Paper: Mechanical Integrity Evaluation Of Pressure Vessels

The Federal Government released a new requirement under the Occupational Safety and Health Administration Standards on May 26, 1992. This code for process safety management was issued under 29 CFR 1910.119 in the Federal Register. The code contains requirements for preventing or minimizing the probability and consequences of catastrophic releases of toxic, flammable or explosive chemicals. Oil production and processing facilities which have processes involving more than 10,000 lbs of flammable liquids or gases and which are "normally manned" are covered under this code. Under Section J of the code, employers shall develop written procedures to maintain the on-going integrity of pressure vessels, tanks, piping systems, vent and relief systems, pumps, controls and emergency shutdown systems. Employers are also required to document that tests and inspections are consistent with applicable manufacturers" recommendations, industry codes and practices, and that they have actually been performed. ARC0 Oil and Gas Company has spent a significant amount of time and resources developing programs to be in compliance with this code. One such program involves determining and documenting the mechanical integrity of pressure vessels. Prior to the 1930's pressure vessels were typically constructed to the purchaser's specifications. At that time a code was developed to cover standard construction of unfired pressure vessels. This code, the API/AWE Code for Untired Pressure Vessels for Petroleum Liquids and Gases, was the standard construction code in the petroleum industry until January 1, 1957. At that time, the ASME Section VIII code was developed to cover design, fabrication and inspection of pressure vessels. Most pressure vessels in the petroleum industry which were constructed after 1956 were constructed under ASME Section VIII, Division 1. There are basically two recognized codes covering the inspection of pressure vessels. One code, the National Board Boiler and Pressure Vessel Inspection Code, NB 23 is often used in chemical plants and refineries. It is also used by companies which have registered with the National Board as Owner/User groups. Another code which is available for use is API 5 10 - Pressure Vessel Inspection Code. ARC0 Oil and Gas Company has chosen to use the API code for inspections of pressure vessels. API 5 10 has two specific sections covering inspection and testing of pressure vessels. Section 4 covers all pressure vessels except those used in natural resource service. Under API 510 Section 6 - Alternative Rules for Natural Resource Vessels, owner-user field establishments involved in drilling, production, gathering, transportation, lease processing and treatment of liquid petroleum, natural gas, and associated salt water (brine) may elect to use an alternative set of inspection rules. The only stipulation for this section is that any organization which decides to use this set of alternative rules should apply them to all vessels in that field or service environment. ARC0 Oil and Gas Company has elected to use Section 6 for all field and plant pressure vessels. API Section 6 allows vessels in common circumstances of service and pressure in a field environment to be grouped together as a "class of vessels". This allows inspections to be grouped by class and scheduled over a longer time period on lower risk vessels. ARC0 has elected to use common class of vessels to group similar vessels on non-OSHA 19 10.119 B and C Class facilities.