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ROOT CAUSE ANALYSIS FOR COMPLAINT OF

LESS WALL THICKNESS FOUND IN PUP PIECE – TRUNNION MOUNTED BALL VALVES

Team Members:

Date: 27.04.2018

N Kesavan – Manufacturing

S Kannan – Quality contr

M. Balasubramanian – Manufacturing

Senthil Kumar - Service Engg.

R. Selva Kumar – Sr. Engineer, Quality Control

A Ravi. – Sr. Engineer, Quality

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CONTENTS

1.0) Background of the complaint

2.0) Preliminary Investigation done at LTVL on receipt of complaint

3.0) Root Cause Analysis: To identify the underlying cause

a) Problem Description

b) Cause and Effect Diagram

c) Significant Causes

d) Why- Why analysis

4.0) Correction

5.0) Corrective Actions

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1. Background of the complaint:

We have supplied the Manual Valves with pup piece of 72 Nos to M/s. L&T Hydrocarbon Engineering Limited, from Dec’2017 to March -2018. They have received and found less

wall thickness in pup piece of 12” # 600 welded valve – 1 No. They have communicated

same to LTVL, to submit the repair procedure for rectification at site itself.

Sl No Valve Serial No Size Class

Supply Date Type of Non-Conformity

1 17G706143 12” #600

24/01/2018

2. Preliminary Investigation done at LTVL on receipt of complaint

a) The following documents were verified and found in order:

Internal Valve Test Report (VTR) Verified & Found OK.

Final inspection report (SCN) Verified & Found Not ok. (i.e. we noticed the land height in the range of 4 to 7 mm in one end of pup piece against the maximum of 1.5mm, during pre-dispatch inspection. Hence, the inner surface of pup piece was grounded to make the land height uniform thorough the circumference. Therefor cleared as such.)

b) Following stages were verified w.r.t the reported complaint

Verified the process conditions of other valves tested during the same date of complaint.

Site photos:

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3.0 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? Grinding marks observed in one end of the pup piece

WHERE

Where specifically on the valve do you see the defect? On the pup piece

Where geographically is the object observed? At customer end

WHEN

First seen - By the customer? Yes

When seen since? April -2018

When is the observation seen in the valve- while testing @ site, operation (i.e. when the valve is used)?

It was observed during their inspection

When is the observation seen in the life of the object?(eg. when new or after few years of service)

After two monthes

HOW BIG How many objects have noticed this observation? one Valve

Similar Parts

How many/much observation(s) per object One

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b) Cause & Effect Diagram:

c) Stratification of causes

No

Possible Causes Verification Significant / Insignificant

1.1 Method of inspection incorrect RIS-17 for Inspection IN-SIGNIFICANT

1.2 Method of packing wrong during transit Received with cut piece and ok IN- SIGNIFICANT

1.3 Method of machining incorrect Verified with supplier and they have done in VTL

IN- SIGNIFICANT

2.1 Visual & Dimensions were not as per requirements

Verified Inspection report and found ok

IN-SIGNIFICANT

2.2 Pup piece got orality due to high input during welding

Heat input verified by using thermal IN-SIGNIFICANT

3.MAN 4.MATERIALS

1.METHODS / PROCESSES 2.MACHINE

Grinding marks observed in end of the pup piece

1.1 method of inspection incorrect

3.1 Pup piece bulged due to collar welding at edge of pipe.

3.2 Wrongly measured the dimensions in inspection

1.2 Method of packing wrong during transit

2.1. Visual & Dimensions were not as per requirements.

3.3 Pup piece handled improperly

4.1. Wrong materials used

3.4 Butt weld end preparation done by taken wrong reference

3.5 Excess clamping done during setting in machine

1.3 Method of machining incorrect

1.2 Pup piece got orality due to high input during welding

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chock and ok

3.1 Pup piece bulged due to collar welding at edge of pipe.

- IN-SIGNIFICANT

3.2 Wrongly measured the dimensions in inspection

Qualified operator inspected IN-SIGNIFICANT

3.3 Pup piece handled improperly - IN-SIGNIFICANT

3.4 Butt weld end preparation done by taken wrong reference

- SIGNIFICANT

3.5 Excess clamping done during setting in machine

- IN-SIGNIFICANT

4.1 Wrong materials used Materials found as per e- bom IN-SIGNIFICANT

d) Consideration for Why-Why analysis

1.1 Why – Why Analysis

1.1.1 Why– Butt weld end preparation done by taken wrong reference

Why– Operator not measured the full circumference of pipe ID

Root cause: Operator not measured the full circumference of pipe ID. Because of this one of the pup piece made with orality by 4-7mm

4.0 Correction:

Repair procedure has been submitted on 27.04.2018 to M/s.LTHE for rectification at site itself.

5.0 Corrective actions:

1. We have given the awareness to the supplier to take the 100% measurement of pipe ID circumference before starting the Edge preparation.

2. 100% Pup piece to be inspected in receipt stages.