Delivering Improved Asset Integrity and Increased Production Efficiency through the Targeted Maintenance of Pressure Safety Valves
Authors: Robson Howard , Hollins Andy , Merryweather Kym , Moss Harry 
Published: August 2015

BP has been operating in the Caspian Sea and associated area (AGT Region - Azerbaijan, Georgia and Turkey) since the early 1990's and today the area is one of the world's leading hydrocarbon provinces. The assets consist of 7 offshore platforms, one of the world's largest terminals and export pipelines.

The topic of this paper is a description of a practical implementation of an assessment procedure for determining optimum inspection frequencies (endorsement interval) for pressure relief devices protecting pressure system equipment. We describe the development process, the resulting solution and work processes, the challenges related to the data requirements and dependency of the maintenance and inspection organizations to record and collate such data.

Within the AGT Region there are in excess of 5,800 pressure relief devices. Pressure relief devices provide a key layer of protection for the process safety of oil and gas fields and installations and need to operate on demand as and when required. All need to be inspected, tested and recertified on a regular basis.

The objective of the exercise from the outset was to increase the process safety protection and reliability on the installations. Flow charts were developed to ensure the methodology was clear, simple, repeatable and auditable. This methodology was then combined with knowledge and expertise on the failure mechanisms of safety devices and the consequences of an uncontrolled release to atmosphere to determine an optimal endorsement interval and verify that the device was functioning properly thereby preventing the over-pressuring (or under pressuring) of equipment during abnormal operating or emergency conditions or leakage past the seat during service.

The output from the work showed that around 70% of the pressure relief devices could have their maintenance and inspection intervals increased, by up to 6 years. The work was initiated when the oil price was in excess of 100US$ per barrel and on BP facilities that are top of the league in terms of production efficiency (greater than 90%). The primary objective was to improve the safety, reliability and integrity of the installations, however the resulting benefits of performing the assessments aligned to the ability to increase inspection intervals are to significantly reduce maintenance costs, reduce offshore and onshore interventions and increase availability and production efficiency.

The team also reviewed and enhanced the management procedure for the testing, repair and recertification of pressure relief devices, to provide additional guidance to the maintenance teams in the areas of data collection and recording and witnessing pressure relief device testing and re-certification..

To the authors knowledge this is the first practical implementation of the assessment procedure that embraces the total combination of asset integrity information and work process data sources within a whole oil and gas producing region.