Alfa Laval AC800
Alfa Laval AC800 copper-brazed plate heat exchanger for evaporator/condenser, large industrial. Plate count 30-350, max flow rate 480.0 m3/h, design pressure 31 bar. Part of the AC series, suited for air conditioning, refrigeration and heat-pump duties.
Inspector Detail
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Common issues
- Fouling/scaling on the water or refrigerant side reducing heat transfer efficiency
- Brazed-joint leakage from thermal cycling fatigue over the unit's service life
- External corrosion of stainless plates/headers in a humid or salt-laden environment
- Partial flow blockage from debris or scale reducing capacity
- Freeze damage if the evaporator side runs with insufficient flow or too low a suction temperature
- Gasket/flange leaks at the pipe connections (not the brazed core itself)
Inspection checklist
- Trend the approach temperature (inlet/outlet delta-T) against the design/commissioning baseline to detect fouling
- Trend pressure drop across the unit against baseline
- Visually check for external leaks, frost patterns or staining that indicate an internal leak
- Check insulation condition and vapour barrier integrity
- Inspect connection flanges/gaskets and support brackets
- Confirm the unit's design pressure rating is not exceeded by current system operating pressure
- Check for external corrosion on shell, headers and connections
- Pressure-test after any intervention or suspected leak
Service intervals
| External inspection | every 6-12 months depending on water quality and duty |
| Performance check (delta-T / pressure drop trend) | quarterly to annually |
| Descaling/chemical cleaning if performance trend indicates fouling | as indicated, commonly every 1-3 years - not a fixed interval |
| Pressure test after any opening or repair | each time |
Critical spares
- This is a brazed monobloc plate pack - the internal plates are not field-serviceable or individually replaceable, so the practical spare is a complete replacement unit
- Connection flange gaskets/O-rings
- Insulation/vapour barrier material for reinstatement after inspection
- Pressure relief device if fitted to the circuit, per the system design
Safety
- Refrigerant release hazard - asphyxiation/toxicity risk depends on the refrigerant type in this circuit, ventilate before working near a suspected leak
- High working pressure (unit rated up to 31 bar) - stored energy hazard, isolate and depressurise before opening connections
- Hot surfaces possible on the condenser side depending on service
- A brazed-core leak cannot be locally repaired - failure can mean sudden loss of the circuit rather than a gradual, isolable leak
Class survey
Depending on design pressure and internal volume, plate heat exchangers can fall under class pressure-equipment rules requiring periodic pressure testing or inclusion in the pressure vessel register - confirm this specific unit's classification status and keep the maker's data sheet/nameplate details on board for survey.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Visual inspection inside heat exchanger after opening plate package; UV light detection—white spots indicate water-soluble scaling, black spots indicate oil-soluble deposits. Monitor pressure drop across unit during operation as early fouling indicator. If fouling detected, perform optimized CIP (Cleaning-in-Place) with custom-formulated cleaning agents (2–4 hours typical duration). Backflushing (3× daily, 30-second pulses) may prevent accumulation.
During operation: inspect for any liquid weeping from gasket glands or plate boundaries—must be zero. Perform periodic integrity testing (recommended every 2 years per Alfa Laval): place donor fluid in primary path, recipient fluid in secondary path, apply positive pressure differential, monitor electronically for donor fluid leakage into secondary circuit. On brazed/fusion-bonded units (CB, AlfaNova), inspect solder/bond lines for microcracks using visual inspection and dye-penetrant testing if available.
Monitor inlet and outlet temperature differentials during operation. Document frequency and magnitude of temperature swings. For brazed CB units, be especially cautious—Alfa Laval notes brazed units are sensitive to large, sudden, frequent temperature changes. Inspect solder-joint interfaces during maintenance outages for hairline cracks. Check tightening torque of frame bolts according to Alfa Laval specifications; incorrect bolt load accelerates fatigue. Request Alfa Laval assessment if temperature cycling frequency exceeds design envelope.
Visually inspect all gasket grooves when plate package is opened—look for cracks, discoloration, swelling, or hardening. Confirm gasket material compatibility with both heat transfer media (check Alfa Laval compatibility matrix). If cracks detected or if unit has been in service >5–7 years, replace gaskets with certified Alfa Laval equivalents using correct groove placement procedure. After replacement, perform torque-down sequence per manual and conduct integrity test before restart.
After opening plate package, inspect plate surfaces under good lighting for pitting, discoloration, or rust staining—prioritize gland/seal areas and plate corners where stagnation may occur. In marine service, perform visual assessment annually or after seasonal lay-ups. For high-corrosion marine duty, verify AlfaNovaM (all-stainless-steel) is in use rather than standard CB (which may have dissimilar metals). Confirm flush/circulation program is followed to prevent salt/sediment accumulation. If pitting observed, consult Alfa Laval on material upgrade or replacement.
Monitor differential temperature across inlet and outlet on each circuit. Uneven temperatures indicate distribution maldistribution or internal blockage. Inspect plate inlet and outlet ports visually for debris or sediment before opening. Compare actual thermal performance (capacity, outlet temperature) against design baseline—significant drop indicates fouling or flow restriction. If blockage suspected in narrow channels, perform flushing with appropriate solvents (per CIP protocol) or request Alfa Laval chemical cleaning. Verify inlet filtration is active to prevent future particulate ingress.
Type-general inspection and maintenance points for this equipment category — not model-specific.
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