Hmmm, shame 3801's boiler wasn't built in Sydney!

I think the removable steam dome is brilliant! You can work on the throttle in comfort and not have to worry so much about dropping the U-bolt on the tube bundle.

Paul: Yes that design of dome is a VERY good one, it is a direct reproduction of the dome on the original South African NG/G-16 boiler. I'm pretty sure that was the normal way of constructing steam domes in the "British" school of design. As you say it makes fitting up the throttle, as well as getting in and out of the boiler a lot easier.
Pat
Edit: Of course I shouldn't say direct reproduction, the original wasn't welded.

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Any restrictions to using this design for a new build boiler in the US? Any ASME code or FRA restrictions? This seems like such a good idea.

Would this use a copper wire ring gasket for sealing the flange, or something more of a full-face composite or Teflon gasket?

Howard P.

Yes, on the NG/G-16 boilers they use a typical copper ring gasket, in a groove on the lower face, I would think that's pretty standard. No reason they could not be adapted to a more modern corrugated metal gasket.
Pat

Quote of the day!

No restrictions at all. ASME Section VIII (pressure vessels), Divisions 1 and 2 have sections dedicated to flange design. Those rules can be used for Section I (power boiler) construction as Section I does not address flange design.

FYI
It works the other way around just as often. Seen it here.

OK, so the obvious question is... If there are no regulations prohibiting this, and the design works well, why hasn't it been done before? We've certainly seen all kinds of other strange designs over the years such as T boilers. Surely somebody thought of this before.

My guess, and it's only a guess, is that the smaller steam dome opening provides a smaller area that needs to be sealed and prevented from leaking. The whole pi*d makes it go up quickly. 3' diameter is roughly 9.5 feet of seam. 6' diameter is nearly 19 feet of seam. Could that be the problem?

Back in the days before welded boilers were commonplace, it required a lot of additional flanging for little gain. Cheaper and easier to just hire skinny boilermaker helpers.

Today, how are you going to hide that ugly bulge under the dome jacket? Or don't you care?

Make the dome bigger to accomodate the flange?

dave

Many dome jackets already have room for a couple inches of insulation all the way around the dome. If you design your flange to match the OD of the insulation it'll fit in the existing jacket.

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