Thermite Welding 175lb rails

[hotdrop]

The port I work for has been installing 175 crane rails and welding them togheter with thermite. Unfortunatly there seems to be about a 75% falure rate in those welds and were uncrtain that the ones that passed arent just going to fail in a year or two. We did ultrasonic testing on them but the tests seemed inconclusive as welds that passed UT testing failed a few days later. Dose anyone know:
1) If thermite welding is even an acceptable process for such a large rail
2) Any common reasons that the welds would have such a high falure rate
3) A better testing alternative to ut testing.

 

[MintJulep]

What is the nature of the failure?

If I had to guess, and I do due to the lack of information, I would suspect inadequate pre-heat.

 

[metengr]

Thermite welding has been used for many years in the field to join rails. Flash butt welding is normally used in the shop. What is the rail material? Also, what are the reasons for rejection as stated above - defects from lack of fusion, or inadequate penetration? Have you qualified the Thermite welding procedure? An alternative NDT method would be radiographic testing (x-ray).

 

[Screwman]

Are the welders doing the work used to doing rail welding? I am not an expert in rail welding but have been around a lot of crews welding 155# rails on a daily basis. They had what seemed like a lot of little things that they did when prepping and finishing the weld that I didn't understand real well. Those rails were on the heaviest tonnage track in America and they held up as weld as the factory welds.
That was all Thermite welding.