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 Post subject: Measuring composition of boiler steel
PostPosted: Sun Jul 09, 2017 1:20 am 

Joined: Mon Feb 17, 2014 4:20 pm
Posts: 487
The latest NW Railway Museum blog post is interesting. It talks about measuring the chemical composition of original boiler steel using a portable metals analyzer. Blog says:

    "One of the remaining boiler vessel requirements is completing the package of documentation used to obtain regulatory approval. And one of the remaining details is confirming the chemical composition of the boiler plate, which is a factor used in determining the pressure vessel's maximum operating pressure."

The locomotive they are working on is an 1899 Rogers 0-6-0.

Here on the RYPN Interchange, I don't think I've seen anyone talk about measuring boiler steel composition as part of re-certifying the boiler. Is it done often, sometimes, or seldom?

Link to the blog post -
http://trainmuseum.blogspot.com/2017/07/steel-chemistry.html


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 Post subject: Re: Measuring composition of boiler steel
PostPosted: Sun Jul 09, 2017 10:10 am 

Joined: Tue Aug 24, 2004 10:34 pm
Posts: 680
It is my understanding that every single pc of steel in a locomotive boiler {not smoke box} needs to haave analyses and be documented. Any pcs of steel added in a repair new or old. Non destructive testing is normally done. Not sure exactly what method everyone uses but the testing is done along with thickness testing. The paper work that goes in for final FRA approval is pretty extensive. In the terrible good old days some would literally cut a chunk of the barrel out for analysis, which was not necessary for determining the composition. This is all part of the formula used to determine safety and pressure specs. I would hate to find out the logging company used steel from somewhere else to patch a barrel. You would no doubt end up replacing that pc of steel regardless of the quality of repair or condition. This is my understanding but do not profess to be a boiler maker and have all knowledge. Regards, John.


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 Post subject: Re: Measuring composition of boiler steel
PostPosted: Sun Jul 09, 2017 10:52 am 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 5488
Location: southeastern USA
First look at the documentation. Most locomotive boilers built in the US have either National Board or Hartford certifications which trace the pedigree of the steel back to a production heat number from the mill that made it, which certifies its specifications. Unless there's a documentary trail for replaced steel, you could be in for a surprise, so testing may be required. Look for the numbers stamped into the backhead or steam dome and do your research before testing what may already be appropriately certified. Archives are out there, you might be able to trace it back using a builders construction or order number if the stamped numbers have become illegible. And, if you must test, only test steel that has been well cleaned including cleaned of abrasive residue from the cleaning itself.

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 Post subject: Re: Measuring composition of boiler steel
PostPosted: Sun Jul 09, 2017 10:53 am 

Joined: Sat Aug 21, 2004 10:52 pm
Posts: 914
Hi,

Could a spectrometer determine the steel composition?

Doug vV


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 Post subject: Re: Measuring composition of boiler steel
PostPosted: Sun Jul 09, 2017 11:44 am 

Joined: Mon Aug 23, 2004 2:09 pm
Posts: 362
Location: Los Angeles
[quote="Dougvv"]Hi,

Could a spectrometer determine the steel composition?

Doug vV[/quote]
Testing now is fairly easy and in some cases can be done on the locomotive. Basically the device uses electricity like a welder, vaporizes a spot and "sniffs" the vapor for the analysis.
This can be done in a lab with a piece(s) of shell peeled from an edge of the sheet. Large pieces do not have to be cropped from the different courses.


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 Post subject: Re: Measuring composition of boiler steel
PostPosted: Sun Jul 09, 2017 7:09 pm 

Joined: Wed Jan 28, 2009 4:30 pm
Posts: 141
The testing of steel is a very valuable option when working up the Form 4 or attempting to qualify a boiler with some other agency. The composition is especially important if you are intending to perform a weld repair. The testing of steel for composition is very easy and there are any number of qualified labs around the country that can perform the test.

When we undertook the restoration of the Glenbrook we took samples of all of the steel we were planning to preserve. Although some of the sheets were stamped and were legible, the stamp said “Warranted Steel” and meant nothing. Also the locomotive was built in 1875 and Hartford wasn’t involved in locomotive boiler construction at the time. The samples were sent to a lab in California and the results were returned quickly.

But composition isn’t the only story. We cut out coupons of sufficient size to get a tensile test. The 50,000 psi value the FRA expects you to use if tensile is not demonstrable is a very conservative number. It is absolutely worth the time and money to get a real value. One sheet came by with a wet stamped test report of 71,500 psi which is an excellent number when you want the factor of safety to be beyond reproach.

Each coupon cost about $200 to be tested for composition and tensile, absolutely worth the dollars. The tests were all returned with good results, carbon in a reasonable range and sulfur and phosphorus below the maximum allowable limit. We ran our data past a professional engineer who stamped the report attesting that the material was good and the design was sound. This made the state boiler inspector happy.


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