Replacing O-Rings

Usually the O-rings must be repaced when the equipement is opend.

Replace the o-rings its not worth the waste of time to pull what your working on apart because one failed do to some unseen problem when you inspected them.

The cost is minor compare to your time.

Best to change if you have apart anyway. But if need a way pressing on the o ring with you finger nail and if you see a dent and it soon takes it shape again it is still elastic enough to use. But again the price of O ring is a lot less then doing the job again.

As others have said, O rings are cheap. replace them if the application involves pressure and certainly if it is critical.

Unfortunately there are times when the correct size is not readily available, and as the original question asks, how can you check if the used one can be reused.

Look at it under an inspection microscope. Under reasonably high magnification, you can see if there are imperfections, imbedded particles, flashing from the molding process, etc. I have run into situations where new O rings were found to have flashing on their edges but since they were being used to seal on their faces, it was not an issue. Mil spec O rings have been buffed to remove all flashings but their use in our application would have been cost prohibitive and unnecessary.

It would also be a good idea to use a little silicone grease when reinstalling, if it is compatible with the particular composition of the O ring and the process where it is being used. It could be just enough to allow the O ring to seat better with the mating surface.

"O rings are cheap"

That depends. We use Kalrez (PTFE) o-rings in some harsh environment applications. After you price one and fall off your chair, you might consider re-using it.

O-ring failures depend somewhat on the application and the ring material. Is the ring being used in a static or moving surface? Is it being used with a backup (usually teflon)? When O-rings are causing problems, you will see one or more of the following: 1. Normal abrasive wear, scratches along the surface. 2. Actual extrusion of the rubber along its length, typically caused by a faulty backup ring, the ring tries to extrude itself into the clearance between the mating parts. 3. Some custom-fabricated rings will break at the adhesive joint holding the ends together. 4. Disintegration of the ring due to incompatibility with whatever it is exposed to. All the above are visual indicators. As most above have said, o-rings to me fall under the same category as gaskets in your car. As long as you have the components apart, and if the o-ring is common and inexpensive, it is safest to replace it. Be sure to lubricate the ring when re-installing, using a lube that is compatible with what it will be exposed to, and take extra care when re-installing as not to pinch the ring between the parts.

hi

please tell me which material for o ring will be better for high temperature applications.

They are not worth reusing - replace then with new ones after cleaning the grooves - I would also use some o ring grease. Ed

Unless you have a noncritical system always replace "O"rings when components are apart. Wasn't the first shuttle disaster attributed to a bad "O" ring? "O"rings have always cheap in my mind considering the consequences.

Dear Sir,

1, Please check O ring Cross section carefully

2. Check wt of o ring before and after use

Regards

oommen