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Gasket manufacturing process explained

Specialist Sealing Products have been providing high-quality gaskets to customers throughout the UK for many years. We pride ourselves in the range of gaskets we have available, suitable for a variety of applications across a range of industries.  Rubber gaskets are...

Designing seals for the food industry

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Spiral Wound Gaskets and Sheet Gaskets

Gaskets come in a range of different shapes and sizes.  All are offering similar functionality; gaskets are produced using a range of different materials to suit a range and a variety of environmental factors, industrial uses, and product requirements.  When it comes...

Benefits of Kammprofile Gaskets

Used to prevent leakage, gaskets are constructed to fit between a range of different sizes and types of surfaces in order to provide the perfect seal.  Typically used in pipes and heat exchangers, gaskets are widely used as industrial sealants.  Kammprofile gaskets,...

Purpose of a Kammprofile Gasket

The ultimate purpose of a gasket is to stop leaks while being able to deal with varying levels of compression.  When it comes to Kammprofile gaskets, these are ideal for standard pipeline and heat exchanger applications.  As due to their grooved metalcore, with a...

Are your gaskets completely compliant?

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Everything you need to know about Manway Gaskets

When it comes to manway gaskets, we want to keep things simple, introducing them as the small sealing ring found in hatches/openings that are constructed for large tanks. Openings which give people access to the inside of the aforementioned tanks and vessels. The...

GRAPHITE MOULDED DIE
FORMED RINGS

Flexible graphite die-formed rings are valve stem packing rings manufactured from high purity flexible graphite foil with a corrosion inhibitor but without any binders, elastomers or fillersGraphite Moulded Sealing Rings are produced using a pre-determined length of flexible graphite tape which is then, using a mould, compressed to form a solid ring of precise density and size. For ease of installation, when the valve bonnet cannot be removed, split rings should be used. 

We have four model numbers of graphite moulded rings, Style 1, 3, 4 and 5 

Model 1, 3 and 4 are manufactured in exactly the same way and have the same main characteristics, only the purity of the graphite used changes.  

Model 1 – 98% is commercial grade and makes up the vast majority of usage for industrial applications. 

Model 3 – 99% conforms to Shell material specification MESC SPE 85/203 

Model 4 – 99.85% is exclusively specified by the Nuclear power industry 

 

 Model 1 Model 3 Model 4 
Graphite Purity – % 98 99 99.85 
Ash Content – % 2 1 0.15 
Density Range – g/cm³ 1.4-1.8 1.4-1.8 1.4-1.8 
Sulphur Content – ppm ≤300 ≤300 ≤300 
Chloride Content – ppm ≤25 ≤10 ≤10 
Fluoride Content – ppm ≤25 ≤10 ≤10 
Halogen Content – ppm ≤100 ≤50 ≤50 
Oxidation rate in air at 670⁰C – %/hour <5 <4 <4 
Passive corrosion inhibitor Yes Yes Yes 

Valve Stem Duties 

  • Maximum Operating Temperature 
  • Steam : +650⁰C    Oxidising : +500⁰C    Non-Oxidising : +1000⁰C 
  • Minimum Operating Temperature -200⁰C 
  • Maximum system Pressure : 250 bar 

Typical Applications 

  • Valves and rotary equipment handling virtually any media 
  • High temperature steam 
  • Heat transfer media 
  • Petroleum products  
  • Demineralised water 
  • Inorganic and organic acids and alkalis, hot waxes and oils 

Material Properties 

  • Compatible with media in the range pH 0-14 
  • No loss of volatiles at high temperature 
  • Lower limiting temperatures apply when used with oxidising agents 
  • Thermal conductivity, ring of density 1.4g/cm³ : Axial 400W/mK : Radial 6W/mK 
  • Coefficient of friction to steel : 0.05 

Main features 

  • Outstanding sealing performance over long adjustment-free periods 
  • Excellent chemical resistance 
  • Very wide temperature range   

Model 5 

These rings use the 98% graphite purity of Model 1 but with the addition of a special low friction coating which has been sinter bonded to the graphite before the moulding process which helps ensure maximum service life.

 Model 5 
Graphite Purity – % 98 
Ash Content – % 2 
Density Range – g/cm³ 1.4-1.8 
Sulphur Content – ppm ≤300 
Chloride Content – ppm ≤25 
Fluoride Content – ppm ≤25 
Halogen Content – ppm ≤100 
Oxidation rate in air at 670⁰C – %/hour <5 
Passive corrosion inhibitor Yes 

Valve Stem Duties 

  • Maximum Operating Temperature +350⁰C 
  • Minimum Operating Temperature -200⁰C 
  • Maximum system Pressure : 250 bar 

Typical Applications 

  • Valves that handle dry gases and other fluids where friction on standard graphite seals is unacceptably high. 
  • Valves that suffer judder, hesitation or erratic action due to carbon pick-up or high-spot friction on the spindle 

Material Properties 

  • Compatible with media in the range pH 0-14 
  • No loss of volatiles at high temperature 
  • Lower limiting temperatures apply when used with oxidising agents 
  • In comparative tests Model 5 displayed exactly half the friction coefficient of standard graphite and provided a continued low friction performance over more than 300 cycles 

Main features 

  • Greatly reduces the torque needed for efficient valve action 
  • Saves on power consumption and enables smaller actuators to be used 
  • Lowers the break out friction for smoother valve operation 
  • Retains exceptionally low friction characteristics  for up to 20,000 valve cycles 
  • Subsequent manual adjustment extends performance to 60,000 cycles 
  • Fire-safe capability enables rings to be used in plant subjected to fire rating tests 
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