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Pressure Safety Valve Credibility During a PHA

Are you ensuring that the PSVs that you credit during a PHA are truly reliable? Overpressure is a major concern for engineers where the pressure within a vessel or pipework exceeds the maximum design pressure of the equipment.

Brian Camey, EIT, Project Engineer I – published 5/8/2023

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Rupture Disc: Usage, Strengths and Weaknesses, Incident Study

Many common industrial processes involve highly pressurized vessels and piping, which leads to the potential for overpressure and vessel damage resulting in personnel injuries or even fatalities. For this reason, a variety of protections have been developed – such as relief valves, safety valves, explosion doors, explosion vents – one of which are rupture discs.

Joyce Shen, EIT, Project Engineer I – published 5/1/2023

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Modernizing Your PHA Experience

Why is a quality PHA important? Initiating events can have impacts well-beyond the individuals directly involved and the goal of industry is to avoid tragedies and mitigate process failures before they occur.

Stephanie Smith, PE, Principal Engineer – published 3/20/2023

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Evaluating Vessel Overpressure Scenarios During the PHA

It is understandable why overpressure scenarios are some of the more commonly identified hazards across many PHAs. However, evaluating overpressure scenarios in the context of the PHA is not always simple. Please see the URL below to read the full article. 

Craig Stickelmaier, Senior Engineer – published 02/15/2023

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Calculating Pressure Drops Across Valves

Calculating pressure drops can be very helpful in identifying more accurate pressure profiles during a Process Hazard Analysis (PHA) / Hazard and Operability Study (HAZOP). There are scenarios during a PHA/HAZOP where taking a conservative estimate ends up overstating the severity of a potential incident significantly. 

Facilitators and team members need to remember that taking credit for the laws of physics is allowed and can be significantly more accurate. In cases such as blowthrough due to level valves going wide open, teams should analyze pressure drops across valves. This allows for a more realistic analysis of what pressure the downstream vessel can reach. This calculation is not difficult if valve information is readily available. In this TechTip, we will provide a simplified discussion on pressure drops and how to calculate pressure drops across valves. 

Michael Pfaff, Project Engineer- published 12/17/2021

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Maximum Intended Inventory

The maximum intended inventory, as the name suggests, is the maximum amount of the regulated substance or chemical in a covered process, which the facility plans to store onsite. Facilities with a covered process typically will have various pressure vessels, storage tanks, heat exchangers, pipelines, etc., all of which contribute to the overall quantity of material. This Tech-Tip aims to briefly introduce the process safety information requirement listed under Occupational Safety Health Administration Process Safety Management / Environmental Protection Agency Risk Management Plan and California Accident Release Prevention programs. 

Oscar Hernandez, Project Engineer- published 8/27/2021

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Quantifying Thermal Expansion

Thermal expansion is the increase in volume of a fluid as the fluid is heated (e.g., due to solar radiation, steam tracing, external fire, etc.). In the case of a blocked-in liquid-full system, this gradual expansion of the fluid can cause extreme build-ups in pressure. While most people are vaguely aware of the potential for thermal expansion; they may not understand the physics behind it. This Tech-Tip aims to briefly introduce the governing principles of thermal expansion as well as an equation to calculate the change in pressure. 

Craig Stickelmaier, Project Engineer- published 7/7/2021

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Efficient and Effective Incident Investigations

Ammonia, a versatile toxic compound, is one of the most widely used refrigerants, and is one of the world’s most produced chemicals. Despite using inherently safer design philosophy and conducting risk assessments, problems and failures leading to releases of this toxic substance still occur frequently. 

James De Graw, Project Engineer- published 6/3/2021

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CalARP Program 4 - Hierachy of Control Analysis (HCA)

California’s CalARP Program 4 requires Hazard Control Analysis (HCA) be performed to aid in hazard prevention. This article serves as a starting point for understanding how to implement HCA within an overall safety management system. 

Katya Mandziuk, Project Engineer- published 5/21/2021

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Bypassing EPA RMP Submittal Snags

Misunderstood EPA RMP Submittal elements, explained! Do not worry, you are not alone. Confusion surrounding the data to be input into the EPA RMP Submittal is all too common, which leads to inaccurate details and errors in the submittal process. Some reporting fields within the submittal are not self-explanatory and require further investigation, which takes time and effort to understand.

Bailey Klepacki, Project Engineer – published 5/6/2021 

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For TechTips prior to 2021, please email with your request.