Sealing systems at plumbing

07 March 2016 / By: rmmcia

At plumbing installations one of the most important issues is the right fixing and water tightness of pipes, fittings and connection accessories. In this article we will go through some of the elements commonly used for assuring the water tightness when using thread accessories.
With thread fittings, either thread ISO -228 (parallel) or thread ISO-7 (taper), it is always necessary a sealant in order to reach a correct water tightness of the system. The sealant element is applied on the male thread.

Herewith we are going to describe the three materials most commonly used for avoiding any kind of leaks within installations.

1/ Hemp fiber. A vegetal fiber, in the form of yarn. It comes from hemp, a plant from the cannabis family. It is also used the natural fiber of linen. Both options are ecological. It is advised to be used together with a non-hardener dough compound to facilitate the sealing.

  Advantages:
- swells with humidity, so if there’s a minimal leak it seals by increase of its size
- specially effective with threads of big diameter o with more width

  Disadvantages:
- it requires knowledge on how to place it
- can put extra pressure over the fittings and cause breaking

2/ PTFE tape (“Teflon”). PTFE is "polytetrafluoroethylene", a type of plastic polymer with multiple properties. The format for plumbing is showed up as thread or tape of different widths and densities, to facilitate its application around the thread accessories. PTFE is the preferred one among plumbing users, as per data from a survey we made at rmmcia (March'2016), over an empiric sample from clients and users’ database of the company.

  Advantages:
- comfortable format and easy to be placed
- it allows to turn back the tight without any leak
- very efficient at installations and repairs with minor diameter threads

  Disadvantages:
- non advisable with certain pneumatic circuits or precision hydraulic circuits, because it may detach and block sensitive points
- due to its lubricant property, it may induce an over tighten of the thread

3/ Liquid sealant. Of chemical composition, they fill in the space between thread accessories and they provide an instantaneous sealing for low pressure. For brass it is advised a sealant with chemical base of methacrylate, though it is very common the PTFE liquid, with the same composition than PTFE plus organic resin and solvent. There have been developed also anaerobic sealants, of a single component, which ameliorate substantially the sealing properties.

  Advantages:
- very easy to use
- it is not putting pressure over the fittings, avoiding any breakings
- the slow curation of some liquid sealants is allowing the light adjustment of the fittings during installation
- they do not contaminate the fragile pneumatic or precision hydraulic circuits, as opposed to the PTFE tape

  Disadvantages:
- the curation time must be respected
- some of the liquid sealants do not have retention capacity

hilo cáñamo hemp fiber fils chanvre PTFE teflon cinta tape ruban sellante líquido liquide liquid sealant scellement
             Hemp fiber                                  PTFE tape                             Liquid sealant

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