What are you doing to combat the signs of ageing?

With the UK sector of the North Sea (UKCS) approaching 40 years of oil and gas production, the majority of platforms in the UKCS are beyond their original design life. Operations beyond design life in addition to constant exposure to rain, wind and salty water is imposing asset integrity issues on equipment used in offshore installations. When it comes to measurement instruments, the cumulative impact of this constant exposure to the elements is the increased likelihood of premature ageing and failure.

In its document ‘Managing Ageing and Thorough Reviews of Ageing Installations’, the Health and Safety Executive (HSE) states that: “Ageing is not about how old your equipment is; it’s about what you know about its conditions, and how that’s changing over time.”

The combined accelerated effects of weathering, corrosion, fatigue damage arising from the inherently hostile conditions of an offshore installation, plus any damage from accidental breakage can all impact on the ability of an instrument to provide accurate and reliable measurement. Where such instruments are part of a safety system intended to detect and pinpoint wider failures, such deterioration and damage can be potentially catastrophic.

With the UK offshore industry currently comprised of 108 installations over 25 years old, the Health and Safety Executive (HSE) is keen to do everything possible to limit the risk of failures caused by ageing.

Through its Key Programme (KP) scheme, the HSE has steadily been taking stock of the condition of the UK’s offshore facilities. Consisting of a thorough inspection into various key aspects of the operation of an offshore facility, each programme lasts three to four years, with a concluding report outlining recommendations for areas for improvement.

The issue of plant and equipment degradation and ageing has been covered by the latest key programme, KP4. Commencing in July 2010 and running until December 2013, the programme sought to promote awareness of the risks surrounding ageing plant and life extension, and to put in place basic best practice requirements relating to asset integrity, competence, safety culture and leadership with a view to minimising the failure and /or loss of an installation.

In terms of electrical control and instrumentation (EC&I), KP4 was specifically concerned with safety critical elements, including:

• Electrical equipment in hazardous areas and external electrical equipment which is not isolated in the event of gas detection

• Safety critical instrumented systems covering fire and gas (F&G), emergency shutdown (ESD) and high integrity pressure protection (HIPPS)

• Well control instruments & control systems

With many of the instruments in an offshore safety system having no explicit design life or means by which their design life can be determined, the onus falls on operators to regularly inspect their installed devices. Under the programme, all inspections needed to be documented, with details kept on dates of inspection, plus information on any signs of ageing detected and how they will be addressed. If necessary, the findings from an inspection will also need to be used to modify the frequency of monitoring, with more frequent inspections needing to be carried out where ageing is identified as an issue.

Equally, operators also need to take into account the issue of obsolescence and / or the likelihood of suppliers ceasing to support a particular product or products.

Although the KP4 programme itself might now be old news, having ended in December 2013, its findings and consequent recommendations themselves are unlikely to get old, having an on-going impact on the way that operators manage the signs of ageing on their offshore assets. Furthermore, developments in technology are presenting new possibilities for keeping instruments in good working order. Developments in wirelessHART technology, for example, mean that a wealth of hitherto unobtainable diagnostic data can now be extracted from instruments in even the hardest to reach parts of a facility.

ABB’s product offering for oil and gas applications is backed up by extensive expertise in inspection, specialist functional engineering, integrity management, operations improvement, process safety, projects services, technical software and the provision of technical training.

For more information, email moreinstrumentation@gb.abb.com ref. ‘Ageing assets’.

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