Relief Valves


We’ve recently seen an uptick in the number of clients asking for support to complete the PSM (process safety management) documentation and calculations for relief valves. Although the reasons for the recent compliance efforts vary, we thought it would be worthwhile to review the regulations and requirements OHSA has established for process vessels.

OSHA’s concerns regarding vessels include:
Vessel Rupture:
  • Blast effects due to sudden expansion of the pressurized fluid
  • Fragmentation damage and injury, if vessel rupture occurs
Vessel Leakage:
  • Suffocation or poisoning, if the leakage occurs into a closed space
  • Fire and explosion from flammable liquids
  • Chemical and thermal burns from contact with process liquids
It is important to install relief valves capable of withstanding the given load placed on them by these vessels to avoid the above problems. Maintaining an exact blowdown is not optional. If these relief valves fail, serious injury and equipment damage may occur.
Below is a summary of OSHA’s requirements for vessels containing hazardous materials:
Identification & Documentation: Product identification (such as a relief valve) and where this particular product is being used – location, owner, serial number, manufacturer, date of manufacture and service date.
Design & Construction: Information that identifies the standard use or code for the design and construction of vessel/safety relief valves – fabrication, design code, construction type, requirements and inspection methods.
Service History: Identify operating history – fluids handling, type of service, changes in service conditions and overall history.
In-Service Inspections: Information that identifies inspections performed on the vessels that will assist in the safety assessment – type/extent/dates of inspections performed, examination methods, qualifications of personnel and results of inspections.
Specific Applications: Identify the type of operations that have a tendency to lead to damage, leakage or rupture – type of fluids used, awareness of information and procedures/guidelines.
Process Safety Information: Information pertaining to the hazards of the highly hazardous chemicals in the process including factors like toxicity information and reactivity data and other calculations that help evaluate the specific risks and characteristics of the particular vessel and process.
Evaluation of Information: Assessment of above criteria (identification & documentation, design & construction, service history, in-service inspections and specific applications) will reveal if the practice, operation and maintenance of these vessels and relief valves are all in accordance with OSHA industry guidelines and standards.
For the full text of OSHA’s Process safety management of highly hazardous chemicals please click: (


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