Plant & Works Engineering
Improving asset performance
Published:  04 August, 2016

Harald Großmann, service centre manager for Sulzer's Neuss Service centre in Germany looks at the maintenance challenges facing petrochemical refineries and how to improve asset performance and reliability.

The high density of rotating equipment used in refineries means that effective asset management of pumps, turbines, compressors, motors and generators, can play a vital role in maintaining plant up-time and achieving OEE targets, in addition to ensuring high safety levels and profitability. Since every refinery operates with a variety of steadily ageing plant and equipment, drawing on the knowledge and experience of a global engineering company - especially one that performs both routine servicing and emergency repairs for rotating equipment around the world - can help ensure a site is executing the most cost effective maintenance programme.

Looking at the broadest picture to begin with - we know that daily production costs within refineries can run to enormous sums and these can only be met through the efficient production of all the by-products that are created by the processes within the facility. Hence, keeping all of the production equipment and components running at optimum performance levels is crucial in delivering a positive bottom line.

Understanding the costs

Rotating components within any production process will eventually wear and require service or replacement; the type of maintenance program that is used to effect any work can make the difference between a good investment and unnecessary expenditure. The costs associated with a breakdown rather than a service for example include the price of the new parts as well as the additional labour that is required to install it. In most cases, this will be insignificant compared to the costs associated with lost production and process re-starts, hence, any policy must be focussed on preventing breakdowns, which means monitoring and ensuring a high quality of repairs.

In industries where high value or high volume commodities are produced, the failure of a seemingly insignificant component can have enormous knock-on effects that can bring some or even all production to a halt. In some instances it may be economic to develop stand-by equipment that can be brought on line to return production levels to normal much quicker.

However, there will still be a period of lost productivity and when the process is restarted there may be a significant quantity of final product that cannot be used due to the reduced quality. Clearly the overall costs depend on the piece of equipment and the process in which it operates, but being able to quantify these costs enables the maintenance team to start the process of prioritising the assets within the facility.

Reactive and preventative maintenance

Historically, many refineries have taken a decision to employ a reactive maintenance policy whereby assets are replaced or repaired on a fix-as-fail basis which in the short term can deliver some cost savings, unless a more serious failure occurs. Reactive maintenance relies on the skills of the on-site maintenance team and the availability of spare parts. If either of these factors fails to meet expectations, there is a real possibility of substantial losses due to lost production.

The purpose of preventative maintenance is to use all available information and techniques to build a maintenance programme that will identify assets that require some form of service intervention and schedule the works to be completed as a preventative measure. In this way the work can be scheduled to cause minimal disruption and counter-measures can be used to reduce or even avoid lost production costs.

Across a refinery site there can be thousands of assets, some more important than others, some more expensive than others. In a number of cases some of the equipment may be overlooked in terms of regular maintenance and inspection schedules for a variety of reasons, but this can develop into a false economy. Developing even the most rudimentary scheme for preventative maintenance can pay dividends in terms of reliability and productivity.

It is common for the refinery to have a well developed relationship with a local service and maintenance provider that can offer skills and services that are not available within the facility itself. Developing the relationship between the technical engineering department within the refinery and the local service agent, that may also be on-site, is crucial for improving the processes within the facility both in terms of operation and maintenance.

A preventative maintenance programme that will reduce the costs associated with repairs caused by unexpected failures can be developed to include all the key assets within the refinery and may involve procedures such as thermography and vibration analysis. However, complete service providers can also provide design improvements to a number of larger rotating components such as pumps, compressors, motors and generators that will deliver improved reliability and efficiency.

Process specific solutions

A great deal of equipment within a typical refinery could benefit from changes in design or simply an upgrade to more modern materials in order to increase reliability. Improvements to bearing designs on larger pieces of equipment for instance can increase service life and reduce time spent on regular maintenance.

The impeller design in many multi-stage compressors could be improved as part of a scheduled maintenance programme in order to deliver greater output which would allow a more flexible working envelope and improve efficiency.

New solutions can also be applied to the huge number of pumps installed within the facility. Remanufacturing of impellers, balancing and bearing overhauls can all be accomplished within scheduled maintenance intervals, while the application of surface treatments can also be used to extend the operational life of the pumps.

Improving long-term reliability

With so many production processes involving a multitude of pumps, compressors, turbines and motors, it is essential to have a well-developed asset management system in order to reduce the amount of reactive maintenance within the refinery. As these assets mature so an increased amount of intervention will be required and it is the responsibility of the site engineering team to ensure that the most cost effective solution is implemented.

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