Flux-cored arc welding

Using Hobart's FabCO Triple 7 operating row at 6.6 lb/h deposition, an assumed 1.32 lb deposit takes 12 minutes arc-on. With an assumed 35% arc-on fraction, the estimate is 34.29 minutes elapsed, including 22.29 minutes non-arc. Add separately planned setup and inspection as applicable. Estimate purchased wire separately from deposited metal. Hobart Triple 7 operating table

FCAW feeds a tubular electrode that supplies flux and can contribute alloying additions. Confirm whether the wire is self-shielded (FCAW-S) or gas-shielded (FCAW-G). Remove slag between passes and before inspection. Linde, Flux Cored Welding, undated

This reference covers process selection and control. It is not a welding procedure specification (WPS), qualification record, or authorization to weld a particular structure.

Choose the wire and shielding as a combination

Linde's September 18, 2023 wire guide explains these variants and relates C and M designations in its carbon-steel examples to CO₂ and mixed-gas classifications. Check the exact consumable classification and approved gas; do not replace the specified mixture with a convenient cylinder merely because the arc still runs. Linde, Understanding the Basics of Flux-Cored Welding Wire

Self-shielded wire is useful for field conditions because it is less dependent on protecting an external gas envelope. This is greater tolerance of wind, not immunity to all weather, contamination, or procedural limits. Gas-shielded FCAW requires effective gas coverage at the joint, including attention to drafts, leaks, nozzle condition, and access.

Lincoln's Innershield Welding Guide, publication C3.2400, issue 03/15, explicitly warns against adding shielding gas to its FCAW-S electrodes because doing so changes the intended metallurgical reactions. It also identifies DC-positive exceptions within a family where many products use DC-negative. The lesson is to follow the exact electrode, not the shortcut “all self-shielded wires use DCEN.” Lincoln Electric Innershield guide, special considerations

Bounded producer examples

Hobart's Fabshield 21B sheet identifies AWS A5.20 E71T-11, self-shielded operation, DCEN, and no required shielding gas. It lists re-drying as not recommended and dry storage in intact original packaging. Its printed revision is 260424, replacing 250811. The sheet's typical as-welded properties and listed approvals do not establish suitability for an arbitrary base metal, joint, service temperature, or code application. Hobart Fabshield 21B data sheet

Hobart's FabCO Triple 7 sheet, printed revision 250829, replacing 250828, specifies DCEP and CO₂ or 75–85% argon/balance CO₂. Its 0.045-inch/1.2 mm all-position row at 325 in/min wire feed lists approximately 200 A, 20–25 V, 3/4-inch CTWD, and 6.6 lb/h deposition. This is a producer operating row, not a WPS for any joint. Rows at higher feed rates can have different position restrictions. Hobart FabCO Triple 7 data sheet

Classifications describe specified consumable tests and characteristics. Product approvals can additionally depend on diameter, gas, condition, or application. Neither a classification strength number nor a typical test result is a welded-joint design allowable. Obtain the applicable edition, certificate, and procedure requirements rather than treating a catalog table as the order's complete acceptance specification.

Control setup and joint access

Specify wire diameter, polarity, power-source mode, feeder/gun compatibility, drive rolls, liner, contact tip, wire-feed speed, voltage, contact-tip-to-work distance (CTWD), travel speed, and position. CTWD includes the arc gap as well as electrode extension; it is not interchangeable with extension alone. Verify the terminology used by the producer's chart before setting distances.

Lincoln's Innershield guide calls for constant-voltage output for those products and emphasizes voltage, CTWD, and electrode-specific polarity. These controls affect arc behavior and weld properties; a chart for solid-wire GMAW is not a direct substitute. The guide also identifies single-pass-only FCAW-S electrodes, illustrating why pass limits must be checked rather than inferred from the process name. Lincoln Electric, Innershield Welding Guide

Define groove preparation, root access, fit-up, backing where applicable, tack disposition, and welding sequence. Select filler for the base metals, required strength/toughness, restraint, service conditions, and qualified procedure. Resolve preheat, interpass temperature, and any postweld treatment from that application; there is no universal FCAW preheat or heat-input recipe.

Slag, cleanliness, and defects

Remove slag and unacceptable surface contamination before subsequent passes. Hobart's self-shielded troubleshooting guide connects slag inclusions with bead placement, travel/work angle, insufficient access, and poor interpass cleaning. It also distinguishes porosity, worm tracking, incomplete fusion, and penetration problems. A visible symptom may have several causes; do not apply one voltage adjustment without checking the wire's range and the rest of the procedure. Hobart, Troubleshooting Common Self-Shielded FCAW Problems, undated

Greater tolerance of surface contamination is not permission to weld through oil, moisture, paint, or unidentified coatings. Nor does an H-designator eliminate hydrogen-cracking risk. Maintain the producer's storage and exposure controls and the application's material-temperature requirements. Do not invent a baking cycle for tubular wire: both named Hobart sheets explicitly state that re-drying is not recommended. Fabshield 21B, FabCO Triple 7

Worked example: deposition rate versus elapsed production

This original planning example uses the Triple 7 row's 6.6 lb/h deposited-metal rate only as an illustrative input. Assume an approved weld requires 1.32 lb of deposited metal and that arc-on time is 35% of elapsed production time:

• Arc-on time = 1.32 / 6.6 = 0.20 h = 12 minutes.
• Elapsed time at the assumed duty factor = 12 / 0.35 = 34.29 minutes.
• Non-arc time within that estimate = 22.29 minutes.

The 35% factor is invented for this example, not a product rating or equipment duty cycle. The estimate excludes any additional separately planned setup or inspection. Deposition rate is not wire purchase consumption: core ingredients, slag, spatter, losses, and remaining wire require a separate consumption basis. The producer row does not guarantee that the assumed weld mass or rate is suitable for the actual joint. Hobart Triple 7 operating table

Safety and finished-weld acceptance

Use the actual product SDS and welding-equipment instructions. The retrieved Fabshield 21B S2221 SDS, version 1.0, prints issue/revision date 1/7/2026 in its English-US document. It warns about welding fumes and gases, arc radiation, and electric shock, and explains that fume composition depends on electrode, base metal/coatings, process, and procedure. A wire's shipping hazard classification does not describe the hazards of welding with it. Hobart product-specific SDS

Release welds against the drawing, governing specification, and qualified procedure: required size/profile, fusion and penetration, permitted discontinuities, inspection extent, and test timing. Clean the weld sufficiently for inspection. A smooth bead after slag removal is not proof of internal soundness or toughness.

A useful handoff records base-metal identity, joint preparation, WPS and qualification basis, electrode product/lot/diameter, gas, actual setup and thermal controls, welder/operator qualification where required, and inspection results. Keep product guidance, procedure qualification, and finished-weld acceptance distinct.

Related reference

Welding methods