ASTM A709 currently requires that HPS-70W be produced by quenching and tempering (Q&T) the steel plate. Because of furnace length restrictions, this process results in maximum plate lengths of approximately 50 ft. Our 160 in. plate mill at Burns Harbor, IN is now capable of producing HPS-70W "on line" up to 2 in. thick by thermo-mechanical controlled processing (TMCP). The elimination of Q&T processing removes the 50 ft length limitation, speeds up delivery, and reduces costs. Depending upon plate width, the use of TMCP allows production of plates to over 116 ft long.

Until A709 is revised to permit TMCP as an alternative to Q&T it will be necessary to supplement your specification for A709-Grade HPS-70W by adding the following sentence:

"Non-quenched and tempered thermo-mechanical controlled processed (TMCP) HPS-70W steel may be directly substituted for Q&T; HPS 70W steel for plate thickness' up to 2 in. thick."

Work is under way to update the ASTM specification to allow TMCP. We will keep you informed of progress toward that goal.