Chlorine Alkali Industry 

The extremely high resistance to corrosion makes PTFE and PFA lined products very effective in the handling of HCl which is generated as part of the process.  Installing PTFE and PFA lined equipment avoids the need to use expensive higher alloys such as Monel and Hastelloy.  The systems can be safely used at temperatures up to 150 deg C depending on the specific process conditions.
As the Cl atom in the molecular structure of Hydrochloric acid is in the same family as the Fluorine atom contained in the PTFE and the PFA there is a tendency for the HCl molecule to permeate slowly through the lining of the PTFE lined component. 
This permeation needs to be taken care of in the design of the components and the way they are installed.
Every component requires sufficient venting to enable the slow permeation of the HCl to be prevented from building up between the metal outer and the liner.  Detailed guidelines are available from CRP personnel.
We recommend the use of PFA for fittings wherever possible as this has a greater resistance to permeation than the alternatives, usually an isostatic pressed PTFE.  We provide liners of paste extruded PTFE which has the best permeation resistance of the PTFE materials available for spool lining.
The permeation rate through a PTFE liner is dependant of the molecular structure of the product, the structure and thickness of the liner, the temperature and pressure of operation, the method of manufacture and the quality of the liner production process.
CRP can provide special liners of enhanced thickness especially for halogen service for additional permeation resistance if required by the application.  We would strongly recommend that vent bosses are fitted with PTFE vent plugs when PTFE lined components are used in chlorine service.  If the system is lagged always fit 100mm vent extensions with PTFE vent plugs  and take care during installation, lagging, or painting that all vent holes are kept clear and in working order.
We recommend that you contact our technical team on each occasion you are intending to use PTFE and PFA lined products on Chlorine Alkali service – we are always happy to advise on the safe use of our products on these services

Contact Details

Corrosion Resistant Products Ltd
Todmorden Road
Littleborough
OL15 9EG

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