A UK consortium is to evaluate the best technologies available for identifying corrosion under insulation
Almost without exception, oil and gas infrastructure will experience changes in climactic conditions and temperature, and almost without exception that results in the possibility of corrosion under insulation (CUI). Even with the most resistant coatings and insulation, water can seep in and begin to damage the pipework, and that has profound effects on operating costs: historic studies have suggested that CUI is the cause of 40-60% of the money spent on piping maintenance.
Outside any permanent monitoring solutions, non-destructive testing (NDT) is the primary method by which pipes and temporary pipe wraps are checked for integrity. However, with a range of technologies available, each with a particular set of advantages and disadvantages, it is not always clear which method may be best for the particular NDT job.
A new consortium has set out to tackle the problem. The group – which includes TRAC Oil & Gas, the University of Strathclyde and the Scottish Innovation Centre for Sensor and Imaging Systems (CENSIS) – will audit the tools, capabilities and approaches currently used by industry to look at the steel surfaces of assets which are often obstructed by layers of material.
Those surveying assets have a range of NDT methods and techniques at their disposal, but many are ineffective at accurately alerting and calculating the extent of CUI. Instead, most technologies tend to produce an average wall thickness reading where corrosion “scabs” have formed, thus failing to pinpoint specific areas of vulnerability. Recording and interpreting these readings is further complicated by the varying dimensions, materials, locations and accessibility of different oil and gas assets. Alternatively, insulation can be removed – but this requires significantly more time being spent in challenging conditions – potentially even causing minor shutdowns – all of which can make the whole process more dangerous for the technician, and more expensive for the asset owner. After assessing what is available, the consortium will explore how improvements can be made, including the development of new techniques for accurately identifying and measuring areas of corrosion.
On the right TRAC TRAC Oil & Gas technical manager Bill Brown explained: “Inspection is becoming more important as the UKCS continues to mature. We’re at the point now where, against the backdrop of a sustained low oil price, if a platform has to shut down for maintenance, it may never start producing again. We therefore need as much accurate data as possible to make informed decisions.
“By taking regular readings on an asset’s condition, we can determine whether they are fit for purpose and operations can keep oil flowing, all within as safe an environment as possible. To do this effectively, we need to take stock of all the technology available, verifying its capabilities and limitations. From there, we’ll be able to look at potential new methods for inspecting the integrity of assets, using non-destructive techniques.” Dr Gordon Dobie, of the University of Strathclyde’s Department of Electronic & Electrical Engineering, added: “Working with TRAC’s team, we’re examining what companies currently do to measure wall thickness, repeating it in the lab on specimens, and trying to develop a standardised approach to getting more accurate information from NDT. We’re validating what the instrumentation is saying about the thickness of walls with a view to filling a real and significant gap in the technology already available.”
CENSIS, which brokered the relationship between TRAC and the University, will also provide project management support as the initiative progresses. CENSIS’ Rachael Wakefield commented: “Being able to accurately analyse corrosion under insulation is the holy grail of NDT. This project demonstrates that there’s a real opportunity for oil and gas companies to enhance their offering and tackle some of the biggest problems facing the industry.”
The first phase of the project is a feasibility study, the results of which will be shared with wider industry and its stakeholders, including the Health and Safety Executive.