Pipe advice

[Beanmetalworks]

Hi got a job were I have got to put a pipe on the inside of a industrial building roof it has got to go across the span of the roof and hand for brackets to the other side of building and out the wall for ventilation. The customer has asked me to use 3 inch steel pipe. Was just wondering what would be Easyer to do would be Easyer to join and change angle with threaded joins or is it Easyer to get up in there and weld the joints, I'm happy to do either, thanks for any help

 

[outofthefire]

I would have thought using threaded fittings would have been quicker and easier

 

[Hitch]

Decent measure up, simple welded on flanges, fab'd up in the workshop....

 

[Beanmetalworks]

Like the idea of weld on flanges can do them on site. I guess have to use some sort of gasket in between the to stop the fumes and liquid seeping out?

It's one them jobs that is slightly hard to measures its a till u get going at job and work things out as go along, I no that's not idea but I got rough measurement from the ground.

 

[Beanmetalworks]

Got bit of room to play with not got be mm fit. Also we're best place to get weld on flanges ?

 

[Welderpaul]

I guess have to use some sort of gasket in between the to stop the fumes and liquid seeping out?

Frightening comment....

What is running through the pipe?.....

 

[Engineer1964]

I've done this before and its a lot easier than threading, I would say that for 3 inch pipe, you would be better off using a slip on flange, as oppose to a flange that you weld onto a collor, its so much easier i used 15mm flanges, just g-clamp them onto a small piece of plate roughtly about the same size as the flange, use a small offcut say 7mm of the pipe and place that in the flange, then offer the whole flange and push up tight to the pipe, Stick your tacks and weld round.

Remove the G clamp and spacer, and you'll find that your flange has sat evenly 8mm into the flange. Some people weld the inside too but i didn't bother it depend what you have going through and what sort of pressure.

Bleow is the sort of slip on flange i used, Just had them lasered, cheaper than buying the ones with the collar that you just butt weld to. if your not too bothered to re drill the holes you could even get them plasma cut with the holes abouy 3 or 4mm smaller and then just drill through with the right sized drill