CategoryFlame Cutting
Flame cutting for steel: thickness range, tolerance class and what a quote needs
Flame cutting — also called oxyfuel or oxy-fuel cutting — cuts steel by burning it with a jet of pure oxygen after preheating with a fuel-gas flame. It is a mechanically simple, low-cost process best suited to thick carbon-steel plate, and this page covers what actually decides the outcome: the thickness and materials it works on, the tolerance class it falls into, how much material the kerf consumes, and what a provider needs from you before quoting.
Kerf and material loss
2–6 mm per cut
Indicative
Source: Messer Cutting Systems — published comparison of kerf width across thermal cutting processes; flame cutting's kerf is wider than laser's or plasma's because the flame itself is wider
What drives the price
- Material thickness
- Steel grade
- Cut complexity — straight line or contour
- Total volume
- Tolerance requirement
- Finishing — deburring or secondary machining
What to send for a quote
- Grade or material number
- Plate thickness and dimensions
- A contour or DXF/drawing file
- Required tolerance
- Whether you need an inspection certificate
- Delivery address and required date
Traceability and EN 10204 certificates
Standard for steel purchases: 3.1
The certificate belongs to the plate, not to the cut. Flame cutting does not create an EN 10204 certificate — the real question is whether traceability survives the thermal cut, and how the pieces are marked so that it does.
Standard-defined
Source: EN 10204 defines inspection-document types.
Thickness range for flame cutting
| EN ISO 9013 applicability range | 3 – 300 mm | Standard-defined | |
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| Where flame cutting is the economical choice | 20 mm · 100 mm | Indicative | |
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| Example of current equipment capability | 200 mm | Supplier-published | |
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Indicative figures. Confirm thickness, tolerance and material suitability with the provider for your job.
Which steels can be flame cut
- Low-carbon steel
- Mild steel
- Wrought iron
Indicative
Cut quality and tolerance class
EN ISO 9013
Standard-defined
Services
What plate thickness can flame cutting handle?
EN ISO 9013 covers oxyfuel flame cuts from 3 to 300 mm. In practice the process is chosen where it stays economical — commonly plate over about 20 mm, and it's often the preferred method above 100 mm, where plasma and laser lose their speed advantage on thick material. As one concrete data point, Dünnewald's CNC flame-cutting machines cut contours up to 200 mm thickness — check the specific provider's machine limits for your job.
Which steels can be flame cut?
Flame cutting works by oxidising the metal, so it is limited to plain low-carbon and mild steel, and wrought iron. It cannot cut stainless steel, cast iron, aluminium or copper alloys — their chemistry or melting point defeats the oxidation reaction the process depends on — and high-carbon steel is also unsuitable because the slag it produces interferes with the cut. If your material isn't plain carbon steel, ask the provider which process they'd use instead.
What tolerance can I expect from flame cutting?
EN ISO 9013 classifies oxyfuel flame cutting as quality/tolerance Class 2 — the same class as plasma cutting, and coarser than laser's Class 1. The standard sets the exact tolerance by thickness and cut length in a table we don't reproduce here; treat any figure a provider quotes as indicative, and confirm it in writing for your thickness and geometry before committing to a dimension-critical part.
What information do you need for a quote?
Send the grade or material number, the plate thickness and dimensions, a contour or DXF/drawing file if the shape isn't a straight cut, the tolerance you need, whether you require an inspection certificate, and the delivery address and date. Those six things turn an enquiry into a firm price rather than a range.
How much material is lost to the kerf?
Allow roughly 2 to 6 mm per cut for the kerf — flame cutting removes more material than sawing or laser cutting because the flame itself is wider than a saw blade or laser beam. Over a long contour or several parts nested from one plate, that adds up, so include it when you calculate how much plate a job consumes.
Do I get an EN 10204 3.1 certificate?
EN 10204 defines inspection document types 2.1, 2.2, 3.1 and 3.2, and 3.1 is the usual buyer default in steel procurement. But flame cutting does not create a certificate — the certificate belongs to the plate. What matters is whether traceability survives the thermal cut, and how each cut piece is marked so it stays linked to its heat. Ask the provider that directly.
Flame cutting vs plasma or laser — which should I choose?
Flame cutting earns its place on thick plate — roughly 20 mm and up, and especially above 100 mm — where its lower equipment cost and lack of a thickness ceiling on carbon steel outweigh being slower. Plasma and laser cut faster and hold a tighter tolerance class under EN ISO 9013 (Class 1 for laser versus Class 2 for oxyfuel and plasma), but plasma suits thinner material and laser thinner still. For thin, precision or non-ferrous work, ask the provider about plasma or laser instead.
Does flame cutting affect the material near the cut edge?
Flame cutting leaves a heat-affected zone at the cut edge because the process works by melting and burning the steel, not shearing it. The sources we reviewed describe that zone only as larger than plasma's or laser's — none publish a sourced width in millimetres, so we won't invent one. If HAZ hardness or grain structure matters for your application, ask the provider for their measured figures or plan for a post-cut machining allowance.
Can I send my own plate to be flame cut?
Cutting customer-supplied plate is common practice, but whether a given shop accepts it, and on what terms for liability and remnants, varies by provider. Ask before shipping, and if the material carries an inspection certificate, ask in the same message how they mark the cut pieces so traceability survives.
Is there a minimum order quantity?
There is no industry-wide minimum order quantity for flame cutting; it varies by provider. Some will cut a single part from your plate, others price small jobs in a way that makes them impractical. Ask as part of your enquiry rather than assuming.
What is the lead time?
No general lead time can be stated honestly — it varies by provider, plate thickness, contour complexity and their current workload. Ask for a committed date with your quote rather than assuming a standard turnaround.
What does flame cutting cost?
Flame cutting is not priced from a single rate, so any figure quoted here would mislead. What drives it is plate thickness, steel grade, cut complexity — a straight line costs less than a contour — total volume, the tolerance you require, and any finishing such as deburring or secondary machining to bring the edge into a tighter tolerance. Send the six items in the quote checklist and you will get a firm price instead of a range.
