TL;DR
Internal or external leaks on a plate pack usually trace to corrosion pits or cracked plates. Isolate the unit, de-plate, perform a dye or pressure test on suspect plates, and replace the damaged ones.
What you might see
- visible liquid dripping from the plate pack
- streams mixing detected by product contamination
- pressure drop on one side rising abnormally
- corrosion staining on plate edges
Likely causes
Corrosion pitting from incompatible process fluid or chloride attack on stainless plates
Erosion from suspended solids or high velocity at the port nozzles
Stress cracking from thermal cycling or improper tightening during previous reassembly
Gasket failure allowing cross-contamination between streams
Required tools
- Dye-penetrant inspection kit
- Torque wrench sized to the frame bolts
- Permanent marker
- Pressure gauge
- LOTO kit
- Replacement plates and gaskets per Alfa Laval M-Series part numbers
Safety first
- Hot fluid and stored thermal energy remain in the plate pack after shutdown. Allow cooling and verify cold before de-plating.
- Dye-penetrant chemicals are flammable and irritating. Use in ventilated space and follow the SDS.
Procedure
- 1
Take the heat exchanger offline and depressurize and drain both sides completely.
Warning: Stored thermal energy remains in the plate pack after shutdown. Allow adequate cooling time before opening. - 2
Lock out and tag out both process connections.
- 3
Loosen frame bolts in the alternating sequence specified in the Alfa Laval instruction manual and slide out the plate pack.[1]
- 4
Number each plate with a permanent marker on the frame edge before removing it, this preserves the correct chevron reassembly order.
- 5
Inspect both faces of every plate under bright light. Look for pits larger than 1 mm, visible cracks, or thinning near the port holes.
- 6
Test suspect plates with a dye-penetrant kit: apply the penetrant, wait 10 minutes, wipe off, apply developer, and look for bleed-through that indicates a crack.
- 7
Replace any plate that fails the dye-penetrant test or shows pitting through to the other face. Use only Alfa Laval-specified replacement plates for the M-Series frame.[1]
- 8
Inspect and replace all gaskets where the plate failed or where the gasket shows compression set or cracking.
- 9
Re-assemble and tighten to the frame dimension on the nameplate. Perform a cold pressure test at 1.1 times the design pressure before returning to service.
Sources
Alfa Laval M-Series Plate Heat Exchanger Instruction Manual, Alfa Laval
Alfa Laval M-Series PHE Instruction Manual, plate removal sequence and replacement guidance (general)
View source
More guides for Alfa Laval M-Series PHE
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