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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...

How Do You Recognise a Quality Gasket?

A gasket is a very simple item that is reasonably inexpensive. Considering how gaskets work, you may be facing a costly bill should a gasket fail. Choosing a quality gasket from Specialist Sealing Products helps to create a seal that will last until well after the...

5 Common Gasket Failures

Common Failure Causes  A blown head gasket in a vehicle is something that needs to be fixed promptly. If left untouched, you run the risk of seriously damaging your engine. Knowing what causes gasket failure or gasket problems is the key to gasket failure prevention,...

O-ring Size Guidelines

The performance of an O-ring seal depends largely on two factors— the right material and the right size. However, determining the right size O-ring is usually the hardest part when it comes to choosing the right O-ring for an application.   Unfortunately, selecting...

Tips for Proper O-Ring Installation

  An O-ring is a crucial component of a fluid system, and how it is installed can make or break that system. To ensure the success of an application, O-ring requires not only careful material selection and design but also proper installation procedures. A small...

Why Colour Matters When Choosing Gaskets?

Gasket manufacturers have turned to colour coding gaskets to make the selection and categorisation of the product more accessible.   It is possible to identify the winding and filler materials that were used for fabrication by the colouring of the outer top side of...

Materials that can be Used in Producing Gaskets

Seals and gaskets are meticulously manufactured to be able to withstand the exacting conditions under which they function. Not only does a gasket seal two distinct parts and allow the containment of extreme temperature fluids, steams and gases, but it must meld the...

Choosing the Perfect Gasket for Your Needs

The perfect gasket choice and fit is an essential component of engines, appliances, and industrial machinery projects. They are a fundamental part when engineering anything from power tools to oil drills. A high-quality manufacturer of gaskets and seals will use only...

Manufacturing of High-Quality Gaskets

A large number of engineering and machinery applications use gaskets. This mechanical seal is employed whenever gaps between two or more surfaces are joined together. This process is also required to prevent leakage and withstand the extremes of compression when...

O Ring Materials Selection

This is a quick overview of the various O-Ring materials that are available for applications and found at select UK O-Ring suppliers. When it comes to Specialist Sealing Products, it is a good idea to be clued into every option that is on the market. The materials can...

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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