Predicting Safe Welding Parameters for Hot Tapping

by Jeffrey D. Cochran / January 2016

 

Hot tapping is the process of welding one pipe onto another while fluid is still flowing through the pipe. This is performed to avoid production losses due to unplanned downtime. There are two main concerns while hot tapping: cold cracking due to rapid cooling and burn through when the temperature of the inside wall gets too hot. To prevent both of these modes of failure, thermal models have been developed to predict the cooling rates in and near the weld region and the maximum inside wall temperature for various welding parameters.

 

Traditionally, the risk of cold cracking is reduced by ensuring the material’s carbon equivalent is less than some critical value dependent upon the cooling rate, and the risk of burn though is reduced by ensuring the inside wall does not get too hot. Often, these two conditions are opposed to each other; therefore, the welding procedure must be chosen carefully to avoid both of these failure mechanisms. To accomplish this, E2G has developed an easy-to-use, web-based software tool to help welding engineers make the right choice. This tool is demonstrated in this webinar, and the background behind our assessment methodology discussed. Future enhancements are also mentioned.

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