dtn6770
Mechanical
- Jul 10, 2006
- 200
Does anyone have experience with adding an auxiliary connection to a valve that has been in service?
My situation involves adding a one-half inch bleeder (sockolet, pipe nipple, and gate valve) to an 8-inch, 600 class, forged steel gate valve that has been in 600-psig steam service for quite some time. The valve appears to have “bosses” at the locations you would expect to see (B16.34), one of which would be utilized for the bleeder. The plan includes UT verification of the valve body thickness before welding, liqid-penetrant testing of the welds, and pressure testing the new assembly after welding before the valve is drilled.
Reservations have been voiced based on the valve being “old” and the fact that the steam header will be live on the other side of the closed gate. Our answer to the latter is to treat the installation as a hot tap and utilize appropriate contractors. The only technical credit I can attribute to the “old” concern would be to consider creep strain which will not be influenced by the addition of a bleeder.
I respect the concern over the situation but am struggling to get management to have that warm and fuzzy feeling they need. To that end, does anyone have stories (good or bad) that they’d like to share?
Thanks in advance.
My situation involves adding a one-half inch bleeder (sockolet, pipe nipple, and gate valve) to an 8-inch, 600 class, forged steel gate valve that has been in 600-psig steam service for quite some time. The valve appears to have “bosses” at the locations you would expect to see (B16.34), one of which would be utilized for the bleeder. The plan includes UT verification of the valve body thickness before welding, liqid-penetrant testing of the welds, and pressure testing the new assembly after welding before the valve is drilled.
Reservations have been voiced based on the valve being “old” and the fact that the steam header will be live on the other side of the closed gate. Our answer to the latter is to treat the installation as a hot tap and utilize appropriate contractors. The only technical credit I can attribute to the “old” concern would be to consider creep strain which will not be influenced by the addition of a bleeder.
I respect the concern over the situation but am struggling to get management to have that warm and fuzzy feeling they need. To that end, does anyone have stories (good or bad) that they’d like to share?
Thanks in advance.
