Cracking of a 16” stainless HSSE... · AMCHAM T&T 22nd ANNUAL HSSE CONFERENCE AND EXHIBITION :...

AMCHAM T&T 22nd ANNUAL HSSE CONFERENCE AND EXHIBITION : TECHNOLOGY . CULTURE . RESULTS

Cracking of a 16” stainless

steel elbow at Point Lisas

Nitrogen Limited’s Ammonia

plant.

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Disclaimer

This presentation is provided by Point Lisas Nitrogen Limited (PLNL) for information purposes only and does not constitute the provision of professional advice of any kind. The information provided herein should not be used as a substitute for consultation with professional advisers. Before making any decision or taking any action, you should consult professional engineering companies. PLNL does not accept any responsibility for loss to any person who acts or refrains from acting based on the information contained in this presentation.

The information contained in this presentation is meant to share learnings and best practices based on experiences at PLNL. It is subject to amendment or change. Whilst every precaution has been taken in preparing this presentation, we cannot accept responsibility for any inaccuracies that may arise.

This document contains information that is proprietary and confidential to PLNL which shall not be duplicated, used or disclosed outside the recipient's company. Any other use or disclosure in whole or in part of this information without the express written permission of PLNL is prohibited.

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Point Lisas Nitrogen Limited Commissioned in July 1998.

The plant is rated to produce 1850 MT/day.

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Ammonia Plant Schematic (Typical)

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Agenda Process Safety Management Elements

The Sequence of events

Incident Investigation

Visual inspection

Metallurgical analysis

Chemical analysis

Conclusions

Lessons learned

Process Safety Information

Process Hazard Analysis

Mechanical Integrity Program

Questions that relate to your facility

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Process Safety Management Elements


The incident - Sequence of events

August 24th 2012, during a plant start-up, an abnormally loud hissing sound

was heard coming from the air piping connecting the Primary and Secondary

reformers.

The plant was taken off line to conduct thorough inspection of the line.

The line comprises 155’ of 16” 304H Stainless Steel, 14 elbows etc.

Inspection revealed failure of a 16” (304H) fabricated elbow.

Additional inspection revealed identical cracking along the internal welds of

two other 16” Stainless Steel fabricated elbows.

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Visual

Complete thru wall crack along the inside weld.

No corrosion or deposits.

Inner and outer surfaces of all elbows

were heavily oxidized.

Inner and outer surfaces had matte black

appearance consistent with high

temperature oxidation.

Remaining line and supports inspected.

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Possible Failure Mechanisms

Mechanical

Metallurgical

Loss of thickness

High Temperature Corrosion

Environmental Assisted cracking

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Examination: Inside seam weld

The following was found:

Weld ruptured along the centreline of the groove weld.

Crack initiated at the outside diameter and propagated toward the inside.

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Innersurface

Sample 2(metallography)


Metallurgical Examination:

Inside seam weld The following was found:

Numerous secondary cracks existed parallel to the fracture.

Significant amount of reddish brown sigma phase in weld metal.

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Metallurgical Examination:

Outside seam weld

Some linked creep voids have formed.

Evidence of sigma phase but less than inside weld.

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Metallurgical examination:

Base Metal Cracking occurred in base metal in heat affected zone adjacent to weld.

Sigma phase (reddish-brown) in the horizontal girth weld.

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Chemical Analysis

Base material consistent with specification.

Weld slightly deficient in Chromium.

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Conclusion of findings

No evidence of thinning, mechanical damage or corrosion.

ASME B31.3 / API code review showed 304H to be excellent choice.

Metallographic examination of inside weld showed high percentage ofsigma phase.

Metallographic examination of outside weld and base metal showedpresence of sigma phase.

Based on comprehensive review, the cracking in the welds is a result ofhigh temperature material degradation (creep and sigma phase).

There was an ASME B31.3 code revision where a W factor was added forweld strength due to creep effects form long term exposure at hightemperature.

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PSM elements impacted

Process Safety Information improvements.

Process Hazard Analysis improvements.

Mechanical Integrity Program improvements.

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Process Safety Information (PSI)

OSHA groups PSI in 3 categories:

Hazards of the chemicals and flammables in the process.

Information related to the technology of the process.

Information pertaining to the equipment in the process. ASME/API code changes.

Actions taken by PLNL:

Systematic assessment of process parameters relative to equipment design &

material selection, particularly with respect to:

Safe Operating Control Limits (SOCLs)

Normal operating conditions.

Plant upset conditions.

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Process Hazard Analysis (PHA)

PLNL had implemented significant administrative controls over the

years.

Inconsistent PHA revalidation frequency.

Actions taken by PLNL after 2015:

Improved levels of engineering controls applied.

Compliance to the recommended 5 year PHA revalidation frequency.

PHA revalidations facilitated using external SMEs for increased rigour.

Embraced AICHE papers and incidents at other plants into PHA.

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Mechanical Integrity (MI) Programs

Actions taken by PLNL:

2012 Implemented Corrosion Study considering main damage mechanisms.

2016 Corrosion Study completed by external service provider.

2012 Implemented Metallurgical Adequacy & Piping Material Class Adequacy.

2017 Metallurgical & Piping Material Class Adequacy completed by external

service provider.

Incorporated ASME & API biannual code changes from 1998 – 2012 into MI

program.

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Lessons Learned

The incident reinforced the need to constantly review the adequacy of plant

designs and fitness for service.

Adherence to a robust PSM methodology must be formally integrated into

systems of work to provide assurances that the likelihood of future incidents

of this nature is significantly reduced.

Line upgraded to seamless piping and fittings preferred for this service.

Careful weld procedure practices and heat treatment of welds recommended.

TAR activities now include an extensive array of Dye Penetrant, X-Rays, Field

Metallography Replication at susceptible locations identified by the studies.

Stay up to date with code revisions.

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Questions

From what I’ve shared from PLNL experience and thinking about your facility:

How susceptible is your plant to such failures?

How do our lessons learned help you avoid a failure?

What makes you uneasy about your facility / practices?

What potential risks needs to be addressed on your plant urgently?

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Thank you kindly.

I would be pleased to address any questions/concerns at this

time.

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Cracking of a 16” stainless HSSE... · AMCHAM T&T 22nd ANNUAL HSSE CONFERENCE AND EXHIBITION :...

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