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 Post subject: Boiler Inspections
PostPosted: Thu Dec 07, 2023 1:45 pm 

Joined: Fri Dec 22, 2006 12:44 pm
Posts: 51
Location: Cheyenne, WY
Hello All,

Linn Moedinger has published in the National Board of Boiler and Pressure Vessel Inspectors Journal, a very concise and informative review of inspection points and potential defects as found in steam locomotive boilers.

The entire article is attached.

Respectfully,

Dave Griner


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Locomotive-fall 23.pdf [438.31 KiB]
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 Post subject: Re: Boiler Inspections
PostPosted: Thu Dec 07, 2023 8:02 pm 

Joined: Fri Nov 07, 2008 11:21 am
Posts: 473
With due respect to Mr. Linn,

Regarding this comment:
Quote:
employing UT on stayed sections, readings should be taken on a grid
not exceeding the maximum pitch at the center of each section of four staybolts.

I have always taken a different approach. I always take readings immediately adjacent to the bolts, not in an area between them. The reason is that stress corrosion cracking will cause craters around the bolts, and thus a thinning immediately adjacent to the bolt that will not show if the UT reading is taken in an area between the bolts. My thinking is that this is the weakest link, and should be addressed. Photo is a cross section of a crown sheet and staybolt from a CASE traction engine operating at 150psi until the owner noticed a leak.


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staybolt web.jpg
staybolt web.jpg [ 62.58 KiB | Viewed 14307 times ]
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 Post subject: Re: Boiler Inspections
PostPosted: Thu Dec 07, 2023 11:23 pm 

Joined: Thu Jul 28, 2022 11:48 pm
Posts: 10
I understand what you are saying about the complexity of getting a comprehensive set of data for the crown sheet around the stays. In Linn's defense he did say to check within 3/8" of a bolt. In criticism he glossed over this point quickly without a in depth explanation. In defense of Linn he never said this was an exhaustive explanation of boiler inspection. I feel this could be a reasonable opening chapter to a long and in depth treatise of boiler inspections. In criticism of Linn he missed a couple of details that I have run across and I think are of merit. But then again I don't see a lot of other people trying to do this. I give him high marks for opening the discussion.

On a lighter note, the cross section of the stay bolt is a very nicely prepared specimen. It is instructive to note the the boiler was operating, probably at MAWP, to get to this point. It is a testament to blind luck that it didn't come apart and kill someone and to the great design of boilers that they will endure this kind of deterioration.


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