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DOF Subsea’s Skandi Achiever’s high pressure tubes have full periodic inspection and test

24th January 2018 at 09:20
DOF Subsea’s Skandi Achiever’s high pressure tubes have full periodic inspection and test while remaining in ROV operation. In situ acoustic emission testing cuts time and budget.

UK-based Chesterfield Special Cylinders’ dedicated Integrity Management team (CSC IM) has completed a full inspection and test of Skandi Achiever’s high pressure tubes while the offshore support vessel remained operational on an ROV inspection project in the Gulf of Mexico.  By utilising specialist acoustic emission (AE) testing techniques CSC IM did not need to remove the tubes from their installation and reduced operator DOF Subsea’s budget substantially compared to the cost of traditional hydro testing.

Ten-year inspection and testing completed while still in ROV operation

Skandi Achiever was built in 2007, so its dive system’s 40 seamless tubes required their ten-year DNV-GL re-classification inspection and test.  DNV-GL recently added AE to its ruleset due to it being faster, cheaper and safer than traditional hydro testing.  CSC IM is a global specialist in AE testing for the offshore sector.

The CSC IM project included: 

  • Removal of tube adaptors and fittings
  • Periodic Inspection and Test in accordance with EN 16753:2016
  • Build-up of adaptors, utilising new seals, and fittings making suitable to carry out testing
  • Acoustic Emission testing in accordance with EN16148:2006.

While on board, the CSC IM team also inspected and tested 40 small cylinders used on Skandi Achiever’s diving bell, Self-Propelled Life Boat and Divers Reclaim system. 

Stephen Butler, director of CSC IM, comments: “In situ AE testing really delivered on this project.  If we had removed the tubes for testing it would have taken far longer, been far more costly and would have presented a potential safety risk. 

“AE testing is simply faster, cheaper and safer than hydro testing and can be carried out while the vessel remains in operation, earning its keep. 

“Because we applied AE techniques we carried out the work on all 40 tubes concurrently, again saving time.  DOF Subsea has benefitted from re-accreditation without having to break off from a productive ROV operation.

“Acoustic Emission Testing Kelly Tubes is a superior and preferred method to Hydro Testing because the risk of moisture and subsequent rust forming in the HP tubes is eliminated, and we did not need to consider the structural weight impact of adding water to the system. Further to this the system downtime is significantly less than performing a Hydro Test.”