FM Approved Blast Rated Construction Exclusive Haz-Safe Buildings' Wall Design by Haz-Safe

FM Approved Blast Rated Construction Exclusive Haz-Safe Buildings' Wall Design


Frame members, roofing and floor channels clad with 10 gauge wall, roof and floor plate are all continuously welded.	Exposed 2" square x 1/4" thick tubular steel vertical members up to 8' high clad with 10 gauge steel plate have a 120 lbs. per square foot rating.	FM approved and tested 4' wide x 8' long explosion relief panel has 30 ft. per square foot of clear opening.

Haz-Safe Building's proven approach to custom engineered pre-manufactured rooms, enclosures and buildings provide superior blast rated performance as well as practical operation and aesthetic considerations. Basic explosion resistant construction requires the following elements, some or all of which Haz-Safe can provides.

a. Two methods of blast rated construction techniques have Factory Mutual (FM) approval up to 16' tall, floor-to-ceiling. By combining methods, approval is available beyond 16' high. Haz-Safe Buildings are the only hazmat steel buildings manufactured with FM approval above 7'6" high.

b. N.F.P.A. 30, as interpreted by FM, requires pre-manufactured steel buildings to be blast rated up to 100 lbs. per square foot. Haz-Safe standard construction begins at 120 lbs. per square foot blast rating.

c. Some hazmat buildings are required to be protected with explosion relief capability. Haz-Safe provides a patented hinged 8' wide x 4' high relief panel that has been FM tested and approved. N.F.P.A. 30 requires 1 ft. per square foot of clear relief opening per every 50 cubic feet of volume.

NOTE: All U.L. listed and FM approved components and assembled explosion relief panels are not capable of being fire rated. All hazmat rooms and buildings equipped with explosion relief panels have compromised the fire rated wall(s) and ceiling(s). A rated wall of 1, 2 or 4 hours has in fact, with explosion relief panel(s), approximately 5 to 10 minutes before extreme heat from the chemical fire destroys the panel(s) and allows fresh oxygen into the space to feed the fire. Also, fire suppression systems are designed for the protected space to be sealed in order to put out the fire.

d. Blast relief may be substituted with patented sloped floors and trenches, low level posi-ventilation tubes within the sump elevated flooring connected to dual exhaust fans on emergency power grid or generation. Requires approval by local authority having jurisdiction.

e. When hazmat building is to be within 50' of another structure or facility on site, Haz-Safe has provided a patented blast shaft installed over relief panels to protect against the harmful venting of explosives.

f. Haz-Safe's blast rated wall construction is designed to be as thin as possible, thereby providing either more real estate outside or more usable floor space inside.

Figure A. Show/Hide

Haz-Safe Building's 2" square x 1/4" thick tubular steel vertical members, up to 8" high, separated on 24" centers and clad with 10 gauge steel plate, has a blast rating of 120 ft.per square foot. The Haz-Safe wall is only 2-1/8" thick as compared to an 8" wide x 8' high hollow core block wall, as shown above on left, with only a 100 lbs. pre square foot blast rating. When the wall height increases, the wall needs to be strengthened with both masonry and steel in order to maintain a given blast rating.

Figure B. Show/Hide

When the height is raised from 8' to 10', just the rebar in the masonry wall has to be increased from 1/2" to 3/4" to maintain its 100 lbs. pre square foot blast rating. The 10' high Haz-Safe wall utilized a "solid sandwich" method to maintain its 120 lbs. per square foot blast rating. The 23" space between vertical steel members is filled in with 2" thick Dow Chemical Thermax rigid foam insulation board. 7/8" 20 gauge furring strips are fastened to the vertical member at 24" on center spacing. A 3/4" rigid foam board fills in the space between furring strips. Screwed into the furring strips is a single layer of 3/4" thick gypsum that's been clad with 22 gauge steel sheeting. The cumulative total resistance of all the ingredients of the wall maintains 120 lbs. per square foot at 10' high with the wall only being 3-3/4" thick. Note: Walls constructed with common steel studs are not FM approved past 8' high. Haz-Safe Building's walls are pre-approved by Factory Mutual (FM) up to 16' high.

Figure C. Show/Hide

The walls have been raised to 12' high. The masonry wall required going from 8" wide block to 10" to maintain 100 lbs. per square foot blast rating. In this example, the Haz-Safe wall went back to the above first example and upgraded to vertical tubes from 2" square to 2" x 4" x 1/4" thick tubes to reach 12' high and keep 120 lbs. per square foot blast rating.

Figure D. Show/Hide

Keeping the height at 12' but increasing the wall's blast resistance requirement from 100 lbs. to 150 lbs. per square foot requires the masonry walls rebar to be increased from 3/4" to 1" dia. and the block to increase from 10" to 12" wide. On the Haz-Safe example, the 2" x 4" tubular wall of the above third example has applied to it the same "sandwich" ingredients of the second example, which raises the wall's blast rating to 159 lbs. per square foot. It should also be stated the masonry walls are inherently fire rated but would require furring strips and insulation board to be added in order to acquire equal insulation value of the Haz-Safe insulated wall example.