Need information on railway welding (MMA, not Al-Thermite weld)

[kingnero]

I am currently investigating the difference in repair welding minor faults (MAX 1/4" deep, a few inches long) on the upper side of the rail with both MMA and FCAW.
Repair welding as well as welding in order to enlarge the surface vertically, eg. when joining new rails to old, worn-down rails. In that case the old rail needs to welded up in a ramp-style (about 1 mm / metre) which is achieved by welding and grinding.

I am currently in a very basic stadium, however I will already start this topic in order to be as detailed as I can be, not forgetting crucial information etc.

First question: I guess the C-content will be about .8% (still waiting for the exact chem. composition).
The IIW formula for Carbon Equivalent does not cover this range. The CEN-formula (with the TanH coefficient) does so, correct?
If I use the latter, what is the correlation to the needed pre-heat temp. ? Can I use the same diagrams as for the IIW-formula? Or can someone point me towards a source of information where this is already explained?

I have searched this forum and have seen threads on railway welding, however there is mentioning of Alumino-Thermite welding. Which is not the subject of my investigation.

I apologize in advance for any spelling/grammatical mistakes in my English, if there is need for any more specific explanation please let me know.

Many thanks in advance...

 

[unclesyd]

AWS (AWS D15.2.2003) has some standards on welding on Railroad Rails but it looks like the most information comes from the electrode vendors. I would also check the AAR site for some leads.
The welding procedure I've seen on rail ends appears to based on the tensile strength of the rail which determine the preheat. The only common thread I've seen in welding if rails is the buttering of the rail with 7018 then capping with some work hardening alloy which has remained a unknown to me. I did see a Hardox box on one truck.


Here is some information from UTP. You might be able to find a clearer copy or print this one out.

http://www.utp.de/russian/files/UTP_Railway_2008-10-02.pdf

here are two additional pares that you may gleen a little information from.

http://eprints.qut.edu.au/16180/1/Melissa_Bona_Thesis.pdf

http://extranet.artc.com.au/docs/engineering/cop/sections/sec_1_rail.pdf

 

[kingnero]

Thanks for the input, I went through all of them and they contain very valuable information.

I have read in this thread one uses preheat temp from 800 to 1000 Fahrenheit, how does one achieve this?
I've seen Propane (C3H8) used over here, but that gets the rail barely above 700 Fahrenheit.

A picture of the heater, if possible, would do me a great favour.