API Recommended Practices

API RP 752/753 Compliant Modular Blast-Resistant Buildings

HUNTER’s mission to perfect the construction of blast-resistant structures is personal: it’s about the protection of individual lives. We understand that our structures make the difference in the unnecessary loss of life in the event of an industrial accident, ballistics or natural disaster. That’s why all of our buildings are API RP 752 / 753 compliant and have a 8.0 PSI blast rating. The following overview is offered for your convenience and is intended to provide a basic understanding of API RP 752 and 753. Please refer directly to the API’s formal verbiage as the ultimate authority on these and other recommended practices.

API Recommended Practices 752: Building Overpressure Consequences

According to API RP 752, there are several types of buildings commonly used in process areas. These building types and the effects of explosion overpressure on each are as follows: API Recommended Practice 752, Table 4 (1st Edition, 1995)
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API Recommended Practice 752, Table 4 (1st Edition, 1995)
Figure 1 – Portable Buildings Location Guidance
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Figure 1-Portable Buildings Location Guidance
HUNTER’s standard blast-resistant buildings are designed for use at overpressures up to 8 PSI, above the overpressure of reinforced concrete. We can also custom design a blast-resistant building with higher overpressures.

API Recommended Practices 753: Allowable Building Locations

According to API RP 753, there are three (3) explosion hazard zones or blast zones as defined by “Congested Volume” and “Standoff Distance.” "Congested Volume" or “CV” is the volume, in cubic feet, of a collection of closely spaced objects that have the potential to increase flame speed to an extent to generate a damaging blast wave, such as an area populated with pipes, pumps, valves, vessels and other process equipment and supporting structures (See API RP 753.1.7.1 and 1.7.2 for actual API verbiage).

Buildings should be located in zones as follows:

Table 1 – Allowable Locations and Personnel for Portable Buildings Intended for Occupancy
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Table 1-Allowable Locations and Personnel for Portable Buildings Intended for Occupancy
Standoff Distance” is the distance from the edge of the congested zone to the edge of the portable building. Toxic Release Hazards/API RP 753.5 Portable buildings located in areas where a toxic release can reach ERPG-3* levels should meet either of the following: 1. Be designed for shelter-in-place; or 2. Have an emergency response plan (see API RP 753.5). Portable buildings used for shelter-in-place should have the following features minimum: 1. Heating, ventilation, and air conditioning (HVAC) systems capable of rapid shutdown of the system or placement in recirculation mode, whichever is more appropriate. This HVAC shutdown response should be included in the emergency response plan. 2. Exhaust fans and duct penetrations of exterior surfaces equipped with a positive seal against infiltration of outside air. 3. Emergency communications equipment (telephones are acceptable). 4. PPE to be used by all occupants during the evacuation as necessary. 5. Seals for windows and doors. Blast Zone Diagram
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Blast Zone Diagram
*The ERPG-3 is the maximum airborne concentration below, which it is believed that nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects.