Secondly, if something does go wrong with a piece of subsea equipment, retrieving it for repair and/or replacement is not only complex, but also very costly. And even if you want to retrieve and repair a piece of equipment, hiring (or chartering in shipping terminology) a vessel with the correct equipment might not be possible – availability is always an issue.
How things are not different is in the way in which car mechanics carry out diagnostics on an engine, as this can also be completed in a roughly similar way with subsea equipment.
At least a decade ago, one of the major subsea equipment manufacturers carried out a survey to determine the cost of maintenance of subsea equipment. It determined that having a regular programme, sometimes called a proactive campaign, of subsea maintenance is much less expensive, than a reactive response to equipment failure. One of the main costs cited was the difference between tendering in advance for a vessel to carry out a work programme in the future versus going into the spot market and trying to secure a vessel on short notice, if even one is available.
What complicates the issue of asset integrity management of underwater equipment now is that ever more complex machines and systems are being installed on the seabed. At one time, such equipment was limited to subsea xmas trees, mostly valves and piping, and control modules, which have been retrieved and replaced for decades.
The catalogue of equipment installed on the seabottom in the last 20 years includes not only more complex individual units, such as single and multiphase pumps, but also includes very complex systems such as subsea separation units and subsea gas compressors.
What the operators of such equipment, as well as those often troublesome subsea umbilicals, want and need to be able to do now is to monitor their machines and equipment remotely and anticipate failures before they actually happen.