Smith & Burgess' Blog

Did You Know: Allowable Backpressure for a Conventional Valve...

Posted by Brandon Ring on Aug 1, 2018 5:51:00 PM

 

Did you know, the allowable total backpressure for a conventional valve can be larger than 10% of the set pressure? According to API 520-1 §5.3.3.1.3:

"In a conventional PRV application, when the allowable overpressure is 10%, the built-up backpressure should not exceed 10% of the set pressure. A higher maximum allowable built-up backpressure may be used for allowable overpressures greater than 10 % provided the built-up backpressure does not exceed the allowable overpressure."

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Topics: Did You Know?, API 521, PRV, Set Pressure, Allowable Backpressure, Spring Loaded Valves

Case Study: Relief Systems Evaluation and Mitigation

Posted by Dustin Smith, P.E. on May 1, 2018 6:04:00 PM

The Opportunity:

A major United States Refinery hired Smith & Burgess to perform a site-wide revalidation.

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Topics: Pressure Relief Valves, Relief Systems, Case Study, Refinery, Engineering Review, PRV Study, PRV, Relief System Design, Relief Systems Revalidation, Undersized PSVs

Case Study: Third Party Relief Valve Mitigation Review

Posted by Dustin Smith, P.E. on Nov 1, 2017 6:03:00 PM

The Opportunity:

A major US refinery used a competing engineering contractor to perform a flare and relief systems analysis. Upon completion of the project, the refinery was left with a list of facility upgrades that management deemed excessive. Smith & Burgess was hired to review the relief and flare systems documentation and provide engineering solutions that met corporate and industry requirements.

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Topics: Pressure Relief Valves, Relief Systems, Flare Mitigation, Action Item Resolution, Case Study, Refinery, Engineering Review, PRV Study, Third Party Review, Overly Conservative Assumptions, PRV, Relief System Design, Relief Systems Revalidation, Relief Valve Mitigation, Mitigation

Case Study: Gas Plant Detailed Relief System Design Review

Posted by Dustin Smith, P.E. on Sep 1, 2017 6:04:00 PM

The Opportunity:

A recent audit of a “rebuild” design package for a major Asian gas plant identified that the EPC may have failed to follow company or industry standards. The owner needed an engineering review of the entire facilities’ relief systems designs prior to their start up in two months. Any deficiencies in company or industry standards needed to be addressed prior to the facilities’ start up.

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Topics: Pressure Relief Valves, Relief Systems, Case Study, Engineering Review, Gas Plant, PRV Study, Third Party Review, PRV, Relief System Design

Did You Know: Vessels Riding on Flare...

Posted by Brandon Ring on May 1, 2017 5:53:00 PM

 

Did you know, When performing a flare header analysis, it is not uncommon to find pressure vessels that ride on the flare, i.e. they have an open path to the flare header?

These vessels are often degassing drums, maintenance knock out drums, or other similar equipment. While there are practically never any relief loads from these equipment contributing to the global scenarios we typically evaluate, it is still important to ensure that the pressure in the drum does not exceed the code allowable accumulation.

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Topics: Did You Know?, Pressure Relief Valves, Flare Header, PRV, Relief Header, Flare Header Analysis

Did You Know: Cold Differential Test Pressure (CDTP)...

Posted by Brandon Ring on Jan 1, 2017 5:55:00 PM

 

Did you know, under certain circumstances, you need to verify if the Cold Differential Test Pressure (CDTP) is properly compensated for the superimposed backpressure from the flare header?

Have you come across a conventional pressure relief valve relieving to a flare header? Did you know that, under certain circumstances, you need to verify if the Cold Differential Test Pressure (CDTP) is properly compensated for the superimposed backpressure from the flare header?

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Topics: Did You Know?, Pressure Relief Valves, Flare Header, API 521, PRV, Cold Differential Test Pressure, CDTP, Relief Header, Set Pressure

Did You Know: Liquid Service PSVs...

Posted by Brandon Ring on Jul 1, 2016 5:52:00 PM

 

Did you know, a relief device in liquid service does not always mean that the device is liquid-certified?

Liquid-certified devices are mechanically designed and sized by an engineer to relieve liquid. Per UG-125 of ASME Section VIII, "Vessels that are to operate completely filled with liquid shall be equipped with pressure relief devices designed for liquid service, unless otherwise protected against overpressure."

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Topics: Did You Know?, Pressure Relief Valves, API 521, PRV, Liquid Service PSV

Did You Know: Exit Pipe Fitting...

Posted by Brandon Ring on Jun 1, 2016 5:56:00 PM

 

Did you know to exclude the exit pipe fitting in your PSV outlet pressure drop calculations if your PSV discharges to atmosphere?

If you have performed an outlet pressure drop calculation for a PSV relieving to atmosphere, you may have noticed that often a significant portion of the pressure drop is contributed by the exit pipe fitting. This is because the equivalent resistance of the fitting is high relative to a typical length of pipe.

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Topics: Did You Know?, Pressure Relief Valves, PRV, Pressure Drop Calculations, Pressure Drop, Exit Pipe Fitting

 Safety Knowledge Should be Share...

“It should not be necessary for each generation to rediscover the principles of process safety which the generation before discovered. We must learn from the experience of others rather than learn the hard way. We must pass on to the next generation a record of what we have learned.” - Jesse C. Ducommun, Safety Pioneer
 
As Process Safety engineers and consultants, we believe our unique position creates a responsibility for Smith & Burgess to share our years of accumulated safety knowledge.


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