Grasso V 700 800/15

Common issues

• Valve plate wear or breakage causing reduced capacity and abnormal knocking
• Crankcase oil carryover into the refrigerant circuit, reducing heat exchanger efficiency
• Shaft seal leakage - a known wear item on reciprocating ammonia compressors
• Liquid slugging from a flooded start or poor suction superheat control, damaging valves or pistons
• Capacity control (unloader) malfunction affecting part-load operation
• Bearing wear from inadequate lubrication or oil degradation
• High discharge temperature from low suction superheat, worn valves or a fouled condenser

Inspection checklist

• Check crankcase oil level and condition, including ammonia dilution
• Check discharge and suction valve plates at scheduled opening for wear or breakage
• Check shaft seal for leakage or weeping
• Check capacity control (unloader) function across load steps
• Monitor discharge temperature and pressure trend against baseline
• Check safety/relief valve setting and test date
• Inspect coupling/drive alignment
• Check vibration levels at running speed
• Verify oil separator function and oil return

Service intervals

Typical wear limits

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

Critical spares

• Suction and discharge valve plate sets
• Shaft seal (mechanical seal) kit
• Gasket/O-ring set for cylinder head and crankcase
• Unloader/capacity control components
• Oil filter elements
• Pre-set spare safety relief valve

Safety

• Ammonia (R717) is toxic and flammable in certain concentrations - full PPE including gas-tight suit and breathing apparatus is required for refrigerant-side work
• Confirm the machinery space ammonia detection/alarm is functional before entering the compressor room
• Isolate and pump down high-pressure refrigerant lines before opening any joint
• Electrically isolate and de-energise the crankcase heater before internal work
• Emergency ammonia shower/eyewash and escape routes must be accessible and unobstructed

Class survey

Ammonia refrigeration compressors of this type typically fall within the scope of the vessel's refrigeration plant survey; class wants records of scheduled valve/seal maintenance, current safety/relief valve test certificates, and evidence that ammonia detection and emergency systems are tested per the statutory schedule.