Electrode Classification, Storage, and Selection

What the AWS Electrode Classification System Tells You

Every SMAW electrode sold in the United States carries an alphanumeric designation stamped on its bare end. AWS A5.1, Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding, defines exactly what each character means. Learning to read that string turns a stick of coated wire into a precise engineering specification.

The most common format is E-XX1X-X, for example E6010 or E7018. Break it down position by position:

• E — electrode; confirms this is a consumable arc welding electrode.
• First two (or three) digits — minimum tensile strength of the deposited weld metal in thousands of pounds per square inch (ksi). E60XX deposits weld metal with a minimum of 60 ksi tensile strength; E70XX deposits at least 70 ksi.
• Third digit (second-to-last) — welding position. 1 = all positions (flat, horizontal, vertical, overhead); 2 = flat and horizontal fillet only; 4 = flat, horizontal, vertical-down, and overhead.
• Last two digits together — power supply and flux/coating type. This two-digit code is the most information-dense part of the system.

The Five Electrodes You Will Use Most

E6010 — Deep-penetrating cellulosic coating; runs DC electrode positive (DCEP) only. Excellent for pipe root passes and dirty or rusty plate because the forceful arc burns through mill scale and contaminants. All-position. Minimum tensile strength 60 ksi.

E6011 — Similar cellulosic chemistry to E6010 but formulated to run on AC as well as DC. A good field choice when only an AC transformer welder is available. All-position. Minimum tensile strength 60 ksi.

E6013 — Rutile (titania) flux; soft, stable arc; easy slag removal; produces a smooth bead profile. Runs on AC or DC. Best suited for clean, light-gauge steel in the flat and horizontal positions (though rated all-position). Not recommended for high-restraint or high-strength joints. Minimum tensile strength 60 ksi.

E7018 — Low-hydrogen iron-powder coating; the workhorse of structural steel fabrication and the primary electrode tested under AWS D1.1. Runs AC or DCEP. All-position. Deposits very low levels of diffusible hydrogen, which is critical for avoiding hydrogen-induced cracking in medium- and high-carbon steels and on thicker sections. Minimum tensile strength 70 ksi. This electrode requires strict storage and reconditioning procedures — see below.

E7024 — Heavy iron-powder, rutile coating; extremely high deposition rate; flat and horizontal fillet welds only (position code 2). Best for high-volume shop production on clean plate. Not suitable for vertical or overhead work. Minimum tensile strength 70 ksi.

Typical Amperage Ranges

Amperage depends on electrode diameter, not classification alone. As a general guide for common diameters:

| Electrode | 3/32 in | 1/8 in | 5/32 in |

|-----------|---------|--------|--------|

| E6010 | 40–80 A | 75–125 A | 110–170 A |

| E6011 | 40–85 A | 80–130 A | 105–165 A |

| E6013 | 45–90 A | 80–130 A | 105–160 A |

| E7018 | 65–100 A | 100–150 A | 130–190 A |

| E7024 | — | 100–150 A | 140–200 A |

Always confirm amperage against the manufacturer's data sheet, which supersedes generic tables.

Storage and Reconditioning of Low-Hydrogen Electrodes

Moisture is the enemy of low-hydrogen electrodes (any EXX15, EXX16, or EXX18). Moisture absorbed by the coating breaks down in the arc and releases hydrogen into the molten weld pool. Dissolved hydrogen can diffuse to areas of high stress and cause hydrogen-induced cracking (HIC), also called cold cracking or delayed cracking. This failure mode can appear hours or days after welding and is invisible to the naked eye — it is detected only by nondestructive examination.

Storage rules for E7018 and other low-hydrogen electrodes:

• Sealed manufacturer's containers may be stored at room temperature until opened.
• Once opened, electrodes must be stored in a rod oven held at the temperature specified by the manufacturer (commonly 250 °F to 300 °F / 121 °C to 149 °C — confirm on the packaging).
• Electrodes left out of the oven for extended periods must be reconditioned (rebaked) at higher temperatures specified by the manufacturer before use, or scrapped.
• Always log the oven temperature in the shop rod-oven log. This is a quality-control record that may be reviewed during AWS D1.1 or ASME Section IX audits.

Cellulosic electrodes such as E6010 and E6011 must not be stored in a rod oven; heat damages their coating chemistry.

Electrode Selection Logic

When choosing an electrode, ask four questions in order:

1. What is the base metal? Match or overmatch tensile strength; select low-hydrogen for hardenable or thick steel.

2. What position? Eliminate electrodes not rated for that position.

3. What power source is available? AC-only machines rule out DCEP-only electrodes like E6010.

4. What are the joint conditions? Dirty, rusty, or gapped joints favor cellulosic electrodes. Clean shop plate favors iron-powder types for productivity.

Safety Points

• PPE: Always wear a welding helmet with the correct lens shade for SMAW (shade 10–13 is typical; consult ANSI Z87.1 and the lens manufacturer for your amperage). Leather gloves, flame-resistant jacket, and leather boots are required.
• Ventilation: SMAW flux coatings generate fumes. Work with adequate ventilation or local exhaust. Fumes from coated electrodes can include manganese and other hazardous compounds — consult the electrode's Safety Data Sheet (SDS).
• Rod oven: The oven surface and elements reach temperatures that cause serious burns. Use heat-resistant gloves when loading or unloading electrodes. Never store flammable materials near the oven.
• Electrical safety: Electrode holders carry welding current. Never change electrodes with the machine energized if your gloves are wet or damaged.