Badak LNG was capable to operate eight LNG Process Trains to produce LNG with maximum annual capacity of 22.5 MTPA. However, Badak LNG is currently entering idle phase for several of process trains due to declining of feed gas supply. Long Term Idle (LTI) preservation program has been developed to maintain the condition of all plants including insulation removal for all insulated lines and equipment. Insulation removal program is intended to reduce risk of Corrosion Under Insulation (CUI) that may attack all insulated lines and equipment.

Unfortunately, due to cost effectiveness program, insulation removal has been postponed and evaluation was needed to understand the severity of CUI and its effect to material integrity and cost benefit that maybe generated from this postponement. Therefore, evaluation of CUI severity was conducted during 5 years of idle period by using visual observation on selected inspection windows to determine the severity. Thickness measurement for the worst CUI grade items was also performed in the end of idle period to find out the effect of CUI degradation to integrity of material.

The evaluation reveals that about 21 percents of all inspected pipings and equipment were actually degraded in term of corrosion grade after 5 years in idlecondition. However, no degradation into grade D (worst grade) from grade A and B items was observed. Thickness measurement on worst grade items shows that the degradation of CUI is not affecting the material integrity significantly. Recommendation might be given in the future to exclude better condition, such as grade A and grade Bfindings from insulation removal programwhile removal still has to be conducted for worse grade items (grade C and grade D).

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