Can Ring Joint Gaskets be reused?

Metal gaskets rely on the deformation or fusing of the gasket material in the flange surfaces to provide an effective seal. Coining causes the gasket to deform and yield, meaning its reuse will not reliably achieve the required seal.

According to API 6A section

Ring gaskets have a limited amount of positive interference which assures the gaskets will be coined into sealing relationship in the grooves. These gaskets shall not be re-used.

Style R Gaskets

According to ASME PCC-1 (2013)

Reuse of a gasket is not recommended. However, the substrates of grooved metal gaskets with facing layers may be reused after having been reconditioned and refaced in a manner consistent with the original product specification. The reinstallation of gaskets so refurbished is not considered gasket reuse since the sealing performance of the gasket has been restored. For other gasket types, experience has clearly shown that only a new gasket will reliably provide the necessary plastic deformation and elastic recovery characteristics essential to achieve an effective seal. Visual or physical inspection of a used gasket for apparent damage is not sufficient to detect such sealing surface factors as work-hardening, brittleness, or the effects of heat or interaction with the service fluid.

AIChE Paper Number 97c says..

When an RTJ is bolted up, a very high surface stress is generated between the RTJ gasket and the flange groove. This stress causes plastic deformation – permanent deformation of the metal. The RTJ gasket hardness increases due to the work hardening after it is compressed. The difference in initial hardness between the flange and gasket should be 15-20 Brinell.

If an RTJ gasket is reused (a common mistake in the field), it eventually becomes harder than the flange causing cracking and permanent damage to the flange, typically in the groove itself. RTJ gaskets should never be reused.

Is it safe to reuse RTJ gaskets for hydrotesting purposes only?

Some manufacturers believe that it is safe to reuse ring joint gaskets for hydrotesting purposes. However, this is not the case. Upon compression of the flange assembly, the gasket deforms plastically and is subject to stress hardening. It is important that the annular joint is significantly softer than the flange groove so that the gasket deforms plastically and not the groove. The use of harder ring connections may result in damage to the flange grooves.

In accordance with ASME B16.20 section 2.3.1, it is recommended that ring joint gaskets have a lower hardness than that of the mating flanges because they will deform and flow within the flanges and fill any gaps and corrugations in the flanges while still always provide sufficient strength to withstand the pressure therein.

Ring Type Joint flange

Remark(s) of the Author...

Reuse of RTJ gaskets

In recent months and long before that, I have been asked whether RTJ gaskets can be reused. I have always answered that question negatively and I have hopefully been able to give a clear answer to that question with this article.

By the way, my opinion is that any gasket, of any material, before commissioning the equipment in question, every gasket must meet the specification. With a second-hand gasket, this is not possible.

Related Post(s)

Tongue and Groove flange
Types of Flange faces
Different types of flange faces are used as the contact surfaces to seat the sealing gasket material...

Explore the World of Piping

© Werner Sölken 2008 -  
All rights reserved. uses Google Analytics

Privacy Policy

I must be old. I still believe in respect.