Technical Papers

Analysis of surface roughness and profile parameters of graphite packing deposition on valve stems and how this influences frictional performance

Specific stem surface finishes that optimise friction and fugitive emission performance of graphite based control valve packing have been identified and reported; however the reasons behind this varied performance, specifically friction, and the effect of the resultant graphite boundary layer deposit remains unclear.

Compatibility testing of elastomeric materials for rotary sealing use with Environmentally Acceptable Lubricants (EALs) in marine propulsion applications

At James Walker we have been carrying out static immersion testing on EALs for many years, and continue to do so; although during this time it has become apparent elastomeric compatibility can vary between static and dynamic applications.

Elastomers in bioprocessing EPDM gaskets - what debate?

This white paper examines why adapting materials from other applications causes serious underperformance in high specification industries such as biopharmaceuticals.

Extractables and leachables - a converter’s view

A technical paper first presented at the RAPRA conference, London, September 2010.

How stem finish affects friction and fugitive emissions with graphite-based control valve packing

Achieving reliable performance with graphite packing sets in high cycle duties requires a different approach to the boundary tribology between the packing and stem.

Low temperature sealing capability of O-Rings: The relationship between laboratory tests and service performance

Many engineers or purchasing professionals have requirements for O-Rings that operate at low temperatures. They rely on the information provided from technical data sheets, and in many cases will compare the minimum operating temperature claim from several seal suppliers before making their choice.

Piston seal and material design EBA chromatography column - client Biotechflow Ltd

Technical case study following the developmentof piston seals for a new design of Chromatography column.

Problems and solutions with expansion joints in gas turbine applications

Expansion joints have been installed on gas turbine exhaust ducts since they were first introduced for power generation applications.

Successful sealing of problem flanges in high temperature/pressure applications

This paper explains the main causal factors of problems encountered with stainless steel pipe flanges in areas subject to high temperatures and pressures and details the solution now employed as a result of the James Walker study and research.

Technical report - Gaskets for polyethylene (PE) pipe connections

A technical guide for gaskets to suit PE pipe connections.

Washers - a critical element of successful bolting integrity

Why use washers? Approximately 50% of the torque applied when tightening a bolt is absorbed by under -head friction where the mating surfaces of a nut and flange are being forced together.

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