A SEMINAR REPORT ON

TUBE EXPANSION

BY

Mr. NAVEEN .D. UNDE

BACHELOR OF ENGINEERING(MECHANICAL)

EXAM NO: B-2210872 ROLL NO: 4170

UNDER GUIDANCE OF PROF. PRADEEP A PATIL

DEPARTMENT OF MECHANICAL ENGINEERING

ALL INDIA SHRI SHIVAJI MEMEORIAL SOCIETY’s

COLLEGE OF ENGINEERING

KENNEDY ROAD, NEAR R.T.O.,PUNE- 411001.

2003-2004

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CERTIFICATE

This is to certify that the Seminar Report entitled ‘Tube Expansion’ submitted

by Mr. Naveen. D. Unde, Examination No. B2210872 for the partial

fulfillment for the award of the degree of B.E. (Mechanical Engineering) of

university of Pune, Pune, is approved.

(Prof. Pradeep A Patil) (Prof.

V.N.Phadkule)

Guide, Head of the

Deptt.

Mechanical Engineering Deptt.., Mechanical

Engineering,

A.I..S.S.M’S COE, A.I.S.S.M.S’, C.O.E.,

Pune Pune

Date: Date:

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ACKNOWLEDGEMENT

I pay my profound gratefulness and express my sincere gratitude to

Prof. Pradeep A Patil , Department of Mechanical Engineering,

A.I.S.S.M.S.’s, C.O.E., PUNE for providing me very useful and valuable

information, for providing guidance and extending their co-operation in

writing this report.

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CONTENTS

DEFINATION OF TUBE EXPANSION 05

TUBE SHEET PREPARATION 06

PROCEDURE FOR EXPANSION 07 EXPANSION LIMIT FOR TUBE EXPANSION 13 TIPS FOR GOOD EXPANSION 15

TUBE EXPANDER 16

TUBE PULLER 21

TUBE REMOVAL 23 CONCLUSION 25

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Abstract:- Tube expansion means elimination of diameter differences between two pipe end and are joint with welding .The process is carried out to prevent stress induced in the tubes due to expansion and contraction. The process is also useful to avoid misalignment.

In this process tension is created between tube and tube sheet to make the

joint leak proof. In some cases buckling and bends are induced in the tubes, which are minimized by tube expansion.

Tube expansion has minimum distortion of tube sheet and has high reliability and reduces stress corrosion.

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TUBE EXPANSION

Definition: elimination of diameter difference between the two pipe ends to be

joined with welding (girth weld).

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Fig.1

Measures:

outside diameter of the pipe to be expanded, D1 [mm];

wall thickness of the pipe to be expanded, t1 [mm];

expansion length, L [mm].

Possible cause of origin:

pipe installation (laying);

repair.

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TUBE SHEET PREPARATION

Procedure for the preparation of tube sheet :

The sizes of the plates vary from 12.5 mm to 25 mm depending on the size

and capacity of the chiller. Normally the chiller with a lower capacity has a plate of a

small thickness and vice versa.

The preparation of tube plate start from the plate cutting shop where the plate

is cut into the required shape on the laser cutting machine. This machine is basically

a Linde cutting machine incorporated with a CNC control.

Once the plates are cut they are welded with small hooks which facilitate in

the lifting of the tube plate. These plates are then sent to the Parkerizing where all

the foreign particles (oil, grease etc.) present on the surface are made cleaned.

After the cleaning procedure is complete then the plate are then sent to the

machine shop where the operation of drilling, remaining and deburring are carried

out.

Normally the drilling operation is carried out with the help of a delta drill which

is little less in size than the actual hole to be drill. For example in case of copper

tube of size 16.25 mm a delta drill of 16.00 mm is drilled. After the delta drilling

operation is complete a groove is made in the hole which helps the tube to sit firm

inside the hole and also it prevent the loctite from flowing inside the chiller and

causing contamination of the liquids present inside the chiller and also the groove

also provide additional strength to the joint between the tube sheet and tube.

After the grooving operation is complete the plate are moved to the deburring

area where the entire burr present on the surface of the plates is removed with a

help of a deburring tool.

After carrying out all the operation on the tube plate the plates are then

shifted to the assembly shop where they are welded as the lower shell tube plates

and the upper shell tube plate. During this operation care must be taken that the

plates are aligned parallel to each other.

After the set up is complete the tube are instead and the tube expansion is

carried out as explained before. 8

PROCEDURE FOR EXPANSION OF THE TUBE OF HIGH TEMPERATURE

GENERATORS:

In case of high temperature generators where the temperature of the liquid is

about 187 degree Celsius more care is to be taken as with the expansion of the

tubes inside the high temperature internal stresses are introduced in the generators

and hence a special process is implemented for the expansion of these tubes.

In this case one of the sides of the tubes of the generators are expanded

before with a help of a four roller tube expansion tool with the torque kept at about 4

ampere. during this operation the other sides of the tube are kept free. After this is

complete special type of expansion procedure is used for the expansion which

involves the use of steam.

The steam is made to pass through the tube to be expanded from the side

already expanded, when steam is made to pass through the tube which have

sagged due to the self weight of the tube become straight and the projects outside,

due to the expansion due to longitudinal expansion of the tube. Now the expansion

is carried out on the other side. After this the ends of the tube are trimmed to close

tolerances.

There are three main critical factors that have to be taken care of during this

process :

1) The pressure of the steam which is been used in the process : Normally the

pressure of the steam us only about 5 Kg/meter square that means the pressure

is very less but at the same time it is very critical.

2) The thickness of the tube and the tube sheet.

3) The torque which is being used in the process : Normally more the torque more

is the expansion and more is the percentage reduction in the thickness if the

tube. In some cases the tubes normally crack due to over expansion.

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COPPER Expansion Loops:

Copper tube, like all piping materials, expands and contracts with temperature

changes. Therefore, in a copper tube system subjected to excessive temperature

changes, a long line tends to buckle or bend when it expands unless compensation

is built into the system. Severe stresses on the joints may also occur.

Such stresses, buckles or bends are prevented by the use of expansion joints or by installing offsets, "U" bends,

coil loops or similar arrangements in the tube assembly. These specially shaped tube segments take up

expansion and contraction without excessive stress. The expansion of a length of copper tube may be calculated

from the formula:

Temperature Rise (degrees F)

x Length (feet)

x 12 (inches per foot)

x Expansion Coefficient (inches per

inch per degree F)

= Expansion (inches)

Calculation for expansion and contraction should be based on the average

coefficient of expansion of copper which is 0.0000094 inch per inch per degree F,

between 70 F and 212 F.

For example, the expansion of each 100 feet of length of any size tube heated from

room temperature (70 F) to 170 F (a 100 F rise) is 1.128 inches.

100 F x 100 ft x 12 in./ft. x 0.0000094 in./in./°F = 1.128 in.

. Alternatively, the necessary length of tube in an expansion loop or offset can be

calculated using the formula:

where:

L = developed length in the expansion loop or offset (in feet), as shown in

E = modulus of elasticity of copper (in psi)10

P = design allowable fiber stress of material in flexure (in psi)

do = outside diameter of pipe (in inches)

e = amount of expansion to be absorbed (in inches)

For annealed copper tube:

E = 17,000,000 psi

P = 6,000 psi

Thus, the developed length L is simply:

Hydro Expansion

Fig2

Advantages of the Airmo’s Model 222 Hydro Expansion System

Fast - Expansion operation of 2 to 5 seconds per tube Portable - You can bring the

expander to the coil Consistent - Normal wall thickness tolerances have no effect on

the expanded diameter result Flexible - Coil size and shape are of no concern Safe -

Operator is exposed to no moving parts Compact - Machine requires 10 square feet

of floor space Efficient - Very low power consumption Environmentally safe -

Expander uses ordinary tap water as the hydraulic expansion medium Economical -

Less expensive to purchase and maintain than mechanical expansion systems

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Hydro expansion is a method of tube expansion, which fills the tube (either straight

length or hairpin tubes) with water. Once filled, the water is pressurized past the

yield point of the tube thereby providing expansion. This method is used extensively

in baseboard header assemblies and in air conditioning coil production for bonding

tubes to fin assemblies.

The hydro expansion system utilizes high-speed PLC control and pressure sensors

to produce an exact expansion. This is achieved by matching a preset pressure

value (operator entered) with actual line pressure or expansion pressure. When the

actual line pressure reaches the preset value, the expansion system instantly dumps

pressure providing a fast constant expansion and fin bond.

Hydro-Pel (is Hydro Mechanical) Expansion

Fig.3

Fast

Repeatable

Compact size

Hand held tooling

Low maintenance

Ball tube expansion

Ball insertion systems and tooling

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Tube end bell systems and tooling

Hydrostatic test systems and tooling

Fig.4 Fig.5

Airmo, Inc. offers unique systems and tooling designed for full length, mechanical

tube expansion.

Hydro-Pel is a method of tube expansion which places a projectile, usually a ball,

into a tube with water pressure forcing the ball through the tube. Generally, the

amount of expansion is a function of the ball diameter and the tube wall thickness.

This method is suggested where straight length tubes are used with one operator

performing the expansion.

Airmo offers two Hydro-Pel expansion methods:

For applications in which tube belling is performed as a standard operation,

conventional ball expansion methods are used. With the tube pre-belled or

preexpanded, the operator places a ball into the tube and places an expanding tool

over the tube end and starts the system pressure cycle. High pressure water is

directed behind the ball, forcing it down the tube. If the tube is not in a prebelIed

condition, ball insertion can be done with the Airmo ball insert tool.

TITANIUM ROLLER EXPANSION:

The most commonly use method of making tube/tube sheet joints is roller

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expansion.

Roller expansion procedures for titanium tubes into tube sheets are similar to those

used for other materials. For best results, the tube sheet holes should be within the

limits specified by TEMA (Tubular Exchanger Manufacturers Association) or within

the limits specified by HEI (Heat Exchange Institute)

There are three commonly used methods of determining the correct

amount of expansion:

1.Measuring wall reduction

2.Simulating wall reduction by interference

3.Pull-out strength versus torque curve

The above pull-out test is preferable.

The suggested wall reduction for titanium tubes is 10%. Thus, in a .028" tube or

a .020" tube, the required reduction is .0028" or .0020". A small error in

measurement can result in a large deficiency in pull-out strength.

Using the interference fit method, four measurements are required:

1. Tube I.D.

2. Tube wall thickness

3. Tube sheet hole diameter

4. Tube O.D.

RUBBER EXPANDTION

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Fig.6

The Advantages Of Rubber

Expansion Joints and Flexible Connectors

1. Prevents stress due to expansion and contractions  2.   Insulates against the transfer of noise and vibration 3.  Compensates for misalignment 4.  No electrolysis         5.   Greater recovery from movement6.   Freedom from corrosion

7. 7. Ease of installation

8. Small space requirements    

Expansion limit for expansion of tubes

Tube expansion can be compared to the cold rolling of steel sheets. The tube to be

expanded can also be equated with an endless steel sheet which, during the rolling

process, has been lengthened or enlarged to a point when the external diameter of

the tube equals the diameter of the tube sheet hole.

This first stage is called 'metal to metal contact'. Note that the expansion at this

stage is not yet leakproof.

Further rolling is necessary to increase the expansion and reach the point when the

material is deformed. This creates tension because of the compression between the

tube and the tube sheet. A leakproof expansion is assured if the pressure tension is

greater than the service pressure, which arises from the heating, the lengthening

and finally the tension of the medium. The difference of expansion between the

'contact' and the final expansion is called 'expansion limit'

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This 'expansion limit' must never cause a rupture in the cohension of the molecules

of the tube material by an exaggerated deformation of the material. If this were the

case the tube material could become dammaged – it could crack or break – and this

would create the danger of explosions etc. when the tube comes under high

pressure.

It could then happen that, though the tests had turned out positive, the tube will

prove useless after a few days in service.

Example:

Tube dimension: 30 x 3 mm

Tube sheet hole: 30.4 mm

less 2x3mm tube wall thickness: - 6.0 mm

theor. internal dia. of the tube at 'metal to metal contact': 24.4 mm

plus expansion limit i.e. 20% of the tube wall thickness: + 0.6 mm

Theoritcal inner dia. of tube after having reached the expansion limit: 25.0 mm

Recommended expansion ranges:

Metal to metal contact: about 3 - 5% of tube wall thickness

Expansion limit: about 15 - 20% of tube wall thickness

:

Listed below are the tips for proper tube expansion

The tube plates must be shot blasted – parkerised – CNC drilled – vapour

degreased before fabrication.

A groove must be provided for preventing the loctite entering the machine and

the groove must also contribute to the strength of joint between the tube and the

tube sheet. 16

The tube hole should not have a prefect round shaped hole without any

longitudinal or helical scratches as they contribute to he leak path.

Expander tool maintenance

The grub screw should be made tight before the start of the shift.

The roller should be changed after the expansion of ever 70 ends.

The mandrel should be changed after the expansion of ever 1400 ends.

The tube expander should be cleaned with the soap solution after completing

the four tube ends.

All burr and loctite stick should be removed after ever hundred tube ends are

completed or even before.

Under rolling may be preferred as it can be easily reworked but in case of over

rolling it is not accepted.

In case of direct fired vapour absorption machine all gaps should be sealed in

order to prevent crevice corrosion.

In case of titanium tubes which are used in conjunction with saline water a four

roller expander is normally recommended with low rpm. This is done in order to

prevent cracking of tubes.

The expansion length should normally be about 2 mm less then the thickness of

the tube sheet.

In case of stainless steel tubes steam is used to prevent elongation of the tubes

during expansion process.

In case of special tubes always swage the ends always remove the tube from the

same side.

In case wherein the clearance between the tube and the tube sheet is very large

then the max tube expansion limit is in sufficient than trust collar butting tube is

used.

The high temperature stainless steel tubes which are internal seam welded

should be ground to length of 60 mm and the projection should not exceed 0.3

mm.

The best method of cleaning tubes and tube sheet is the use of vacuum pump

and not the use of compressed air. 17

The holes of the tube sheet should be cleaned by the use of vapour degreasing

method. After this is done then the cleaning is done by the use of clean rag and

not with cotton waste.

Gloves should be used while handling tubes.

In case of a Sugino expansion machine with present torque – value the machine

may stop before the set limit due to error or at a set limit due to manual error or

at a set limit without any expansion due to a malpractice.

TUBE EXPANDER

113/123 Series

Fig.7

For Heat Exchangers and other Heat Transfer Units. The function of the series

113/123 heavy duty tube expander is to make a good mechanical seal between tube

and tube sheet.

Elliott expanders do this by means of a set of rotating, parallel-rolling and self-

feeding rolls which cold-work the tube joint metals until the tube ends fit tightly in the

holes in the sheet. This occurs because the forces built up in the tube sheet reach

inward toward the center of the hole, and those in the tube react outward.

Parallel-roll expanders roll tubes more uniformly than other types, thus developing

maximum strength in the joint. Elliott expanders have adjustable ball- bearing thrust

collars. A radius on the front of the rolls, prevents any sharp offsets inside the tube.

The rolls have also been given a feed angle that assures uniform expansion and

tightness of the tube in the tube sheet.

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3300 Series:

Fig.8

For use in Fire and Water Tube Boilers, Air Coolers, Heatersand Re-Rolled Flared or Welded Tubes

Series 3300 Elliott tube expanders are recommended for any requirement for parallel rolling of tubes in tube sheets.

These tube expanders have a ball bearing thrust collar which reduces friction to a

minimum. They typically are used with torque controlled rolling motors for uniform

rolling of tubes.

DRE Series

Fig.9

Series DRE tube expanders for deep rolling and hard rolling of steam and mud

drums of high pressure boilers. 

Series DRE tube expanders are furnished with a minimum reach of 3.5", maximum

reach of 10.50", and an effective roll length of 2-5/8".

The Series DRE and the Elliott Series 1500 make a great combination of boiler tube

erection or boiler tube replacement expanders

For High and Low Pressure Steam Boilers

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Fig.10

Series 1500 Elliott tube expanders are self-feeding for power or hand use. Will roll

tube parallel and smooth in tube hole and flare projecting tube end at an angle of 20º

from center line in one operation.

These tube expanders are made for sheet or drum thicknesses from ½ to

3". The expanding rolls are sufficiently long to roll tubes 3/8" beyond sheet thickness

listed plus a generous radius to eliminate sharp offset within tubes ... enabling

erectors and boiler makers to roll tubes the desired distance beyond tube sheet,

drum or header wall.

3300 Series

Fig.11

For use in Fire and Water Tube Boilers, Air Coolers, Heaters

and Re-Rolled Flared or Welded Tubes

Series 3300 Elliott tube expanders are recommended for any requirement for

parallel rolling of tubes in tube sheets.

These tube expanders have a ball bearing thrust collar which reduces friction to a

minimum. They typically are used with torque controlled rolling motors for uniform

rolling of tubes

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Universal Joint Drives:

Fig.12Provides an effective operating range at angles up to 35°, designed especially for

use with tube expanders when rolling tubes where space is limited and where tubes

are not in direct line wit hand holes

SPECIAL TYPES OF TUBE EXPANDERSTable:-1

Step By Step Tube ExpanderThis model expander is especially designed for thick tube sheetsAutomatic overlapping of the rolling in stages. For tubes 3/8" to 13/8"(9.5 mm to 34.9 mm) I.D. and tube sheet thickness 2 1/2" to 27 1/2" (63.5 mm to 698.5 mm) .

Five Roll ExpanderModel Ch800 and Ch 1200 A special line of Expanders to expand thin wall tubes, titanium, stainless steel and other high quality metals. Available with special thrust collars, to eliminate the possibility of the tube being drawn into the trust collar.

Tube Expanders Model: SRIdeally suited for tube rolling with minimum travel of mandrel. Expander mandrel is retained at rear to shorten mandrel length and to allow use near tube bends or I.D. fixed tubes

Table :-2

21

STESB Series

Top plate tube expansion in pans, juice heaters with sugar mills. Sizes range from 38.1mm (1 1/2") to

114.3mm (4 1/2").STE CSB Series

Bottom plate tube expansion in pans, juice heaters within the sugar mill. Tube sizes from 44.5mm (1

3/4") to 101.4mm (4") O.DSTE114 Series

The STE114 series is a "general purpose" expander for expanding and flaring boiler tubes,

waterwall, downcomer, economiser, riser and airheater tubes. Tube sizes from 50.8mm (2") to

114.3mm (4 1/2") O.D. - Tube Sheet 12.7mm (1/2") to 66.7mm (2 5/8")

1)Collet-Type Tube Puller

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#M5360-00

Fig.13

Some customers say they can pull tubes in less than ten seconds, light-wall tubes in

five. Heavy wall tubes in thick tube sheets require more time to allow pump to

develop the needed pressure.

Features

For pulling 1/2" through 1-1/2" O.D. tubes in seconds.

Automatically sets teeth to the same preset pressure every time.

Powerful 2 HP, 110 Volt industrial rated motor.

17 Ton Pulling capacity.

4000 PSI 20 ft. hydraulic hose connects the pump to the tube pulling cylinder

assembly

Model M5733-00 for 230/1/50 electric applications.

:

2)Collet-Type Tube Puller Accessories

Collet and drawbar look like this before entering tube

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Fig.14

Drawbar retracts by hydraulic pressure, setting collet teeth to fit tube I.D. Tube I.D.

will often vary, but the collet adjusts automatically to each tube and sets the collet to

a preset pressure for pulling

Fig.15

3)Cyclegrip

M5630-00

Fig.16

Continuous Tube Puller for maximum operating efficiency

Features:

Extracts ferrous and non-ferrous tubes from ½" through 1"- O.D. Adapts to

these diameters without additional tooling.

Grippers exert 2 tons of force at 4,000 PSIG

Continuous 5 inch stroke operation as long as the pendant switch is

depressed.

Comfortable "D" handle grip reduces operator fatique

In continuous operation, a pulling rate of 120"/min. is produced

Small profile permits extraction of tubes close to the water jacket

Quick connect control cable and single hydraulic supply hose

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Weight 16 lbs

PROCEDURE FOR TUBE REMOVAL OF THE TUBES

After the tubes are placed in the tube sheet expanded they are checked for leaks

between the tube sheet and the tubes. The normally procedure for the leak detection

is nitrogen testing which is well known as soap test or bubble test, which is

explained in the following steps below :

1) The unit is cleaned with a vacuum pump and the adapter is welded to the unit.

2) After the welding operation is completed nitrogen is filled in the unit to a pressure

of about 1.3 Kg/m2. Then soap solution is sprayed on the entire surface and

checked for bubbles.

3) The places with leaks are indicated by the formation of bubbles. Once the tubes

with expansion leaks are detected they are marked.

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4) After the detection of leaks in the tubes joints one end of the tubes is crushed

(collapsed) with the help of a tube crusher, care should be taken that during the

collapsing operation no damage is made to the surface of the tube sheet hole.

5) After the above operation, a Tube Puller with tapes is inserted on the other side

and the tube is puller out by the hammering operation. And a new tube is

inserted and expanded by the same standard procedure.

CONCLUSION:

Tube expansion is a faster and most reliable method of obtaining a perfect joint between the tube sheet and the tube for the heat exchanger and high temperature generator

The cost of tube expansion equipment work to economical at compared to any other tube to tube sheet joint. To avoid this loss in some cases stresses are induced in bends so it may causes a leakage in the joints so to avoid this, tube expansion process is carried out.

Tube expansion is used to provide proper mechanical seal between tube and tube sheet and to minimized friction.

Tube expansion process is having minimum distortion between tube and tube sheet so to have proper leakproof joint.

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REERENCES:

WWW.GOOGLE.COM WWW.ALTAVISTA.COM Tips for good expansion.THERMAX LTD INDIA

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