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Sonomatic Delivers Structured Approach to NII to Assure Integrity

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ABERDEEN, UK – Sonomatic provides the full range of services for delivery of Non-Intrusive Inspection (NII) programmes, which can be used to replace or defer Internal Visual Inspection (IVI) of pressure vessels. NII allows for substantial reductions in shut down durations, thereby maximising production up-time.

Safe operation of pressure vessels relies on inspections to assess their condition, including that of the interior. Internal visual inspection (IVI) is widely accepted and understood by Operators and Regulators. An advantage of IVI is that it is effective without needing up-front knowledge of what to look for in terms of defects and corrosion types.

But there are a few downsides to IVI:

  • There is a high cost of vessel preparation.
  • Records of inspection findings are sometimes limited, for example the depth or extent of a defect may not be recorded and therefore cannot be used for life assessment calculations.
  • The vessel has to come off-line meaning lost production
  • And increasingly of greater concern is that there are hazards associated with entering the vessel.

Sonomatic’s approach to NII aims to replace or defer IVI without any compromise on integrity. The company is the leading provider of NII services to operators in the North Sea and has substantial experience of large scale NII projects and setting up NII on a company wide basis for major operators.

To summarise the NII process:

  • An assessment is performed on the vessel
  • Suitable vessels are identified and workscopes produced
  • They can then be inspected externally at any time
  • The data from the NII is analysed
  • Justification is made as to whether IVI can be replaced or deferred
  • Vessels unsuitable for NII or those which raised concerns during the NII can be prioritised in shutdown
  • Shutdown requirements can be reduced

Benefits of NII include:

  • No entry requirements to vessel, resulting in improved safety and reduced vessel preparation costs
  • Permanent digital records of inspection findings with ability to use data for life assessment calculations.
  • The vessel can continue to operate resulting in increased asset availability.

Last year alone, Sonomatic assisted clients, in the UK and internationally, with review of over 400 vessels for suitability for NII. The savings arising from a structured approach to NII are often substantial, running into millions of pounds. Some examples are provided below.

  • An NII carried out on a large Separator offshore reduced a planned 21 day shutdown by 10 days adding 3% to the annual availability of the platform.
  • Following a successful NII campaign, one operator was able to eliminate a 14 day shutdown saving £4 million.
  • NII on an H¬2S guard vessel saved the cost of internal inspection as well as that of removing and replacing the packing (approximately £750,000).
  • Internal inspection on a TEG Contactor will involve 1200 man hours and 930 hour duration during turnaround due to removal of internals. NII is expected to take 600 man hours with 120 to 240 hour duration (depending on 12 hour/24 hour work pattern).
  • NII at a gas plant has resulted in 30 vessels being able to be removed from a planned shutdown.

Sonomatic is a market leader in the development and provision of automated non-destructive ultrasonic inspection and related integrity services for the oil and gas, power generation and defence sectors. It has operational bases in Aberdeen and Warrington in the UK, Perth and Brisbane in Australia, Abu Dhabi and Muscat in The Middle East, Johannesburg, Secunda and Vanderbijl Park in South Africa, and North Carolina and Houston in the US.

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