Belpaire Boiler for a PRR G-5

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Mon Dec 18, 2017 10:38 am

jlakes85 wrote:Hi Marty,

On the photo from 12/8 showing the firebox tubesheet to crownsheet joint, about what size gap did you guys start with? Also, is it cheating to tack up and then gouge from the same side, finally going back to gouge out and finish weld the spots with tacks?

-John
In reference to the tubesheet to crownsheet joint we use the alternate joint of corner to corner reducing the gap but still getting penetration.
When fitting the outer firebox to the shell, depending on the type of firebox, tacking and back gouging is common.

jlakes85
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Re: Belpaire Boiler for a PRR G-5

Post by jlakes85 » Mon Dec 18, 2017 2:13 pm

Hi Marty,

Sounds good. Can you clarify alternate joint of corner to corner? I was thinking that meant the full thickness of one sheet at 90 degrees to the sheet being welded too rather than touching corners.

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Mon Dec 18, 2017 4:41 pm

The corner weld is a controversial joint. The ASME specifically prohibits it, since it concentrates the stresses at the root of the weld.
But the Australian Model Boiler Safety Code allows it for the inner firebox, provided the first stay is within 1/2 pitch of the joint.
Attachments
corner joint.jpg

jlakes85
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Re: Belpaire Boiler for a PRR G-5

Post by jlakes85 » Mon Dec 18, 2017 5:14 pm

Hi Marty,

Gotcha. It also seems easier to get the geometry right when fitting up right off a print with a corner joint, as opposed to bringing the back firebox sheet towards the barrel a distance of it's thickness, then trying to figure out the gap on each side e.t.c. I remember the shay had 4 1/8 inch Tig wires stuck between the yet to be tacked joints as well as a bunch of 90 degrees magnet clamps to hold it all together. If only I had known about back gouging then..

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Wed Dec 20, 2017 4:27 pm

The boiler is now finished and tested. We tested it to 250 PSI, for operation at 125 PSI. We held the pressure for one hour.
Attachments
IMG_9033.JPG
IMG_9036.JPG

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Wed Dec 20, 2017 4:29 pm

The last thing to do was install the supports for the stainless steel arch.
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IMG_9037.JPG
IMG_9029.JPG

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Wed Dec 20, 2017 4:32 pm

We will have this boiler on display at the Little Engines Open House in Lancaster, PA January 12 and 13.
Attachments
IMG_9023.JPG

SteamHeaton
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Re: Belpaire Boiler for a PRR G-5

Post by SteamHeaton » Wed Dec 20, 2017 11:48 pm

Beautiful work Marty. Thanks for sharing the pictures.

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Sat Dec 23, 2017 12:46 pm

SteamHeaton wrote:Beautiful work Marty. Thanks for sharing the pictures.
Thank You, Ray.
The customer asked me to take a lot of pictures. Since I had them already I decided to post them here.

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Fender
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Re: Belpaire Boiler for a PRR G-5

Post by Fender » Sat Dec 23, 2017 2:07 pm

Marty,
What angle countersink do you use for the stays? I have an 82 degree countersink, which would leave a 41 degree opening between the side sheet and the stay for the weld. Would it be desirable to put a taper on the end of the stays, so there is a more “open” joint for the weld? (I’m making up some “practice” stays and a piece of scrap to test the welding process.)
Thanks.
Attachments
B1F2F90A-F608-449E-9DF1-61DA8B0514D7.jpeg
1A1845BB-E89A-4CAF-91D1-5E5DB7147697.jpeg
Dan Watson

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Marty_Knox
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Re: Belpaire Boiler for a PRR G-5

Post by Marty_Knox » Sat Dec 23, 2017 3:48 pm

Fender wrote:Marty,
What angle countersink do you use for the stays? I have an 82 degree countersink, which would leave a 41 degree opening between the side sheet and the stay for the weld. Would it be desirable to put a taper on the end of the stays, so there is a more “open” joint for the weld? (I’m making up some “practice” stays and a piece of scrap to test the welding process.)
Thanks.
Dan, we use 90 degree countersinks, but put very little prep on the stay. Basically we just break the corner, a 1/16" - 3/32" bevel.
You want to leave the end of the stay showing. Where you have room it also helps to have the stay higher than the sheet.
You may want to try a different style countersink - it looks like you have a lot of chatter. We use the 6 flute countersinks from MA Ford.

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Fender
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Re: Belpaire Boiler for a PRR G-5

Post by Fender » Sat Dec 23, 2017 6:23 pm

Thanks, Marty. Some of the holes look like that, and others are ok. These were done with a single-flute countersink. Part of the problem is that the lowest speed on my Crapsman drill press is 380 rpm (too fast for 1" countersink), and I wasn't using enough pressure on the bit.
Dan Watson

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