(68c) Examining the Use of Blast Resistant Modules (BRMs) within API 753 Zones 1 and 2

On March 23, 2005 a vapor cloud explosion at a Texas City oil refinery injured more than 180 people and claimed fifteen lives.  The deaths were a result of a blast pressure wave striking contractor trailers located near the explosion fuel source.  Accident investigation determined the trailers were sited inappropriately close to relief device outlets which contributed strongly to the loss of lives.   As a result, API Recommended Practice 753 was drafted in 2007.  API 753 provides guidance to reduce the risk of injury as a result of fire, explosion or toxic release for inhabitants of portable buildings located in the proximity of refineries, petrochemical and chemical operations, natural gas liquids, extraction plants and other industries.

API 753 Recommended Practice stipulates a minimum safe standoff distance of 330 feet from congested volumes for light wood construction portable buildings intended for frequent occupancy (referred to as Zone 3 in API RP 753).  It is often impossible to meet this criterion in a manufacturing facility, so the recommended practice allows placement of portable buildings within the 330 ft boundary if detailed analysis of blast, fire and toxic release scenarios is performed. Design of portable buildings used in Zones 1 and 2 must be evaluated on a case by case basis.  Construction must meet or exceed requirements to protect inhabitants from area specific blast, fire and toxic release scenarios.  Many options exist to meet the intent of API RP 753.  Several choices will be examined and evaluated for suitability based on construction, function and economic considerations.