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.