Shipbuilding and marine fabrication
Weld monitoring for shipbuilding
High-volume welding under classification-society rules. The codes that apply, the four monitoring pain points that cost yards most, and which Therness signal addresses each.
ISO standard · reference card
ISO 5817: scope, quality levels and where it applies
Does ISO 5817 govern your joint? Scope decision flow for the steel, nickel and titanium quality-level standard, the codes it is read with, and the records that evidence conformity.
- Designation
- ISO 5817
- Issued by
- ISO
- Title
- Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) — Quality levels for imperfections
- Edition
- Confirm the edition your contract cites.
ISO 5817 is a grading standard, not an acceptance decision. It defines quality levels for imperfections in fusion-welded joints and states what each level permits. It does not tell you which level your job needs, how to find the imperfection, or whether the joint passes — those answers come from the application standard, the detection standard, and the inspector.
That distinction is where misuse starts. A specification saying “welds to ISO 5817” and stopping has named a rulebook without selecting a rule, and two suppliers reading it will work to different levels. A usable specification names the standard, the level, and the extent of testing.
The second recurring error is reaching for it with the wrong material or process in hand. Aluminium belongs to ISO 10042 and beam welds to ISO 13919; both carry a level structure similar in shape and different in substance.
Therness does not grade welds. The equipment produces the evidence layer underneath the grading: proof of what the machine delivered, a thermal record of each seam, and a per-weld trail an auditor can follow.
Scope: does it apply to your job?
Applies to
- Fusion-welded joints in steel, nickel, titanium and their alloys
- Arc and gas processes, any position, shop or site
- Imperfections already classified under ISO 6520-1
Does not apply to
- Laser and electron beam joints, graded by the ISO 13919 series
- Aluminium and its alloys, covered by ISO 10042
- Choosing the detection method, or choosing which level your job needs
Applicability decision flow
| Question | If yes | If no |
|---|---|---|
| Is the parent material steel, nickel, titanium or one of their alloys? | ISO 5817 is the quality-level standard for the joint. | Aluminium goes to ISO 10042; any other material follows the standard the application code names. |
| Was the joint made by a fusion process other than laser or electron beam? | Stay in ISO 5817. | Beam-welded joints are graded by the ISO 13919 series. |
| Does the contract or application standard already name a quality level? | Use the level it names. ISO 5817 offers levels; it never selects one. | The application standard selects it, usually through an execution class or equipment category. Settle that before planning inspection. |
| Do you know the ISO 6520-1 reference number of the imperfection? | Look it up by that designation and read the requirement for the selected level. | Classify it in ISO 6520-1 first. ISO 5817 is indexed by reference number, not by shop-floor names. |
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 |
|---|---|---|
| Proof the process stayed inside the qualified window on the graded welds | Per-weld voltage, current, wire feed and gas records against the weld identifier | WeldTrace |
| Targeting visual and NDT effort at the welds most likely to carry imperfections | Continuous thermal record of each seam with per-weld anomaly flags | HeatCam IR-C |
| A searchable record set for the welds in a lot when an auditor asks | Per-weld evidence exported with identifier, operator and timestamp | HeatCore AI |
Questions engineers ask about ISO 5817
Does ISO 5817 cover laser and electron beam welds?
No. Its title excludes beam welding and the ISO 13919 series carries those quality levels. For a hybrid process the application standard has to say which of the two governs before inspection is planned.
Can weld monitoring data replace ISO 5817 acceptance inspection?
No, and no supplier should claim otherwise. Monitoring evidences that qualified conditions were held and flags welds worth inspecting first. The acceptance decision still rests on the visual or NDT result.
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.
