the following products made primarily of iron or steel: lined or unlined pipes and fittings, manhole covers and other municipal castings, hydrants, tanks, flanges, pipe clamps and restraints, valves, structural steel, reinforced precast concrete, and construction materials. (b) Subsection (a) shall not apply in any case or category of cases in which the Secretary of Agriculture (in this section referred to as the Secretary ) or the designee of the Secretary finds that— (1) applying subsection (a) would be inconsistent with the public interest