The finishes include plain and galvanized for additional corrosion protection. As a high strength tension control bolt distributor, AFT offers ASTM A325 and A490 TC bolts in bolt sizes ranging from 5/8” up to 1” and lengths from 1-1/2” up to 7”. The tip is calibrated to shear off when the proper tension is applied. Cairns +61 7 4035 5442 Townsville +61 7 4774 3107 Rockhampton +61 7 4922 8580 Tension control bolts, TC Bolts or “Twist-Off” bolts, have become one of the world’s most widely used method to tension high strength structural bolts, as they can be used in almost all steelwork connections. As a high strength tension control bolt distributor, AFT offers ASTM A325 and A490 TC bolts in bolt sizes ranging from 5/8” up to 1” and lengths from 1-1/2” up to 7”. The tension control bolt consists of a three-piece fastening system with 1) a round head bolt with a truncated, flat surface area at the top of the bolt, and a 24-sided tip which protrudes from the opposite end. The finishes include plain and galvanized for additional corrosion protection. 2) a heavy hex nut and, 3) a structural flat washer.