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Global pipeline owners/operators are experiencing firsthand the benefits of high-strength steels (X-70 and above) used in pipeline construction: lower cost-per-foot, less weight, reduced transportation costs, increased strength and pressure tolerances, and the ability to work with thinner wall thicknesses (reducing welding and filler metal usage).

The potential for hydrogen-assisted cracking, however, increases as the strength of the steel increases. The push for higher strength steels has resulted in the need for lower hydrogen welding consumables and processes. In this presentation we will discuss the common sources of hydrogen in the welding environment and a few best practices in minimizing the levels of hydrogen in the final weld, including:

• Filler metals: filler metals are arguably the most common source of hydrogen in a weld. Cellulosic shielded metal arc welding (SMAW, or Stick) electrodes commonly used in this application are the worst offenders. Transitioning to other processes such as metal-cored or flux-cored welding can help significantly reduce hydrogen.
• Pre-weld, post-weld and interpass temperatures: Maintaining required pre-heat and interpass temperatures is critical, both for producing a softer, less crack-susceptible microstructure, and for allowing hydrogen to diffuse out of the weld metal and heat-affected zone. We鈥檒l examine how induction heating helps manage the heating and cooling rates of these steels and how it helps remove hydrogen from the weld.
• Eliminating common sources of hydrogen: hydrogen is everywhere when working in an outdoor environment (dirt, moisture), but it also can exist in other organic materials such as residual cutting oils, rust or paint. Contaminated shielding gas or leaks in shielding gas delivery systems may also introduce hydrogen into the weld. We鈥檒l discuss best practices for eliminating additional hydrogen sources in the weld environment.