Relief Studies & Flare Studies

Relief systems are considered as a line of defense at any operating facility, hence it is very critical to ensure they are adequately sized in case there is an unplanned event or upset condition. Safety depends on accurate, consistent, and accessible process safety information. Relief systems design and design basis is considered one of the key process safety information. At any given operating facility, the one thing that is common is change. Relief systems and flare design must keep pace with all changes at the facility, as some changes can have potentially devastating consequences.

Occupational Safety and Health Administration (OSHA) CFR 1910.119- Process Safety Management of Highly Hazardous Chemicals promulgated the requirement that operators (all PSM covered facilities) shall keep their relief systems design and design basis up to date. Until some major industry incidents in early 2000's, the industry fulfilled this mandate by using internal corporate guidelines and practices and by borrowing engineering analysis outlined in API 520 and API 521. This literature formed RAGAGEP (Recognized and Generally Acceptable Good Engineering Practice). Prior to these industry incidents, regulatory and/or site or corporate audits occurred infrequently.

The frequent industry incidents changed the landscape of how relief systems analysis is performed. One significant changed was the issuance of a National Emphasis Program (NEP) for Refineries in 2011. The NEP has two sets of questions that review a plant’s overall process safety management program. NEP contains a static list of inquiries or questions explicitly set out in the NEP document. A second dynamic list is issued on a rotating basis from a federal level. The idea of a dynamic list of question is to break an operator’s complacency by being ready for issues discussed in the static set of question.

The relief analysis received special emphasis under the NEP. OSHA increased its staff and its surveillance with incisive scrutiny into the documentation reported by an operator for its relief system. In particular, the emphasis changed from merely the inquiry of whether relief devices are properly sized to whether the plant is fit for service. The latter emphasis requires that a plant ensure that each piece of equipment and piping could withstand or has adequate protection to sustain various overpressure scenarios.

In parallel, API was busy with reworking the 520 and 521 standards. The first significant change over past few years occurred when API was promoted from its recommended practice stature to a standard. Violation or deviation from technical analysis in API could be a per se violation of RAGAGEP that could result in a citation by OSHA. To this end, the party performing the analysis must understand the nuances in API 520/521 as well as have a broad understanding of how industry generally deals with gray areas yet to be resolved by the API.

Smith & Burgess is a voting member of API subcommittee for Pressure Relief & Flare Analysis and has been conducting relief systems studies for major operating facilities globally. Our position gives us a broad perspective of a reasonableness of analysis and approach to relief systems & flare analysis. It has been our recent experience that not only the operator has the obligation to conduct a well-engineered pressure relief & flare study but also the contractor must have in-depth knowledgeable of proper standards and has the capacity to perform a relief & flare study at a given site.

Further, the action items that result from a relief & flare study require a mitigation plan. Smith & Burgess provides mitigation/follow-up support to its client ensuring that any deviations from standards are risk-ranked prioritized and tracked to closure. It is instructive that OSHA’s citations expand to the inaction by an operator to resolve engineering issues that have been thoroughly vetted through the mitigation and action item closure process.

In conclusion, the landscape of relief systems & flare analysis has changed significantly over the last decade. Major safety incidents have increased pressure on the regulators to ratchet up their surveillance. Likewise, the industry is reinventing itself to a higher technical engineering standard that may have been a norm of the past.