Maintaining profitable assets

It is widely acknowledged that effective maintenance strategies and practices have a direct impact on process efficiency and productivity and therefore on bottom line profitability. Yet maintenance is still often seen as a cost, rather than an investment. Despite commercial demand for process plants to operate with optimum efficiency, in terms of emissions, energy consumption, production levels, and length and frequency of down time, there remains a tendency to view maintenance not as an essential service to ensure maximum reliability and availability of assets at minimum overall cost, but as a necessary evil, with costs to be cut as far as possible.

In such a climate where spend is closely scrutinised, approaches to asset management and maintenance that can help to drive down cost, keep assets earning and optimise efficiency and productivity are therefore of high value and various methods and approaches can be applied to this end. Avoiding unscheduled down time is of course critical to any process plant, but measures to help keep scheduled outage periods to a minimum and, moreover, to reduce demands on the often tightly-subscribed shutdown schedules are also invaluable. In addition, routes to implement an increasingly proactive or preventive approach (recognised as increasing process efficiency and production capacity) will add further value.

In terms of minimising scheduled down time, two broad approaches can help. One is to make greater use of online maintenance and repair services and keep the shutdown work list as short as possible, restricted to those items that can only be done during shutdown. The other is to make maximum use of on-site services during shutdown to help ensure allocated time is used with optimum efficiency. Both can afford significant time and cost savings.

Minimising down time

A number of technologies can reduce time demands during scheduled shutdowns, helping to avoid delays and keep down time to a minimum. One of these is online valve testing. The ability to test safety and relief valves online prior to shutdown at normal operating pressures and temperatures, using technology such as Trevitest, means that only those valves identified as needing repair then have to be removed from the line for overhaul during the outage.

Similarly, joint integrity programs such as pressurised systems integrity (PSI) management can also help to keep shutdowns on schedule. An analysis of the joints in advance of the shutdown and full documentation of the work requirements for each joint allows accurate planning and time allocation for the work required. Moreover, the service, which includes inspecting, machining as required and controlled bolting of bolted connections, addresses all the issues that can affect joint integrity to guarantee a leak-free start-up. This in turn avoids costly delays, reduces equipment and testing costs and need for re-work and enables earlier demobilisation of labour.

Nearly 1000 flanges were successfully removed, overhauled and reinstalled on site in one project during a scheduled outage at a Queensland process plant, with a zero leak start-up. Some 970 PSV GL/SM groove, RTJ, ANSI and metal-to-metal face flanges were tensioned in the project, which also included inspecting and overhauling steam traps; inspecting, lapping and overhauling gate and globe valves; working on components in the syngas and turbine compressor; removing and reinstating 170 PSV valves; and inspecting all critical joints.

Additionally, because all the work and mechanical data is entered on bespoke psi management software, this provides a real-time status report which can be accessed remotely by the operator's shutdown manager via a secure pass-code entry, representing a valuable outage management tool. The detailed history and comprehensive record that is built up for each joint can also be accessed in future for full traceability and use in future maintenance planning for maximum efficiency.

In-situ services save time

Equally valuable in keeping shutdown periods on schedule is the use of on-site services such as machining. Enabling work to be undertaken in situ, this avoids the logistical issues and additional time (with potential for delays) associated with removal of parts for delivery to the workshop and awaiting their return to replace them. Importantly, with the latest specialist machining tools any concerns over the quality of a machining job done in situ are allayed. Furmanite, for instance, regularly exceeds workshop results, achieving accuracy to within tolerances as tight as 0.001 mm (the equivalent of one micron).

The advantages of in situ machining are especially apparent in the case of large structures. Equipment such as Furmanite's circular self-levelling milling technology, capable of machining circular structures up to 24 m in diameter to extremely high tolerances, comes into its own here. In one example in New South Wales the technology was used to mill a plate to a flatness of less than 0.05 mm with a polished surface finish, while another face was machined to return it to true celestial zero. Surveying and machining of slew rings and mounting faces is another area in which this technology is commonly used, to address any distortion through wear and tear and restore manufacturer-specified flatness and surface finish.

While these are some of the services that can be applied to help minimise down time in scheduled shutdowns, a further route is of course to remove some of the repair and plant modification work from the shutdown schedule altogether by completing the necessary work online, without disrupting production and while the plant remains in operation.

Online maintenance

While temporary online repairs such as leak-sealing clamps have been successfully used to avoid unscheduled down time for some time, technologies to enable permanent repairs online include pipeline intervention (hot tapping and line stopping), allowing a section of plant to be bypassed and changed out while operation continues.

Hot tapping and flow stop services were deployed on a 350 mm pipeline for one petrochemical plant, for example, to enable a control valve to be inserted (part of measures to improve cooling water flow to heat exchangers in the polyolefins plant) without disrupting production. In another instance, a hot tap undertaken by Furmanite into a 48" flare line at an ethylene plant enabled a new propylene plant to be tied in to the existing flare line on-stream.

Importantly, however, while all these approaches are valuable in the battle to maximise plant availability and reduce time pressures to help keep planned shutdowns on schedule, applying these within a proactive or preventative maintenance strategy will be one of the keys to delivering a higher performing plant, longer runs and reduced down time. Given that performance of assets at full potential is critical (anything less than optimum productivity or more than minimal down time can dramatically erode margins and profit), the need to avoid problems rather than taking a 'fix it when broken' approach is evident. But achieving this with minimised budgets and personnel can be difficult.

Outsourcing has a role to play here. While it may initially appear to be an additional cost, when effectively managed it is in fact an investment. One of the potential downsides to outsourcing is where this implicates the involvement of a large number of contractors, bringing further management and logistical issues to be addressed. Key to successful outsourcing, therefore, is to minimise the number of contractors through long-term maintenance agreements with a single company or limited number of companies able to provide a comprehensive range of skills and technologies, often specialist.

Contracting for efficiency

In one major refinery shutdown recently Furmanite took on an extensive work scope that would previously have involved up to three separate contractors. In this case the work included valve removal, overhaul and replacement of 40 valves in the refinery common utilities area and the hydro-cracker complex, removal of over 20 leak sealing clamps and joint integrity management including refacing some 30 flanges in sizes from 12 to 300 mm, fitting new gaskets, and controlled bolting. In addition, Furmanite undertook line boring work on a hydro-cracker HP heat exchanger shell using specialist on-site machining technology to machine a stainless steel overlay, involving machining 3.5 m down inside the 1.2 m diameter exchanger shell.

Following extensive planning in advance of the shutdown, this work scope was completed by the eight-strong Furmanite maintenance team within the 14-day allocated timeslot. In addition, Furmanite provided a further eight technicians for the critical four-day period to perform the work within the common utility and steam systems, where completing the necessary work within the given time window was crucial and was successfully achieved.

The time and cost efficiencies from involving an organisation able to offer multi-skilled technicians capable of providing a range of specialist services while maintaining high quality and safety standards are clear. Moreover, by gaining an ongoing knowledge of the plant as a long-term partner to the operator, the contractor becomes able not just to undertake designated requirements but to make a proactive contribution.

Such contracts, whether based on a 'healthcare' approach (often focusing on a particular specialist area such as valve maintenance) or broader maintenance services, or indeed a permanent core team on-site presence, can lead to identifying methods for optimising the overall plant system, identifying and improving any inefficiencies. The operator gains unrestricted access to both technical expertise and a personnel resource, while outsourced technicians often bring in not only specialist skills but also a broader knowledge of the technologies and solutions available. Moreover, allowing a contractor to develop a close working relationship with the operator, understanding its needs, its operation and getting to know the plant, will enable the operator to gain maximum value through such long-term agreements, ultimately helping to reduce maintenance costs.