Smith & Burgess' Blog

Did You Know: PSV Isolation on Air Receivers

Posted by Brandon Ring on Jan 14, 2020 11:26:07 AM

 

Did you know, OSHA does not allow block valves on the inlet of relief valves installed on air receivers in compressed air systems?

OSHA CFR 1910.169(b)(3)(ii) states, “No valve of any type shall be placed between the air receiver and its safety valve or valves.”

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Topics: Did You Know?, Pressure Relief Valves, Detailed Engineering, OSHA, PRV, Relief System Design, Relief Header, Set Pressure, Exit Pipe Fitting

Did You Know: Set Pressure of PSVs Protecting Process Pipes

Posted by Brandon Ring on Jan 14, 2020 11:15:36 AM

 

Did you know, relief devices that protect process pipe may be set to open above the piping design pressure?

Per ASME B31.3-2016, Sections 322.6.3. (see Figure 1) and 302.2.4 (f) (see Figure 2), a thermal relief valve may be set up to 120% of the design pressure of the protected system with the owner’s approval, as long as, the allowable accumulation criteria in 302.2.4.(f) are met. Set pressures lower than 120% of the design pressure may be required depending on the allowable accumulation pressures in 302.2.4 (f).

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Topics: Did You Know?, Pressure Relief Valves, Detailed Engineering, PRV, Relief System Design, Relief Header, Set Pressure, Exit Pipe Fitting

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

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

 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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