FAILURE ANALYSIS OF A BELLOW AT THE EXHAUST OF A DIESEL ENGINE ON BOARD OF AN FPSO

摘要

Floating Production, Storage and Offloading (FPSO) units are floating vessels used by the oil and gas industry offshore for the production and processing of hydrocarbons as well as storage of oil. It is equipped with the required facilities to produce, process, and store produced fluids. Among the equipment on board of the FPSO are pumps used to inject water or pump crude oil. This FPSO is fitted with seven positive displacement pumps powered by diesel engines; three for water injection and four for power fluid. At the exhaust of the driving engines, stainless steel bellows experienced frequent failures on a monthly basis; thereby, incurring a huge financial overburden on operating companies. Therefore, the aim of this paper is to explore the possibility of identifying some remedies to overcome this problem. The paper discusses the root causes of bellow failures attached to the exhaust system of a diesel engine on board of an FPSO. Effect of vibration, temperature, corrosion, and vessel rolling on the bellow structural response were investigated to identify the root causes of failure. A finite element modeling of the problem under study was conducted by taking into account the combined effect of thermomechanical loads. It was found that the thermal stress was well below the allowable stress. In addition, vibration analysis of the bellow-engine system revealed that the fundamental frequency of the bellow was way below the engine's natural frequency. However, it was found that the vessel's rolling generated an elevated stress that can cause failure of the bellow in a very short period time. The paper also presents some possible solutions to remedy or delay failure from occurring frequently as in this case.