providing and fixing pressed steel door frames conforming to is: 4351, manufactured from commercial mild steel sheet of 1.60 mm thickness,including hinges, jamb, lock jamb, bead and if required angle threshold of mild steel angle of section 50x25 mm, or base ties of 1.60 mm, pressed mild steel welded or rigidly fixed together by mechanical means, including m.s. pressed butt hinges 2.5 mm thick with mortar guards, lock strike-plate and shock absorbers as specified and applying a coat of approved steel primer after pre- treatment of the surface as directed by engineer-in-charge: fixing with carbon steel galvanised dash fastener of required dia and size (to be paid for separately steel door frame
