Authors: Natalie Doe & Dustin Smith, P.E.
“The consequences of an overfilling overpressure scenario can result in increased risk to the facility when mitigated with pressure relief devices. This could occur due to many different root causes. In order for liquid overfilling to require overpressure protection from a relief device, the following must all be true...”
Authors: Waheed Wakil & Travis Bruner
“Many young engineers have a point early in his or her career when process safety hits home. Different companies develop their own unique strategies towards safety that they are comfortable with, which results in considerably different safety cultures within industry. Unfortunately, it is all too common for engineers to treat process safety as an afterthought, with priority given to efficiency and profitability. However, as we will see, treating safety with the utmost importance can prevent costly and life-threatening incidents.”
Authors: Michael Mayo & Dick Baum
“From defining the Causes, developing the Consequence scenarios and ending with Safeguards, accurate PSI information is required to provide the most credible assessment of risk. The best practice of minimizing the assumptions used during a PHA study has two significant benefits: i) management can be assured (feel good) that the PHA process utilized all relevant and up-to-date PSI information thereby reducing potential inaccurate assumptions, ii) it will reduce time spent for discussions between participants to come to common conclusions and speed up the PHA process while maintaining the integrity of the study. As learned from many PSM audits, PSI information is typically spread throughout many locations and maintained by numerous groups…”
Authors: Zubin Kumana, P.E., Venkata Badam, P.E., & Achilles Arneaz
“Over the lifetime of a facility, it is almost a certainty that the throughput of a process will be increased, often repeatedly. Rate-dependency is frequently used as a way to identify pressure relief system sizing that would be affected by the scaling up of process throughput. This paper will define rate-dependency as it relates to pressure relief systems and describe the various ways in which rate-dependent classifications may be affected by the mechanical and thermodynamic constraints of the process and equipment. In addition, examples of when the "rate-dependent" designation may no longer apply due to…”
Authors: Dustin Smith, P.E., John Burgess, P.E., & Zubin Kumana, P.E.
“In November 2011, Hydrocarbon Processing published a paper that documented a method to determine if relief devices were susceptible to chatter. This model is the only screening method that places the relief devices into two categories: (1) those installations that may chatter and (2) those installations that need no further review. The goal of any experimental comparison is that it will error on the side of predicting chatter, but will be reliable enough to screen valves. Since the publication of that article, the Oil & Gas industry has continued to struggle with the issue of relief device stability, so much so that API delayed issuance of API STD 520 Part II Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries-Part II, Installation. This paper compares instances of known chatter to research…”
Authors: Nicholas Cristea & Dustin Smith, P.E.
“When doing a Relief Systems Documentation Analysis, the ability to accurately model a “worst case” relief scenario is paramount to ensuring the system is protected from the overpressure event. The engineer is undoubtedly limited to the availability of equipment data and accuracy of the process simulation developed to predict upset conditions. If some conservative yet unrealistic assumptions are used, the relief device can be labeled as providing inadequate protection in the event of the initiating event. Physically modifying the system to fix the problem, as well as the loss of profit from having to shut down the unit to perform the update, can cost the facility large sums of money. The ability to make relief load estimates match what may happen out in the field can still be accomplished, but knowing the difference between…”
Authors: John Wilkins & Dustin Smith, P.E.
“Process engineers and designers have recently turned to dynamic analysis as a more realistic method for modeling upsets used to size relief devices. Dynamic analysis is used to suggest making modifications of relief devices instead of costly upgrades suggested by traditional methods that are more conservative. Dynamic analysis involves creating a simulation of a process with control valves that operate in either manual or automatic mode. The simulation calculates process conditions (pressure, temperature, etc.) that vary with time as a result of a change in the process. This can be used to simulate a relief scenario like cooling failure or a blocked outlet. With the addition of a relief valve, the simulation can calculate a peak relief load used for sizing the valve.”
Authors: Dustin Smith, P.E.
“In November 2011, Hydrocarbon Processing published a paper that documented a method to determine if relief devices were susceptible to chatter. This model is the only screening method that places the relief devices into two categories: (1) those installations that may chatter and (2) those installations that need no further review. The goal of any experimental comparison is that it will error on the side of predicting chatter, but will be reliable enough to screen valves. Since the publication of that article, the Oil & Gas industry has continued to struggle with the issue of relief device stability, so much so that API delayed issuance of API STD 520 Part II Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries- Part II, Installation. This paper compares instances of known chatter to…”
Authors: Jason White, P.E.
“Overpressure protection analysis has evolved significantly since the inception of the PSM standard, but the mechanical stress applied to the piping during overpressure events appears to have been overlooked. The purpose of this study is to allow an existing facility to focus resources on the relief device installations most likely to fail due to reaction forces. A series of representative installations were evaluated in order to determine which parameters associated with pressure relief have the strongest impact on the installations, with particular concentration on the dynamic effects of the release. A pressure safety valve is a relief device that controls the amount and disposition of material during a process upset, while simultaneously protecting the process equipment from…”
Authors: Dustin Smith, P.E.
“The purpose of this poster is to help the Plant Engineer review the concerns as part of a relief systems audit. Most companies review the relief systems and flare systems design basis to ensure compliance with Recognized and Generally Accepted Good Engineering Practices, referred to as RAGAGEP.”