... welding seamstraight seam welded pipespiral welded pipe.As per section shape1round steel pipe2rectangular steel pipe.As per wall thicknessthin ... seamless steel pipes are strip steels which are of hollow section and no seam around the side. 1.The manufacturing ... flat, coil steel, I-beam, H-beam, square tube, rectangular tube, L section steel to customers for use in construction, petrochemical ...