Assembly Instruction

FB 8.3.5 Assembly and Operational Safety Instruction

In princple, lined pipes and fittngs may not bewelded, since otherwise the fluoroplastics can be destroyed. Assembly work should only be carried out by properly qualified personnel.


Protective Cover

All parts are provided with protective covers, for protecting the lining against dirt and mechanical damages by handling and storage and for holding down the flanges. The protective covers should only be removed immediately before assembly!


Additional seals between the PTFE sealing surfaces are not necessary. This may, however, be necessary when mounting a flared surface to a flange made of, for example, metal, glass or ceramics.


Flange fittings should be tightened evenly with a torque wrench, crosswise in several steps and in the end clockwise according to the following table. Due to the oflw characteristics of the lining, the fittings sholud be retightened after one day.

Recommendation: After the first temperature cycle and commissioning, we recommend a repaeted itghtening of the screws. To avoid a deformation of the sealing surfaces by over tightening the screws during the assembly, the following torques are to be seen as a guideline (DIN): 

The tightening torques are valid for lightly oiled/grease screws at normal temperature and are laid out for a slight flow of the lining in order to achieve an effective sealing. A further increase in the psecified torques does not necessarily lead to a better seliang, but may lead to a deformation of the flare.

Vent holes

With the exception of blind flanges, reducing flanges as well as spacers “Form G”, all PTFE parts have vent holes with a diameter of 3 mm. These vent holes serve for testing the tightness after the production as well as leakage indicator during operation. During the assembly care should be taken to avoid that the vent holes are closed by paint or by the insulation. For environmental reasons or other regulations, these holes can be closed. In this case, the manufacturer excludes any warranty for damages incurred.

Pressure-Temperature Resistance of Components according to DIN 2848 + 2874/strong>

The maximum thermal endurance amounts to 230°C. The allowable pressure in bar(g) above 120°C can be derived linearly from the values mentioned below.



Vacuum Resistance in bar(a) of PTFE-lined Pipes

The vacuum resistance of fittings is partially different. Please contact the manufacturer if necessary.


PTFE and PFA have proven as long-time corrosion protection. With electrically conductive lining (black) it is recommended to check the existing conductivity of components regularly. In case of certain media, the conductivity can decrease by and by due to washing-out. Depending on various factors, permeation as well as absorption effects may occur. Permeation is the transport of media through the lining.

This is based on two physical processes:

  1. First, on the diffusion of them edium through the molecule chains as well as the soul bility of the medium in the polymer. The diffusion can be reduced by the selection of appropriate PTFE types, by a thicker lining as well as by a higher cristallinity. However, in this case, the vulnerability to stress cracking increases, and therefore, in the interest of porduct safety it is important to weigh up between the different requirements.
  2. Absorption describes the diffusion of a medium into the lining. In case of cyclical temperature and pressure loads, this can lead, due to extension mechanisms, to accumulations or even to blistering. With given operating conditions, the insulation of such components can reduce this effect considerably or even avoid it.

    Due to all these effects, we recommend, for reasons of operational safety, a regular checking of all components.

    All our components have TÜV component mark and correspond to the PED (Pressure Equipment Directive), the TRR 100 (German technical regulations for metallic piping systems) as well as to the WHG (German Water Management Act). If requested, we can also produce linings with FDA approval (Food and Drug Administration)according to CFR177.1550 (Code of Federal Regulations) as well as with approved pigments.

    We assume no responsibility for the adequacy of the components delivered by us with respect to the planned utilization. Our components are not suitable for medical applications. For the assembly and the service of PTFE Expansion Joints, the corresponding instructions in our catalogue have to be observed. Please also take note of the corresponding operating pressure diagrams in the catalogue. The admissible operating pressure curves are downward sloping with increasing temperature. With standard wall thicknesses of the PTFE bellows, other diagrams than with thick-walled executions are valid.