Boiler bushings

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: cbrew, Harold_V

Wolfgang
Posts: 184
Joined: Fri Jul 03, 2015 9:47 am
Location: S-W Ontario
Contact:

Re: Boiler bushings

Post by Wolfgang »

Just my opinion from my real-world experience oh so long ago...

Since our model boiler sizes fall well into the piping category, such fittings known commercially as weldolets, thredolets, etc. may be appropriate.

We certainly used these on nuclear piping.

Really small connections were machined from the solid with only a clearance screw hole to hold it in place during welding, with the weld preparation sized such that the root of the weld was removed when the fitting was finally drilled to connecting pipe size after welding was completed.

Wolfgang
jlakes85
Posts: 228
Joined: Thu Feb 23, 2012 6:07 am

Re: Boiler bushings

Post by jlakes85 »

Hi Marty ,

I think this is a dumb question but if I have a steam dome flange diameter of 4.5 in, im assuming I would need a 4.750 hole in the barrel to get the proper 0.125 gap?

-john
Marty_Knox
Posts: 1724
Joined: Thu Jan 09, 2003 6:50 pm
Location: Michigan, USA

Re: Boiler bushings

Post by Marty_Knox »

John, I don't mean to insult you, but it doesn't sound as though you have had any formal training in pressure vessel welding. It sounds like you read somewhere you need a 1/8" gap, and you apply it everywhere. You don't need any gap at all if you can put your first pass on the inside, then grind down to the weld metal from the outside. The rules require a full penetration weld; there is more than one way to achieve this.
In TIG welding you can butt things, fuse them on the first pass, then run hot and push the filler wire through the puddle to get your penetration.
jlakes85
Posts: 228
Joined: Thu Feb 23, 2012 6:07 am

Re: Boiler bushings

Post by jlakes85 »

Hi Marty,

Sounds good, thanks again. I've been following some of the more popular YT guys going though open root groove welds on 3/8 plate and sch 40/80 pipe in a test scenario, but other than that I'm self taught. That's where I got the 1/8 gap imprint, which as I'm finding out, definitely can't be applied in all situations.

That's definitely a cool workaround to be able to do fusion first then grind to fusion from outside and complete weld from outside
jlakes85
Posts: 228
Joined: Thu Feb 23, 2012 6:07 am

Re: Boiler bushings

Post by jlakes85 »

Just got the latest addition of the book Welding: Principles and Applications. It had mentioned somewhere that because of flux changes/updates, some groove weld procedures accept 7018 rod for all passes including the root. Can anyone advise on what the back story is regarding this? Thanks again.

-jlakes85
Post Reply