What welding techniques/ supplies are used in cold climates?

We are welding oil field pipe in a cold climate. As the temperature drops below 0* F, we are having trouble with welds breaking. Are there certain techniques, or certain type of welding rods that work better in these cold climates?

Answer:
In general, heat-treated mild steels are arc welded without pre-heat. However, a preheat should be used when the metal temperature is below about 50 degrees F (10 degrees C), and a preheat of about 100 degrees F (38 degrees C) or higher should be used if the plate thickness is over 1 in. (25.4 mm) or if the joint is highly restrained.
When you are welding a pipe in ambient temperatures below 70 degrees F. Especially when the pipe is made out of high-strength alloy steels it is essential to preheat the member to reduce the temperature differential between the weld zone and the rest of the base metal. As the weld zone is heated it expands, the cold base metal outside of the weld zone does not expand with that portion and this creates stresses that cause cracking. Preheating will reduce the danger of cracking, reduce the maximum hardness, minimize shrinkage stresses, lessen distortion and help gasses especially hydrogen escape from the weld. The ammount of preheat depends on the chemical composition and mass of the base metal, the ambient temperature (in this case 0*F), and the welding procedure. When making multipass welds it is very important to monitor the interpass temperature. This is the minimum and maximum temperature of the deposited weld metal and adjacent base metal. The minimum interpass temperature will usually be the preheat temperature. Thus if the preheat temp is 500*F the interpass temp. should never be below that mark. The maximum interpass temperature is the maximum temperature allowable before metallurgical changes occur in the weld metal causing undesirable qualities to form. If welding is interrupted the weld temperature MUST be brought up to the minimum interpass temperature again before welding is resumed. The best way to monitor the temperature of the weldment is with a temp stick, a crayon that melts at a specific temperature. They can be found with melting points between 100*-1000+ degrees. Good luck. Any more questions can be directed to volt2u@yahoo.com.

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