Know about MLP in Tube #Tubesheet joint

MLP – Minimum Leak Path

Concept – while designing the heat exchanger, critical and potential leak path of the fluid is tube to tubesheet joint. Thus, T#TS joint design become more important. It has to be decided whether to go for expansion joint, seal weld or strength weld or combination of strength weld and expansion.

Definition – Minimum Leak Path for the strength weld joint is the minimum distance required by a fluid from root side of the weld to get leaked from face side i.e. Tubesheet side.

Generally, requirement of MLP is same as the tube thickness.

Above sketch represents the T#TS joint, where “b” is measured as Minimum Leak Path.

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Swirling of molten weld puddle 

Many forces acts on the weld puddle with different welding conditions. 

Swirling motion of weld puddle can be more often seen precisely with autogenous arc welding process.  

This swirling motion ensures proper fusion of edges of the weld joint. 

This can be more observed in PAW and GTAW process.