Lack of Fusion and Incomplete Penetration: Identify the Region Left Unjoined

Name the unjoined interface

TWI describes lack of sidewall fusion and inter-run fusion as incomplete joining at the relevant adjacent interface. Root penetration concerns a different joint-depth question. Primary reference: TWI technical explanation.

A report should locate the region rather than use incomplete weld as its entire description. A joint can require information about both depth and interface continuity; neither field substitutes for the other.

Compare invented section labels

Consider hypothetical section A with a fused root but an unjoined sidewall segment. Section B shows joined upper sidewalls while the required root region remains unpenetrated. These deliberately separated illustrations concern two different locations.

Calling A fully joined because its root is fused would omit the sidewall. Calling B fully penetrated because its upper interfaces are joined would omit the depth requirement. The examples report no actual specimen, defect extent or permissible fabrication condition.

Preserve location in the evidence request

Sketch the joint root, sidewalls and any inter-run boundaries. Attach each observation to that sketch and identify the method used to establish it. Retain which region the actual requirement concerns.

Ask the fabricator to reconcile a broad full-fusion statement with the specific locations supported by its evidence. This review does not choose process settings or a repair method. It makes an incomplete description precise enough for the relevant joint assessment and prevents a favorable result in one region from concealing an unresolved region elsewhere.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Primary reference: TWI technical explanation