PRCI Thermal Analysis Model for Hot-Tap Welding (Version 4.2)

The PRCI Thermal Analysis Model for Hot-Tap Welding, developed by Edison Welding Institute for PRCI, is intended to provide welding engineers with guidance for establishing safe parameters for welding onto in-service pipelines (hot-tap welding). The model significantly reduces the risk of predicting burnthrough and hydrogen cracking risk for welds made onto in-service pipelines.

The ability to weld onto in-service lines enables both the installation of repair sleeves and hot-tap branch connections without interruption of flow. While there are economic benefits to this practice, certain issues must be addressed to ensure that public, environmental, and worker safety is maintained both during and after welding. Specifically, high cooling rates occur when welding onto an in-service pipeline, because the flowing contents quickly remove heat from the pipe wall. These cooling rates promote the formation of hard heat-affected zone microstructures, making these welds susceptible to hydrogen cracking during or soon after welding, and to sulfide stress cracking in subsequent sour service.

Use of the PRCI Thermal Analysis Model for Hot-Tap Welding provides a cost-effective solution while still minimizing the risk of hydrogen cracking by eliminating the high costs associated with using unnecessarily complex procedures.

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The Pipeline Research Council International, Inc. (PRCI) is a 50-year old not-for-profit organization whose members include 23 of the worlds largest pipeline companies. PRCI invests in research and development of new technology for the energy pipeline industry, and the current technology budget for PRCI exceeds US$12.5M per year. PRCI pipeline technical research and software is available for purchase by non-member companies and can be obtained at the PRCI web site located at www.prci.com