4 replies to this topic

[Wheristo]

Hi gents-

Need your expert view. Got a question whether "Pressure Relief Analysis" is considered as Process Hazard Analysis (PHA) or not. Among the 14 PSM Elements in OSHA 29CFR1910.119 says that, for PHA - Update & Revalidation....

"At least every five (5) years after the completion of the initial process hazard analysis, the process hazard analysis shall be updated and revalidated by a team meeting the requirements in paragraph (e)(4) of this section, to assure that the process hazard analysis is consistent with the current process."

I'm trying to prove that Pressure Relief Analysis is a component or a kind of PHA, so it should be performed every 5 years as per the above requirement by OSHA.

To me "Pressure Relief Analysis" should be considered as PHA, since the process hazard (in this case OVERPRESSURE SCENARIOS) are being analyzed. Just that I feel that when people say PHA, then the mindset is limited to the kinds of HAZOP, What-if method, Fault Tree, FMEA, etc.

Appreciate your views.

[GTYJ81]

Wheristo,

A “Pressure Relief Analysis”, as you put it, is not a PHA. A HAZOP is not a PHA, although many people seem to think these terms are synonymous. The design of a relief system and its design basis would certainly be included in the information one would compile as part of the Process Safety Information required by OSHA 1910.119. The Process Safety Information would include information on the hazards of the chemicals used in the process, on the technology of the process, and information on the equipment (including, but not limited to, relief system design).

Only after a thorough compilation of the Process Safety Information has been assembled, can a proper Process Hazard Analysis be performed. At that point, the appropriate methodology can be chosen whether it be a HAZOP, What-If Analysis, Failure Mode and Effects Analysis, or a simple checklist. Which method is appropriate will depend on the complexity and nature of the process.

Dan

[kkala]

Thank you Dan (GTYJ81) for the clarifications, assuming to concern Safety surveys elaborated in USA. Procedures in Greece (and probably in European Union) seem to have some formal differences, but not substantial ones. It may be useful to mention them briefly, suggesting no legal obligation to submit Pressure Relieve Analysis (or similar) and its revisions (comments welcomed).
1. The Safety (or Seveso) Study of a Unit is composed of Process Safety Information and Process Hazard Analysis, as mentioned above. It makes reference to any HAZOP study already elaborated.It also reports design bases of PSVs in general, not specifically (e.g. in the Preventive / Fighting measures). Main purpose is to trace possible catastrophic failures due to escape of flammable or poisonous substances and assess the relevant risks (*).
According to law, Safety study has to be resubmitted every 5 years, unless Unit has undergone important modifications earlier.
(*) Hazardous area classification is not part of this study.
2. It is concluded that there is no legal obligation to submit a document similar to "Pressure Relief Analysis" (or its revisions) concerning overpressure protection. Otherwise local refineries would assign this task to the firm of my work, or to other similar companies.
Irrespectively of this, local refineries have their pressure relief systems reviewed and updated every now and again to cope with Unit modifications. Several assignments of this kind have been known.
Note: PSV hydrocarbon emissions from local refineries are directed to flares and potentially dangerous events could be assessed in Safety study, if not in the Environmental Impact Study (referred in Safety study).. The latter is usual over here.

Edited by kkala, 10 November 2012 - 04:21 PM.

[TS1979]

Example of PHA information:

• Chemical reaction equations and stoichiometry for primary and important secondary of side reactions
• Type and nature of catalyst used
• Reactive chemical data on all streams, including in process chemicals
• Kinetic data for important process reactions, including the order, rate constants, approach to equilibrium, etc
• Kinetic data for undesirable reactions, such as decompositions and autopolymerizations
• Process limits stated in terms of pressure, temperature, concentration, feed-to-catalyst ratio, etc. along with a description of the consequences of operating beyond these limits
• Process flow diagrams and a description of the process steps or unit operations involved, starting with raw material storage and feed preparation and ending with product recovery and storage
• Design energy and mass balances
• Major material inventories description of general control philosophy (I.e. identifying the primary control variables and the reasons for their selection)
• Discussion of special design considerations that are required because of the unique hazards or properties of the chemicals involved
• Safety, health, and environmental data for raw materials, intermediates, products, by-products, and wastes
• Regulatory limits and/ or permit limits
• Applicable codes and standards
• Variances
• Plot plans
• Area electrical classification drawings
• Building and equipment layouts
• Electrical classifications of equipment
• Piping and instrumentation drawings
• Mechanical equipment data sheets
• Equipment catalogs
• Vendor drawings and operation and maintenance manuals
• Valve and instrumentation data sheets
• Piping specification
• Utility specification
• Test and inspection reports
• Electrical one-line drawings
• Instrument loop drawings and logic diagrams
• Control system and alarm description
• Computer control system hardware and software design
• Operating procedures (with critical operating parameters
• Maintenance procedures
• Emergency response plan and procedures
• Relief system design basis
• Safety system(s) design basis
• Fire protection systems design basis
• Incident reports
• Meteorological data
• Population distribution data
• Site hydrology data
• Previous safety studies
• Internal standards and checklists
• Corporate safety policies
• Relevant industry experience

[Wheristo]

Gents-
My apologizes for late in replying. Your views make sense to me & greatly appreciated. Thank you.