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Page 1 of 15
ROOT CAUSE ANALYSIS & CORRECTIVE ACTION FOR PNEUMATIC OPERATED 36”CL 150 TRUNNION MOUNTED
BALL VALVES OPERATABILITY ISSUES
Team Members:
Date:11-Jan -2016
Ref: Mail dated: 21-Dec-2015
Prepared by Approved by
S.Rajesh-Sr.Engineer QA
M. Gunasekaran –DGM QA
N Kesavan – Sr.DGM, Manufacturing
M Gunasekaran – DGM, Quality Assurance
P Sudharsanam – Asst.Manager, Design
R. Selva Kumar – Sr. Engineer, Quality Control
S. Rajesh – Sr. Engineer, Quality Assurance
H. Lakshminarayanan – Asst. Manager, Manufacturing
M. Balasubramanian – Executive, Manufacturing
Vikash kulshrestha – Manager, Servicing
M.K. Baranidharan – DGM, Quality control
Page 2 of 15
CONTENTS
1.0) Background of the complaint as received.
2.0) Preliminary Investigation done at LTVL on receipt of complaint
a. Verifications at L&T Valves Factory
3.0) Site visit and observation
4.0) Based on site observation of damaged components Correction carried out
5.0) Root Cause Analysis: To identify the underlying cause
a. Problem Description
b. Cause and Effect Diagram
c. Significant Causes
d. Why- Why analysis
6.0) Conclusion
7.0) Corrective action
8.0) List of Spares supplied
9.0) Reference Documents
Page 3 of 15
1.0 Background of the complaint as received:
Complaint Description: It was reported from CAIRN site at Barmer that large TMBV valves in size 36”class 150 - 2 No’s reported as jamming during preliminary on/off test after few cycles before start up while commissioning the valves in pipelines. Following table gives the summary of the valve details
Sl No Valve Description Valve Sl No Tag No Complaint Reported at Site
1 36” # 150 TMBV 14G701116 MPT-XSV-2542 Pneumatic actuator valve got jammed 2 36” # 150 TMBV 14G701115 MPT-XSV-2642
2.0 Preliminary Investigation done at LTVL on receipt of Complaint A) Verifications of Documents
The following documents were verified and found in order:
Shell & End connector Dimension Reports verified & found OK.
Ball Dimension Report Verified & Found OK
Seat Ring Dimension report Verified & Found OK
Stem Dimension report verified & Found OK
Stem Housing Dimension Report verified & Found OK
Bearing Block Dimension Report Verified & Found OK
Junk Ring & Gland Dimension Reports verified & OK
Hydro Test Report (VTR) Verified & Found OK
Actuator Functional Test Report Verified & Found OK
Material Test certificate verified for Pressure Bearing components & Found OK
Internal valve test report Verified & Found OK.
Page 4 of 15
Actuator Test Certificate for Pneumatic actuated Valves verified & Found OK.
Partial Stroke Test (PST) Report Verified for Pneumatic actuated Valves & found OK.
Final inspection report Verified & Found OK.
Pre Dispatch Inspection Report Verified & Found OK.
1 Valve TPI Witness done by Bureau Veritas
B) Verifications of WIP valves at shop assembly
Similar WIP valves were sampled for functional test and found having smooth operation.
Random sampling check carried from the available WIP Stem, Stem housing , Stem Bearing components of its dimension & found meeting the requirement.
Page 5 of 15
3.0 Site Visit & observation LTVL deputed his engineers from service as well as from production to do the onsite assessment and evolve correction work 1st visit by LTVL Engineers - 30th Nov 2015 o 04th Dec 2015 ( Visit by Mr. Sugumar) 2nd visit by LTVL Engineers - 13th Dec 2015 to 28th Dec 2015 (Visit by Mr. Balasubramanian) 3rd visit by LTVL Engineers - 19th Dec 2015 to 9th Jan 2016(Visit by Lakshmi Narayanan) Site Observation made by LTVL engineers as follows,
Split bearing damage
Spilt Bearing found totally damaged
Stem & Stem housing contact area severely damaged
Page 6 of 15
Photos from Site - 36” Cl 150 Valve MPT-XSV-2542 Dismantled
Page 7 of 15
4.0 Based on the site observation of damaged components following Correction carried out
1. 01 Nos. 36”#150 (3P) Tag No. 2642, Valve Serial No. 14G701115 with Rotex Pneumatic Actuators Scratches observed on stem, removed by 0.2 mm cut on stem bearing
areas; Stem housing dismantled & necessary soft spares replaced (Refer
Clause 8.0 for spare details). Valve Found operating smoothly.
Rework Details done at site
Description Bearing - Ball Bearing - Stem Gland
Tag No. Lower side
Upper side
Stem housing Bearing Gland Bearing
MPT-XSV-2642
Not removed.
Not Removed.
Scratches, 0.2 mm cut on Stem and bearing replaced.
Scratches, 0.2 mm cut on Stem and bearing replaced.
0.2mm cut
2. 01 No. 36”#150 (3P) Tag No. 2542 Valve Serial No. 14G701116 with Rotex Pneumatic Actuators Scratches observed on stem, removed by 0.2 mm cut on stem bearing
areas & Seat ring found damaged; Valve Dismantled & Necessary soft
spares & Seat Ring replaced ( Refer Clause 8.0 for spare details).
Valve Found operating smoothly.
Rework Details at site
Description Bearing - Ball Bearing - Stem Gland
Tag No. Lower side
Upper side
Stem housing Bearing
Gland Bearing
MPT-XSV-2542
Replaced with new
one.
Replaced with new
one
Scratches, 0.2 mm cut on Stem and bearing replaced.
Scratches, 0.2 mm cut on Stem and bearing replaced.
0.2mm cut
Page 8 of 15
After the rework 36”cl 150 - 1 No (Tag No MPT-XSV-2542), which has been hydro seat
and pneumatic seat tested to confirm the seat Integrity as per the GAD and witnessed by LTHE & CIL Quality representatives.
Hydro Seat Test 22 bar / 5 Mins No Visual leakage
Page 9 of 15
5.0 Root Cause Analysis: To identify the underlying cause
a) Problem Description
DESCRIPTION AREA
DESCRIPTION
WHAT
What object has the defect Trunnion Mounted Ball Valve
What is the defect? Operatability Issue on the Pneumatic actuated Valves
WHERE
Where specifically on the valve do you see the defect?
On the Stem Bearing & Ball Bearing area
Where geographically is the object observed?
Cairn Site,Rajasthan
WHEN
First seen - By the customer? Yes
When seen since? Nov 2015
When is the observation seen in the valve- while testing @ site, operation (i.e. when the valve is used)?
during preliminary on/off test after few cycles before start up while commissioning the valve in pipeline
When is the observation seen in the life of the object?(eg. when new or after few years of service)
4 Months after Installed in the Pipeline
HOW BIG How many objects have noticed this observation? 36” – 2 No’s
Similar Parts
How many/much observation(s) per object 1 (Jamming of Valve)
Page 10 of 15
b) Cause & Effect Diagram:
c) Significant Causes
S No CAUSES SIGNIFICANT / IN-SIGNIFICANT
1.1 Wrong Actuator Selection IN-SIGNIFICANT
1.2 overlapping of edges of split bearing assembly SIGNIFICANT
1.3 Damage to the PTFE coated split bearing surface SIGNIFICANT
1.4 Actuator exhausts port not open while operating manual mode. (Pn. Actuator)
IN-SIGNIFICANT
1.5 Improper Seat pressing. IN-SIGNIFICANT
2.1 Inadequate surface Finish on Stem IN-SIGNIFICANT
3.MAN 4.MATERIALS
1.METHODS/PROCESSES 2.MACHINE
Operatability Issues
1.1 Wrong Actuator Selection 2.2 Geometrical Variations on the Components
2.1 Inadequate surface Finish on Stem
4.1 PMI Failure on the Components
3.4 Wrong Usage of MOC
1.2 overlapping of edges of split bearing assembly
3.1 wrong Measurement of Dimensions
3.2 Improper Open / Close Setting on actuators
1.5 improper Seat pressing.
1.4 Actuator exhausts port not open while operating manual mode. (Pn. Actuator)
1.3 Damage to the PTFE coated split bearing surface
2.3 Due to Compressed spring.(Pn. Actuator)
3.3 Due to over tightening of gland packing.
4.2 Improper Heat Treatment of Stem
Page 11 of 15
2.2 Geometrical Variations on the Components IN-SIGNIFICANT
2.3 Due to Compressed spring.(Pn. Act) IN-SIGNIFICANT
3.1 Dimension Variations on the Components IN-SIGNIFICANT
3.2 Improper Open / Close Setting on actuators IN-SIGNIFICANT
3.3 Due to over tightening of gland packing. IN-SIGNIFICANT
3.4 Wrong Usage of MOC IN-SIGNIFICANT
4.1 PMI Failure on the Components IN-SIGNIFICANT
4.2 Improper Heat Treatment of Stem IN-SIGNIFICANT
d) Why – Why Analysis
Root cause : 1 overlapping of edges of split bearing assembly
Why? Stem Bearing is a split design to facilitate easy assembly.
.
Why? Stem bearing geometrical Dimensions not measured.
Why? Since it is catalogue product from reputed manufacturer, 100 %
Dimension inspection not carried.
Page 12 of 15
Root cause : 2 Damage to the PTFE coated split bearing surface
Why? Increase in friction torque for valve operation.
Why? Entrapment of foreign particles between the bearing surfaces
Why? Foreign particles present during installation
6.0 Conclusion:
1. In our considered opinion, based on site visit by our engineer and
correction work carried out to rectify the valve operability and based on
the root cause analysis carried out, the underlying cause for the valve
failure at site found to be overlapping of edges of split bearing used in
the stem housing causing stem damage and thereby increase in Torque
for operation of the valve.
Page 13 of 15
2. Our observation at the site after dismantling of the stem assembly in
36 “ valves shows damages to the stem surface on the bearing seating
area.
3. As correction action, when the valve stem was skin cut to remove the
damages and with the replacement of new set of bearings, it was
demonstrated the valves operations was found satisfactory.
4. It is also to be noted, fine particles which entrapped in the bearing area
during installation could have damaged the PTFE layer of the split
bearing inner surface which also increased the friction hence affected
the valve operability
5. The Foreign particle which has come into our valve seat area have
damaged the seat on 1 valve (MPT-XSV-2542) which could have
affected our valve seat performance.
Basic function of a split in the Bearing :
The split in the bearing is provided in order to facilitate easy assembly of bearing into the stem housing.
The PTFE Coating given in the inner bearing surface is mainly to reduce friction
Page 14 of 15
7.0 Corrective Action:
1. Split stem bearing bore diameter shall be measured and recorded after
assembly to ensure compliance to design requirement.
2. Visual examination of split stem bearing assembly shall be performed to
ensure there is no sharp edge as well as overlap of the split edges
3. Before the valve assembly, the stem shall be inserted into the bearing
and check for free rotation to ensure smooth operation.
4. To avoid damage to the seat and also fine particle getting into the
bearing area it is recommended that the valve is stored properly with
end protector till the time of commissioning as per IOM instruction.
5. Metal Caution Tag indicating the storage condition shall be
implemented.
Page 15 of 15
8.0 List of Spares Supplied For Rectification:
Description Qty Date Dispatch Mode
O-RING ID 870 mm x 5.33 mm CS - VITON 2
30.11.2015 Sugumar R&D Hand carried
O-RING PARKER NO.6-924 - VITON 2 GASKET 36" Cl.150 1 'O' RING PARKER NO.2-364 - VITON 1 BACK-UP RING VITON PARKER 8-364 1 BODY-SEAL 36" Cl.150 1 'O' RING PARKER NO.2-357 - VITON 2 PACKING 36" Cl.150 2 BODY-SEAL CROSS SEC - 8 x 8 6 O-RING ID 1280mm x 10mm CS 2 BEARING ID 300 x OD 305 x 60 mm LONG 4 19.12.2015 Vikash Hand
carried BEARING ID155 x OD 160 x 25mm LONG 2 BEARING ID130 x OD 135 x 15mm LONG 2 19.12.2015 courier O-RING ID 870 mm x 5.33 mm CS - VITON 4
23.12.2015 courier
O-RING PARKER NO.6-924 - VITON 4 BEARING ID 300 x OD 305 x 60 mm LONG 4 THRUST WASHER 28" CL.600 TMBV 4 BEARING ID155 x OD 160 x 25mm LONG 2 'O' RING PARKER NO.2-364 - VITON 2 BACK-UP RING VITON PARKER 8-364 2 BODY-SEAL 36" Cl.150 2 'O' RING PARKER NO.2-357 - VITON 4 THRUST BEARING 36" Cl.150 2 PACKING 36" Cl.150 4 BEARING ID130 x OD 135 x 15mm LONG 2 SEAT RING 36" Cl.150 2 02.01.2016 courier
9.0 Reference Documents
I. GAD – 110002550-TM-010 Rev 1
II. QAP – M205LNT5104A-MPT-Q-ITP-0001 A2 Dt 18.06.2014
III. VTR - 110002550-40 Dt 06.11.2014
IV. Test cum warranty cert – 110002550-40 Dt 06.11.2014