The importance of cleanliness in the oil & gas sector

03 January, 2020

Tim Wright, Northern Europe sales manager (Fuels & Chemicals) and Keith Webb, marketing manager EMEA, both from Pall Corporation, explained that in the case of subsea control systems, there has been a strong trend towards the use of water-based fluids; however, mineral oil-based systems are still used which means oil purifiers (dehydration) are also needed in order to remove water from systems due to the hygroscopic nature of these fluids.

For offshore control applications filters are normally designed for water glycol-based fluids for the likes MacDermid Oceanic series production control fluids. With this in mind, Barnett explained that Hydac has developed and fits special elements to its filters to optimise them for these fluids.

Compatibility

Wright stated that typical industry standards for filter media materials include glass fibre, polypropylene and nylon and fluid compatibility issues must be considered carefully for each application. “For example, in the case of diesel, polypropylene filter media should not be used,” Wright stressed. “Light hydrocarbons are also not suitable for long-term use with polypropylene. Similarly, for water applications that are running at +60degC, glass fibre is not compatible. Compatibility is important, especially with the wide range of chemicals that are used for injection – you must ensure chemical compatibility for each application.”

Further downstream, there are more fluid power-related applications, such as hydraulic motors, pumps, compressors and various other hydraulic systems in an oil refinery or a gas plant, for example. “For this equipment to remain reliable and operational – with little or no unforeseen and costly downtime – correctly sized and compatible filtration systems are crucial,” explained Wright. “Filtration systems used for these types of onshore applications would normally be constructed of standard industrial-grade carbon steel rather than stainless steel or higher alloys, which are commonly used in offshore applications due to the harsh corrosive environment in which they operate.”

Integrity

As with any hydraulic system, cleanliness affords greater reliability and longevity. “Indeed, in the case of applications in the desert or subsea, reliability and longevity are particularly important,” said Barnett. “This is because it can be very expensive to replace parts and equipment due to the relative inaccessibility of where they are situated – you can't train a dolphin to change an element 3000m below the ocean. Therefore, the integrity of the filters is particularly critical in these types of environments.” Barnett added that when repair or replacement is necessary, having a filter supplier with global presence able to offer speedy supply of spare and replacement parts is very important to keep things operational and productive. The supplier should also be able to provide bespoke filters when required and be able to offer a comprehensive range together with full documentation.

Monitoring

Wright and Webb made the point that equipment monitoring is also important. “Because most of the subsea market is moving to water glycol systems, monitoring their fluid cleanliness becomes more difficult using the laser technology that is common across the industry,” explained Webb. “In this regard, a key differentiator for Pall Corporation is the use of the company’s PCM500 series fluid cleanliness monitor. The PCM500 series monitor uses a mesh blockage technology that is not affected by the presence of water, so it provides consistently accurate and reliable fluid cleanliness measurements.”