Soft seated SW valves 3

[cjabhijit]

Dear All,

I am new to Piping Materials so a question regargin Soft seated socket welded ball valves.

Is it possible to remove the soft seat prior to welding to avoid damage to the soft seat? Can the seat be reinstated after completion of welding? OR Soft seated ball valves with socket weld ends will be supplied complete with pup piece (at least 150 mm long) welded at each end of the valve prior to valve assembly.

Thanks & Regards,
Abhijit

 

[moltenmetal]

There are several solutions to this problem. The most common is to use a 3 pc valve and to partially disassemble prior to welding- this approach is successful (with a competent fitter/welder) 100% of the time and leaves you with a valve you can maintain without resorting to cutting the valve out later. The 1000 WOG CF8M commodity cast valves are dirt cheap these days and as long as your expectations of performance are reasonable, they do a fine job for the most part.

Another is a top-entry valve which is disassembled from the top prior to welding- also acceptable, though not that common in socket welding sizes (1/2-2") for cost reasons.

The third is a 2 pc end-entry valve which is not disassembled prior to welding but rather is designed with fins or lengthened body sections that allow you to weld the ends (with a wet rag over the body) without cooking the internals. It is not 100% effective, and I stay away from those valves like the plague.

 

[cjabhijit]

Moltenmetal, thanks for the helpful response.

Thanks & Regards,
Abhijit

 

[MickMc]

It is common to order with stub ends (150 mm) and specify these to welded before final machining therefore shop/field welds will be far enough away from later inserted soft seats to cause no damage.

 

[bcd]

This is an debate that has no correct answer. Some say it is best to disassemble prior to welding to avoid damage. Other say it is better to carefully weld in fully assembled because the welders trying to reassemble valves do more damage than the heat. And others say you must use pup pieces to keep the weld heat out of the valve. In this case, everyone is right, and everyone is wrong. Any of these methods can be used under the right circumstances. The decision depends upon the experience of the welders installing the valve, and the environment they are in when doing their work.

 

[cjabhijit]

BCD, thanks for the clarification....good one.

Thanks & Regards,
Abhijit

 

[JMISELEM]

You might want to check Flo-tite WELD IN PLACE ball valve designs. They are specifically designed for welding the valve to the line, without disassembling the valve, nor using special welding procedures. 3 pc valve designs are available in 1250 WOG design from 1/4" to 3" (smaller size 1/4" to 2-1/2" are rated 1500 WOG) and 2250 WOG design from 1/4" to 4" (smaller sizes 1/4" to 3/4" are rated up to 3000 psi WOG)

Visit their website at

http://www.flo-tite.com

This is a link directly to the product:

http://www.flotite.com/index.php/pr...hoice-weld-in-place-ball-design?category_id=3

Check out also the following test report:

http://www.flotechinc.com/wp-content/uploads/2014/02/FLOTITE-WeldinPlace-Technology-Test-Report.pdf

Hope the above helps

Juan C Miselem