The compressors sounded like a microwave full of spoons. I’d barely been in American Samoa an hour and there I was in a tuna vessel’s machinery space in Pago Pago, wondering how three Sabroe screws were still turning. The crew was struggling to hold temperature, and there was close to NZ$4 million worth of skipjack tuna aboard.
The vessel was waiting for an unloading berth. In the meantime, the job was to keep the fish cold. I’d worked on enough fishing boats to understand the pressure. I’d also heard enough sick compressors to know we were running out of time.
The samples told the story
The sight glass on number three’s oil separator showed layers and what looked like crystals. We took oil samples from all three machines. One was thin and cloudy, another thick and black, and number three gave us a strange pink ooze. A sample from a low-pressure accumulator confirmed that serious water contamination had reached well beyond the compressors.
The oil filters were badly blocked. One capacity slide was seized, and when we opened its suction strainer we found salt crystals the size of softballs. The samples and the condition of the equipment showed how far the deterioration had gone. The route the water had taken into the plant remained uncertain.
The cut-outs had been bypassed
When I checked the compressor controllers, I found the oil-pressure cut-outs had been adjusted so they would no longer trip on oil failure. With the filters already choking up, we were depending on machines that had lost a protection they needed most.
I told the captain to make arrangements to offload the fish. We tried to buy the vessel some time. By the next morning, one compressor had destroyed itself. A second failed by 10 am. The fish finally came off that afternoon. What started as a call-out turned into a rebuild that took months.
What I’d ask on any plant today
Water contamination can build quietly. It changes the pressure–temperature relationship of the refrigerant mixture and can contribute to sludge and poor refrigeration performance. A plant that takes longer to pull down or keeps blocking filters deserves a closer look. On that boat, by the time I could hear the problem from the machinery space entrance, the plant was well past subtle.
The rebuild also gave us a chance to improve ventilation and get the ammonia alarms through to the bridge, where somebody could act on them. We tested the safeguards regularly. That mattered as much to me as getting the compressors running again.
Look at what’s changing
Read oil condition, repeat filter blockages, abnormal noise and falling performance together. If they point to contamination, have competent people assess its extent and investigate how water may be entering the system.
Ask for proof the trip works
Check the approved settings and the record of the last functional test. Agree in advance what must happen if a critical trip is found impaired, including who must be notified and when the equipment must be stopped.
Plan for the product before the plant fails
Agree who can arrange product transfer or bring backup capacity online. Check whether the backup depends on the same system that’s already in trouble.
Name who can stop the plant
Agree who has shutdown authority, what conditions trigger a stop and who clears the plant for restart. Make sure the people on shift know the answers.
The shutdown decision
Who has the authority to shut the plant down when the evidence says stop?
I’d want a name and a clear answer before the next breakdown, while everyone still has time to think.
Adapted from Pádraic Durham’s account, first published on LinkedIn on 16 March 2018. Read the original on LinkedIn ↗