L52025 Calibration of the PRCI Thermal Analysis Model for Hot Tap Welding

In-service welding is a common industrial practice for both maintenance and repair purpose. Its applications include, but not limited to repair of pipeline damages caused by construction or corrosion, and hot tap welding used to add branch connections to existing pipelines. In-service welding enables maintaining and repairing pipelines without removing them from service. Such welding operations generate significant economic and environmental benefits, for example, no interruption of pipeline operations and no venting of pipeline contents. One of the common problems associated with in-service welding is hydrogen cracking. Pipeline operating conditions combined with unscrupulous welding procedures could lead to high heat-affected zone (HAZ) hardness values and this, in turn, could cause hydrogen cracking. The risk of hydrogen cracking is particularly high for older pipeline materials with high carbon equivalent.

The objective of the project was to produce a significantly improved HAZ hardness prediction procedure over the procedure in the current PRCI thermal analysis software by utilizing state-of-the-art phase transformation models for steels. Systematic validation of the prediction algorithms was conducted using extensive experimental data of actual welds. The hardness prediction model is expected to become the basis on which the hardness prediction module of the PRCI thermal analysis software will be upgraded and improved.