Thermal Expansion

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Thermal Expansion

Post by ConrailRailfan » Thu Oct 10, 2019 10:38 pm

Hi all, when thermal expansion occurs under high temps, how are the kinked rails repaired? Is it a similar process to initially installing the rail when it is heated to its stress level?


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Re: Thermal Expansion

Post by Mark0f0 » Sat Nov 16, 2019 11:16 pm

Wouldn't they unexpand when the temperatures return to normal?

Never heard of 'heating' rail when its installed. There are systems that create the welds for joining sections of continuously welded rail, that involve thermite. But there's no machine that installs rails "hot". High temperatures can cause geometric distortion of rail which can lead to temporary operating restrictions (ie: speed restrictions).

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Re: Thermal Expansion

Post by GOLDEN-ARM » Sat Dec 28, 2019 10:57 pm

when the temperature is lower than the prescribed min/max for cwr repairs, crews use a product called FIRESNAKE, that heats the rail to expand it enough, to make a repair in temperatures below optimal range. it used to be done with diesel fuel, and cotton waste, i guess the new stuff is more "environmentally friendly".


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Re: Thermal Expansion

Post by neman2 » Sun Dec 29, 2019 9:32 am

All railroads that install CWR are required by the FRA to have a detailed procedure and training for employees to adjust rail to its "rail neutral temperature." (Varies by Railroad but usually between 90 and 110 F) There's a lot to the process I won't go in to. A simple explanation on Wikipedia-

Examples of CWR rail heaters from Teleweld Inc -

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Re: Thermal Expansion

Post by Engineer Spike » Tue Jan 14, 2020 2:34 pm

The rails are heated when installed. They have a track machine with big propane tanks on them. They have burners to heat the rail. I believe that the temperature to which the rail is heated is based on the climate. The temperature is chosen so that there aren't too many pull parts in the winter, and the chance of a heat kink are not too likely in the summer.

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