What is the required minimum pipe spool between two welds.

The minimum pipe spool length is a major concern and a great confusion in many engineering firms.On what basis the minimum pipe spool length require will differ from one company standard to other in various ways.

The main criterioh for deciding the minimum pipe spool length will be welding stresses induced while welding the pipe ends.As per stress analysis a min of 7mm to 10m is effected by welding stresses (also called the Heat Affected Zone-HAZ).To overcome this then the calculation might come to 20mm and to allow some allowance for ductility to prevail in the piping to take some occational stresses,let us consider another 10mm ,that will total upto 30mm.Now if we see different engineering guides will differ on this issue.Some suggest 100mm min spooll length,some suggest 70mm and some suggest three time the thickness of the pipe .Well it all depends on how the client will accept the min accepted spool length.


What is the minimum pipe spool length between two welds points in straight pipe and the guidelines is the question of this week ?