273*8 spiral welded steel pipe

　　273*8 spiral welded steel pipe are produced by expanding machine. The technical process is the same as elbow machine. The difference is the pipe mould is straight and pipe elbow have bending radius. The advantage of hot expanding pipes is the low prices and easy to collect the sources. The disadvantage of  the expanding pipes is the wall thickness. The thickness of hot expanding pipes is not as good as hot roll or cold drawn pipes. The tolerance is big but within the American standard.