Warning Signs Before
a Tube Sheet Fails

Most tube sheet failures that force unplanned shutdowns were visible months earlier — as joint weeps, deposit patterns, or dimensional drift during planned outages. This article maps inspection findings to likely mechanisms so maintenance and reliability teams can act before a leak becomes a turnaround.

Early mechanical and leak indicators

• Joint weepage at tube ends during hydro or service — often expansion relaxation or weld defects.
• Localised staining around ligaments — chloride concentration cells or under-deposit corrosion.
• Face corrosion on the shell-side face while holes look clean — wrong material for shell fluid.

What the pattern usually means

Scattered random weeps suggest installation or expansion quality. A ring of damage near the periphery can point to thermal distortion or gasket/baffle interaction. Uniform attack on one face is a materials mismatch — revisit material selection.

Inspection package that catches issues early

Dimensional resurvey of critical ligaments, PMI on suspect repairs, and targeted UT on thick plate. See testing & quality. For severe petroleum service, align with TEMA Class R expectations in TEMA classes.

When replacement beats repair

Repeated plug campaigns, clad disbond, or ligament cracking near minimum thickness usually favour a new sheet — fixed, floating or U-tube per the original thermal design (products).

Talk through findings with NPRO engineering: enquiry form · sales@nproindia.in.

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