statistical quality report for 42 inch odx13.44 mm (0.529) wt

7/22/2019 Statistical Quality Report for 42 Inch ODX13.44 Mm (0.529) WT

1/57

Strictly Private & Confidential

QUALITY REPORTSTATISTICAL PRESENTATION

on

TECHNICAL QUALITY DATA

for

CLIENT: ENTERPRISE-PRODUCTS OPERATING L.P.

PROJECT: HAYNESVILLE-ACADIAN

PIPE SIZE: 42ODX0.529(13.44 mm) WT

GRADE: API5L X70M PSL2

STEEL SOURCE : POSCO, KOREA

25-01-2010

WELSPUN GUJARAT STAHL ROHREN LTD.,ANJAR, INDIA


2/57

Strictly Private & Confidential2

Index

1. General Terminology about Statistical Data Analysis

2. Project Summary

3. Coil to Pipe Mechanical Properties Variation

4. Mechanical Testing Status for Pipe Heat (YS < 540 MPa as per POSCO RMTC)

Heat (YS 540 MPa as per POSCO RMTC)

5. Co-relation of Coil YS & Pipe YS for

Heat (YS < 540 MPa as per POSCO RMTC)


6. Dimensional Variation in Pipes

7. Pipe Outside Diameter Before & After Hydro-Testing (HT)

8. Conformance to Chemical Composition

9. Repair and Rejection Details with Reasons Fish-bone diagrams


3/57


General Terminology about Statistical Data Analysis

LSL = Lower specification Limit

USL = Upper Specification Limit

Mean = Average of data set in a sample

StDev (Within) = Standard Deviation showing the variation within sub-groups/shorttime variation.

StDev (Overall) = Standard Deviation showing the total variation within sub-groups +between the sub-groups/long time variation

N = No. of data points in a sample

CoV = Coefficient of Variation (Overall Standard deviation/mean*100). CoV < 3%indicates that the process is operation under good control (narrow range of Lower

Control Limit (LCL) & Upper Control Limit (UCL).

Range = Maximum Minimum

NOTE: It is assumed that data is continuous in nature and follow the Normal distribution.


4/57Strictly Private & Confidential

4


Ppk = Performance Index = Minimum of [ { (USL-Mean)/(3x overall standard

deviation)}, { (Mean LSL)/(3x overall standard deviation)} ].

Ppk shows the actual performance of the process taking care of the shift in theprocess which occurs in long run.

This is good for external view of the process performance as seen by the

customer to meet the specified limits in the product.

Cpk = Capability Index = Minimum of [ { (USL-Mean)/(3x within standarddeviation)}, { (Mean LSL)/(3x within standard deviation)} ].

Cpk shows the could be performance of the process not taking process inaccount.

This is good for internal process control. If Cpk = 2, then process is operating atsix sigma level. Cpk > 1 shows that the process is stable and well under control.



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Probability plots:

The probability plot is a graphical display of the estimated probability regressionequation. The middle line on the graph estimates the percent of units at a given level ofstress. The upper and lower limits give an approximate 95% confidence interval forthe percent of units at a given level of stress.

The probability plot also assess how well the chosen distribution fits your data. Thecloser the points fall to the middle line the better the distribution fits the data. This isestimated by p-value (> 0.1)

Anderson-Darling statistic:

Measures how well the data follow a particular distribution. The better thedistribution fits the data, the smaller this statistic will be. Anderson-Darling statisticcompares the fit of several distributions to see which one is best or to test whether asample of data comes from a population with a specified distribution.

If the p-value for the Anderson-Darling test is lower than the chosen significance level(usually 0.05 or 0.10), conclude that the data do not follow the specified distribution.



6/57


Project Summary

295COIL CONSUMED

28HEATS WITH YS 540 MPa (COIL)

15HEATS WITH YS < 540 MPa (COIL)

43TOTAL HEATS USED

NUMBERRAW MATERIAL DETAILS

0.1080.940.102FORMATION TRIAL PIPE

0.48395.110.4810PIPES REJECTED

0.0650.662.6254PIPES REPAIRED

-39.57-AVERAGE LENGTH ACHIEVED

98.368115099.422051TOTAL PIPE TPI CLEARED

-82507-2063TOTAL PIPE FORMING

-36-AVERAGE LENGTH AS PER ORDER (MINIMUM)

-80445-2235TOTAL ORDER QUANTITY

%FEET%NUMBERPRODUCTION SUMMARY


7/57


Coil to Pipe MechanicalProperties Variation


8/57


Statistics of Coil & Pipe Mechanical Properties

Total no. of heats = 43

Observations:1. Mean increase in YS from Coil to pipe = 9 MPa (1.66%).2. CoV decrease in YS from Coil to pipe = 0.20%

Reasons for observed changes are:1. Unwinding of coils & forming strains resulting in reverse plasticity. The effect of reverseplasticity is almost negligible in this 13.44 mm as compared to 15.88 mm.

2. Different sample locations in coil & pipe3. Flattening of samples for testing4. The other important reason is D/t ratio where the effect of Bauschinger will be less in 42

OD pipe compared to 36 OD pipe.

0.100.900.802.200.020.85138Pipe YS/UTS

641343.5137138Pipe elongation, %

696866161.812650138Pipe UTS, MPa

695955262.112550138Pipe YS, MPa

0.110.840.732.830.020.79138Coil YS/UTS

640343.7136138Coil elongation, %

617226611.913682138Coil UTS, MPa

615815202.313541138Coil YS, MPa

RangeMaximumMinimumCoefVarStDevMeanCountVariable


9/57


YS Change from Coil to Pipe

590580570560550540530520510500

70

60

50

40

30

20

10

0

YS, MPa

No.oftests

LSL 485 MPa USL 635 MPa

540.6 12.52 138

550.4 11.74 138

Mean StDev N

Coil YS

Pipe YS

Variable

013

22

14

65

13

20

1

63

34

49

37

8

0

Histogram of Coil YS, Pipe YS


10/57


610600590580570560550540530520510500490480470

99.9

99

95

90

80

70

60504030

20

10

5

1

0.1

Pipe YS, MPa

Percen

t

LSL 485 MPa

Mean 550.4

StDev 11.74N 138

AD 1.070

P-Value 0.008

Probability Plot of Pipe YSNormal - 95% CI

Probability Plot of Pipe YS

0.1% probability for YS < 509MPa at 95 % confidence level.


11/57


UTS Change from Coil to Pipe

750720690660630600570

80

70

60

50

40

30

20

10

0

UTS, MPa

No.oftests


682.1 12.69 138

650.1 11.68 138

Mean StDev N

Coil UTS

Pipe UTS

Variable

72

60

53

16

000 001

6

51

61

17

2

Histogram of Coil UTS, Pipe UTS


12/57


YS/UTS Change from Coil to Pipe

0.920.870.820.770.72

80

70

60

50

40

30

20

10

0

YS/UTS ratio

No.oftests

USL 0.92

0.7928 0.02242 138

0.8468 0.01864 138

Mean StDev N

Coil YS/UTS

Pipe YS/UTS

Variable

0001

40

59

32

0

6

02

36

68

27

5

000

Histogram of Coil YS/UTS, Pipe YS/UTS


13/57


Elongation Change from Coil to Pipe

4140393837363534333231302928272625

60

50

40

30

20

10

0

Elongation (2"GL), %

No.oft

ests

LSL 25%

35.68 1.323 138

37.03 1.278 138

Mean StDev N

Coil elongation

Pipe elongation

Variable

0

4

7

0

7

48

56

16

1

711

29

32

45

12

1

Histogram of Coil elongation, Pipe elongation


14/57


Mechanical Testing Status

for Pipe




15/57


Mechanical Testing Status as per YS in Heats (RMTC)

Test status forheats YS < 540MPa

Test status forheats YS 540

MPa

Formed Tested

1 SP41476 42 5

2 SQ68373 42 5

3 SQ68641 49 5

4 SQ68646 49 5

5 SQ68649 56 6

6 SQ68800 56 6

7 SQ68883 49 5

8 SQ68887 61 7

9 SQ68909 63 7

10 SQ68912 63 7

11 SQ68943 49 1

12 SQ68948 56 6

13 SQ69003 56 6

14 SQ69007 63 7

15 SQ69160 49 5

Total 803 83

Sr. No. Heat No.

No. of pipesFormed Tested

1 SP41257 49 1

2 SP41262 35 1

3 SP41346 21 1

4 SP41358 42 1

5 SP41478 35 4

6 SP41647 35 4

7 SP41699 42 1

8 SP41706 63 2

9 SP41708 42 1

10 SP41711 49 1

11 SP41858 42 1

12 SQ68380 56 6

13 SQ68383 49 1

14 SQ68386 35 115 SQ68545 49 1

16 SQ68550 49 1

17 SQ68653 35 1

18 SQ68790 42 1

19 SQ68815 42 1

20 SQ68822 56 2

21 SQ68890 63 722 SQ68892 49 1

23 SQ68900 42 1

24 SQ68906 63 2

25 SQ68951 63 7

26 SQ68954 63 2

27 SQ69001 28 1

28 SQ69167 21 1

Total 1260 55

Sr. No. Heat No.

No. of pipes


16/57


Co-relation of Coil YS &

Pipe YSfor




17/57


Statistics of Coil YS & Pipe YS for - Heats YS < 540 MPa (RMTC)

Total no. of heats (YS < 540 MPa) = 15

Observations:1. Mean increase in YS from Coil to pipe = 17 MPa (3.19%)2. CoV increase in YS from Coil to pipe = 0.9%

Reasons for observed changes are:1. Unwinding of coils & forming strains resulting in reverse plasticity. The effect ofreverse plasticity is almost negligible in this 13.44 mm as compared to 15.88 mm.

2. Different sample locations in coil & pipe3. Flattening of samples for testing4. The other important reason is D/t ratio where the effect of Bauschinger will be less in

42 OD pipe compared to 36 OD pipe.

0.080.880.802.230.020.8583Pipe YS/UTS


576786211.71165083Pipe UTS, MPa

585835262.11155083Pipe YS, MPa

0.080.810.732.510.020.7883Coil YS/UTS


507136631.81268283Coil UTS, MPa

195395201.2653383Coil YS, MPa



18/57


YS Change from Coil to Pipe - Heats YS < 540 MPa (RMTC)

620600580560540520500

60

50

40

30

20

10

0

YS, MPa

No.oftests


532.6 6.238 83

549.8 11.28 83

Mean StDev N

Coil YS (< 540 MPa)

Pipe YS

Variable

0000

50

13

20

42

18

32

22

5

0


P b bili Pl f Pi YS H YS 540 MP (RMTC)


19/57


600590580570560550540530520510500490480470

99.9

99

95

90

80

70

60504030

20

10

5

1

0.1

Pipe YS, MPa

Percent

LSL 485 MPa

Mean 549.8

StDev 11.28N 83

AD 0.801

P-Value 0.036


Probability Plot of Pipe YS Heats YS < 540 MPa (RMTC)

0.1% probability for YS < 509MPa at 95 % confidence level.

S i i f C il YS & Pi YS H YS 540 MP (RMTC)


20/57


Statistics of Coil YS & Pipe YS Heats YS 540 MPa (RMTC)

Total no. of heats (YS 540 MPa) = 28

Observations:1. Mean decrease in YS from Coil to pipe = 2 MPa (0.36%)2. CoV increase in YS from Coil to pipe = 0.5%

Reasons for observed changes are:1. Unwinding of coils & forming strains resulting in reverse plasticity. The effect ofreverse plasticity is almost negligible in this 13.44 mm as compared to 15.88 mm.

2. Different sample locations in coil & pipe3. Flattening of samples for testing4. The other important reason is D/t ratio where the effect of Bauschinger will be less in

42 OD pipe compared to 36 OD pipe.

0.100.900.802.170.020.8555Pipe YS/UTS


696866161.91365055Pipe UTS, MPa

675955272.31255155Pipe YS, MPa

0.060.840.781.380.010.8155Coil YS/UTS


617226612.01368155Coil UTS, MPa

415815401.81055355Coil YS, MPa


YS Ch f C il t Pi H t YS 540 MP (RMTC)


21/57


YS Change from Coil to Pipe Heats YS 540 MPa (RMTC)

620600580560540520500

25

20

15

10

5

0

YS, MPa

No.oft

ests

USL 635 MPaLSL 485 MPa

552.7 9.661 55

551.4 12.43 55

Mean StDev N

Coil YS ( 540 MPa)

Pipe YS

Variable

01

3

22

1415

001

21

1617

15

3

0


P b bilit Pl t f Pi YS H t YS 540 MP (RMTC)


22/57


610600590580570560550540530520510500490480470

99

95

90

80

70

6050

40

30

20

105

1

Pipe YS, MPa

Percent

LSL 485 MPa

Mean 551.4

StDev 12.43

N 55

AD 0.630

P-Value 0.096


Probability Plot of Pipe YS Heats YS 540 MPa (RMTC)

1% probability for YS < 516MPa at 95 % confidence level.


23/57


Dimensional Variation inPipes

Pipe Dimensions Out of Roundness (mm)


24/57


SPECIFICATION LIMITS: USL = 5.0 mm


54321

USL

LSL *

Target *

USL 5Sample Mean 2.70453

Sample N 2051

StDev (Within) 0.464885

StDev (O v erall) 0.545021

Process Data

C p *C PL *

CPU 1.65

Cpk 1.65

Pp *

PPL *

PPU 1.40

Ppk 1.40

O v erall C apability

Potential (Within) C apability

Within

Overall

BODY OUT OF ROUNDNESS



25/57




5432

USL

LSL *

Target *


Sample N 2051



Process Data

C p *

C PL *

C PU 1.81

Cpk 1.81

Pp *

PPL *

PPU 1.55Ppk 1.55


Potential (Within) Capability

Within

Overall

F END OUT OF ROUNDNESS



26/57




5432

USL

LSL *

Target *


Sample N 2051



Process Data

C p *C PL *

C PU 1.79

C pk 1.79

Pp *

PPL *

PPU 1.60Ppk 1.60



Within

Overall

T END OUT OF ROUNDNESS

Pipe Dimensions Body Diameter (mm)


27/57


SPECIFICATION LIMITS: LSL = 1063 mm, USL = 1071 mm


1070.41069.21068.01066.81065.61064.41063.2

LSL USL

LSL 1063

Target *

USL 1071

Sample Mean 1067.02

Sample N 2051



Process Data

C p 4.39

CP L 4.41

C PU 4.36

C pk 4.36

Pp 3.75

P P L 3.77

PPU 3.73Ppk 3.73



Within

Overall

BODY DIA METER ( B - 1 )

Cov 0.1%



28/57




1070.41069.21068.01066.81065.61064.41063.2

LSL USL

LSL 1063

Target *


Sample N 2051



Process Data

C p 3.86

CP L 3.63

C PU 4.09

C pk 3.63

Pp 3.28

P P L 3.08

PPU 3.47Ppk 3.08



Within

Overall


Cov 0.1%



29/57




1070.41069.21068.01066.81065.61064.41063.2

LSL USL

LSL 1063

Target *


Sample N 2051



Process Data

C p 3.73

CP L 3.55

CPU 3.92

Cpk 3.55

Pp 3.21

PPL 3.06

PPU 3.37Ppk 3.06



Within

Overall


Cov 0.1%



30/57




1071.01069.951068.901067.851066.801065.751064.701063.65

LSL USL

LSL 1063

Target *

U SL 1071Sample Mean 1066.8

Sample N 2051

S tDev (Within) 0.349542

S tDev (O v erall) 0.399545

Process Data

C p 3.81CP L 3.62

C PU 4.01

C pk 3.62

Pp 3.34

P P L 3.17

PPU 3.51Ppk 3.17



Within

Overall


Cov 0.1%

Pipe Dimensions End Diameter (mm)


31/57



1068.51068.01067.51067.01066.51066.01065.5

LSL USL

LSL 1065.41

Target *

USL 1068.59Sample Mean 1066.44

Sample N 2051



Process Data

C p 2.14

CP L 1.39

C PU 2.89

C pk 1.39

Pp 1.83

P P L 1.19

PPU 2.47Ppk 1.19



Within

Overall

F END DIA METER

Cov 0.1%

SPECIFICATION LIMITS: LSL = 1065.41 mm, USL = 1068.59 mm



32/57


p ( )

1068.51068.01067.51067.01066.51066.01065.5

LSL USL

LSL 1065.41

Target *


Sample N 2051



Process Data

C p 1.79

CP L 1.29

CPU 2.30

Cpk 1.29

Pp 1.58

PPL 1.13

PPU 2.02Ppk 1.13



Within

Overall

T END DIA METER

Cov 0.1%


Pipe Dimensions Wall Thickness (mm)


33/57


p ( )

14.5614.3014.0413.7813.5213.2613.00

LSL USL

LSL 12.9

Target *

U SL 14.78

Sample Mean 13.4202

Sample N 2051



Process Data

C p 4.19

CP L 2.32

C PU 6.06

C pk 2.32

Pp 3.62

P P L 2.00

PPU 5.23Ppk 2.00



Within

Overall

F END WALL THICKNESS

Cov 0.6%


Pipe Dimensions Wall Thickness (mm)


34/57


p ( )

14.5614.3014.0413.7813.5213.2613.00

LSL USL

LSL 12.9

Target *

USL 14.78

Sample Mean 13.4258

Sample N 2051



Process Data

C p 4.52

CP L 2.53CPU 6.52

Cpk 2.53

Pp 3.85

PPL 2.15

PPU 5.55

Ppk 2.15



Within

Overall

T END WALL THICKNESS

Cov 0.6%


Pipe Dimensions Root Face (mm)


35/57



p ( )

2.42.11.81.51.20.9

LSL USL

LSL 0.8

Target *


Sample N 2051



Process Data

C p 2.98

CP L 3.25

C PU 2.72

C pk 2.72

Pp 2.51

P P L 2.73

PPU 2.29Ppk 2.29



Within

Overall

F END ROOT FACE

Pipe Dimensions Root Face (mm)


36/57



p ( )

2.42.11.81.51.20.9

LSL USL

LSL 0.8

Target *

U SL 2.4

Sample Mean 1.70878

Sample N 2051



Process Data

C p 2.85

CP L 3.23C PU 2.46

C pk 2.46

Pp 2.53

P P L 2.87

PPU 2.18

Ppk 2.18



Within

Overall

T END ROOT FACE

Pipe Dimensions Straightness (mm)


37/57



109876543

USL

LSL *

Target *


Sample N 2051



Process Data

C p *

C PL *

C PU 2.21

C pk 2.21

Pp *

PPL *

PPU 2.08Ppk 2.08



Within

Overall

STRAIGHTNESS

Pipe Dimensions Squareness (mm)


38/57



1.61.41.21.00.80.60.40.2

USL

LSL *

Target *

U SL 1.6

Sample Mean 0.466017Sample N 2051



Process Data

C p *

C PL *C PU 4.79

C pk 4.79

Pp *

PPL *

PPU 4.15

Ppk 4.15



Within

Overall

F END SQUARENESS

Pipe Dimensions Squareness (mm)


39/57



1.61.41.21.00.80.60.40.2

USL

LSL *

Target *

USL 1.6

Sample Mean 0.476451

S ample N 2051



Process Data

C p *

C PL *C PU 4.78

Cpk 4.78

Pp *

PPL *

PPU 4.06

Ppk 4.06



Within

Overall

T END SQUARENESS

Pipe Dimensions Peaking (mm)


40/57



1.61.41.21.00.80.60.40.2

USL

LSL *

Target *

USL 1.6

Sample Mean 0.66509

Sample N 2051



Process Data

C p *

C PL *C PU 2.05

C pk 2.05

Pp *

PPL *

PPU 1.87

Ppk 1.87



Within

Overall

F END PEAKING



41/57



1.61.41.21.00.80.60.4

USL

LSL *

Target *

USL 1.6


Sample N 2051



Process Data

C p *

C PL *C PU 1.97

C pk 1.97

Pp *

PPL *

PPU 1.76

Ppk 1.76



Within

Overall

T END PEAKING



42/57



3.22.82.42.01.61.20.80.4

USL

LSL *

Target *

USL 3.2


Sample N 2051



Process Data

C p *

C PL *

C PU 8.63

C pk 8.63

Pp *

PPL *

PPU 7.19Ppk 7.19



Within

Overall

BODY PEAKING


43/57


Pipe Outside DiameterBefore & After

Hydro-Testing (HT)

Increase in Pipe OD After Hydro-testing Body


44/57


1070106910681067106610651064

2800

2400

2000

1600

1200

800

400

0

Outside diameter, mm

No.of

pipes

LSL 1063 mm USL 1071 mm

1066 0.3804 2051

1067 0.3254 2051

Mean StDev N

Body (Before HT)

Body (After HT)

Variable

00577

1526

440

21 19

277

1750

13010

Histogram of Body (Before HT), Body (After HT)

Mean shift after hydro-testing = 1.0 mmMax. shift after hydro-testing= 2.0 mm

(At 97% SMYS)

Increase in Pipe OD After Hydro-testing T-End


45/57


1068.01067.21066.41065.61064.8

1200

1000

800

600

400

200

0

Outside diameter, mm

No.of

pipes

LSL 1065.41 mm USL 1068.59 mm

1066 0.3139 2051

1067 0.3359 2051

Mean StDev N

T-END (Before HT)

T-END (A fter HT)

Variable

02619

149

828883

162

1

1 3824

201

692

929

186

80

0

Histogram of T-END (Before HT), T-END (After HT)

Mean shift after hydro-

testing = 1.0 mmMax. shift after hydro-testing= 1.0 mm

(At 97% SMYS)

Increase in Pipe OD After Hydro-testing F-end


46/57


1068.01067.21066.41065.6

1000

750

500

250

0

Outside daimeter, mm

No.of

pipes

LSL 1065.41 mm USL 1068.59 mm

1066 0.3013 2051

1066 0.2895 2051

Mean StDev N

F-END (Before HT)

F-END (After HT)

Variable

01211

115

678

1008

233

3

121094

521

1124

295

40

Histogram of F-END (Before HT), F-END (After HT)

Mean shift after hydro-testing = 0 mmMax. shift after hydro-testing= 0.9 mm

(At 97% SMYS)


47/57


Conformance to ChemicalComposition

Statistics of CE (Pcm) & CE (IIW)


48/57


No. of heats = 43

0.030.4080.381.40.0060.3986CE(IIW), %

0.020.1890.172.00.0040.1886CE(Pcm), %


CE (Pcm) 43 Heats


49/57


0.2150.2100.2050.2000.1950.1900.1850.1800.1750.1700.165

50

40

30

20

10

0

CE(Pcm), %

No.oftests(2

pipes/heat

)

USL 0.21%

Mean 0.1797

StDev 0.003557

N 86

1

17

45

21

11

Histogram of CE(Pcm)

CE (IIW) 43 Heats


50/57


0.410.400.390.38

70

60

50

40

30

20

10

0

CE(IIW), %

No.oftests(2

pipes/heat)

Mean 0.3941

StDev 0.005665

N 86

3

28

52

3

Histogram of CE(IIW)


51/57


Repair and Rejection

Detailswith

Reasons

Repair & Rejection Summary


52/57


0.5912TOTAL

0.051Excess weld repair

0.051Scratch

0.051Over diameter

0.051Indentation mark (Raw material defect)

0.102Sliver

0.102Formation trial pipe

0.204Low thickness (Excess grinding due to scratch)

Rejection, %No. of pipesReason

REJECTION SUMMARY

2.6254TOTAL

0.051Gas pocket

0.051Under fill

0.5311Porosity

0.8718Slag

1.1123Under cut

Repair, %No. of pipesWeld defect

WELD REPAIR SUMMARY

Repair Details


53/57


23

18

11

1 1

0.05

0.53

1.11

0.05

0.87

0

5

10

15

20

25

U

ndercut

Slag

Porosity

Underfill

Ga

spocket

Weld defect

No.ofpipesrepaired

0.0

0.5

1.0

1.5

2.0

2.5

%o

fpipesr

epaired(basedonno.of

pipe

formed&welded)

No. of pipes

Repair, %

Total no. of pipe formed & welded = 2063

Rejection Details


54/57


4

2 2

1 1 1 1

0.05

0.10 0.10

0.05 0.05 0.05

0.20

0.0

0.5

1.01.5

2.0

2.5

3.0

3.5

4.0

4.5

Lowthickness

(Excessgrinding

duetoscratch)

Formationtrial

pipe S

liver

In

dentationmark

(Rawmaterial)

Overdiameter

Scratch

Excessweld

repair

Reason

No

.ofpipesrejected

0.00

0.05

0.100.15

0.20

0.25

0.30

0.35

0.40

0.45

%o

fpipes

rejected(basedonno.of

pipeformed&welded)

No. of pipesRejection, %

Total no. of pipe formed & welded = 2063

Fish-bone Diagram for Slag


55/57


Slag

Man Machine

Method Material

Incorrect flow of flux from hopper

Due to improper dust cleaning prior to back repair& ID/OD welding

Due to scale on the coil surface

Due to heavy ruston the coil

During RSI/RSO, improper flux level/imbalance inwelding parameters (very high voltage at start)

More dust along with fluxdue to improper cleaning

Improper grinding duringtack repair Open arc due to

improper flux boat

Due to loose scale &dust on coil surface

Improper grinding duringSMA welding repair

Improper fluxscreening

Setting of very high / very low voltage

Fish-bone Diagram for Porosity


56/57


Porosity

Man Machine

Method Material

Incorrect flow of flux from hopper

Due to improper dust cleaning prior to back repair& ID/OD welding

Due to moisture, paint, grease &oil presence in edge groove

Usages of damp/hydrogenentrapped fluxes

During RSI/RSO, improper flux level/imbalance in

welding parameters (very high voltage at start)

More dust along with fluxdue to improper cleaning

Improper grinding duringtack repair

Improper gas shielding

during MIG (auto & manual)welding

Open arc due toimproper flux boat

Due to loose scale &

dust on coil surface

Improper flux shielding (shallow flux level) open arcproblem

Improper fluxbacking/

preheatingSetting of very high / very low voltage

Fish-bone Diagram for Undercut

M i l


57/57


Under Cut

Man Machine

Method Material

Wire bending due to absence of

wire straightener

Improper travel of welding head due to

more/less pipe pitch length

RSI/RSO weld bead not matchingwith the original weld bead

Improper setting/manipulation of lasers

Presence of dents on groove edges

Improper lasertracking as temp.exceeds the limit

Improper edge milling leading to distortedbevel/groove geometry

Setting of high current, voltage & speed

Setting of incorrect wireangle/incorrect stick-out

Malfunction of laser if lasertemp. exceeds 50 deg C

statistical quality report for 42 inch odx13.44 mm (0.529) wt

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