AQ14 Series

Common issues

• Gasket leakage from compression set/hardening after repeated thermal cycling
• Plate pitting or cracking, often starting near the inlet/outlet ports where flow velocity is highest
• Fouling or partial blockage from scaling, biological growth or process-side debris
• Internal cross-leakage between the two media, most often traced to a damaged or misfitted gasket
• Cavitation noise and vibration at excessive flow rates for the plate pattern
• External corrosion of the frame plate, tightening bolts and carrying/guide bars
• Uneven or under/over-tightening of the plate pack causing leaks or plate distortion

Inspection checklist

• Pressure/leak test after any reassembly, both sides
• Visual check of every gasket for cracking, hardening, or misalignment in the groove
• Measure the compressed plate pack (tightening) dimension against the value stamped on the frame
• Inspect plate surfaces for pitting, erosion or discolouration, especially near ports
• Check the drain/vent ports between the two media for signs of cross-leakage
• Verify tie bolts are torqued evenly in the correct sequence
• Check frame plate, carrying bar and guide bar for corrosion or damage
• Compare actual approach/outlet temperatures against design duty
• Inspect connection flanges and their gaskets for leakage or damage

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Full gasket set matched to the fluid service (e.g. NBR or EPDM) and plate pattern
• Spare plate set for replacing damaged or heavily pitted plates
• Tie bolts, nuts and washers
• Connection flange gaskets and studs
• Carrying bar / guide bar bushings

Safety

• Pressurised system - fully isolate and depressurise before opening the plate pack
• Hot surfaces where the unit is on a heating/thermal oil duty
• Crush hazard from the tightening bolts and heavy end frame when assembling/disassembling
• Possible exposure to process fluids (fuel, lube oil, chemicals) when opening - use appropriate PPE

Class survey

Plate heat exchangers on essential cooling or heating duties are commonly included in a Continuous Survey Machinery programme; surveyors typically expect gasket renewal records, a leak/pressure test after re-assembly, and evidence that the tightening dimension has been checked against the frame stamping.

Estimated lifetime: Gaskets commonly give 3-8 years of service depending on temperature, cycling and fluid; plates can last many years if free of pitting and corrosion, so plate life is generally governed by water/process chemistry rather than a fixed hours figure.