Steam Hydro Test Vent

Good question!

Why don't you try to find out who wrote the "company standard" and ask them?

I'm sure they had a reason. Let us know when you find out.

I inquired about the same. One of the senior said that as in normal vent case, threaded coupling and plug are used(which are seal welded later after hydrotesting). But in steam connections threaded components are nor recommended as they may lead to leakage and also its not a good practice to do seal welding. In fact seal welding should not be done in steam, condensate and boiler feed lines. What say experts??

anoopbindal,

Now I am confused. Your original question was directed at the use of a valve on the high point vent for Steam services but no valve on the high point vents for other services.

Your next comment is now questioning the practice of Seal Welding of vents.

What is the real question.

In my past I have seen all cases. There are all vents with valves, all vents without valves, some vents with valves and without, some with seal welding and some without seal welding. Most of the time it was "Client" (Maintenance) preference.

You did not give any details about the Steam service (re: pressure and temperature) so we are left in a fog on this issue. Normally unless the Steam service is very low pressure the high point vent valves and the low point drain valves are Socket-Weld including the "O-Let" connection to the header. Some people go so far as to use a "Nip-O-Let" or even a "Valve-O-Let".

There are lots of ways to do this, but what is best for your Client?

Sir,

Real question is still the same "Why valves are being used in steam line vents though vents for other services are not carrying the valves in vent connections"?

Now the reply which I quoted was as interpretation that " Threaded components are being used for every other service vent connection. After hydrotesting they will be seal welded. Hence system will be completed. But in case of steam service after hydrotesting if threaded components with seal welding is used we may lose steam through threaded part. Hence it more appropriate to use socket welded valves."

Is this interpretation ok?

"Is this interpretation okay?"

Well..... Yes and no.

Yes! it is okay to have a socket weld valve in steam service if you are afraid of leaks in threaded piping.

No! it is not okay to have all joints down stream of the vent valve socket welded because (a) that valve was put there for a purpose and (b) if you seal-weld or socket weld ALL joints down stream then you cannot use the vent valve for it's intended purpose and there would be no reason to put it there in the first place.