PTFE-Protection & Sealing Ring

For manhole openings with sealing cover.

Situation Summary #

The enamels in enamelled reaction and agitator tanks are shock and impact sensitive.

By impact or impact, the enamel layer flakes off easily, often requiring very expensive repairs or re-enameling of the entire boiler.

In particular, the inner sides of manhole, filling and sampling nozzles are endangered, since impact and impact stress can not be ruled out during manipulation with the lid open. 

To reduce the risk to the container has therefore been used structures according to Figure 1 above.

Between the nozzle opening (1) and cover (2) there is an enamelled steel intermediate ring (3), which is sealed on both sides by means of seals (4) to the detail "A" against nozzle and cover.

A disadvantage of this embodiment is that

  • opposite the enamelled steel intermediate rings the aforementioned stresses are also sensitive and unusable can be
  • no protection of the socket inside present
  • When applying a vacuum, the upper Seal slightly buckled and leaking
  • a more frequent change of the upper seal with frequent opening of the lid (sampling, Addition of feedstock and additives) was required.

To eliminate the disadvantages, IDT offers an intelligent solution that works without intermediate rings and gaskets applied on both sides, is functionally reliable and has a high degree of sealing quality.

Troubleshooting #

Essential elements of the new seal design are a base body (5) with incorporated on the inner shell circumferential groove and a retracted apron (6).

The body and skirt are made of electrically conductive Hostaflon® TFM 4220 (PTFE modified in the molecular chain with outstanding sealing properties).

The main body has at the top and bottom a comb profiling for liquid sealing On The double-sided dovetail groove is used to hold each of a sealing O-ring (7).

*These O-rings serve to achieve gas-tightness and are made of elastic material (FPM) with or without PTFE sheath. A designed depending on the operating conditions bandage (8) made of stainless steel ensures bursting safety at internal pressure in accordance with the requirements of the Pressure Vessel Ordinance.

The height of the bandage is about 70% of the thickness of the body, its thickness is greater than 2.5 mm.

The bandage carries in the outer area tabs (9), which fix the seal on the container neck and thus prevent possible leaks by slipping thereof, as well as for discharging electrical charge can be used.

The seal design can be made for both circular and oval nozzles.


  • Almost universal resistance against chemicals and solvents
  • Blow-out resistant sealing system
  • Avoids expensive repairs or re-coating of the of the entire boiler
  • Avoids use of expensive glass lined intermediate rings and seals don't have to be replaced as frequently
  • Has a long service life even in batch operation and during frequent opening and closing • Conductive [discharge of electrostatic load], body made from conductive Dyneon™ TFM™


  • Operating pressure max. 10 bar
  • Operating temperature approx. 200 °C
  • Flange sensitive to stress
  • Aggressive and toxic media in gaseous and liquid states
  • Pharmaceutical and chemical industry
  • Batch operation [temperature and pressure changes]

Installation Recommendations

  • Fit seals between clean, dry and grease-free flanges
  • Minimum surface pressure 5 N/mm²
  • Tighten bolts crosswise in steps up to 50 %, 75 % and 100 % of the final torque
  • Check and tighten bolts until all intended final torques have been reached
  • The tightening and re-tightening recommendations of the manufacturer have to be followed
  • The component is subject to the pressure equipment guideline

Installation Diagram #

  1. Body: Conductive Dyneon TFM™ 6221, serrated
  2. PTFE apron
  3. O-Ring with PTFE jacket
  4. Stainless Steel sleeve with TÜV-approval

Safety instruction / fire behaviour

Overheating (above 400 ° C) of Hostaflon®-TFM produces harmful decomposition products, mainly in the form of hydrogen fluoride compounds.
Therefore, the safety measures must be observed (see leaflet "Hostaflon® safety data of Raw material types and safety instructions for processing ", KS 613).
Hostaflon®-TFM is hardly inflammable.
According to the Limiting Oxygen Index Test, the LOI value is 95 (ie only in an atmosphere containing more than 95% oxygen can the material be made to burn).