Supagraf® Premier, a compression packing from James Walker, has beaten TA-Luft VDI 2440 emission control requirements by a significant margin in tests carried out by the Amtec laboratory in Germany. Reportedly, gas emission levels in the test at 240°C would not fill a golf ball in a year.

The tests on a set of 56mm OD rings of Supagraf Premier were carried out for Ruhr Oel, a 50/50 joint venture of Deutsche BP and Petróleos de Venezuela. BP Refining & Petrochemicals operates the Ruhr Oel Gelsenkirchen refinery. It needed to know the sealing efficiency of graphite valve packings from several suppliers in order to comply with the European Union’s IPPC (Integrated Pollution Prevention and Control) directive.
The targets of the investigation were to confirm A-Luft leakage rates less than 10-4 mbar.l/(s.m) at sealing system temperatures below 250°C, and less than 10-2 mbar.l/(s.m) at above 250°C. The test cycle involved 1000 vertical valve stem movements of 40mm—without live-loading on the packing—whilst sealing helium at 25bar for 24 hours.
Leakage measurements after 24 hours at 240°C showed 7.0 x 10 -6 mbar.l/(s.m). This is less gas than will fill a golf ball in a year, measured at ambient pressure, and demonstrates that Supagraf Premier very easily surpasses the TA-Luft requirements for a high grade valve packing. After 24 hours at 400°C, the leakage rate was 2.3 x 10-5 mbar.l/(s.m).This rate is exceptionally better than TA-Luft requirements for duties above 250°C. A year’s emissions at this level would not fill a tennis ball.

History of success

Supagraf Premier has a ten-year record of beating fugitive emission control specifications. In 1997 it was subjected to over 12,000 valve operating cycles with methane at 40bar and kept emission levels below 500ppm. It was also API 607 Fire Safe tested and certified to an extended specification by an independent laboratory in the USA.

In 1999, it came top of its class in comparative tests run on behalf of the CAPI Group (AkzoNobel, Shell, Dow and DSM). Leakage rates were between six and 100 times less than competitor’s brands—and it lasted 12 times longer than the next best valve packing. Since then it has twice been independently certified toTA-Luft requirements by different customers, and third-party verified for emission control to Shell SPE 77/321 Class A specification.

Supagraf Premier is a cost effective compression packing for fugitive emission control in valves that operate in harsh conditions. It is widely used in systems handling media such as all hydrocarbons, liquid fuels, and processing chemicals.

The packing is manufactured in exfoliated graphite, reinforced in a novel way to provide extra strength and resistance to pressure and extrusion. It incorporates an advanced lubricant system to prevent the pick-up of graphite on valve stems and provide low-friction action on rotary and rising stem valves. No special fitting techniques are needed, just use good engineering practices and torque the packed valve to the calculated load. Supagraf Premier is supplied in preformed rings and sets for ease of fitting or as a boxed length for cutting on site into rings as required.

It is inert within the range pH 1–14, excluding strong oxidising agents. Operating temperature range is -200°C to +450°C; maximum system pressure is 250bar.
For long-life control valves – up to 100,000 cycles – a recently developed variant is Supagraf Control. This has been extensively tested by valve manufacturers and users, including to meet TA Luft requirements, and is now proving very popular Supagraf Premier ring sets and packing coil in control valves.