CEN standard · reference card
EN 1011-2: does it govern your preheat and cracking risk
EN 1011-2 recommends how to avoid hydrogen (cold) cracking in ferritic steel arc welding. Scope decision flow, the codes it sits next to, and the records that show preheat was actually reached.
- Designation
- EN 1011-2
- Issued by
- CEN
- Title
- Welding — Recommendations for welding of metallic materials — Part 2: Arc welding of ferritic steels
- Edition
- Confirm the edition your WPS was derived from.
EN 1011-2 is a recommendations document, not an acceptance standard. It gives a method for estimating the preheat a ferritic steel joint needs to avoid hydrogen-induced cracking, built from carbon equivalent, section thickness, diffusible hydrogen and heat input together — not any one of them alone.
The common misuse is treating it as optional once a WPS exists. The WPS should already reflect the standard’s logic, but a preheat recommendation that is never verified at the joint is a number on paper, not a control. The second misuse is applying ferritic-steel guidance to a stainless steel, which cracks by a different mechanism and sits in EN 1011-3 instead. Nickel alloys are outside the EN 1011 series entirely; the construction code and material specification govern preheat and cracking control for them.
Cold cracking can develop hours after welding finishes, which is exactly why a spot check at the start of a pass tells you less than it seems to. Therness thermal equipment measures preheat and interpass across the whole joint on every pass, and exports the record a welding coordinator can attach to the job file rather than a chalk-and-guess entry.
Scope: does it apply to your job?
Applies to
- Arc welding of ferritic steels where hydrogen-induced (cold) cracking is a risk
- Deriving a recommended preheat from composition, thickness, hydrogen scale and heat input
- Guidance used alongside a qualified WPS, not as a replacement for one
Does not apply to
- Stainless steel welding, covered by EN 1011-3 (the EN 1011 series has no nickel-alloy part)
- Aluminium alloy welding, covered by EN 1011-4
- Accepting the finished weld; that is a quality-level standard such as ISO 5817
Applicability decision flow
| Question | If yes | If no |
|---|---|---|
| Is the base material a ferritic steel being arc welded? | EN 1011-2 is the recommendation standard for preheat and cracking avoidance. | Stainless steels go to EN 1011-3; aluminium goes to EN 1011-4. Nickel alloys have no EN 1011 part of their own; follow the construction code and material specification instead. |
| Does the WPS or contract already specify a preheat and interpass regime? | Follow the specified regime; EN 1011-2 is a recommendation, not an override of a qualified procedure. | Use the standard's method to derive a recommended preheat from composition, thickness and hydrogen scale. |
| Is hydrogen control being achieved mainly through consumable choice and handling? | Preheat can carry less of the burden, but the combined approach still applies. | Preheat carries more of it; verify it is reached and held before arc-strike. |
| Will the joint see post-weld heat treatment, or does the construction code require impact testing? | Interpass control links to properties beyond cracking avoidance; read this alongside the construction code. | The cracking-avoidance recommendation stands on its own. |
What proves conformity, and what only supports it
Conformity is decided by inspection and testing against the criteria the standard and the contract set. The records below are evidence that the process was held where it was qualified; they support an inspection result, they never replace one.
| Requirement | Record produced | Source |
|---|---|---|
| Confirming preheat was reached across the joint, not just at one spot check | Full-field thermal image of the joint area immediately before welding starts | HeatCam IR-C |
| Holding interpass temperature within the recommended band on multi-pass welds | Non-contact interpass measurement recorded on every pass | HeatCam IR-C |
| A per-weld record linking measured preheat and interpass to the joint and operator | Timestamped thermal and process record exported per weld | HeatCore AI |
Evidence the process, not just the paperwork
Therness records what the machine actually delivered on every weld — parameters, thermal signature and a per-weld trail — so a conformity argument rests on measurements instead of recollection.
