Unions vs. Flange

Chips

Is there any difference or preference between using unions or flanges on a low pressure steam system?
Thanks
Chips

bob young

Use unions up to 2 " ips 2 1/2 " & larger use flanges

bill_97

Unions all the way

to 4 inch for us . You have to be dead on , and I mean dead on , to line up flanges .

I'm simply not that dead on to do it . Unions are a little more forgiving if the piping doesn't line up perfect .

Longevity - I've seen both flanges and unions in service for many decades without leaking .

Craig_8

"You have to be dead on , and I mean dead on , to line up flanges"

try this trick next time you use a flange. line up 1 hole. drop a bolt in. now turn the flange with a pipe wrench untill the the rest of the bolts line up. the compound leverage creates an unbelievable amount of force that can pretty much line anything up.

using this method i easily lined up a a 6" flange on a header that was off by 2 inches

bill_97

Craig

That is a good trick , I'll have to try that next time we use flanges . Swing joints probably make it even easier . I bet a union couldn't handle that amount of torque .

gerry gill

I'm in the Bob Young camp

over two inches i like flanges..sometimes even two inch i'll use flanges..

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