[1F1] Liquefied natural gas plant orbit valve risk-based failure analysis

E Pereira
Glasgow Caledonian University, UK 

This paper presents a study conducted to investigate repetitive failures on orbit valves installed on the outlet of a molecular sieve dehydration unit in a liquefied natural gas (LNG) plant using the risk analysis approach. The orbit valve seizes during operation and causes damage to the lower trunnion bushing. It was identified that the main causes of damage to the orbit valve were as a result of particulate contamination and the speed of operation. The valve was found to be operating at a faster rate than that recommended by the original equipment manufacturer (OEM). The orbit valve seizure incidents are critically assessed using root cause analysis (RCA) and a risk-based maintenance approach to estimate the failure probability and, hence, determine maintenance opportunities towards reliability improvement.

Keywords: maintenance, root cause analysis, failure probability, reliability improvement, risk-based maintenance, damage.