Fabrication and Installation of Boiler Patches

 

No. 28

No. 28

The No. 28 project is moving right along. Recent focus has been on replacing thinned sections of the firebox. The firebox was assessed after a thorough descaling of  water deposits. Through ultra sonic inspection the crown sheet, knuckle, and area under the firebox door all showed some signs of thinning. The original crown sheet and knuckle were removed and were sent out to have the pieces replicated. The fabricated crown sheet was formed at Benicia Fabrication & Machine, Inc. in Benecia, CA., and the knuckle was formed by Chelatchie Boiler Works, Inc. in Camas, WA..

Original crown sheet being removed.

Norm Comer cutting out original crown sheet.

Portions of the boiler that needed to be replaced were removed in sections by a cutting torch. These pieces were lowered with a electric chain fall and sent out to be duplicated.

Crown sheet removed from     the interior of the boiler.

Crown sheet removed from the interior of the boiler.

Once the crown sheet was removed, the exposed interior of the wrapper sheet was needle scaled to remove accumulated water deposits. After a detailed cleaning the wrapper was inspected for defects. No issues were detected.

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Crown sheet marked for stay bolt holes.

After the crown sheet was formed and returned it was then laid out and measured. The sheet was marked in a grid format. 130 holes were drilled on each half of the crown sheet. These holes will later be tapped and threaded to receive stay bolts. The stay bolts will connect through the wrapper to the firebox sheets.

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Tony Stroud and Phil Hard.

Stay bolt pilot holes were drilled out at 7/8” and later will be opened up by aligned reaming to .920. They will then be tapped with a 1 inch-12 continuous thread through the firebox and wrapper.

Original and fabricated knuckle peices.

Original and fabricated knuckle peices.

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Scott Botfield beveling the knuckle prior to installation.

Upon arrival, the slightly larger fabricated patches were rough cut to size by a cutting torch. The pieces were then ground down until they fit the side sheets. The edges were beveled down to a V which is needed for the welding procedure.

Engine side of crown sheet installed.

Engine side of crown sheet half installed.

 

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New crown sheet halves tacked into place.

 

Greg Nelson welding inside the firebox.

Greg Nelson welding inside the firebox. Photo by Dan Ryan.

 

Greg Nelson welding the seem between the firebox knuckle and crown sheet.

Greg Nelson welding the seam between the firebox knuckle and crown sheet. Photo by Dan Ryan.

New crown sheet and knuckle welded into place.

New crown sheet and knuckle welded into place.

 

Now that the firebox is patched up a substantial amount of work is on the brink. Next step is to thread the stay bolt holes, then installing the stay bolts.

Previous Sierra No. 28 Update: Hydrostatic Testing of Superheater Tubes

Next Step: Tapping and Installing Stay Bolts.

 

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