Gaskets and seals significantly reduce fugitive emissions

Paul Boughton

From October 2007 all existing UK processing plants and power stations will have to comply with the EU’s IPPC directive 96/61/EU, which aims to improve the management of industrial processes and ensure a higher level of protection for the environment.  An important part of this legislation is reducing fugitive emissions, which will have significant consequences for all processes in any factory.

The directive has applied to new-build factories since 1996, but, crucially, it becomes applicable to all existing sites in October 2007. This date will be a turning-point for the way in which EU industry operates: all plants and factories which fail to comply with the standards set by the directive may be closed from this point. Therefore it is imperative that industry starts acting now.

To put the problem into perspective, a typical European refinery loses between 600 and 10000 tonnes of volatile organic compounds (VOCs) per year. It is estimated that 72percent of this is attributable to plant equipment such as pipe flanges, pumps, valves and vessels.

The consequences of these losses are far reaching: the loss of product is only the tip of the iceberg in terms of total cost of fugitive emissions; there are clean-up costs, loss of production time, labour costs to repair leaks, environmental fines and more. In this way, reducing fugitive emissions not only protects the environment, but can also save companies a lot of money.

The directive compels process plants to reduce dramatically the loss of these materials through unanticipated leaks, evaporation, flaring, or spills, and, as such, the next few years will be vital: everything possible must be done in order to bring plants up to standard.

The new legislation is wide-ranging and introduces a concept of Best Available Technique (BAT), urging plants to find the best available solution for reducing fugitive emissions right the way along the process, from areas such as design, product selection, fitting and fitter training, to maintenance, site monitoring, and so on. As such, it requires companies to change the way they operate: industry must begin to make decisions on the basis of what is the best available product and operating method, and move away from its current cost-orientated framework.

According to BASF, 28percent of their emissions come from flanges, so improving flange connections will be a priority. While it is true that all gaskets leak, the variation between gaskets is enormous, and therefore choosing the best available gaskets is critical.

Traditionally, a gasket or seal has been selected according to the particular fluid being sealed, and on the grounds of temperature, pressure and available bolting, but from now on, a new specification will have to be considered: all plants and factories will have to ask themselves how much the gasket will leak. Many gasket suppliers will not be able to answer this question, indicating the huge changes industry will have to undergo in the next two years.

So, what can be done to solve this problem? It is important to start acting now. Several high quality products are now being introduced to the UK market, such as the Novaphit SSTC-TAL gasket, designed and manufactured by Frenzelit in Germany. This graphite gasket meets the stringent German TA Luft emission standard, which is set to become the benchmark across Europe for determining gasket performance.

The SSTC-TAL is tested by a complex procedure which involves sealing helium at 300°C, and is extremely difficult to meet. SSTC-TAL is rated for use from -240 up to 550°C and has excellent resistance to hydrocarbons, steam and many chemicals. Easily meeting the German blow-out test VDI2200 at 60bar, this new Frenzelit gasket can be seen to offer a viable solution for plants to adopt over the next two years.

Following the ban on asbestos, reinforced graphite is now the most common gasket material in the chemical and petrochemical industries with the tang metal reinforced version being the most prevalent. However, this grade will not meet the TA Luft standard for leakage and is unlikely to become the Best Available Technique.

The SSTC-TAL is suitable for most metal flanges in most applications, but for sealing oxidising acids, food applications, glass lined and plastic flanges, a different gasket is available.

The Universal Pipe Gasket (UPG) from W L Gore also easily meets the TA Luft standard. It is a moulded gasket comprising 100 per cent expanded PTFE, and is already in stock in the UK. Rated for use from -240 to 270°C, the gasket has very wide chemical resistance and is FDA approved for use in contact with food, with the lowest creep of any PTFE gasket. It has no binders or fillers, and so will not harden in service, and has very low minimum gasket stress to seal.

However, choosing the best gasket is only half the story: it is crucial to fit the gasket correctly in order to ensure a long, trouble-free service life, with the lowest possible fugitive emissions. Some suppliers now offer an on-site fitter training course, which details and explains best practice. These courses also offer certification as part of the audit trail to prove that the best available techniques are being used by the plant concerned.

While I cannot stress enough the impact the directive will have, industry should not fear this new legislation. Gaskets have been developed and are now available, which significantly reduce fugitive emissions. The small extra cost involved will be quickly regained by the savings achieved from reduced product loss. October 2007 is not far away and action is recommended now. 

Peter Childs is managing director of Beldam Burgmann, Norton Canes, Cannock, Staffordshire, UK. www.beldamburgmann.com

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