REPORT ON ROOT CAUSE ANALYSIS CORRECTIVE ACTION...

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REPORT ON

ROOT CAUSE ANALYSIS & CORRECTIVE ACTION FOR

1) LEAKAGE AT GLAND PACKING IN MOTORISED VALVES & BYPASS VALVE

2) BLACKENING & SCRATCHES IN STEM

Team Members:

S. Rangaprasad – Sr.DGM, Manufacturing

M.K. Baranidharan – DGM, Quality control

D. Muralidharan – DGM, Manufacturing

C.Elumalai‐ Engineer, Production

Raja Chacko – Manager, Quality Assurance

S.Suriyanarayanan‐ Manager, Design

S.Kannan‐ Manager, QC

L. Rajagopal – Manager, Quality Control

H.Sadanand ‐ Executive, Sales

Date: 08‐Jan‐2014

Ref: NCR number LTVL/KO/001 dated 13/08/2013 from Koradi Boiler

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CONTENTS

1.0 Background

2.0 Preliminary Analysis

3.0 Correction

4.0 Root cause Analysis

5.0 Corrective action

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1.0 Background:

Valve details:

Project Koradi Boiler

Valve Type Gate

Valve size Various sizes

Class 2500

Material All grades

Quantity

41 Nos Refer annexure for total valve supplied in Cl 2500 Vs problem reported from various sizes.

Customer P.O LMB/V04/21000‐13795 & 13877

L&T Valves Sale Order 6001864, 6002056, 6001866, 6002057

Pressure & temperature conditions

Leakage noticed at 400bar pressure & 500°C temperature

Details for Primary SH drain line valve: Gland leakage observed in by pass valve

Project Koradi Boiler

Main valve details 3” 2500 SPL GATE WC9 T5 BW IBR

Main valve serial no C903074

Bypass Valve Type size / Material

Globe/DN 20/F22

Quantity /Bypass valve serial no

1 No (Bypass valve serial no : C803047)

Customer P.O LMB/V04/21000‐13841/46, BOQ No: 87

L&T Valves Sale Order/line item

6001866/2910

Tag number 09HAH01AA902

GAD Number 89000‐1027 Rev 5

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Annexure for CAR LTVL/KO/001 DATED 13/08/2013

Customer Site No. of valves

supplied in CL 2500

No of valves

problem reported

Koradi boiler Unit 8 52 23*

Koradi boiler Unit 9 52 18**

*Unit 8 valve details: Gland Leakage in valves

8” CL 2500 Gate 14 Nos

DN 20 CL 2500 T globe 4 Nos

20” CL 2500 Gate 1 No

6” CL 2500 Gate 1 No


12” CL 2500 Gate 1 No

**Unit 9 valve details: Gland Leakage in valves


DN 20 CL 2500 T globe 12 Nos

20” CL 2500 Gate 1 No



Complaint Number‐ LTVL/KO/001 dated 13/08/2013

Leakage noticed in gland packing in motorized valves. Out of 156 valves supplied in CL 2500, gland leakage

noticed in 41 valves

Valves supplied in this project:

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CLASS RATING CL 1500 CL 2500 CL 3100

SUPPLIED QUANTITY 36 Nos 156 Nos 18 Nos

2.0 Site feedback:

Koradi boiler: Unit 8 ‐Valves installed in SH DeSH Spray water line. L&T Valves team visited the site on 13‐

Aug‐2013. During site visit, it was informed by Mr. Arpit Washik, Site Engineer that while conducting hydro

testing @400 bar, 16 valves installed in the line leaked thro’ gland packing.

Observations noticed during site visit are given below:

1) 7 valves leaked even after tightening gland bolts. Spares sent subsequently & gland packing

changed (packing ‐1 bottom braided packing +4 Endless die moulded packing +1 Top braided

packing)

2) Observed unevenness in gland flange tightening.

3) Blackening & scratches noticed in stems in two valves

4) Leakage in Bypass line valve:‐ DN20 #2500, F22, Sr.‐ C803047,Hand wheel operated T Globe valve,

welded with main valve 3” 2500 WC9 Gate

Gland leakage

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3.0 Correction:

3.1 – Gland leakage

STEM –Blackening & scratch marks

Bypass Valve Gland Leak (Valve Serial No. : C803047)

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Koradi (Unit 8 & 9):‐

a) Gland leakage during hydro test @ 400 bars at Unit 8 – 23 nos. & Unit 9 ‐ 18 nos. (temperature

500°C)

b) In the above valves, leakage has been arrested by retightening of gland and changing the gland

packing

c) Training program conducted at customer site on 13th Aug 2013 to brief on the gland torque

requirements, Dos’s & Don’ts to be followed during installation and operation

d) All WIP valves (at factory) have been retightened to design torque

e) In order to validate the design torque, we have taken 10 Nos of WIP valves (at factory) in Class

2500 in various sizes. These valves were retested (hydro seat) after ensuring the tightening to

the design torque & found satisfactory.

f) Bypass line valve:‐ DN20 #2500, F22, Sr.‐ C803047 (unit‐8 valve), Hand wheel operated T Globe

has been replaced with Unit ‐9 valve & new valve has been dispatched from factory on 02nd Jan

2014.

g) Requested the Site Engineer to return the Defective valve to L&T Valves for detailed

investigation

4.0 Root Cause Analysis for gland leakage:

RCA‐ROOTCAUSEANALYSISSHEET–GLANDLEAKAGEPROBLEMDESCRIPTION DESCRIPTIONAREA DESCRIPTIONDATA

WHAT

Leakage thro gland packing in CL 2500 rating valve

Leakage thro gland packing was observed @ 400 bar

WHERE Gland packing The stuffing box is packed with 6 packing rings to avoid leakage thro stem. During hydro test, leakage was observed thro packing @ 400 bar

WHENDuring pressure testing During pressure testing @4 00 bar, leakage noticed

HOW BIG

Minor leakage observed in 41 valves & profuse leak observed in 1 bypass valve

After gland tightening also, leakage noticed in 7/16 valves.

SimilarParts- -

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S No CAUSES SIGNIFICANT / IN-

SIGNIFICANT

1a Gland packing material quality not meeting to specification Insignificant

1b Packing dimensions out of specification Insignificant

2 Design torque not sufficient Insignificant

CAUSEANDEFFECTDIAGRAM‐ DEFINE&VERIFYROOTCAUSE

MAN MATERIALS

METHODS/PROCESSES MACHINE

Leakage at

gland packing

Torque setting not done as per

design specification

Gland tightening torques disturbed

after pressure testing

Uneven gland bolt tightening

Gland packing material quality

not meeting to specification

Usage of torque wrenches

without proper calibration

Awareness on gland tightening

torque prior to commissioning

Gland holes offset w.r.t stuffing box

inner dia during machining

Stem OD & Bonnet ID surface

roughness poor & dimension out of

specification

Packing dimensions out of

specification

Design torque not sufficient

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3 Torque setting not done as per design specification during pressure testing Insignificant

4 Stem OD & Bonnet ID surface roughness poor & dimension out of specification Insignificant

5 Gland tightening torques disturbed after pressure testing Significant

6 Usage of torque wrenches without proper calibration Insignificant

7 Gland holes offset w.r.t stuffing box inner dia during machining Insignificant

8 Uneven gland bolt tightening Significant

9 Awareness on gland tightening torque prior to commissioning Insignificant

10 Usage of torque wrenches without proper calibration Insignificant

5.0 Analysis for gland leakage:

S No CAUSES Verification status

1a Gland packing material quality

not meeting to specification Material test certificate reviewed and found satisfactory

1b Packing dimensions out of

specification Packing dimensions verified & found meeting the drawing requirements

2 Design torque not sufficient Design specification validated by pressure testing & found satisfactory

3 Torque setting not done as per

design specification during

pressure testing

Hydro seat test performed by tightening the gland nuts to the requirement

4 Stem OD & Bonnet ID surface

roughness poor & dimension

out of specification

Components verified & found meeting the drawing specification.

5 Gland tightening torques

disturbed after pressure

testing

Hydro seat test performed by tightening the gland nuts to the requirement. On completion of pressure testing & subsequent valve performance test, (verification of open/close movement) gland nuts were loosened but not tightened to requirement

6 Usage of torque wrenches

without proper calibration Torque wrenches are being calibrated at periodic intervals as per the quality system procedure ML-05 and found OK

7 Gland holes offset w.r.t

stuffing box inner dia during

machining

Dimensions verified & found meeting the drawing requirements

8 Uneven gland bolt tightening During WIP stock inspection bolts not tightened uniformly on both sides in 1/25 Nos

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9 Awareness on gland tightening

torque prior to commissioning Operators & QC personnel are aware of the requirements. Customer complaint was briefed

6.0 Root Cause Analysis for stem blackening & scoring marks:

RCA‐ROOTCAUSEANALYSISSHEET– STEMBLACKENING&SCRATCHMARKSPROBLEMDESCRIPTION DESCRIPTIONAREA DESCRIPTIONDATA

WHAT

Scoring marks in stem &

graphite packing sticking

Gland packing is found sticking to the valve stem (packing bore area).

& scratch mark noticed in valves

WHERE On Stem Outer diameter

having contact with Packing Black marks observed on stem OD.

WHENAfter valve operation

After open /close movement, black marks noticed on Stem outer

diameter having contact with packing

HOW BIGMinor Black layer of graphite sticking on the stem

SimilarParts- -

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S No CAUSES SIGNIFICANT / IN-

SIGNIFICANT

1 Stem OD & Bonnet ID surface roughness poor & dimension out of specification Insignificant

2 Packing dimensions out of specification Insignificant

3 Uneven gland bolt tightening Significant

4 Excess tightening torque applied in gland bolts

Insignificant

5 Awareness on gland tightening torque procedure Insignificant

CAUSEANDEFFECTDIAGRAM‐ DEFINE&VERIFYROOTCAUSE

MAN MATERIALS

METHODS/PROCESSES MACHINE

Stem

blackening &

scratch marks

Uneven gland bolt tightening

Proper storage condition of

finished valves

Gland packing material

quality not meeting to

specification

Awareness on gland

tightening torque

procedure

Gland holes offset wrt ID during

machining

Stem OD & Bonnet ID surface roughness

poor & dimension out of specification

Packing dimensions out of

specification

Excess tightening torque

applied in gland bolts

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6 Gland holes offset wrt ID during machining Insignificant

7 Proper storage condition of finished valves Insignificant

8 Gland packing material quality not meeting to specification Insignificant

7.0 Analysis for stem blackening & scoring marks:

S No CAUSES Verification status

1

Stem OD & Bonnet ID

surface roughness poor &

dimension out of

specification

Components verified & found meeting to the drawing specification.

2 Packing dimensions out of

specification Packing dimensions verified & found meeting the requirements

3 Uneven gland bolt tightening During WIP stock inspection bolts not tightened uniformly on both sides in 1/25 Nos

4 Excess tightening torque

applied in gland bolts Torque applied as per the design specification

5 Awareness on gland

tightening torque prior to

commissioning

Operators & QC personnel are aware of the requirements. Customer complaint was briefed

6 Gland holes offset wrt ID

during machining Dimensions verified & found meeting the drawing requirements

6 Proper storage

condition of valves Valves are being stored with proper protection

7 Gland packing material

quality not meeting to

specification

Material test certificate reviewed and found satisfactory

8.0 Corrective action:

Based on the above, the following corrective actions have been initiated:

a) Gland tightening torque as per design specification is being ensured and recorded in

Final inspection report by QC ‐ Implemented

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b) Training given to operators to tighten the gland studs using torque wrench & instructed

to tighten uniformly.

c) Stem alignment is being ensured during testing / final inspection stage; Uniform

clearance between stem and gland flange is being ensured now

d) Instruction on gland packing tightness has been provided in IOM (LT‐IOM‐09 Rev 0)

e) During master product development plan, we had decided to use imported packings inn

3100 & above class rating valves. Parallely we have evaluated the necessity to shift this

improvement to 2500 class rating valves also. As part of this initiative, it has been

decided to use imported packing in cl 2500 valves in super critical plant applications for

all our future supplies. As a very special case, it has been decided to replace the existing

packing with imported packing in Cl 2500 valves supplied to Koradi site.

Prepared by Approved by

C.Elumalai L.Rajagopal

Date: 04.01.2014

== End of report ==

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