ABSTRACT
Corrosion Under Insulation (CUI) on industrial piping is a major issue for the oil and gas industry. The potential influence of thermal and acoustic insulation materials is normally assessed through a series of individual laboratory tests on the insulation materials themselves, but very rarely on the applied system. Moreover, the tested physical values do not necessarily and readily reflect the potential influence that a given insulation material or system has on the risk of CUI.
A more sophisticated approach is proposed which takes into account not only the applied insulation system, but also the CUI failure behaviour and water or water vapour ingress and retention processes. This approach allows the individual risk assessment of the applied insulation systems against different scenarios of water ingress to be performed. Other influencing factors for the risk assessment include the configuration of the insulation system (e.g. insulation materials, aluminium barrier foil, outside claddings) and specified construction or installation methods.
It is hoped that the approach proposed in this paper will enable the reader to improve their knowledge of insulation materials and their influence on CUI risk and furthermore, be able to better identify vulnerable areas on the facility where CUI is likely to occur, thereby allowing appropriate CUI management strategies to be developed and implemented.
INTRODUCTION
The World Corrosion Organization estimates that corrosion costs the global economy $2.2 trillion annually.1 According to its figures, almost 45 percent of the cost of this corrosion - about $1 trillion - happens in the oil, gas and petrochemical industries impacting onshore and offshore operations. Corrosion Under Insulation (CUI) is widely acknowledged to be a critical issue facing plant operators.
It is estimated that 40-60% of pipe maintenance costs are a result of CUI, and 10% of total annual maintenance costs in these industries is dedicated to repairing damage caused by CUI. 2,3 Severe cases of CUI may put personnel, environment and industry reputation at risk. Despite the numbers and awareness when it comes to insulation materials little research exists into the best method of preventing CUI to extend the pipework’s life and optimise safety.
