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Catastrophic failure of shell and tube production cooler

  • Safety alert:  01/2006
  • Issue date: May 2006

Introduction

1. A recent serious incident occurred that involved the catastrophic failure of a shell and tube heat exchanger, and there is a potential risk of failure to heat exchangers of the same, or similar, design. This notice describes the incident and outlines the action that should be taken by dutyholders.

Background

2. The incident on an offshore gas production platform occurred when a shell and tube production cooler suffered a catastrophic failure. Seawater was being used to cool High Pressure (HP) hydrocarbon gas. The shell, tubes and titanium cladding sheet were torn from the steel tube sheet and propelled across the deck with sufficient force to rupture an adjacent exchanger. The cooling water pipe work and vent pipe work were torn off the shell and the tube sheet and channel end were ripped off the supports. There was a significant and immediate gas release followed by ignition and an explosion. Fortuitously there were only two relatively minor injuries, but under slightly different circumstances there could have been significantly more serious casualties.

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Heat exchanger information

3. The heat exchanger operates with sea water on the shell side and HP hydrocarbon gas plus condensates and water on the tube side. The tube sheet had been manufactured from carbon steel with an explosively bonded, 13mm thick titanium cladding plate on the sea water side to provide corrosion protection. A key feature of this design is that it allows the HP hydrocarbon gas, condensates and water to come into contact with the steel tube sheet/titanium interface, thus creating the potential for in-service degradation mechanisms as detailed in paragraph 4 below.

Tube to Tube sheet and Titanium cladding to Steel tube sheet interface detail.

Tube to Tube sheet and Titanium cladding to Steel tube sheet interface detail.

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Reasons for failure

4. Based on the results of an ongoing forensic investigation, the current evidence suggests the following sequence of events:

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Action required

5. HSE considers that the emerging findings of this investigation are significant enough to require immediate action by dutyholders in the light of the sudden and possibly catastrophic nature of this type of heat exchanger failure. Therefore, dutyholders should:

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Relevant legal requirements

6. The main legal requirements include:

There are legal duties on both the owner and the operator of the plant.

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Further Information

Any queries relating to this notice should be addressed to:

Team Leader - OSD3.4 Mechanical Systems
Health and Safety Executive
Hazardous Installations Directorate
Offshore Division
5N.2 Redgrave Court
Merton Road
Bootle
Merseyside L20 7HS

This guidance is issued by the Health and Safety Executive. Following the guidance is not compulsory and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance as illustrating good practice.

Updated 2011-09-29