Valve installation on the online pipe

[280474]

Dear All,

Is there anybody here have experience to carry out valve installation on the online pipe (in service pipe) especially for instrument air pipeline...?

regards,
Nasrul

 

[johnp]

Your Instrument Air line may be steel welded, or galvanised screwed. Depending on which you are after the techniques can be fairly similar once the line is shut down.

The tricky part is once you shut down your Instrument Air line you also shut down the Plant. You have to plan a shut-down to determine how it will take place.

We had a single line feeding Compressed Air to the Separation Plant. The compressed air mainly served instruments and actuators. To allow only one half of the Plant to be isolated we had to install ball valves to each main branch. Fortunately a complete Plant Shutdown occurred, so we jumped in and made the change.

(The original Consulting Engineers had some strange ideas about maintenance).

 

[geo57]

Hi,

You could use the same "Hot Tap" procedures you would use on any process line. You basically weld a connection to the pipe, and then use a machine to bore through a valve into the pipe. You did no mention the line sizes, but if they are small, you could forego the hot tap machine, and just use a drill to install the hole in the connection, and a ball valve to quickly close off the connection after you drill it. If your connection is small, and if you are quick, you shouldn't lose too much air. However if you choose not to use a hot tap machine, and something goes wrong during drilling your plant is down until you can fix the problem (i.e. a broken bit halfway though, etc.).
Good Luck George Griggs
Sr Process Controls Engineer

 

[280474]

Thank you guys for your response.
Actually my point is to install the valve without shutting-down our plant.
I've just performed a trick way to install the valve on the operating instrument air pipeline. The line is quite long and some part of it was very bad corroded, especially at downstream line to the regulator. The problem was no gate valve available along the line, only venting facility existed.
Since our hot-tap machine was out of service, then we tried to pinch/squeeze the line near the corroded point while monitoring the supplied pressure from the line to connected equipment.
Bypass line from existing venting facility was installed after cutting the corroded point of the line. And finally the pinched point closed by fabricated pressure tap completing with gate valve. And both of pipe cutting point isolated by cap.
In fact, this trick way was successful, and there comes another request for the bigger size (ie: 4" or above). So, my question, do you guys have similar experience as mine..? especially for the bigger size of pipeline at any services.

regards,
Nasrul

 

[micjk]

There are several manufacturers of "hot tap with out drilling" type fittings. Kitz is one. It uses a primer cap to actualy shear off a section of pipe basically creating a tee type connection. I'm not sure what the size range for these type of fittings is, but they may have a web site that you can research to see the range. Also Lok Ring is a very useful brand. This would require shutdown though, but it would be minimal. If all prep is done prior to shut down cut and install would take @ 3o min for 2 flanges and bolt up valve. Again not sure of size range.
Regards,
MICJK