A welder is tasked with joining two sections of Schedule 40 carbon steel pipe in the 5G position. The root pass requires deep penetration and good fusion, while the fill and cap passes need high strength and ductility. Which electrode combination is most suitable for this application?

Question: A welder is tasked with joining two sections of Schedule 40 carbon steel pipe in the 5G position. The root pass requires deep penetration and good fusion, while the fill and cap passes need high strength and ductility. Which electrode combination is most suitable for this application?

Answer options: ✅ E6010 for the root pass, followed by E7018 for fill and cap passes.

• E7018 for the root pass, followed by E6010 for fill and cap passes.
• E6013 for all passes due to its easy slag removal.
• E6010 for the root pass and E6013 for fill and cap passes.

Correct answer: E6010 for the root pass, followed by E7018 for fill and cap passes.

Explanation: E6010 electrodes offer deep penetration and excellent fusion characteristics, making them ideal for root passes, especially in pipe welding where a strong, sound root is crucial. E7018 electrodes provide high tensile strength, ductility, and good out-of-position capabilities, making them suitable for subsequent fill and cap passes where mechanical properties are paramount. Using E7018 for the root pass would not provide the necessary penetration.