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Protecting your seals

Dust gets everywhere.  We see it across the surfaces of our homes and even in our workplaces, especially when the light shines through to show it in its full glory!  However, dust that seeps and builds up within engineering equipment can be disastrous.  Causing damage...

Importance of durometer testing

Durometer or shore durometer is a way for industry professionals to measure how hard such things as plastic, rubber, and non-metallic materials genuinely are.  Its focus is to measure on a Shore A or Shore D scale, looking at how robust material is when examining its...

Metal Detectable O Rings

Metal detectable o rings became a necessary must when it was identified that some chemicals, exposure to extreme temperatures, and continuous vibrations could cause failings in standard o rings.  Failings that not only mean a breaking of the seal, but there is also an...

Tips for best o ring maintenance

If o rings are not maintained, leaks can occur, and water and other fluids can enter the appliance or application, and even product in the mix!  If this happens, damage can occur to internal parts and mechanisms, causing deployment failings, potential false readings,...

What you need to know about O Ring Lubricants

Silicone grease and lubricants aren’t just a nice to have for o rings, but they can quite often be a must-have.  However, with so many greases and lubricants to choose from, it can often be a minefield choosing the best ones and the right ones for your o ring and...

O Ring Replacement

Replacing an O Ring in pressure washer wands is probably one of the most common replacements you'll find when working with seals.  Unfortunately, O Rings don't last forever, and over time they do deteriorate, and you will require an O Ring replacement.  It's important...

Reasons behind seal failure and a look into seal replacement

Unfortunately, there are occasions where O-rings, in particular, fail.  The failure of these seals is not simply due to one factor, but various factors that can occur across a range of applications – hence why locating the exact cause of such problems is just that, a...

Gaskets and seals for Aerospace

Gaskets and seals used for aerospace applications and equipment must be of premium quality and to a substantially high standard.  They are used across a range of applications such as radars, antennas, lighting, access panels, electrical conductivity, pressure sealing,...

Finding the best sealing materials for Food Grade Applications

You will find rubber seals across various industries, providing an important element and operating as a vital fixing across a wide range of different applications and equipment.  However, these FDA gaskets must follow strict, set guidelines, in terms of their material...

The Evolution of Gasket Solutions

When we talk about gaskets and the history of a gasket, we must start at the very beginning.  What is a gasket?  Ultimately, a gasket is a manufactured seal that is used to fill the gap/space between two or more surfaces.  Gaskets are typically manufactured by cutting...

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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