FITTNESS FOR SERVICE OF STORAGE TANK WITH DEFROMATIONS TO EVALUATE SAFE OPERATING CONDITIONS IN REFINERY
ProSIM is a leading engineering design consultants in oil & gas sector and have executed multiple projects for top oil & gas organizations in India and abroad. ProSIM supports critical evaluations which require sophisticated technical approach and solutions.
ProSIM works as Fitness for service consultants in oil and gas sector for FFS assessment of storage tank which is used to store crude oil for processing in refinery. The tank had several deformations at various height. 3D scan was conducted on the tank, and it was found that there are deformation areas with high values that tends to increase with height and the allowable limit.
ProSIM was approached by the customer for engineering outsourcing and to execute fitness for service evaluation based on FEA simulation to evaluate the safe working height of the tank for as-is condition. As the deformities in the tank hindered its operating ability and slowed the dependent functions in the refinery, the customer had a time constraint for rectification.
The main challenge for ProSIM was the FE modeling of the tank to capture the deformed areas which had been provided from the scanned model. Mesh refinement had to be performed in these critical areas to ensure accurate distribution of stress from the analysis.
The scope of work involved fitness for service assessment of the tank based on FEA simulations. Analysis was carried out for various fill heights Settlement in the tank was also taken into consideration for analysis. The analysis was carried out as per API 579 for the following cases:
- Protection against collapse
- Protection against failure
- Protection against collapse from buckling
The analysis was carried out for various fill heights to evaluate the effect on the deformed parts of the tank. As the tank had to be operated in the as-is condition, the fill height effected its functionality and safe working life. ProSIM was able to determine the safe working height from the analysis which ensured the deformed parts of the tank would not get affected. This also ensured the elastic-plastic strain at the deformed areas qualified for the required load factors.
From the analysis, the customer gained clarity to operate the tank for the recommended fill height to ensure safe operating conditions. Based on the recommendations of the analysis results, the customer was able to operate the tank within safe conditions and minimize the operation losses in the refinery.
