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Supagraf Control

Supplier: James Walker

Supagraf Control is an innovative compression packing that provides long-term, high integrity sealing for control valves.

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Its very low friction enhances the control accuracy of valves. 

This is a best available technique product for reducing industry's VOC fugitive emissions in line with the European Union's IPPC Directive.

It is manufactured in exfoliated graphite, reinforced in a novel way with a non-metallic structure to provide additional strength and resistance to pressure and extrusion. An advanced lubricant system is incorporated to prevent the pick-up of graphite on valve stems. 

Typical applications

Supagraf® Control is designed for emission control - to better than 50ppm leak tightness - on control valves in systems handling fluid media such as hydrocarbon liquid fuels and gases, lubricating oils and hazardous process chemicals.

It is a long-term replacement for the PTFE V-type packings that can be readily damaged by ingress of dirt and other foreign particles to the gland area. 

Specifications
TA Luft/VDI 2440:
Dresser Masoneilan control valves fitted with Supagraf® Control are certified to TA Luft requirements at leak tightness with helium to <10-4 mbar.litre.s-1.m-1. The tests were undertaken with 10MPa at 20°C, and 5.7MPa at a fluid flow temperature of 425°C for 100,000 stem cycles, including four thermal cycles and two gland adjustments.

ISO 15848-1: Dresser Masoneilan control valves fitted with Supagraf® Control are certified to ISO 15848-1 Class BH, CC3, at temperatures from -29°C to +425°C. The valves showed helium leakage rates less than 10-4 mg.s-1.m-1 for 100,000 stem operating cycles. This was achieved with pressure of 5.75MPa at fluid flow temperature of +425°C and 10.34MPa at -29°C to +38°C.

Prime features

  • High integrity gland sealing for control valve stems: to well below 50ppm fugitive emission level.
  • Long-term adjustment-free operation: over 100,000 stem strokes with emission levels below 500ppm.
  • Very low coefficient of friction for smooth and accurate valve action.
  • Reduced friction requirement to save on power consumption and enable smaller actuators to be used.
  • Certificated by TUV-Nord to TA Luft/VDI 2440.

Test result summaries
In addition to the TA Luft and ISO 15848-1 certifications shown under Specifications, the following tests have been completed:
Thermal cycling: 10,800 valve operating cycles at 20°C and 5MPa, followed by 16,700 valve operating cycles at 280°C and 5MPa. Recorded leakage <2.2x10-4 mbar.litre/second. (Third-party test by major manufacturer of control valves.)
Fugitive emission control: 10ppm to 15ppm maximum emission levels for five-ring set of Supagraf® Control after 1100 stem strokes and five thermal cycles between ambient and 160°C. (Test by James Walker Technology Centre). 
Long-term performance: Over 100,000 stem strokes with emission levels below 500ppm using 4MPa methane, without gland adjustment. (Test by James Walker Technology Centre).
Product evaluation tests:
These have been undertaken by six leading manufacturers of control valves. 

Chemical properties
Chemically inert within the range pH 1-14, excluding strong oxidising agents. It has low volatiles content.

Service capabilities - valve stem duties
Maximum operating temperature:  +350°C with thermal cycling.
Minimum operating temperature:   -200°C.
Maximum system pressure:            25MPa.

How supplied
Split preformed rings and sets for ease of installation and optimal performance, or in boxes containing 8m for on-site maintenance economy. Ex-stock: all popular square sections from 3mm upwards to suit all standard valves. Non-standard square or rectangular sections made to order. Full fitting instructions are included.

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