Use of Safety System Performance Standards to Optimise Platform Maintenance
Authors: Smith D.W. , Mawby M.J. 
Published: October 2008

Following the Safety Case Regulations introduced in the wake of the Piper Alpha disaster. offshore safety legislation in the UK continues to develop. One of the most far-reaching changes is the end of the long-standing regime of external certification of each installation. This will be replaced by arequirement for each operator to develop his own risk-based verification scheme based on identified safety critical elements. This paper describes how Texaco and Kvaernerhave used this new approach to shape and optimise the maintenance programme and procedures on the Erskine platform.

Erskine is a high pressure - high temperature (HPHT) normally unattended platform in the UKCS due to start production in 1997. During the design period. key tasks were to select the critical safety systems and draft performance standards for each. These performance standards are specifications, quantitative wherever possible, of the performance required of a system. The use of data already available from the Safety Case quantitative risk analysis assisted in drafting these standards.

Standards established in design then have to be verified in operation. This need for verification helped shape both the final standards and the operational procedures. Example performance standards will be presented and discussed. Where appropriate they set the frequency of testing safety systems, based on the criticality of the system and its failurerate. Failure rates will be monitored through the platform life. and test intervals may be revised if justified.

Texaco and Kvaerner believe that their first application of performance standards in this way has resulted in an optimised and cost effective maintenance regime. The level of verification given to a system is in proportion to its criticality. The approach should have benefits for all offshore operators regardless of the regulatory regime.

Introduction

Offshore operators have traditionally aimed to optimise their maintenance programmes for a number of reasons. These include:

Safety. Operators should ensure that the safety standards established in the design are understood and maintained or enhanced through the operating life of the installation.

Availability. A required minimum level of availability is essential for successful corporate and project financial planning. For many developments an increase in production availability gives an enormous economic benefit.

Benchmarking. The increased use of industry benchmarking means that maintenance which is not to best current practice will be reveled by performance indicators such as production availability and operating expenditure.

Reliability engineering. There have been many developments in this discipline over the past decade. These may be broken down into People, Processes and Systemsissues. A few examples follow:

People. Create a culture where personnel involved in platform maintenance focus attention on what a system doesrather than what it is.

Processes. Select the most appropriate maintenance regime. This involves getting the best balance of corrective (use the equipment until it fails), preventive (implement asystem of planned maintenance) and condition based (monitor performance and intervene after deterioration is detected) maintenance.