Ship Compressor Systems: Achilles’ Heels on Board

Certain compressor systems are integral to your vessel’s functionality. Here’s how you avoid detrimental downtime.

All commercial ships rely on  compressors to some extent. Some compressors, like those that supply N₂ feed air, control air or start air, are considered essential. They drive processes that are critical to the vessel’s operative capability or safety. 

For these systems – “installations supporting Main Functions” per DNV GL general classification rules – the tolerance for downtime is practically nil. 

Let’s look at how you can reduce vulnerability. 

Request High-Quality Compressor Systems

The quality of the compressed air system will determine your overall experience. The compressor itself is obviously important, but it’s only half the story. Some yards will couple high-quality compressors with low-quality auxiliary equipment, leaving you vulnerable just the same.  

A subpar individual component, renders the entire system subpar. 

Additionally, downstream equipment will also suffer from the low-grade air that can be expected from substandard air compressor systems. Moisture and contamination can severely damage air consumers, which are often critical components. 

Therefore, when you embark on a new-build, pay close attention to the following components: 

• Compressors
• Filters
• Dryers
• Air receivers (tanks) 
• Control systems 

Make sure each component (and thus the entire compressor system) is supplied by a renowned maker. 

You need equipment that will withstand the extremely tough conditions you’re bound to face at sea. 

What Your Compressor System Has to Handle

Life on board a commercial vessel can be extremely demanding. Your compressor systems have to withstand harsh conditions for hours on end, so there are several boxes you should be able to tick when designing them. The main things they have to handle are:

• Varying temperatures (–20 ºC to 55 ºC or more).
• Contamination. 
• Mechanical stress (a.k.a. waves).
• Moisture.
• Maintenance by the crew, in less than ideal circumstances.
• Unforeseen events.

The last one is related to the control system, and why it needs to be top-notch. 

Consider the main engine, for instance: If there’s a power outage to the instrument air compressor, the secondary compressor needs to kick in immediately. That’s contingent on a reliable control system, which illustrates the need for quality throughout: The components in a compressor system operate at the mercy of each other. 

Isn’t Back-Up (Redundancy) Enough? 

Back-up (redundancy) is a requirement for all critical compressor systems. But don’t let it give you a false sense of security.

If a critical compressor system breaks down, the redundancy takes the wheel. That’s all well and good, but it puts you in a very vulnerable position. As soon as an unreliable compressor breaks down, its twin takes over (assuming the back-up is a duplicate of the primary system). Not a comfortable prospect, is it?

The backup compressor can be a different make, but both the primary and secondary machine should be high-quality. This reduces the risk of malfunction on either stage. If you enjoy calculating probabilities, you can imagine why that puts you in a much better position. 

Stay the Course with Spare Parts and Self-Servicing 

Wear and tear is a part of life for all rotating machinery. Even the best compressor systems will need scheduled and unscheduled maintenance. When your vessels are in transit, you need to be able to know that spare parts are available on short notice. 

It also makes a lot of sense to have self-serviceable compressor systems. As long as you can get spare parts, you can avoid the further delays associated with specialist servicing. 

After all, it’s easier to move parts than people – or cargo ships.