An oxy-fuel cutting torch oxidizes iron at a kindling temperature of roughly 870 to 900 degrees Celsius, then blows molten iron oxide out of the kerf with a separate high-purity oxygen jet; the process is defined by the iron-oxygen reaction, not flame temperature [S2].
That oxidation is what governs every concrete cutting decision: the torch only burns steel, so the concrete matrix has to be removed mechanically first, and a 1/2 inch mild steel plate uses a Victor-style tip #1 at 35 to 40 PSIG cutting oxygen, 3 to 5 PSIG acetylene, and 8 to 12 IPM travel speed [S1].
Why Oxy-Fuel Alone Will Not Cut Concrete
Concrete is a composite of cement paste and aggregate (silica, limestone, granite) with a melting and decomposition range far above the 1,500-plus degree Celsius steel melting point the torch can sustain; an oxy-acetylene flame at roughly 5,700 degrees Fahrenheit preheats steel fastest but does not melt or vaporize the aggregate in any reasonable time [S3].
Industrial guidance is consistent: a 2026 demolition reference recommends exposing reinforcement with concrete pulverizers, relieving cross-sections with splitters, and only then separating steel thermally or mechanically, which keeps heat input targeted and reduces collateral damage on the surrounding matrix [S8]. Exothermic cutting rods and diamond tools are the common workarounds; the torch is used to sever the rebar after the concrete has been opened up.
Fuel Gas Comparison: Acetylene, Propylene, Propane, Natural Gas
Acetylene delivers the fastest preheat and pierce, an oxygen-to-fuel ratio near 1.2 to 1, and a line pressure capped at 15 PSIG for safety [S1][S3]. Propylene sits in the middle on cost and lasts roughly five times longer per cylinder than acetylene; propane needs about 4 to 4.5 volumes of oxygen per volume of fuel, which means higher cutting-oxygen pressures for the same plate thickness [S2].
For concrete-cutting operations where the torch is mostly severing rebar after mechanical breakout, propylene and propane are usually the right call: the cut steel is mild rebar, not exotic alloys, and the slower pierce is acceptable. The classic acetylene 1/2 inch mild-steel tip #1 at 35 to 40 PSIG cutting oxygen, 3 to 5 PSIG acetylene, and 8 to 12 IPM translates to a 4-GPP propane tip at 50 to 55 PSIG cutting oxygen, 7 to 9 PSIG propane, and 7 to 10 IPM because the cooler flame needs more oxygen mass to sustain oxidation [S1].
Tip and Nozzle Selection by Plate Thickness
Nozzle size is matched to plate thickness because the central orifice diameter sets the cutting-oxygen flow; using a 3/8 inch tip on 1 inch plate just produces a wandering, slag-heavy drag line [S2]. The Victor-style numbering runs 000, 00, 0, 1, 2, 3, 4, 5 for thicknesses from 1/8 inch to 2 inch, while Harris, ESAB, and Purox use different tip codes for the same job [S1].
A reference table for acetylene shows a 1 inch plate using tip #3 at 45 to 55 PSIG cutting oxygen, 7 to 10 PSIG acetylene, and 5 to 7 IPM, while 1-1/2 inch plate uses tip #4 at 50 to 60 PSIG cutting oxygen, 8 to 12 PSIG acetylene, and 3 to 5 IPM [S1]. For propane, the equivalent 1 inch plate uses 6-GPP at 60 to 65 PSIG cutting oxygen, 9 to 11 PSIG propane, and 4 to 6 IPM, and the same source warns against reusing acetylene tip numbers on propane because the oxygen ratios are incompatible.
Concrete-Specific Use Cases and Edge Cases
An oxy-acetylene torch can cut through concrete in the literal sense, but the concrete may exfoliate and fly apart as the heat flashes trapped moisture, so close operator proximity is a safety problem independent of the cut quality [S7].
Three realistic concrete workflows exist. First, post-demolition rebar severing after a hydraulic pulverizer has cracked the slab; a handheld oxy-acetylene torch with tip #1 or #2 is the workhorse. Second, controlled deconstruction of reinforced structures where flame must be avoided entirely, in which case tank cutters or hydraulic cutting tools without an open flame take over [S8]. Third, deep cutting in sensitive or ignition-restricted environments, where a Broco Prime-Cut exothermic rod is the safer pick; these rods burn through concrete and rebar by an exothermic reaction that does not depend on a back-mounted oxygen cylinder [S7].
Cutting Equipment Materials and Construction
Torches, nozzles, and cutting attachments are typically machined from brass, aluminum, or high-grade steel; brass is the dominant choice for the torch body because it machines cleanly, conducts heat away from the seat, and resists the corrosive acetylene/solvent mix [S9]. A typical 100-type jet suction cutting torch is built from copper for the same reason, and uses injector (suction) mixing so the torch can draw fuel from cylinder drawdown without a positive-pressure fuel pump [S4].
Regulator selection matters as much as the torch itself. Acetylene needs a dedicated regulator; a generic propane-only regulator is unsafe on acetylene because the seat materials and pressure scales differ, and acetylene line pressure must never exceed 15 PSIG to avoid decomposition risk [S1]. Flashback arrestors are required at the torch and at the regulator end of each hose per ISO 5175 guidance, and the broader thermal-cutting safety framework is covered by ISO 17916 for cutting machines and ISO 9013 for thermal cut quality classification [S2].
Selection Criteria: When Oxy-Fuel Is the Right Tool on Concrete
Pick an oxy-fuel torch on concrete work when the rebar to be cut is exposed or pre-broken out, the cut length is long enough to justify a portable setup, no ignition-restricted environment applies, and crew skill is high enough to run a multi-flame tip without popping orifices. Walk away to a different tool when the matrix is intact and the cut must run through it, when ignition sources are prohibited, or when stainless rebar is present because a chrome-oxide skin blocks the iron-oxygen reaction and forces plasma or mechanical methods instead [S1][S8].
A useful pre-purchase gate: confirm oxygen purity at 99.5 percent or higher, match the tip chart to the fuel gas (not acetylene charts on propane), install dual flashback arrestors, and stock two tip sizes per torch so a worn tip does not halt production. For demolition-driven rebar cuts on bridge decks and foundation slabs, the handheld oxy-fuel torch is still the cheapest, fastest, and most portable option once the concrete is out of the way, and the spec map on a related plasma cutter selection for demolition covers the cases where plasma is the smarter tool instead.
Track these signals over the next quarter: ISO 9013 and ISO 17916 revisions in the thermal-cutting committee, manufacturer tip-chart refreshes for propylene-class fuels, and any field report on exothermic-rod alternatives for confined-space deconstruction.
Spec-level background on the components involved: oxy fuel cutter, aerial work platform, and aerial work truck.