1 reply to this topic

[R NESAMANI]

Dear all,

We are using one 3/4'' glove valve in our Pr.Transducer line of our 30'' Natural gas pipeline.
This valve is leaking from gland. I tightened the gland bolts, but no use.
Leakage is same in open & close condition.
There is no isolation, so we cant remove.
Kindly help me to stop the leakage.
Valve drg is attached.

Attached Files

•  Globe valve.pdf   146.75KB   21 downloads

[Art Montemayor]

This is an easy (but risky) solution – if the globe valve is installed the way I would have installed it: with the seat of the valve sealing the upstream pressure – or, in other words, the stem of the valve exposed only to the downstream, transmitter pressure.

If the above is the case and the seat of the globe valve is positively seating against the pipeline pressure, then all you have to do is close down on the valve, blocking all gas pressure from the pressure transmitter. Allow for the trapped gas between the valve and the pressure transmitter to bleed off to atmosphere and then quickly loosen the packing gland and insert new packing after removing the top packing. Re-tighten the gland with the new packing and proceed to open the valve slowly.

This should fix the situation – but only if the stem is not scored or its surface is damaged. If that is the case, then you have not other remedy except to do the most hated and unpopular thing: shut down the pipeline and change out the valve.

I am not advocating that the above procedure be used. I have used it – but with previous risk analysis and careful study. There are risks to take in such a procedure and you must analysis and weigh them all. You haven’t, for example told what pressures, temperatures, size of leakage, and priorities are on this pipeline. You have said “Leakage is same in open & close condition” – but you didn’t say for how long after you have closed off the valve. It could be that you haven’t waited until all of the the trapped gas between the valve and the pressure transmitter has bled off to atmosphere.

Good luck.