Blogs
18 July 2016

The importance of purity of inhibited grade graphite in gaskets

Before graphite is suitable for usage in gaskets it is important to know where it is coming from and, which specific properties are needed and why you need to work with graphite in its most pure form. 

Oil companies are one of the largest users in the world for graphite type gaskets, they understand the importance of using a high-grade graphite and set high standards for it. But why is this so important? 

The origin of graphite

The importance of purity of inhibited grade graphite in gaskets To measure the purity of graphite, you need to understand how graphite is build up. Graphite in its raw, natural form exists as a mineral contained in rocks. Natural graphite is extracted from the rock, purified and powdered into flake. The flake is treated, then expanded into worm form with heat and arranged in a smooth bed. The graphite worm particles are compressed into different forms of graphite sheet products.

Measuring the purity of graphite

Graphite particles are composed of elemental carbon. Historically, pure graphite has a carbon content greater than 95 percent, but a different amount of carbon can cause a difference in the elemental structure. Therefore, it also causes a difference in properties. This is why testing the level of carbon is an important step in measuring the purity of graphite. Other important measurements for pure graphite are the levels of fluorine, total halogens, sulfur, sodium and chlorides.

The standard for graphite purity

The standard that oil companies use for measuring the purity of graphite is the standard ASTM F2168:2002. This is the Standard Specification for Packing Material, Graphitic, Corrugated Ribbon or Textured Tape, and Die-Formed Ring. This specification covers various types, classes, and grades of flexible graphite material in which valve media temperatures are limited to a maximum of 1050°F (966°C). The ASTM F2168:2002 standard is based on the standard Mil Std P 24503B. Leader Gasket is compliant with this standard..

The role of pure graphite regarding the emission problem

The use of pure graphite reduces the amount of emissions on a global scale,it has a low weight loss at elevated temperatures and a higher sealability. It is important to set requirements to ensure that the impurities are kept below certain levels. This is important because impurities cause volume loss at elevated temperatures, which as a consequence, reduces the total bolt load on the seal and causes increased emissions. 

Purity alone does not guarantee high performance products when it comes to sealability. Graphite must have an ‘oxidation inhibitor’ such as phosphorous added during the production phase of the graphite in order  to reduce oxidation weight loss rates.

Can we help you with purchasing pure graphite gaskets?

Graphite used in Leader Gasket products only comes from suppliers that meet our strict purchase specification requirements. Feel free to ask us any questions about us and our products by filling in the form on the right.


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