"asses shou"d not !e used durin& inspection

!ecause these &"asses dar%en in the presence o$ U6 radiation) E+aminers

per$ormin& inspection under u"traio"et "i&ht shou"d consider 'earin& #e""o'ish

or specia" u"traio"et $i"ter &o&&"es to reduce e#estrain)

Ea"uation o$ indications 8


/




CONSULTANTS

o$ an indication can a"so &reat"# assist the interpretation process) An

acceptance or re,ection decision shou"d !e made !e$ore this test) The a!i"it#

o$ an indication to re3appear is ca""ed persistence) This 'i"" a"ert the inspector

to the $act that the discontinuit# has depth or o"ume) S'a!!in& an indication

is an use$u" technique to eri$# $a"se or retest a non re"eant indication)

4o'eer( s'a!!in& shou"d not !e done unti" the indication has !een ea"uated

$or si*e)

I$ a""o'ed !# the speci$ic procedure( indications ma# !e ea"uated !#

'ipin& the indication 'ith a $ast dr#in& so"ent3dampened s'a!( a""o'in& the

area to dr#( and redee"opin&) Redee"opment time sha"" !e as "on& as the

ori&ina" dee"opment time( e+cept non aqueous redee"opment time sha"" !e min minimum) I$ no indication reappears( the ori&ina" indication is considered

$a"se) This procedure ma# !e per$ormed t'ice $or an# &ien ori&ina" indication)

Spra#in& non aqueous dee"oper onto a cotton s'a! and 'ipin&( remoes

the indication( c"eans the sur$ace and reapp"ies dee"oper in one step)

Fhether or not the $"a' indication re appears a$ter the so"ent 'ipe

depends on J

.) ho' o"ati"e the so"ent is(

1) ho' much so"ent is app"ied(

) 'hich app"icator is used(

) $in&er pressure e+erted(

0) dee"oper used ZZ po'der or non aqueous(

) dee"opin& time !e$ore eri$ication(

) dee"opin& time a$ter eri$ication(

M) num!er o$ 'ipes)


0




CONSULTANTS

de$ect 'hich is open to the sur$ace) I$ there is dirt in the crac%( there is no

room $or the penetrant to enter it( and the process 'i"" not 'or%) Sur$aces to

!e e+amined are c"eaned so that the# are $ree $rom dirt( sca"es( oi"( &rease(

paint( rust and corrosion and discontinuities are $ree inside o$ 'ater( oi" or

other contaminants) This is %no'n as pre c"eanin&) <o""o'in& c"eanin&( the parts

sha"" !e thorou&h"# dried)

Penetrant app"ication 8 A$ter dr#in&( the entire sur$ace to !e tested must !e

'etted 'ith a "a#er o$ the penetrant and %ept 'et durin& the entire d'e"" time)

This can !e achieed !# immersion( $"o' 3 on( spra#in& or !rushin& the "iquid)

The temperature o$ the test sur$ace shou"d !e !et'een ./X C and 01X C)

Ru!!in& the sur$ace 'ith a penetrant soa%ed c"oth is not permitted)

Penetrant D'e"" 8 The penetrant is "e$t on the test sur$ace $or su$$icient

time to a""o' penetration into the discontinuit# openin&s) The time ino"ed

depends on the iscosit# o$ the penetrant( temperature o$ the part sur$ace and

the ti&htness o$ the discontinuit# openin&) Penetration time used is &enera""#

!et'een ./ and / minutes) At "o' temperatures( "on&er penetration time sha""

!e used !ecause the iscosit# o$ penetrant increases) This time is %no'n as

d'e"" time)

Emu"si$ication 8 <or post emu"si$ication t#pe penetrant( the emu"si$ier is

app"ied a$ter the comp"etion o$ the d'e"" time) Emu"si$ication ma%es the

penetrant 'ater 'asha!"e) Emu"si$ication time aries !et'een . to minutes(

dependin& on the t#pe o$ emu"si$ier( the penetrant ( the sur$ace condition and

actua" time sha"" !e determined !# practica" tests)

Remoa" o$ e+cess penetrant 8 The purpose o$ remoin& e+cess penetrant

is to $ree the sur$ace o$ penetrant so that the penetrant( 'hich has entered a

discontinuit#( 'i"" !e readi"# isi!"e 'hen it re3emer&es onto the sur$ace) A$ter the d'e"" time( e+cess sur$ace penetrant is to !e remoed 'ith a

so"ent 'ipe( 'ater spra# rinse( or the penetrant has to !e emu"si$ied so that it

can !e 'ashed3o$$ 'ith 'ater rinse) E+cess penetrant remoa" depends on the

remoa" characteristic o$ the penetrant !ein& used) The remoa" o$ e+cess


02




CONSULTANTS

Post C"eanin& 8 A$ter the comp"etion o$ e+amination( the test sur$ace is

c"eaned to remoe dee"oper and penetrant) In some industries( such as

nuc"ear( the $ai"ure to post c"ean a part can hae er# detrimenta" resu"ts) <or

parts that 'i"" !e in contact 'ith "iquid o+#&en s#stems( the $ai"ure to post

c"ean a part cou"d resu"t in a $ire and possi!"e serious in,ur#)

I$ penetrants and dee"opers that contain ha"o&en and su"phur products

are used( can hae detrimenta" e$$ects on some meta"s and must !e c"eaned

accordin& to approed technica" data) Penetrant and dee"oper residue tend to

a!sor! moisture and cause corrosion) The remoa" o$ dr# dee"oper and non

aqueous dee"oper is eas#) Fet aqueous dee"oper are di$$icu"t to remoe

!ecause the# are !a%ed onto the part durin& the dr#in& process) So"u!"e

dee"opers can !e remoed !# 'ater rinse) The "on&er the dee"oper remains

on a part the harder it is to remoe) The use o$ steam 'ith deter&ents is

pro!a!"# the most e$$ectie o$ a"" methods) Some parts( such as those used


04




CONSULTANTS

in "iquid o+#&en s#stems( require tota" penetrant remoa" a$ter the inspection)

Entraped penetrant in discontinuities can !e remoed most e$$ectie"# !# hot

tan% so"ent c"eanin& or u"trasonic c"eanin&)

Penetrant inspection norma""# "eaes the parts sur$ace c"ean and e+posed

and thus ma%in& it suscepti!"e to corrosion) A"" e$$orts shou"d !e made to

protect the parts sur$aces $rom corrosion e$$ectie"# a$ter the penetrant

inspection)

Penetrant Testin& usin& $"uorescent and isi!"e d#es

G"ossar# o$ Terms o$ Liquid Penetrant Inspection

Kac%&round8 @$"uorescent or co"our contrast residue o$ penetrant oer &enera"sur$ace o$ part durin& inspection)

Kac%&round Co"ouration8 co"ouration remainin& a$ter incomp"ete remoa" o$ d#epenetrant $rom the test sur$ace)

Kac%&round <"uorescence8 $"uorescence remainin& a$ter incomp"ete remoa" o$ d#e


0/




CONSULTANTS

penetrant $rom the test sur$ace)

Kath8 re$ers to penetrant materia"s into 'hich parts are dipped or tota""# immersed)

K"ac% Li&ht8 "i&ht radiatin& 'ith a 'ae"en&th ran&in& !et'een / to // nm) i)e) ,ust!e"o' isi!"e "i&ht and used to e+cite $"uorescence)

K"ac% Li&ht <i"ter8 a $i"ter passin& !"ac% "i&ht !ut opaque to isi!"e and $ar u"traio"et'ae"en&ths)

K"eedout8 the action o$ penetrant e+udin& $rom discontinuities on to the sur$ace o$ apart)

K"ottin&8 the soa%in& action dee"oper has on penetrant as it !"eeds $rom a

discontinuit#( increasin& sensitiit# and contrast)

Capi""ar# Action8 the action !# 'hich the "ee" o$ a "iquid in contact 'ith a so"idsur$ace is e"eated or depressed to a "ee" di$$erent $rom the "iquid not in contact 'iththe so"id;s sur$ace)

C"ean8$ree o$ so"id or "iquid contaminants)

Co"our Contrast D#e8 d#e used in penetrant to &ie su$$icient co"our intensit# to a""o'&ood contrast to the !ac%&round !ein& ie'ed under 'hite "i&ht)

Co"our Contrast Penetrant8 a penetrant uti"i*in& co"our contrast d#e)

Dar% Adaptation8 ad,ustment o$ the e#es 'hen one &oes $rom a !ri&ht area to adar%ened area a""o'in& !etter isi!i"it# in dim "i&ht)

De&reasin& <"uid8 a&ents used to c"ean oi" and &rease $rom a part prior to app"#in&penetrant)

Dee"oper8 a 'hite po'der app"ied to a part to dra' e+cess penetrant $romdiscontinuities a$ter initia" remoa" o$ penetrant $rom part) A"so( proides a contrastin&!ac%&round to ie' a&ainst)

Dee"oper( Dr#8 "i&ht( $"u$$#( dr# a!sor!ent po'der)

Dee"oper( Nonaqueous8 a!sor!ent po'dered materia"s suspended in a nonaqueous"iquid)


00




CONSULTANTS

4#drophi"ic8 re$ers to t#pe o$ emu"si$ier that is 'ater !ased)

Indication8mar%s a discontinuit#) In LPI it is the presence o$ !"eed out)

Interpretation8same as ea"uation)

Irre"eant Indication8 indication resu"tin& $rom poor technique and not associated 'itha materia" discontinuit#)

Lea% Testin&8 LPI technique 'here penetrant is app"ied to one side o$ a part ando!serations are made $rom the other side to "ocate an# throu&h3'a"" discontinuities)

Lipophi"ic8 re$ers to t#pe o$ emu"si$ier that is oi" !ased)

LOW3Sa$e Penetrant8 penetrant s#stem desi&ned to !e compati!"e or nonreactie inthe presence o$ "iquid o+#&en)

7onochromatic Li&ht8 "i&ht o$ one 'ae"en&th)

Nonre"eant Indications8 LPI indications resu"tin& $rom conditions not associated 'itha materia" discontinuit#)

Penetra!i"it#8 the propert# o$ a penetrant that a""o's it to enter er# $ine openin&s)

Penetrant8 a "iquid possessin& properties ena!"in& it to enter er# $ine openin&s such

as crac%s)

Po"ar Attraction8 e"ectrostatic attraction !et'een positie and ne&atie"# char&ed ions)

Reproduci!i"it#8 the reproducin& o$ one or more LPI indications @primari"# $orstatistica" data)

Re$erence Pieces8 test pieces containin& contro""ed arti$icia" discontinuities or natura"discontinuities( used $or chec%in& the e$$icienc# o$ the penetrant testin& method andmateria"s)

Seea!i"it#8 the a!i"it# o$ an indication to !e seen !# an o!serer under aderseconditions e)&) poor !ac%&round contrast or outside "i&ht @$"uorescent method)

Soa% Time8 same as emu"si$ication time)

So"ent C"eanin&8 process o$ remoin& e+cess penetrant $rom a sur$ace !# 'ipin& or


0




CONSULTANTS

'ashin& 'ith a so"ent)

So"ent Remoa!"e Penetrant8 a penetrant that must !e remoed !# a suita!"e so"ent)

Standard Crac%ed Test Pane"8 an intentiona""# crac%ed test pane" hain& separateareas $or the app"ication o$ di$$erent penetrant materia"s so a direct comparison can !eo!tained)

Fater Fasha!"e Penetrant8 a penetrant 'ith suita!"e emu"si$#in& a&ents incorporatedto render it direct"# 'ater 'asha!"e)

Sur$ace e+amination @such as 'ith "iquid penetrant e+amination 3 PT is not per$ormed$or dama&e mechanisms %no'n to initiate $rom the inside sur$ace as it 'ou"d not !ee$$ectie in these situations) A disadanta&e o$ d#e penetrant testin& is that crac%s not

open to the sur$ace can not !e detected)


0




CONSULTANTS

The ABC's of Nondestructive Weld Examination

Introduction

The phi"osoph# that o$ten &uides the $a!rication o$ 'e"ded assem!"ies and structuresis >to assure 'e"d qua"it#)> 4o'eer( the term >'e"d qua"it#> is re"atie) The

app"ication determines 'hat is &ood or !ad) Genera""#( an# 'e"d is o$ &ood qua"it# i$ it

meets appearance requirements and 'i"" continue inde$inite"# to do the ,o! $or 'hich

it is intended) The $irst step in assurin& 'e"d qua"it# is to determine the de&ree

required !# the app"ication) A standard shou"d !e esta!"ished !ased on the serice

requirements)

>Fhateer the standard o$ qua"it#( a"" 'e"ds shou"d

!e inspected)>

Standards desi&ned to impart 'e"d qua"it# ma# di$$er $rom ,o! to ,o!( !ut the use o$

appropriate e+amination techniques can proide assurance that the app"ica!"e

standards are !ein& met) Fhateer the standard o$ qua"it#( a"" 'e"ds shou"d !e

inspected( een i$ the inspection ino"es nothin& more than the 'e"der "oo%in& oer

his o'n 'or% a$ter each 'e"d pass) A &ood3"oo%in& 'e"d sur$ace appearance is man#

times considered indicatie o$ hi&h 'e"d qua"it#) 4o'eer( sur$ace appearance a"one

does not assure &ood 'or%manship or interna" qua"it#)

Nondestructie e+amination @NDE methods o$ inspection ma%e it possi!"e to eri$#

comp"iance to the standards on an on&oin& !asis !# e+aminin& the sur$ace and

su!sur$ace o$ the 'e"d and surroundin& !ase materia") <ie !asic methods are

common"# used to e+amine $inished 'e"ds8 isua"( "iquid penetrant( ma&netic

partic"e( u"trasonic and radio&raphic @W3ra#) The &ro'in& use o$ computeri*ation 'ith

some methods proides added ima&e enhancement( and a""o's rea"3time or near rea"3

time ie'in&( compar atie inspections and archia" capa!i"ities) A reie' o$ each

method 'i"" he"p in decidin& 'hich process or com!ination o$ processes to use $or a

speci$ic ,o! and in per$ormin& the e+amination most e$$ectie"#)





CONSULTANTS

6isua" Inspection @6T

6isua" inspection is o$ten the most cost3e$$ectie method( !ut it must ta%e p"ace prior

to( durin& and a$ter 'e"din&) 7an# standards require its use !e$ore other methods(

!ecause there is no point in su!mittin& an o!ious"# !ad 'e"d to sophisticated

inspection techniques) The ANSIAFS D.).( Structura" Fe"din& Code3Stee"( states(

>Fe"ds su!,ect to nondestructie e+amination sha"" hae !een $ound accepta!"e !#

isua" inspection)> 6isua" inspection requires "itt"e equipment) Aside $rom &ood

e#esi&ht and su$$icient "i&ht( a"" it ta%es is a poc%et ru"e( a 'e"d si*e &au&e( a

ma&ni$#in& &"ass( and possi!"# a strai&ht ed&e and square $or chec%in& strai&htness(

a"i&nment and perpendicu"arit#)

>6isua" inspection is the !est !u# in NDE( !ut it must

ta%e p"ace prior to( durin& and a$ter 'e"din&)>

Ke$ore the $irst 'e"din& arc is struc%( materia"s shou"d !e e+amined to see i$ the#

meet speci$ications $or qua"it#( t#pe( si*e( c"ean"iness and $reedom $rom de$ects)

Grease( paint( oi"( o+ide $i"m or hea# sca"e shou"d !e remoed) The pieces to !e

,oined shou"d !e chec%ed $or $"atness( strai&htness and dimensiona" accurac#)

Li%e'ise( a"i&nment( $it3up and ,oint preparation shou"d !e e+amined) <ina""#( process

and procedure aria!"es shou"d !e eri$ied( inc"udin& e"ectrode si*e and t#pe(

equipment settin&s and proisions $or preheat or postheat) A"" o$ these precautions

app"# re&ard"ess o$ the inspection method !ein& used)

Durin& $a!rication( isua" e+amination o$ a 'e"d !ead and the end crater ma# reea"

pro!"ems such as crac%s( inadequate penetration( and &as or s"a& inc"usions) Amon&

the 'e"d detects that can !e reco&ni*ed isua""# are crac%in&( sur$ace s"a& in

inc"usions( sur$ace porosit# and undercut)

On simp"e 'e"ds( inspectin& at the !e&innin& o$ each operation and periodica""# as'or% pro&resses ma# !e adequate) Fhere more than one "a#er o$ $i""er meta" is !ein&

deposited( ho'eer( it ma# !e desira!"e to inspect each "a#er !e$ore depositin& the

ne+t) The root pass o$ a mu"tipass 'e"d is the most critica" to 'e"d soundness) It is

especia""# suscepti!"e to crac%in&( and !ecause it so"idi$ies quic%"#( it ma# trap &as


1




CONSULTANTS

and s"a&) On su!sequent passes( conditions caused !# the shape o$ the 'e"d !ead or

chan&es in the ,oint con$i&uration can cause $urther crac%in&( as 'e"" as undercut

and s"a& trappin&) Repair costs can !e minimi*ed i$ isua" inspection detects these

$"a's !e$ore 'e"din& pro&resses)

6isua" inspection at an ear"# sta&e o$ production can a"so preent under'e"din& and

oer'e"din&) Fe"ds that are sma""er than ca""ed $or in the speci$ications cannot !e

to"erated) Keads that are too "ar&e increase costs unnecessari"# and can cause

distortion throu&h added shrin%a&e stress)

A$ter 'e"din&( isua" inspection can detect a ariet# o$ sur$ace $"a's( inc"udin&

crac%s( porosit# and un$i""ed craters( re&ard"ess o$ su!sequent inspection

procedures) Dimensiona" ariances( 'arpa&e and appearance $"a's( as 'e"" as 'e"d

si*e characteristics( can !e ea"uated)

Ke$ore chec%in& $or sur$ace $"a's( 'e"ds must !e c"eaned o$ s"a&) Shot!"astin&

shou"d not !e done !e$ore e+amination( !ecause the peenin& action ma# sea" $ine

crac%s and ma%e them inisi!"e) The AFS D.). Structural Welding Code( $or e+amp"e(

does not a""o' peenin& >on the root or sur$ace "a#er o$ the 'e"d or the !ase meta" at

the ed&es o$ the 'e"d)>

6isua" inspection can on"# "ocate de$ects in the 'e"d sur$ace) Speci$ications or

app"ica!"e codes ma# require that the interna" portion o$ the 'e"d and ad,oinin& meta"

*ones a"so !e e+amined) Nondestructie e+aminations ma# !e used to determine the

presence o$ a $"a'( !ut the# cannot measure its in$"uence on the sericea!i"it# o$ the

product un"ess the# are !ased on a corre"ation !et'een the $"a' and some

characteristic that a$$ects serice) Other'ise( destructie tests are the on"# sure 'a#

to determine 'e"d sericea!i"it#)

Radio&raphic Inspection @RT

Radio&raph# @W3ra# is one o$ the most important( ersati"e and 'ide"# accepted o$ a""

the nondestructie e+amination methods 3 <i&) .)

<i&) . 3 Radio&raph# is one o$ the most<i&) 1 3 Thic%er areas o$ a specimen


2




CONSULTANTS

'ire that can !e c"ear"# seen on the radio&raph)

A penetrameter is not an indicator or &au&e to measure the si*e o$ a discontinuit# or

the minimum detecta!"e $"a' si*e) It is an indicator o$ the qua"it# o$ the radio&raphic

technique)

Radio&raphic ima&es are not a"'a#s eas# to interpret) <i"mhand"in& mar%s and

strea%s( $o& and spots caused !# dee"opin& errors ma# ma%e it di$$icu"t to identi$#

de$ects) Such $i"m arti$acts ma# mas% 'e"d discontinuities)

Sur$ace de$ects 'i"" sho' up on the $i"m and must !e reco&ni*ed) Kecause the an&"e

o$ e+posure 'i"" a"so in$"uence the radio&raph( it is di$$icu"t or impossi!"e to ea"uate

$i""et 'e"ds !# this method) Kecause a radio&raph compresses a"" the de$ects that

occur throu&hout the thic%ness o$ the 'e"d into one p"ane( it tends to &ie an

e+a&&erated impression o$ scattered3t#pe de$ects such as porosit# or inc"usions)

An W3ra# ima&e o$ the interior o$ a 'e"d ma# !e ie'ed on a $"uorescent screen( as

'e"" as on dee"oped $i"m) This ma%es it possi!"e to inspect parts $aster and at "o'er

cost( !ut ima&e de$inition is !ut ima&e de$inition is possi!"e to oercome man# o$ the

shortcomin&s o$ radio&raphic ima&in& !# "in%in& the $"uorescent screen 'ith a ideo

camera) Instead o$ 'aitin& $or $i"m to !e dee"oped( the ima&es can !e ie'ed in rea"

time) This can improe qua"it# and reduce costs on production app"ications such as

pipe 'e"din&( 'here a pro!"em can !e identi$ied and corrected quic%"#)

K# di&iti*in& the ima&e and "oadin& it into a computer( the ima&e can !e enhanced

and ana"#*ed to a de&ree neer !e$ore possi!"e) 7u"tip"e ima&es can !e

superimposed) Pi+e" a"ues can !e ad,usted to chan&e shadin& and contrast(

!rin&in& out sma"" $"a's and discontinuities that 'ou"d not sho' up on $i"m) Co"ors

can !e assi&ned to the arious shades o$ &ra# to $urther enhance the ima&e andma%e $"a's stand out !etter) The process o$ di&iti*in& an ima&e ta%en $rom the

$"uorescent screen 3 hain& that ima&e computer enhanced and trans$erred to a

ie'in& monitor 3 ta%es on"# a $e' seconds) 4o'eer( !ecause there is a time de"a#(

'e can no "on&er consider this >rea" time)> It is ca""ed >radioscop# ima&er#)>


/




CONSULTANTS

discontinuities that are too sma"" to !e seen 'ith the na%ed e#e( and those that are

s"i&ht"# su!sur$ace)

This method ma# !e used to inspect p"ate ed&es prior to 'e"din&( in process

inspection o$ each 'e"d pass or "a#er( post'e"d ea"uation and to inspect repairs 3

<i&) )

It is a &ood method $or detectin& sur$ace crac%s o$ a"" si*es in !oth the 'e"d and

ad,acent !ase meta"( su!sur$ace crac%s( incomp"ete $usion( undercut and inadequate

penetration in the 'e"d( as 'e"" as de$ects on the repaired ed&es o$ the !ase meta")

A"thou&h ma&netic partic"e testin& shou"d not !e a su!stitute $or radio&raph# or

u"trasonics $or su!sur$ace ea"uations( it ma# present an adanta&e oer their

methods in detectin& ti&ht crac%s and sur$ace discontinuities)

Fith this method( pro!es are usua""# p"aced on each side o$ the area to !e inspected(

and a hi&h ampera&e is passed throu&h the 'or%p"ace !et'een them) A ma&netic $"u+

is produced at ni&ht an&"es to the $"o' o$ current 3 <i&) ) Fhen these "ines o$ $orce

encounter a discontinuit#( such as a "on&itudina" crac%) the# are dierted and "ea%

throu&h the sur$ace( creatin& ma&netic po"es or points o$ attraction) A ma&netic

po'der dusted onto the sur$ace 'i"" c"in& to the "ea%a&e area more tenacious"# than

e"se'here( $ormin& an indication o$ the discontinuit#)

<or this indication to dee"op( the discontinuit# must !e an&"ed a&ainst the ma&netic

"ines o$ $orce) Thus( 'hen current is passed "on&itudina""# throu&h a 'or%piece( on"#

"on&itudina" $"a's 'i"" sho') Puttin& the 'or%piece inside a so"enoid coi" 'i"" create

"on&itudina" "ines o$ $orce @<i&) that cause transerse and an&u"ar crac%s to

!ecome isi!"e 'hen the ma&netic po'der is app"ied)

A"thou&h much simp"er to use than radio&raphic inspection( the ma&netic partic"e

method is "imited to use 'ith $erroma&netic materia"s and cannot !e used 'ith

austenitic stee"s) A ,oint !et'een a !ase meta" and a 'e"d meta" o$ di$$erent ma&netic

characteristics 'i"" create ma&netic discontinuities that ma# !e $a"se"# interpreted as





CONSULTANTS

unsound) On the other hand a true de$ect can !e o!scured !# the po'der c"in&in&

oer the harm"ess ma&netic discontinuit#) Sensitiit# decreases 'ith the si*e o$ the

de$ect and is a"so "ess 'ith round $orms such as &as poc%ets) It is !est 'ith

e"on&ated $orms( such as crac%s( and is "imited to sur$ace $"a's and some

su!sur$ace $"a's( most"# on thinner materia"s)

Kecause the $ie"d must !e distorted su$$icient"# to create the e+terna" "ea%a&e

required to identi$# $"a's( the $ine( e"on&ated discontinuities( such as hair"ine crac%s(

seams or inc"usions that are para""e" to the ma&netic $ie"d( 'i"" not sho' up) The# can

!e dee"oped !# chan&in& the direction o$ the $ie"d( and it is adisa!"e to app"# the

$ie"d $rom t'o directions( pre$era!"# at ri&ht an&"es to each other)

7a&netic po'ders ma# !e app"ied dr# or 'et) The dr# po'der method is popu"ar $or

inspectin& hea# 'e"dments( 'hi"e the 'et method is o$ten used in inspectin& aircra$t

components) Dr# po'der is dusted uni$orm"# oer the 'or% 'ith a spra# &un( dustin&

!a& or atomi*er) The $ine"# diided ma&netic partic"es are coated to increase their

mo!i"it# and are aai"a!"e in &ra#( !"ac% and red co"ors to improe isi!i"it#) In the

'et method( er# $ine red or !"ac% partic"es are suspended in 'ater or "i&ht petro"eum

disti""ate) This can !e $"o'ed or spra#ed on( or the part ma# !e dipped into the "iquid)

The 'et method is more sensitie than the dr# method( !ecause it a""o's the use o$

$iner partic"es that can detect e+ceedin&"# $ine de$ects) <"uorescent po'ders ma# !e

used $or $urther sensitiit# and are especia""# use$u" $or "ocatin& discontinuities in

corners( %e#'a#s( sp"ines and deep ho"es)

>7T ma# hae an adanta&e oer RT and UT in

detectin& ti&ht crac%s and sur$ace discon$inui$ies)>





CONSULTANTS

Liquid Penetrant Inspection @PT

Sur$ace crac%s and pinho"es that are not isi!"e to the na%ed e#e can !e "ocated !#

"iquid penetrant inspection) It is 'ide"# used to "ocate "ea%s in 'e"ds and can !e

app"ied 'ith austenitic stee"s and non$errous materia"s 'here ma&netic partic"e

inspection 'ou"d !e use"ess)

Liquid penetrant inspection is o$ten re$erred to as an e+tension o$ the isua"

inspection method) 7an# standards( such as the AFS D.). Code( sa# that >'e"ds

su!,ect to "iquid penetrant testin& ))) sha"" !e ea"uated on the !asis o$ the

requirements $or isua" inspection)>

T'o t#pes o$ penetratin& "iquids are used 3 $"uorescent and isi!"e d#e) Fith

$"uorescent penetrant inspection( a hi&h"# $"uorescent "iquid 'ith &ood penetratin&

qua"ities is app"ied to the sur$ace o$ the part to !e e+amined) Capi""ar# action dra's

the "iquid into the sur$ace openin&s( and the e+cess is then remoed) A >dee"oper>

is used to dra' the penetrant to the sur$ace( and the resu"tin& indication is ie'ed !#

u"traio"et @!"ac% "i&ht) The hi&h contrast !et'een the $"uorescent materia" and theo!,ect ma%es it possi!"e to detect minute traces o$ penetrant that indicate sur$ace

de$ects)


<i&) 3 D#e penetrant inspection is

simi"ar to "iquid penetrant inspection

e+cept iid"# co"oredd#es isi!"e under

ordinar# "i&ht are used)




CONSULTANTS

D#e penetrant inspection is simi"ar( e+cept that iid"# co"ored d#es isi!"e under

ordinar# "i&ht are used 3 <i& ) Norma""#( a 'hite dee"oper is used 'ith the d#e

penetrants that creates a sharp"# contrastin& !ac%&round to the iid d#e co"or) this

a""o's &reater porta!i"it# !# e"iminatin& the need $or u"traio"et "i&ht) The part to !e

inspected must !e c"ean and dr#( !ecause an# $orei&n matter cou"d c"ose the crac%s

or pinho"es and e+c"ude the penetrant) Penetrants can !e app"ied !# dippin&(

spra#in& or !rushin&( !ut su$$icient time must !e a""o'ed $or the "iquid to !e $u""#

a!sor!ed into the discontinuities) This ma# ta%e an hour or more in er# e+actin&

'or%)

Liquid penetrant inspection is 'ide"# used $or "ea% detection) A common procedure is

to app"# $"uorescent materia" to one side o$ a ,oint( 'ait an adequate time $or capi""ar#

action to ta%e p"ace( and then ie' the other side 'ith u"traio"et "i&ht) In thin3'a""ed

esse"s( this technique 'i"" identi$# "ea%s that ordinari"# 'ou"d not !e "ocated !# the

usua" air test 'ith pressures o$ 031/ I!in1) Fhen 'a"" thic%ness e+ceeds . in)(

ho'eer( sensitiit# o$ the "ea% test decreases)





CONSULTANTS

U"trasonic Inspection is a method o$ detectin& discontinuities !# directin& a hi&h3

$requenc# sound !eam throu&h the !ase p"ate and 'e"d on a predicta!"e path) Fhen

the sound !eam;s path stri%es an interruption in the materia" continuit#( some o$ the

sound is re$"ected !ac%) The sound is co""ected !# the instrument( amp"i$ied and

disp"a#ed as a ertica" trace on a ideo screen 3 <i&) 0)

Koth sur$ace and su!sur$ace de$ects in meta"s can !e detected( "ocated and

measured !# u"trasonic inspection( inc"udin& $"a's too sma"" to !e detected !# othermethods)

The u"trasonic unit contains a cr#sta" o$ quart* or other pie*oe"ectric materia"

encapsu"ated in a transducer or pro!e) Fhen a o"ta&e is app"ied( the cr#sta" i!rates

rapid"#) As an u"trasonic transducer is he"d a&ainst the meta" to !e inspected( it

imparts mechanica" i!rations o$ the same $requenc# as the cr#sta" throu&h a coup"et

materia" into the !ase meta" and 'e"d) These i!rationa" 'aes are propa&ated

throu&h the materia" unti" the# reach a discontinuit# or chan&e in densit#) At these

points( some o$ the i!rationa" ener&# is re$"ected !ac%) As the current that causes

the i!ration is shut o$$ and on at /3./// times per second( the quart* cr#sta"

intermittent"# acts as a receier to pic% up the re$"ected i!rations)These cause

pressure on the cr#sta" and &enerate an e"ectrica" current) <ed to a ideo screen( this


<i&) 0 3 U"trasonic inspection detects

discontinities !oth on and !e"o' the

'e"d sur$ace) Compact( porta!"e

equipment ma%es it eas# to use in the

$ie"d)

1




CONSULTANTS

current produces ertica" de$"ections on the hori*onta" !ase "ine) The resu"tin&

pattern on the $ace o$ the tu!e represents the re$"ected si&na" and the discontinuit#)

Compact porta!"e u"trasonic equipment is aai"a!"e $or $ie"d inspection and is

common"# used on !rid&e and structura" 'or%) U"trasonic testin& is "ess suita!"e than

other NDE methods $or determinin& porosit# in 'e"ds( !ecause round &as pores

respond to u"trasonic tests as a series o$ sin&"e3point re$"ectors) This resu"ts in "o'3

amp"itude responses that are easiI# con$used 'ith >!ase "ine noise> inherent 'ith

testin& parameters) 4o'eer( it is the pre$erred test method $or detectin& p"ainer3t#pe

discontinuities and "amination) Porta!"e u"trasonic equipment is aai"a!"e 'ith di&ita"

operation and microprocessor contro"s) These instruments ma# hae !ui"t3in memor#

and can proide hard3cop# printouts or ideo monitorin& and recordin&) The# can !e

inter$aced 'ith computers( 'hich a""o's $urther ana"#sis( documentation and

archiin&( much as 'ith radio&raphic data) U"trasonic e+amination requires e+pert

interpretation $rom hi&h"# s%i""ed and e+tensie"# trained personne")

Ta!"e . 3 Re$erence Guide to 7a,or 7ethods $or the Nondestructie E+amination o$

Fe"ds

Inspection

7ethod

Equipment

Required

Ena!"es

Detectiort o$

Adanta&es Limitations Remar%s

6isua" 7a&ni$#in&

&"ass

Fe"d si*in&

&au&e

Poc%et ru"e

Strai&ht ed&e

For%manshipstandards

Sur$ace $"a's 3

crac%s( porosit#(

un$i""ed craters(

s"a& inc"usions

Farpa&e(

under'e"din&(

oer'e"din&(poor"# $ormed

!eads(

misa"i&nments(

improper $itup

Lo' cost)

Can !e

app"ied 'hi"e

'or% is in

process(

permittin&

correction o$$au"ts)

Gies

indication o$

incorrect

App"ica!"e to

sur$ace

de$ects on"#)

Proides no

permanent

record)

Shou"d a"'a#s

!e the primar#

method o$

inspection( no

matter 'hat

other

techniques arerequired)

Is the on"#

>productie>

t#pe o$


2




CONSULTANTS

procedures) inspection)

Is the

necessar#

$unction o$

eer#one 'ho

in an# 'a#

contri!utes to

the ma%in& o$

the 'e"d)

Radio&raphicCommercia" W3

ra# or &amma

units made

especia""# $or

inspectin&

'e"ds(

castin&s and

$or&in&s)

<i"m and

processin&

$aci"ities)

<"uoroscopic

ie'in&

equipment)

Interior

macroscopic

$"a's 3 crac%s(

porosit#( !"o'

ho"es(

nonmeta""ic

inc"usions(

incomp"ete root

penetration(

undercuttin&(

icic"es( and

!urnthrou&h)

Fhen the

indications

are recorded

on $i"m( &ies

a permanent

record)

Fhen ie'ed

on a

$"uoroscopic

screen( a "o'3

cost method

o$ interna"

inspection

Requires s%i""

in choosin&

an&"es o$

e+posure(

operatin&

equipment(

and

interpretin&

indications)

Requires

sa$et#

precautions)

Not &enera""#

suita!"e $or

$i""et 'e"d

inspection)

W3ra#

inspection is

required !#

man# codes

and

speci$ications)

Use$u" in

qua"i$ication o$

'e"ders and

'e"din&

processes)

Kecause o$

cost( its use

shou"d !e

"imited to those

areas 'here

other methods

'i"" not proide

the assurance

required)


3




CONSULTANTS

7a&netic

Partic"e

Specia"

commercia"

equipment)

7a&netic

po'ders 3 dr#

or 'et $ormJ

ma# !e

$"uorescent $or

ie'in& under

u"traio"et

"i&ht)

E+ce""ent $or

detectin&

sur$ace

discontinuities 3

especia""#

sur$ace crac%s)

Simp"er to

use than

radio&raphic

inspection)

Permits

contro""ed

sensitiit#)

Re"atie"#

"o'3cost

method)

App"ica!"e to

$erroma&netic

materia"s on"#)

Requires s%i""

in

interpretation

o$ indications

and

reco&nition o$

irre"eant

patterns)Di$$icu"t to use

on rou&h

sur$aces)

E"on&ated

de$ects para""e"

to the ma&netic

$ie"d ma# not

&ie patternJ $or

this reason the

$ie"d shou"d !e

app"ied $rom

t'o directions

at or near ri&ht

an&"es to eachother)

Liquid

Penetrant

Commercia"

%its containin&

$"uorescent or

d#e

penetrants

and

dee"opers)

App"ication

equipment $or

the dee"oper)

A source o$

u"traio"et

"i&ht 3 i$

$"uorescent

method is

Sur$ace crac%s

not readi"#

isi!"e to the

unaided e#e)

E+ce""ent $or

"ocatin& "ea%s in

'e"dments)

App"ica!"e to

ma&netic and

nonma&netic

materia"s)

Eas# to use)

Lo' cost)

On"# sur$ace

de$ects are

detecta!"e)

Cannot !e

used

e$$ectie"# on

hot

assem!"ies)

In thin3'a""ed

esse"s 'i""

reea" "ea%s not

ordinari"#

"ocated !#

usua" air tests)

irre"eant

sur$ace

conditions

@smo%e( s"a&

ma# &ie

mis"eadin&

indications)


4




CONSULTANTS

used)

U"trasonic Specia"

commercia"

equipment(

either o$ the

pu"se3echo or

transmission

t#pe)

Standard

re$erence

patterns $or

interpretation

o$ R< or ideo

patterns)

Sur$ace and

su!sur$ace

$"a's inc"udin&

those too sma""

to !e detected

!# other

methods)

Especia""# $or

detectin&

su!sur$ace

"amination3"i%e

de$ects)

6er#

sensitie)

Permits

pro!in& o$

,oints

inaccessi!"e

to

radio&raph#)

Requires hi&h

de&ree o$ s%i""

in interpretin&

pu"se3echo

patterns)

Permanent

record is not

readi"#

o!tained)

Pu"se3echo

equipment is

hi&h"#

dee"oped $or

'e"d inspection

purposes)

The

transmission3

t#pe equipment

simp"i$ies

pattern

interpretation

'here it is

app"ica!"e)

Choices Contro" Qua"it#

A &ood NDE inspection pro&ram must reco&ni*e the inherent "imitations o$ each

process) <or e+amp"e( !oth radio&raph# and u"trasound hae distinct orientation

$actors that ma# &uide the choice o$ 'hich process to use $or a particu"ar ,o!) Their

stren&ths and 'ea%nesses tend to comp"ement each other) Fhi"e radio&raph# is

una!"e to re"ia!"# detect "amination3"i%e de$ects( u"trasound is much !etter at it) On

the other hand( u"trasound is poor"# suited to detectin& scattered porosit#( 'hi"e

radio&raph# is er# &ood)


/




CONSULTANTS

The <ie P;s are

.) Process Se"ection ) The process must !e ri&ht $or the ,o!)

1) Preparation) The ,oint con$i&uration must !e ri&ht and compati!"e

) 'ith the 'e"din& process)

) Procedures ) The procedures must !e spe""ed out in detai" an $o""o'ed

0) durin& 'e"din&)

) Pretestin&) <u""3sca"e moc%ups or simu"ated specimens shou"d !e used

) to proe that the process and procedures &ie the desired standard o$

M) qua"it#)

H) Personne") Qua"i$ied peop"e must !e assi&ned to the ,o!)

Fhateer inspection techniques are used( pa#in& attention to the ><ie P;s> o$ 'e"d

qua"it# 'i"" he"p reduce su!sequent inspection to a routine chec%in& actiit#) Then(

the proper use o$ NDE methods 'i"" sere as a chec% to %eep aria!"es in "ine and

'e"d qua"it# 'ithin standards)

0

penetrants testing

Documents