5 replies to this topic

[Broccoli Rob]

Does anyone know of a credible resource (e.g., API Standard) that states that only rupture discs should be used for tube failure scenarios?  I am trying to find a resource that defends my position that a rupture disc should be installed on an exchanger shell instead of a relief valve in the event that a tube fails, allowing 400-psig gas to leak into the shell side of an exchanger filled with water at 50-psig.

 

Thanks.

[fallah]

Hi,

 

Following link can help you out on your query:

 

http://webwormcpt.bl...elief-valve-psv

[Zauberberg]

PSV can be used in those cases when the rate of pressure buildup inside the equipment will not cause pressure to rise above the maximum allowable accumulation, given the speed of opening of the PSV. This obviously depends on the pressurization flow, fluid parameters, and volume of the protected system. If calculation shows that pressure will build up above maximum accumulation before the PSV reaches fully open position, you need to consider a non-reclosing device.

 

See attached article for more information.

Attached Files

•  Evaluate Heat-Exchanger Tube Rupture Scenarios Using Dynamic Simulation.pdf   650.65KB   21 downloads

[Broccoli Rob]

Thank you both for your help.

[paulhorth]

Rob,

This question is currently the subject of a programme of research and review carried out by the Energy Institute (formerly Institute of Petroleum) in the UK. You might like to follow this link to their website:

https://www.energyin...heat-exchangers

 

They held a presentation a month ago to present their initial findings, which I watched on a webinar. In their experimental rig, which simulated a burst exchanger tube, the reaction time of the PSV allowed a pressure spike to about double the set pressure with a duration of 6 to 7 milliseconds, before the pressure was relieved. The study has not yet concluded whether a spike of this nature would cause any damage to the equipment or whether it would infringe the design codes. Clearly the nature of the pressure spike would also depend on the size of the equipment relative to the inflow.

They are due to publish a final report with recommended design guidelines in "Q2 2015" which will be in another month or two.  This report should then provide the "credible resource" which you and many others would like to have.

The reason for carrying out this joint industry study was the recognition that the use of rupture discs to protect heat exchangers has many disadvantages, and indeed hazardous consequences, such as filling a flare system with cooling water, and PSVs would be better if it can be proved that they will provide adequate overpressure protection. 

This is a summary in my own words, but you and other readers would get a clearer and more complete understanding by reading the Energy Institute's own documentation when it is published.

 

Paul

[Broccoli Rob]

Paul -

 

Thank you for the link.  I will keep my eyes open for the final report from the Energy Institute.