You know that steel pipes can be manufactured in both seamless or welded forms. But what are the benefi ts offered by each of the two production processes? Not only the dimensions are crucial.When selecting a seamless or welded pipe, an abundance of facts should be taken into consideration.
Seamless pipes are manufactured using different procedures, depending on the diameter or the ratio of diameter to wall thickness. The normal raw material is a round spool section preheated in a rotary furnace,or for larger diameters a hollow section preshaped in a perforation press, which is then prerolled in a rotary rolling mill.
In the manufacture of longitudinally welded pipe,either individual steel plates or coils are used as raw material. The pipes are produced in a series of different, sequenced process stages, including cold forming, welding, heat treatment, calibration and non-destructive testing.
Manufacturers of both seamless and welded pipe offer a wide range of standard sizes for different branches of industry. For the individual production of welded pipes, the raw materials can be ordered and used in precise thicknesses depending on the wall thickness calculations, which will deliberately save resources and cut costs.
When you consider cost-effectiveness, the advantages of seamless pipes for small to medium-sized outside diameters with higher wall thicknesses are clear. On the other hand, welded pipes are more advantageous for small, medium-sized and large outside diameters with wall thicknesses of between 2 and 70 mm.Generally the economically strong dimensions for hot rolled seamless pipes have outside diameters of up to NB 100 and a diameter / wall thickness ratio of 5 : 1 or smaller (e. g. 50 : 10, 50 : 20 etc.), for sizes larger than NB 100 normally 8 : 1 or smaller (e. g. 200 : 25, 200 : 30 etc.).The range of possible sizes, however, is restricted by the fact that wall thicknesses of less than 3 mm are not available for hot rolled seamless pipes. When manufacturing welded pipes from individual steel plates or coils, the minimum ratio of outside diameterto wall thickness throughout is around 10 : 1, which therefore presents a very wide range of opportunities.But these pipes can normally be produced more costeffectively in welded condition.