दक्षि�ण रे�लवे� SOUTHERN RAILWAYकॆं� द्री य कॆंर्म�शा�ल�य�, गो�ल्डऩरे�कॆं

Central Workshops, Goldenrockति�रुच्चि�रे�प्पल्लि�ल ६००००४/ Tiruchirappalli 620004

SR ACCN 99119

Anchor Link Failure Analysis

Report

COACH FAILURE ANALYSIS REPORT1. Failure Reported:

Coach No. SR ACCN 99119 was detached en-route from train no. 12642 (NZM – CAPE,

Thirukkural Express) at Vijayawada on 27.01.2015 at about 13.30 hours, due to breakage of Anchor Link in Trailing End Bogie No. RCF 032123/03 at housing end of Bogie Frame Transom and the broken portion was hanging. This was found in Rolling-in-Examination when it arrived at PF-5 of Vijayawada station and the coach was detached. The train resumed its service with a delay of about 100 minutes.

2. Detached Coach Details:

Coach No : SR ACCN 99119Coach Make RCF Date of put into service : 10.01.1999POH : GOC – 10/11/2014Return Date : 30.06.2016No. of days worked : 77 days (Failure within 100 days)Primary Maintenance : NCJ on 23.01.2015Bogie Details in coach (As per POH work diary)

: RCF 032123/03 & RCF 062760/06 (Date of POH of Bogies: 27.10.2014)

Owning Railway & Base Depot : S.Rly & TVC

3. Deputation of staff:

The following staff had been deputed & proceeded immediately for investigation of the failure.

1. Mr. P.Sureshkumar, SSE 2. Mr. Gnanasekaran, SSE

4. Joint investigation at Site:

Investigation was conducted at Vijayawada sick line on 28.01.2015 jointly by GOC team & SSE/C&W/BZA/S.C.Rly. The observations are given below. 4.1 The failed Anchor Link stripped from Bogie No. RCF 032123/03 and put new anchor link.4.2 The NPEV end of the coach ACCN 99119 left hand side Anchor Link pipe broken on the

welding joint to anchor link housing which is connected to bogie frame.4.3 The other side of anchor link connected to bolster end. Welding joint is in good condition

and silent block is in slacked condition. The broken anchor link is new with black colour paint and having sticker as “SGEW 06/13” on anchor link housing outside.

4.4 10% of breakage emanated from weld crack and pipe torn & broken.4.5 Anchor link pin square end insertion in holding bracket on bogie end was found having

shim tack welding.4.6 Locking plate was having corner hit marks as well as Anchor Link housing was having hit

marks on bottom.4.7 Findings by the above team:

4.71 Micro play between Anchor Link housing and silent block coupled with weld defect caused shearing force and breakage.

4.72 Broken anchor link taken by GOC shop for CMT testing & warranty claim on supplier.

Page 1 of 7

5. Photographs taken at site (BZA):

6. CMT Lab Analysis at GOC of Breakage of Anchor Link:

The failed anchor link was subjected to CMT lab analysis and the nutshell of the report is given below.

6.1 Observations given in the Lab report:

a) Chemical composition of the Anchor Link is conforming to the specification IS:10748/2004.b) At the transom end of anchor link, the pipe was broken from the housing along the welded area. c) Remnants of weld metal are partially available on the anchor link housing with fractured piece of

the pipe.d) At the bolster end side, the silent block is freely moving inside the housing.e) The wall thickness of the anchor link pipe is not uniform and varies from 3.62 mm to 3.76 mm as

against the specified value of 4.05 to 4.50 mm as per IS:1161:98 mentioned in drawing no. T-0-7-604, alt – j/13.

f) About 21% of the circumferential welded area along the housing suffers from lack of fusion/ penetration.

g) The macro examination of fractured surface of the pipe reveals 25% of the area having voids characteristic of sudden brittle fracture and the remaining 75% is having formation of shearing lips characteristic of ductile fracture involving high torsion stresses.

6.2 CMT Lab Report - Conclusion:

a) The wall thickness of the anchor link pipe is not uniform and varies from 3.62mm to 3.76mm as against 4.05mm (4.5mm minus 10% tolerance) specified for Heavy grade mentioned in the specification IS: 1161/98 referred in the drawing no. T-0-7-604, alt – j/13.

b) Lack of fusion/Penetration of the weld metal with the anchor link pipe along the periphery of the housing (around 21 %.). It is leading to loss of strength of the weld.

c) The molten metal sputtering near the weldment affecting the region near the weld cast has acted as an initiation site for the process of failure to occur.

d) The play between the anchor link housing and the coupled silent block on the bolster side has created an imbalance on the other side of the anchor housing at the transom end.

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Broken tube hanging

7. Dimensional Check of the failed components:

Anchor Link Housing Bore Silent Block

Inner Diameter of Anchor Link Housing supplied by

M/s. Sugovri Engineering Works, Howrah

Silent Block (Outer Diameter) supplied by

M/s. MGM Rubber Co. KolkataInterference

SampleDrawing

Size(mm)

SideActual(mm) Sample

Drawing Size

(mm)Side

Actual(mm)

As per Drawing Actual

І90.470

to90.515

1

1 90.520

І90.525

to90.550

1

1 90.260

0.01 to

0.08

0.210to

0.760(Clearance

fit)

2 90.490 2 90.2803 90.510 3 90.2801 90.520 1 89.7602 90.460 2 90.1403 90.450 3 90.130

Note: From the above table, the fit is only clearance fit and as against the force fit. Hence the silent block is freely moving inside the housing.

Anchor Link pipe: Thickness of Anchor Link pipe supplied by M/s. Sugovri Engineering Works, Howrah

90.520

90.490

90.51090.450

90.460

90.520

90.280

90.280

90.260

90.130

90.140

89.760

Sample

Drawing Size

Thickness (mm)

Side LocationActual

Thickness (mm)

14.05 mm

to4.50 mm

1

1 3.660

2 3.620

3 3.640

4 3.680

5 3.700

6 3.760

7 3.720

8 3.740

Page 3 of 7

8. Traceability of failed components:

8.1 Anchor Link:The failed anchor link was a new one as per the sticker “SGEW 06/13” available on the anchor link housing. The procurement details of the item is given below.

Sl.No.

Supplier Name P.O.No.Supplied Qty. (Nos.)

Received Date

Inspected by

1.M/s. Sugouri Engineering Works, Howrah

04.12.0161.1.01521 dated 27.05.2013 886 24.09.2013 RITES

8.2 Silent Block: The stamping of manufacturer details on the silent block indicates “MGM 06/14”. The procurement details is given below.

Sl.No.

Supplier Name P.O.No.Supplied

Qty. (Nos.)Received

DateInspected

by

1. M/s. MGM Rubber Company, Kolkata

04.13.0160.1.04425 dated 10.02.2014

2500 19.07.2014 RDSO

9. Preventive check on the items available at GOC belonging to the same consignment:

3.680

3.660

3.740

3.760

3.720

3.620

3.700

3.640

Anchor Link Silent Block

Inner Diameter of Anchor Link Housing supplied by

M/s. Sugovri Engineering Works, Howrah

Silent Block (Outer Diameter) supplied by

M/s. MGM Rubber Co. KolkataInterference

SampleDrawing

Size(mm)

Side Actual(mm)

SampleDrawing Size(mm)

Side Actual(mm)

As per Drawing

Actual

I90.470

to90.515

11 90.400

I90.525

to90.550

1 90.526

0.01 to

0.08

0.020to

0.200

2 90.440

21 90.510

2 90.6022 90.510

II1

1 90.430

II1 90.602

2 90.510

21 90.480

2 90.5512 90.510

Note: As per the tabulation given above, both the items are confirming to the drawing dimensions.

Page 4 of 7

10. Failure analysis based on the available evidences –Lab Report, dimensional check, photographs and joint observation by SSEs/GOC & SSE/BZA:

10.1 Based on the identity on the failed components both Anchor Link and Silent Block were newly

fitted during POH.

10.2 Anchor Link housing bore diameter is 90.450 mm to 90.520 mm as against the drawing size of

90.470 mm to 90.515 mm (dimension checked at six locations as per table above).

10.3 Silent block outer diameter is 89.760 mm to 90.280 mm as against the drawing size of 90.525

mm to 90.550 mm. i.e. the silent block is undersize.

10.4 The silent block should be force fitted into the Anchor Link Housing. But as per Sl.No. 2 & 3

1 1

2 2

Side 1 Side 2

1

2

above, the fit is only clearance fit and hence the silent block is freely moving inside the housing.

10.5 The wall thickness of the anchor link pipe is not uniform and varies from 3.62 mm to 3.76 mm

as against the specified value of 4.05 to 4.50 mm as per IS:1161:98 mentioned in drawing no. T-

0-7-604, alt – j/13.

11. Conclusion:

11.1 The prime reason for the failure is the breakage of Anchor Link pipe at weld point due to lack of

fusion/ penetration. The firm M/s. Sugovri Engineering Works, Howrah had used pipe with

lesser wall thickness and failed to weld properly. The firm should have ensured correct usage of

items with proper quality control during manufacturing process.

11.2 The silent block is found undersize, which causes play between Anchor Link Housing and silent

block. This created imbalance on the other side of the Anchor Link Housing, where weld failure

happened. The firm M/s. MGM Rubber Company, Kolkata should have ensured strict quality

control of their manufacturing process.

11.3 Both the failed items are under warranty and the firms were asked to supply the items as

warranty replacement. The firms had been advised to depute their staff to GOC for joint

inspection of the failed components for further action.

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12. Corrective/ preventive actions taken:

The following corrective / preventive actions had been implemented.

Sl.No.

Maintenance Instructions as per CAMTECH manual

Clause No.

Repair Practice followed at GOC Workshops

Corrective / Preventive Action taken

1. Replace the anchor link, if worn or corroded. Repair the anchor link, if found cracked (normally at weld joints) under magna flux testing, by re welding after

316e (i) Anchor

Link

Anchor Links dismantled from POH Bogies are 100% stress relieved in oven. Then, they are subjected to chalk test for welding crack.

a. Magna flux testing is introduced now to assess weld quality of Anchor Link.

b. A Plug gauge has

gouging. Refit new silent block in every POH.

The corroded/ bent/ cracked/ twisted Anchor Links are disposed as scrap. No repair is undertaken in Anchor Links. New Anchor Links are replaced in place of corroded/ bent/ cracked/ twisted ones.

been developed to check the Anchor Link Housing bore before pressing with silent block.

1 (a) Magna flux testing is introduced now to assess weld quality of Anchor Link

1(b) Plug gauge has been developed to check the Anchor Link Housing bore before pressing with silent block.

Page 6 of 7

Sl.No.

Maintenance Instructions as per CAMTECH manual

Clause No.

Repair Practice followed at GOC Workshops

Corrective / Preventive Action taken

2. Replace the silent block, if the rubber is perished (indicated by fretting) or loose in the anchor link housing, or the silent block pin is worn thin or loose in silent block rubber. It is a “Must change item” in every POH (18 months) as per CAMTECH/2008/

316e (ii) Anchor

Link

Silent blocks are renewed 100% during POH. They are force fitted in the Anchor Link using Hydraulic press as specified.

a. Pressure gauge has been fitted in the pressing machine to observe the pressing-on pressure.

b. Ring gauge is made available to check the outer diameter of the silent block

Coach-POH/1.0 issued inJan-2008 by CAMTECH. The silent block should be force fit in the anchor link and the silent block pin should be slide fit in the anchor link bracket.

before pressing.

Note: Corrective/ preventive action mentioned at sl. No. 1(b) & 2(b) ensures the correct Interference for Force Fit.

Previously Pressing machine without pressure gauge

Pressing machine with pressure gauge after fitment

2(a) Pressure gauge has been fitted in the pressing machine to observe the pressing-on pressure

2(b) Ring gauge is made available to check the outer diameter of the silent block before pressing

********Page 7 of 7

Ring Gauge