Smith & Burgess' Blog

Did You Know: Specifying Trim and Certification for New PSVs

Posted by Gabe Spence on Apr 12, 2022 12:03:59 PM


Did you know that liquid trim valves can be certified for vapor? 

There is often confusion around the required trim and certification when selecting a new safety-relief valve. For example, when there are both vapor relief scenarios and liquid relief scenarios, is a dual-certified PRV required? What about when the service is liquid but the controlling scenario is vapor? In the past, we have recommended “dual-certified” PRVs when there are both liquid and vapor relief scenarios, but these valves can be difficult to obtain or could have long lead times.  When might there be alternatives? In this discussion we will look at what liquid trim means and when different trims may be suitable for different relief possibilities.

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Topics: Did You Know?, Pressure Relief Valves, Detailed Engineering, OSHA, PRV, Relief System Design, Set Pressure, Vapor Relief Scenarios, Liquid Relief Scenarios, liquid trim valves, dual-certified valves

Did You Know: PSV Isolation on Air Receivers

Posted by Brandon Ring on Jan 14, 2020 10:26:07 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 10:15:36 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

Top 5 "RAGAGEP Deviations" in New Construction

Posted by Dustin Smith, P.E. on Aug 28, 2018 9:51:00 AM

Anyone tasked to start up a unit knows the engineers who designed it rarely miss a thing...

Every bleeder valve is in the right place, spectacle blind turned correctly, and bypass line scrutinized. So why would the flare and relief systems design be any different? The truth is that they are not. Engineering Firms today have perfected the art of throwing waves of engineers on design-build projects. Unfortunately for those engineers, relief and flare system designs are governed by a maze of regulations, codes, standards, and guidelines (collectively known as Recognized and Generally Accepted Good Engineering Practice or RAGAGEP). Experienced Project Managers understand that relief and flare specialists are needed to ensure their projects are safely and properly designed before any construction occurs.

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Topics: Did You Know?, Process Safety Management, Detailed Engineering, Maintenance Operation Studies, Relief System Documentation, Process Safety Optimization

Case Study: Wellhead Gathering System Overpressure QRA

Posted by Dustin Smith, P.E. on Jan 1, 2018 4:58:00 PM

The Opportunity:

A review of the “overpressure protection plan” for a wellhead gathering pipeline found that the potential for “multiple simultaneous well shutdown system failures” had been overlooked. The flowing pressure on the inlet to the well choke valve exceeded the allowable pressure in the gathering system. If multiple well safety systems failed, there would be an unacceptable potential for large-scale loss of containment. A Quantitative Risk Assessment of the entire system was needed to determine if the existing overpressure protection system, as a whole, met corporate and regulatory requirements. Initially, the protection plan suggested additional shutdown hardware and increased testing frequency. Smith & Burgess was hired to review this system.

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Topics: Detailed Engineering, Overpressure Protection, Case Study, Regulatory Compliance, Quantitative Risk Assessment, QRA

Case Study: Flare Bid Review Package

Posted by Dustin Smith, P.E. on Jul 25, 2017 5:02:00 PM

The Opportunity:

A major United States refinery was in the process of purchasing a new flare system and needed assistance reviewing the bid package from the vendors. The refinery decided that the system was needed based on the outcome of a facility-wide flare study and flare QRA. The new flare system was specified by an EPC and then bid by a major flare vendor. This refinery heard of Smith & Burgess’ flare design expertise and decided to hire us in order to review their vendor’s design package.

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Topics: Flare Study, Detailed Engineering, Case Study, Flare System, Refinery, Engineering Review

Case Study: Flare System Velocity Concern Review

Posted by Dustin Smith, P.E. on Nov 16, 2016 5:07:00 PM

The Opportunity:

After reading about flare header failures due to high velocities, an owner of a production platform in the Middle East wanted to ensure that the initial inerting/purging of the platform and pipeline would not result in flare header piping failure. Smith & Burgess was hired to review the flare systems for safe operation under the high flow rates associated with the initial facility start-up.

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Topics: Flare Mitigation, Flare Analysis, Flare Study, Detailed Engineering, Case Study, Flare System, Engineering Review, Flare Management, Flare Optimization, Engineering Analysis, Rate Increase, API 521

 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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