Welding of rails

[kingnero]

Dear All,

I am looking for documentation (acceptance criteria, WPQR, ...) for the butt welding of rails using SMAW or FCAW in copper blocks (see attached pic).
I am quite familiar with the welding of rails, and know the relevant EN or EN ISO standards (e.g. for thermite and repair welding of rails, ...), however for this type of welding there is no general code.

Does someone with access to the AREMA manual knows whether this is a subject that is treated in the AREMA (or in a similar code)?

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[dhengr]

Kingnero:
I’ll bet that on this one, you will be doing the development, testing, certification and first code writing on your own. Using SMAW or FCAW for repair and some surface finishing, with some finish grinding, would seem to be reasonable. The thermite process is pretty well proven and practical for real butt welding of rail sections, but how do you propose using SMAW or FCAW for butt welding? With the copper shoes, are you thinking of something akin to electroslag welding (ESW)? But, we used this on larger, more uniform cross sections, we used water cooled copper shoes, and you need a starting pool (spot, nugget area?) to start the process and get it rolling, and this volume (area) ends up being wasted, and is outside the finished product volume. The flange, web and head are so different in width and volume that these differences could give you difficulty. By their very nature the thermite and electroslag processes give a more uniform weld volume and a more uniform HAZ, when they work right, as opposed to a process with many smaller overlapping passes, starts and stops, and many HAZ’s, etc. Tell us more about what you have in mind.

 

[kingnero]

dhengr,

filling up the void withing the copper shoes is a process that is regularly used in Europe for low-impact railroad lines (low speed like i harbours, and where the rails are in concrete where it it too diffucult to cut out the necessary space to place the thermite moulds). Typically, last few layers are welded with a 350 BHN hardfacing rod.

However as I said, apart from (lots of) user experience, I haven't been able to find something written.
I was hoping I would find it outside Europe, however reading your reaction this doesn't seem too obvious...

Attached you'll find pics of this, however with ceramic backing instead of Cu blocks.

https://files.engineering.com/downl...809a-4acd-8b75-6f51cd76db3f&file=IMG_0361.JPg

https://files.engineering.com/downl...18d8-43c8-b162-85c319cc86ab&file=IMG_0367.JPG

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[dhengr]

Kingnero:
Well, I guess that’s called repair welding. I don’t have any codes or stds. or WPQR’s for that welding; just good, clean, common sense welding technique I guess. The ceramic backing seems fine on the bot. of the flange. But, how do you grind that flat if it lands on a conc. tie or on a tie pl.? And, is it o.k. if that is in tension if it falls btwn. ties? The most problematic areas/volumes are probably the radiused areas btwn. the web and the flg. or the web and the head of the rail. There you do a lot of short filling weld passes, in the transitions, and you might trap some slag or crap in a weld puddle. Do you use small ceramic backers on the underside of the rail head, both sides? I would cut these a little long, so that I could built a better/longer shelf for the welding above, with my first couple passes. Without those shelves or a runout tabs, you have kind of a crappy condition at the starts and stops of the head welding, on the sides of the head, as in your photo; and can you do enough grinding to clean that junk up? Do you do some preheating before you start, and maybe some more as you start at the head? Ask your local railroads, they may have some stds. of their own, over the years. Maybe ask some rail suppliers in your area for their ideas or recommendations.

 

[kingnero]

dhengr,

thanks for your remarks.
As you said, I contacted some of the the railroad infrastructure managers in Europe, however apart from practical experience, they don't have written procedures for this process, as it only gets used in not-important sections of the railroad (low velocity lines, ...).

About the underside of the rail head, see above pic: the copper shoes serve as backing. when necessary, copper run on/run off tabs are welded on the shoes.

The standard about rail repair welding only covers welding surface defects, not butt welding of welds. The rail butt welding standards cover thermite welding and flash butt welding, not this process. However somewhere on the world, some railroad infrastructure manager must have some written procedures for this? I just haven't found 'em yet...

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