2.5" socket weld connections 1

[metalhoosier]

When the electric utlity plants I work with were built (60's, 70's, 80's), the original engineering construction firms, two different ones, used construction specifications that did not allow high pressure (2000-2900psi), high temperature (1005F) socket welding over 2". B16.11 is acceptable to use for fittings up to 4" and B16.34 is good for class 4500 valves up to 2.5".

Why did these engineering firms stop short of what is allowed by these specifications? Is there an industry standard or knowledge I'm unaware of and if so, has it changed recently to meet the current specifications? Any thoughts?

Thank you,
Metalhoo

 

[pennpiper]

metalhoosier,

Try this;
Contact your local pipe and fitting supplier and ask for a price quote for:
(1) a 4" butt weld 90 degree elbow

(2) a 4" Socket Weld 90 degree elbow

 

[MJCronin]

hoosier...

You do realize that socket welds on piping are inherently less strong than full penetration welds. ASME B31.1 doe not allow them on certain flammable/toxic services.

Additionally, there comes a point with high- pressure rated (Class 9000 ?) socketwelded fittings where the required fillet weld becomes huge for the service. Butt welds are a better choice.

 

[rmw]

When you deal with the various ASME codes, piping and vessel, you will find that they don't always agree.

I questioned an esteemed forum member who is on one of the ASME committees about that recently; specifically why they can't all get on the same page and he likened it to herding cats.

You have to go with the code that dictates your design.

For the situation you described, it was most probably B31.1.

Remember too that in the day that those plants were built, there was more regulation than now and power companies made money on how expensively they could build plants. The percentage return on investment was regulated, but the amount invested wasn't.

Therefore things may have been done differently for reasons not appearant now days.

rmw