Outsource plant maintenance if it's not your key competency

The ladder to success: Risk-based inspection reduces costs.

By Bernhard O. Herzog and Paul Jackson, ABB

With today’s rapid communication technologies and a highly interconnected world economy, changes in one part of the world rapidly disseminate to another. Whether in times of fast economic growth or economic slowdown, companies that make swift, intelligent decisions that allow them to adapt to an ever-changing environment succeed where others fail.

To make sound decisions that allow a company to weather a storm or capitalize on a rapidly growing economy requires expertise, which might not always be available in-house. Consultants are frequently employed by companies seeking professional advice from experts with high levels of skill, experience and understanding in areas outside the scope of their normal daily business.

An integral part of any consulting project is knowledge transfer. By liaising directly with the people who work in the plant to gain a full understanding of what they hope to achieve, consultants can make a more time-efficient assessment of what needs to be done. Equally, consultants are able to transfer expertise to the customer’s workforce more efficiently by working in a mixed team and developing solutions together.

Optimizing productivity in any market

During times of growth and ample liquidity, senior managers tend to focus on markets, revenues and the development of new products. Often, staff training, particularly in equipment maintenance, can be overlooked.

When faced with an economic downturn, however, management’s focus quickly shifts to the matter of curbing expenditure, wherever possible. Planned investments in new equipment often are the first victims of such cuts. This is understandable, because capital expenditure in one area could necessitate more drastic cuts elsewhere. However, simply blocking capital expenditure isn’t the answer. Such a blanket approach could lead to the breakdown of key equipment, leading to significant losses in productivity and expensive repairs, unless the potential risk of using aging equipment is countered by targeted and adequate measures in maintenance and diagnostics.

When capital expenditure is no longer an option, it falls to maintenance managers to implement the measures that avoid breakdowns and safeguard productivity.

– Bernhard O. Herzog and Paul Jackson, ABB

The most effective approach to optimizing productivity while minimizing cost is to simultaneously monitor levels of expenditure on new equipment, the cost of maintenance and the resulting performance, in terms of productivity. If investments in new equipment are deemed inappropriate, adjustments might be needed in maintenance schedules and equipment-monitoring processes to avoid equipment breakdowns. This approach of improving maintenance processes to extend the useful life of equipment is known as controlled life-cycle extension.

When capital expenditure is no longer an option, it falls to maintenance managers to implement the measures that avoid breakdowns and safeguard productivity. Depending on the industry, special simulation, diagnostic and monitoring techniques are required, and a plant can stand or fall by the actions of its maintenance team.

Inspection services, safety assessments, reliability and integrity management help determine the remaining lifespan of equipment and its future maintenance requirements and can predict the point at which replacement becomes a necessity.

A cost-effective approach to help manage equipment life cycle is risk-based inspection (RBI). RBI assesses the likelihood and consequence of equipment failure and the cost effectiveness of the current inspection regime. This helps target the higher potential benefit items and avoids wasting valuable time and resource on low risk items.

Risk-based inspection for BP

BP Exploration and Production operates a number of on-shore gas terminals in the United Kingdom, including one at Dimlington, in the northeast of England. The terminal is 20 years old and processes natural gas from the North Sea before feeding it into the United Kingdom’s national gas transmission system. The Dimlington terminal plays a significant role in providing natural gas to the UK market.

In late 2007, ABB was contracted to carry out a risk-based inspection review of vessels and piping at the terminal, prioritizing equipment scheduled for inspection during the next planned shutdown period in the following summer.

The project involved personnel with a wide range of competencies from both BP and ABB. It was based on ABB’s RBI+ methodology, which determines the probability and consequences of equipment failure, in combination with BP’s own corporate RBI procedure.

The RBI+ methodology follows American Petroleum Industry-recommended practices for RBI. The RBI+ process is designed to identify critically important equipment and establish an appropriate inspection regime, which takes into account the risks associated with equipment failure and the failure’s impact on the health and safety of personnel, the environment and business operations. The approach can be applied to all types of equipment, including pressure systems, vessels, piping, pressure-relief systems, civil engineering structures and rotating machinery.

To date, more than 70 pieces of equipment have been reviewed, including numerous pressure vessels and several piping systems. The RBI review determined that 40 pressure vessels no longer require internal inspection, but can instead be examined using non-invasive techniques. Furthermore, the period between vessel inspections could be extended from seven to 10 years.

Based on these changes, BP conservatively estimates that it reduced its overall expenditure for 2008 by $770,000, including preparation costs to facilitate inspection (e.g., scaffolding, cranes, cleaning equipment, fitting resource, stand-by crews), and the inspection itself, representing a savings of 33%.

The change to non-invasive inspection for some items provides a number of significant benefits. Personnel no longer are required to enter the confined space inside a pressure vessel, and the environmental risks associated with cleaning effluent also are reduced. An additional advantage of the non-invasive inspection regime is that the plant can operate longer as there are fewer inspections that need to be carried out with the plant shutdown. In addition, online inspections can be carried out to enable any necessary remedial work to be scheduled for the next appropriate shutdown period, thereby avoiding costly unexpected breakdowns.

In summary, the use of risk-based inspection methodology, built on the combined knowledge and expertise of specialists from BP and ABB, has realized a number of benefits. In particular, reducing the cost and duration of shutdown periods required to ensure the structural integrity of pressure system assets at the Dimlington gas terminal.

A similar approach is currently being used to determine inspection regimes for existing installations at BP’s land-based gas terminals at the United Kingdom’s central area transmission system (CATS), Seal Sands in the north east of the country and at the Sullom Voe terminal in the Shetland Islands. RBI+ methodology also will be used to define inspection schedules for new plant equipment at both Sullom Voe and Dimlington.

Strengthening customer relations

While every plant has its own specific objectives, achieving maximum performance from plant and equipment, at minimal cost, is universal. The aim of ABB’s consultancy service is to help clients navigate difficult decision-making processes and to increase productivity, operational excellence and safety in a sustainable manner.

Bernhard O. Herzog is at ABB Global Consulting in Baden, Switzerland. Contact him at bernhard.herzog@ch.abb.com.

Paul Jackson is function leader inspection at ABB Process Automation in Warrington, UK. Contact him at paul.jackson@gb.abb.com.

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