API RP 934 - Materials and Fabrication of Heavy Wall Pressure Vessels for High-temperature, High-pre

Last update: Jan 16, 2017

API RP 934, Materials and Fabrication of 2 1/4Cr-1Mo, 2 1/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for High-temperature, High-pressure Hydrogen Service, is a recommended practice developed and published by the American Petroleum Institute (API). It covers the material and fabrication requirements for heavy wall pressure vessels used in petrochemical and chemical refineries to process hydrogen-containing fluids at high temperatures. Specifically those vessels constructed to the standards put forth by the ASME Boiler and Pressure Vessel Code, Section VIII. 

API RP 934 is composed of five separate sections: API RP 934 A, C, and E and API TR 934 B and D. Each section covers vessels that are made of different steels or that run in different temperature ranges. These RPs and TPs can be applied when either constructing new vessels or modifying already existing pressure vessels. Along with materials and fabrication, these RPs also discuss things such as damage mechanisms, proper wall thickness, and weld overlays

The First Edition of Section A was originally published in December 2000, with the most recent edition  published in May 2008. The other sections are all in their first edition and were published at various times from 2008 to 2011. Two addendums to Section A were published in February of 2010 and March of 2012.

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September/October 2005 Inspectioneering Journal
By John Reynolds at Intertek

Temper embrittlement is another form of metallurgical degradation resulting from exposure of susceptible low alloy steels to higher temperature ranges, usually in service, but can occur to some extent even during heat treatment. And, once again, if significant temper embrittlement has occurred, the equipment may be susceptible to catastrophic brittle fracture.

Have you determined whether or not your equipment is subject to Brittle Fracture?
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Auto-refrigeration can impose low temperatures onto process vessels and piping causing them to be at risk of brittle fracture, the sudden break-before leak phenomena that can result in catastrophic rupture of the equipment.