WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
(OP)
At our plant, 1/2"nps bypass valves are 'stayed' with brackets fillet welded to the body flanges of their 14"nps boiler feedwater valves.
Fatigue failures of the bracket welds has called for beefing up the bracket configuration and weld design to avoid resonance.
The legitimacy of the attachment weld (which has not failed) is being questioned.
The alternative is to use a body/bonnet stud for this purpose, however this could lead to gasket leaks.
Are there any large valve manufacturers that approve this practice?
Are there any specific conditions on type, size and length of weld or pre and post heat treating?
Fatigue failures of the bracket welds has called for beefing up the bracket configuration and weld design to avoid resonance.
The legitimacy of the attachment weld (which has not failed) is being questioned.
The alternative is to use a body/bonnet stud for this purpose, however this could lead to gasket leaks.
Are there any large valve manufacturers that approve this practice?
Are there any specific conditions on type, size and length of weld or pre and post heat treating?





RE: WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
Can you provide a picture or two of the specific situation?
Sometimes its possible to do all the right things and still get bad results
RE: WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
I can get those on Monday. In the meantime I've attached a sketch.
A 4" x 2" x 1/4" plate is welded to the edge of the body/bonnet flange with a fillet weld along the 4" edge.
The 4" edge is slightly contoured to the radius of the large flange.
The plate has two 1/2" holes to which the bypass valve or it's actuator can be bolted.
Being attached to the body side of the flanged connection allows valve bonnet removal without disturbing the bypass valve that is bolted to the bracket.
RE: WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
Here is a picture of a welded and bolted lug installation as requested.
RE: WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
I now suggest, as long as you discussed this need with the Maintenance Department and got their approval then it must be good to go.
Sometimes its possible to do all the right things and still get bad results
RE: WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
I would much prefer to use bolted connections and then weld onto that.
Section 2.1.6 of ASME B 16.34 states that the welding requirements for the main body are not applicable to ...lifting lugs,...
So there appears nothing to directly stop you, but equally nothing giving you any requirements or specifically allowing it. So it looks like a welding procedure / fillet weld testing issue.
A lot seems to depend on the manufacturer - in my place I would say no as it is not of value to me, but you can always ask.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: WELDING BRACKETS TO VALVE FLANGES - ANY CODE REQTS?
I am interested to know your reasons for "much" preferring to use a bolted connection as the attachment to the main valve.