Control valves pass 100k stem cycles with Supagraf

French-manufactured Dresser Masoneilan control valves are now fitted with Supagraf control gland packing to meet the stringent VOC emission control levels specified in ISO 15848

The Dresser Masoneilan control valves manufactured in France are now fitted with Supagraf control gland packing to meet the stringent VOC emission control levels specified in ISO 15848.

This follows close collaboration between Masoneilan and James Walker to meet the tough requirements, in tests carried out by CETIM at Nantes, France.

ISO 15848 specifies testing procedures for the evaluation of external leakage of valve stem seals and body joints of isolating and control valves used with volatile air pollutants and hazardous fluids.

The Masoneilan control valves are now certified to ISO 15848-1 Class BH, CC3, at temperatures from -29C to +425C.

To gain this rating, the valves had to show helium leakage rates less than 10-4mg/s/m for 100,000 stem cycles.

This was achieved with 57.5bar pressure at +425C and 103.4bar at -29C to +38C.

Stephane Leledy of Masoneilan explained: "Using Supagraf control, we can supply control valves that meet the new standards and European directives on VOC emissions.

Our aim is to help industry reduce greenhouse gas emissions in line with the Kyoto protocol".

Supagraf control gland packing was specifically developed by James Walker to cut fugitive emissions from control valves to well below 50ppm.

Made of high purity exfoliated graphite ribbon, reinforced in a novel way, it seals super efficiently with very low friction to enhance smooth and accurate valve movement.

"We view Supagraf control as the 'best available technology' product to seal the stems of control valves and reduce industry's fugitive emissions in line with the European Union IPPC Directive", stated Andrew Goulding, the top James Walker specialist on compression packings.

"The PTFE V-type seals traditionally used for control valves cannot operate efficiently at much above +260C, and they usually need a spring-loaded gland follower to overcome stress relaxation", he commented.

"Supagraf control has a recommended temperature range of -200C to +350C with thermal cycling, and maximum system pressure of 210bar, putting our valve packing in a far superior league: and this performance is achieved without spring loading".

Supagraf control is supplied as precision moulded rings or sets in sizes to suit all standard control valves.

It also comes in 8m lengths for workshop-based maintenance.

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