Investigating Weld and HAZ Effects During SMAW of Pipe and Fitting Materials

Abstract The primary goal of weldments is to have the longitudinal strain not concentrated in the weld. To date, there is no reliable way to accurately predict this, given the variability of welding techniques, mechanical properties, and manufacturing methods of materials in CSA Z662 pipeline designs. Several girth welds were completed using SMAW on common carbon steel pipe and fittings used under CSA Z662 designs. The results focus on comparing as-welded joint properties relative to the base metal. The base materials were chosen to be wide ranging in chemistry and manufacturing process. The deposited weld filler metal tensile strength can be relatively and consistently predicted; however, the overall weldment properties are more difficult to estimate. The results provide an opportunity to learn more about the response of welding on the base metal. The goal is to improve the ability to design and complete weldments that have equal or better mechanical properties than the base metal. Advancements are already being made to new construction best practices, but there is value in understanding how conventional filler metals and base metals are allocated to highest risk welds for new construction and existing assets.