Design Fundamentals

CRP has been manufacturing lined equipment for twenty years, but this still makes us the youngest true manufacturer.  This has provided us with a number of advantages.
With hindsight we have been able to incorporate all of the best aspects of modern design and set out to manufacture a single standard of product, rather than be stuck with practices from the early development of lined piping systems.  In particular we have been able to adopt modern polymers, modern lined equipment wall thicknesses and the best practices for housing manufacture.  The company has been independent throughout its life and has not been forced to follow any technology licensing practices.
The principal focus for our design is for corrosion performance at temperature.  Other materials properties such as non-stick, purity and low-friction although beneficial are secondary considerations.
The core product range has been designed to withstand full vacuum as opposed to having a number of product standards.  It has been designed to use investment cast steel fittings as housings, as they provide great accuracy, high strength, are weld free repeatable and a more aesthetically pleasing component.
CRP have selected the best technologies for the lining processes.  PTFE paste extrusion as it produces the best pipe liners for chemical performance, permeation resistance and surface finish.  PFA, because of its melt characteristics allowing us to form complex shapes, its translucency, surface finish, geometric accuracy and vacuum performance.
Moreover, CRP continues to invest production time in collaboration with major polymer producers to develop extrusion grades of PTFE and thermally stabilised grades of PFA.
Design Choice
The Lined Equipment Specification
The original CRP specification was a requirement to meet the ASTM standard F423.  This has now been superseded by F1545.  This is the basic design standard for PTFE lined pipe and fittings and apart from a restricted DIN standard and some national standards such as in Japan (JIS), it is the only worldwide standard for lined pipe and fittings.
CRP also decided to meet the design standard for the then largest user in the UK – the ICI company.  They had a piping standard considered to be more stringent than F423.  This ICI standard formed the basis for a great number of specifications around the UK.
These design standards fixed the physical standards for the materials.  They determined how the housings should be made, their accuracy, the quality and performance of the liners and most importantly how the parts should be type tested and tested in manufacture.  Type testing comprises subjecting representative production samples to extended periods of heating and cooling, steam cycling and vacuum resistance testing.  All of this is inspected by an independent third party.
This is one of CRP’s test rigs undertaking steam cycling – alternate periods of steam at 9.5 bar(g) maintained for one hour and then rapid cold water flushing to return to ambient within two minutes.  The specifications called for 100 cycles – CRP undertook 500.  In passing these tests the product must not show any detriment and still pass its production tests.
Pipework and Fittings
CRP elected to use the accepted design standards for pipework and fittings using ASME Class 150 flanges.  Concerning the dimensional standard CRP uses ASME B16.5 Class 150 where there is a definition and elsewhere looks to other industry norms where there is no international standard.
CRP decided to go for materials with a proven track record and suitable for use in food and drugs contact.  FDA (US Food and Drug Administration) are the internationally accepted body for determining the suitability of materials for these uses and CRP only use FDA compliant materials as wetted parts.  The only exception to this is in the use of static dissipating (anti-static) materials where only certain grades of PTFE and no grades of PFA are FDA compliant.
CRP elects to use a small number of suppliers with well controlled materials.  All paste extrusion PTFE’s and melt processable PFA’s have gone through evaluation and approval by CRP.  These materials must exceed the minimum requirements set out in F1545 – these being D4895 for paste polymers and D3307 for PFA.

Contact Details

Corrosion Resistant Products Ltd
Todmorden Road
OL15 9EG

Phone: +44(0)1706 756400
Fax: +44(0)1706 379567