Anchors shall be of the twin or double-head type designed for attachment to window frames or mullions by two (2) through bolts to each anchor.
Anchors shall be made of the following metals:
Metals used in the manufacture of anchors and anchor fittings shall have an ultimate tensile strength of not less than fifty-five thousand pounds per square inch (55,000 lbs./in.2), with an elongation of a least twenty-five percent (25%) in two inches (2 in.) and shall have corrosion resistance of sixty percent (60%) as compared to copper.
Anchors shall be seven-sixteenths of an inch (7/16 in.) in diameter, and the head of each anchor shall be three-quarters of an inch (3/4 in.) across the flat and not less than five-sixteenths of an inch (5/16 in.) thick.
Anchors shall be designed or spaced so that it is impossible to attach the safety belt terminal to a single head.
Drop forgings shall have one-eighth inch (1/8 in.) radius fillets at all places where diameters or other dimensions change. Wall flanges shall have a diameter that is not less than one and one-quarter inches (11/4 in.).
The space between the anchor head and the flange or window frame shall be not less than one-half of an inch (1/2 in.) or more than seven-eighths of an inch (7/8 in.).
Double anchor heads shall be spaced not less than two inch (2 in.) or more than three inches (3 in.) from the centers.
The back face of anchors for installation in wood window frames or mullions shall be provided with at least two (2) sharp lugs to prevent turning of the anchor after installation.
All anchors and anchor fittings shall be capable of withstanding the following tests:
D.C. Mun. Regs. tit. 24, r. 24-3204