As entitled. D. Chen found and I confirmed that strange shhhhhhhhhh sound from the pendulum valve at TMSX. The movie has been uploaded on Slack and reported to Uchiyama-san already.
[Kimura and M. Takahashi]
We identified the source of the indicated compressed air leak.
The cause was the use of a parallel threaded seal joint with an O-ring where a tapered threaded seal joint should have been used.
We are currently inquiring with the company that installed the piping as to the reason for the mis-specification of the fitting.
This wrong choice of fitting has been confirmed on all KAGRA pneumatic gate valves.
Therefore, it is necessary to replace the fittings with the correct ones.
The correct taper thread seal standard (dimensions) for gate valves is as follows.
φ800 and φ1000 large gate valve: 1/4" taper thread seal (R 1/4" ISO NPT)
φ400 pendulum type valve: 1/8" taper thread seal (R 1/8" ISO NPT)
[Kimura]
The parallel threaded seal joint with O-ring, which was the cause of air leakage in the pendulum valve drive of the TMSX, was replaced with a regular tapered threaded seal joint.
After the replacement, a leakage test was conducted, and it was confirmed that there was no leakage.
Replacement with tapered thread seal joints is required for all KAGRA φ1000 gate valves, φ800 gate valves, and pendulum valves.
So far, replacement work has been completed at two locations, GVbsx and GVbsy. Replacement work will continue in the future.
[Kimura]
The parallel threaded seal joint with O-ring, which was the cause of air leakage in the pendulum valve drive of the TMSY, was replaced with a regular tapered threaded seal joint.
The parallel threaded seal joint with O-ring, which were the cause of air leakage in the valve drive of the GVmc and GVommt, were replaced with a regular tapered threaded seal joint.
After the replacement, a leakage test was conducted, and it was confirmed that there was no leakage.
Replacement with tapered thread seal joints is required for all KAGRA φ1000 gate valves, φ800 gate valves, and pendulum valves.
The following four gate valves are awaiting replacement.
1. GVitmx
2. GVetmx
3. GVitmy
4. GVetmy
The following 6 gate valves have been replaced with corrective parts.
1. GVmc
2. GVbsx
3. GVbsy
4. GVtmsx
5. GVtmsy
6 . GVommt
[kimura]
The parallel threaded seal joint with O-ring, which was the cause of air leakage in the valve drive of the GVetmx, was replaced with a regular tapered threaded seal joint.
After the replacement, a leakage test was conducted, and it was confirmed that there was no leakage.
Replacement with tapered thread seal joints is required for all KAGRA φ1000 gate valves, φ800 gate valves, and pendulum valves.
The following three gate valves are awaiting replacement.
1. GVitmx
2. GVitmy
3. GVetmy
[kimura]
The parallel threaded seal joint with O-ring, which was the cause of air leakage in the valve drive of the GVitmx,
was replaced with a regular tapered threaded seal joint.
After the replacement, a leakage test was conducted, and it was confirmed that there was no leakage.
Replacement with tapered thread seal joints is required for all KAGRA φ1000 gate valves, φ800 gate valves, and pendulum valves.
The following two gate valves are awaiting replacement.
1. GVitmy
2. GVetmy
[kimura]
The parallel threaded seal joint with O-ring, which was the cause of air leakage in the valve drive of the GVitmy,
was replaced with a regular tapered threaded seal joint.
After the replacement, a leakage test was conducted, and it was confirmed that there was no leakage.
Replacement with tapered thread seal joints is required for all KAGRA φ1000 gate valves, φ800 gate valves, and pendulum valves.
The following one gate valves are awaiting replacement.
1. GVetmy