C. Steel inner and outer surface shall not crack, collapse, crack, crack, rolling and folding, there is separation and scarring defects, these defects should be completely removed (except for tube machining), cleared the wall thickness and diameter of not more than negative deviation. Which do not exceed the allowable negative deviation of the other minor surface defects do not cleared.

D. Straight to allow depth. Hot-rolled, hot extruded steel tube, 140mm in diameter and is equal to not more than 5% of the nominal wall thickness, maximum depth of less than 0.5mm; cold drawn (rolled) pipe wall thickness of not more than 4% of the nominal maximum depth of not more than 0.3mm.

E. Pipe ends should be cut at right angles, and clear the glitch.