In a 4G weld completed with SMAW, which F number is used for the root pass?

In a 4G weld completed with SMAW, which F number is used for the root pass?

• A. F3 root (6010)
• B. F4 root (7018)
• C. F2 root (6010)
• D. F5 root (7028)

Answer: (A)

In a root pass for a pipe weld with SMAW, you want an electrode that can quickly establish a solid, penetrating root through the groove. The 6010 electrode is known for deep penetration and reliable root formation, especially in restricted or dirty joints. In the F-number system, this combination is designated as F3 for root passes. That’s why the root pass for a 4G SMAW weld is best done with F3 root (6010). The other options use electrodes that are great for filler and cap passes due to their ductility and low hydrogen, but they don’t penetrate the root as effectively as 6010. Also, the pairing of 6010 with F2 is not the standard root-pass designation.

In a root pass for a pipe weld with SMAW, you want an electrode that can quickly establish a solid, penetrating root through the groove. The 6010 electrode is known for deep penetration and reliable root formation, especially in restricted or dirty joints. In the F-number system, this combination is designated as F3 for root passes. That’s why the root pass for a 4G SMAW weld is best done with F3 root (6010).

The other options use electrodes that are great for filler and cap passes due to their ductility and low hydrogen, but they don’t penetrate the root as effectively as 6010. Also, the pairing of 6010 with F2 is not the standard root-pass designation.