05 Equipment and consumables · 14 min
How to read an electrode
CSA W48 and AWS A5 names. Low-hydrogen is a storage problem as much as a chemistry problem.
Canadian structural work talks CSA W48. You will still see AWS A5 numbers on the same pallet. E4918 is the CSA cousin of E7018: E = electrode, 49 (or 70) is tensile in ksi-ish / 490 MPa class, 1 = all-position, 8 = low-hydrogen iron powder. E4313 ≈ E6013. E4310 ≈ E6010 (cellulosic, deep penetration, DC).
| Mark | Family | Inspection angle |
|---|---|---|
| E4310 / E6010 | Cellulosic | Deep, digging, root passes; hydrogen is not low; not a thick-hard steel default |
| E4313 / E6013 | Rutile | Easy, cosmetic, thin plate; limited on heavy structural |
| E4918 / E7018 | Low-hydrogen basic | The structural default. Hold in a rod oven. 4-hour exposure rules are a WPS/W48 thing — look them up |
| E49XT-9M / E71T-1C | FCAW gas-shielded | T = tubular, 1/9 usability, C or M gas |
| ER49S-6 / ER70S-6 | GMAW solid | ER = electrode rod, S = solid, 6 = deoxidizers for mill scale |
Low-hydrogen discipline
Moisture in a basic coating becomes hydrogen in the arc. Hydrogen plus a hard HAZ plus residual stress is cold cracking, often hours after the weld cools. Inspectors check: sealed cans, oven temperature, time out of the oven, no throwing 7018 on the bench overnight, no welding over wet plate. If the WPS says 150 °C preheat, a cold, rusty beam is a stop-work, not a suggestion.
Equipment numbers worth knowing
- Duty cycle: minutes out of ten the machine can weld at a stated current without overheating. 300 A at 60% duty cycle means 6 minutes weld, 4 minutes rest at that current.
- OCV: open-circuit voltage, what the holder sees before the arc. Safety and striking.
- CC vs CV: SMAW and GTAW like constant current. GMAW and FCAW like constant voltage with a wire feeder.
- Work (ground) lead as close as practical to the weld. Long, frayed leads drop voltage and add spatter. Magnetic arc blow on DC: the arc wander you see on corners and into residual fields.