BillL
Well Known Member
This topic has come up in a few threads over the years (per a site search) and this post is to add to the knowledge.
Champion has a Technical Bulletin 95-11 that says a new copper gasket should always be used any time a plug is reinstalled.
Per a Tempest engineer (thanks Vlad) -they say the same thing.
Current specifications for the washers is hard to find, but the previous MS17840B showed the thickness as .081" + .004" , i.e. 0.077" minimum.
I have collected gaskets for a while as it seemed inefficient to process 8 in the middle of inspection. They were annealed, tumbled in a small rock tumbler and washed in a brightening solution. This removed all the scale, therefore clean and soft.
All 24 were measured for thickness, the Champion publication mentioned reuse could be "out of spec", so thought I would check.
They sorted to two clear batches. The 16 group measured .0791” (OK), the 8 pieces measured .0755 - clearly below spec.
The conclusion partly supports Champion and Tempest guidance - don't reuse them. But, it is clear that they can be reused once and remain within the MS17840B specification.
Record keeping would have to be good, or just put new in the later check them with a micrometer when a viable batch has been accumulated.
Update #1: I finally got a new batch of gaskets from Spruce. 11 gaskets were measured and the average was 0.08011" - - - it will be interesting to process some of these used and see how much thickness they lost. Maybe the lower (6 sigma) limit is being maintained to save money.
Update #2: A friends group of 100 gaskets was annealed, bead blasted, ultrasonic cleaned and measured. (about 20 min work) They all were .0784" or thicker.
Champion has a Technical Bulletin 95-11 that says a new copper gasket should always be used any time a plug is reinstalled.
Per a Tempest engineer (thanks Vlad) -they say the same thing.
Current specifications for the washers is hard to find, but the previous MS17840B showed the thickness as .081" + .004" , i.e. 0.077" minimum.
I have collected gaskets for a while as it seemed inefficient to process 8 in the middle of inspection. They were annealed, tumbled in a small rock tumbler and washed in a brightening solution. This removed all the scale, therefore clean and soft.
All 24 were measured for thickness, the Champion publication mentioned reuse could be "out of spec", so thought I would check.
They sorted to two clear batches. The 16 group measured .0791” (OK), the 8 pieces measured .0755 - clearly below spec.
The conclusion partly supports Champion and Tempest guidance - don't reuse them. But, it is clear that they can be reused once and remain within the MS17840B specification.
Record keeping would have to be good, or just put new in the later check them with a micrometer when a viable batch has been accumulated.
Update #1: I finally got a new batch of gaskets from Spruce. 11 gaskets were measured and the average was 0.08011" - - - it will be interesting to process some of these used and see how much thickness they lost. Maybe the lower (6 sigma) limit is being maintained to save money.
Update #2: A friends group of 100 gaskets was annealed, bead blasted, ultrasonic cleaned and measured. (about 20 min work) They all were .0784" or thicker.
Last edited: