Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

How are socket fusion welds inspected?

   

Frequently asked questions

Visual inspection is the most widely used technique for checking the quality of socket fusion welds, although radiographic inspection can be used to detect internal voids.

The following inspection routine should be carried out once the weld is complete:

  • Check that the beads between pipe and fitting are uniform on both sides of the joint. The beads should have no wrinkles or discontinuities
  • Examine the weld beads for signs of contamination or degradation
  • Check for misalignment between the pipe and fitting
  • Examine the heated tool for signs of degraded material

If any of the above imperfections occur, the joint should be cut from the pipeline and remade. If a similar defect recurs, all further production welding should stop until the equipment has been thoroughly cleaned and examined.

The limitations of visual inspection must be appreciated: a poorly formed bead may reliably indicate an unsatisfactory weld, but a correctly formed bead is not always a sure indication that the weld is satisfactory and free from internal defects.

See further information about plastics welding and testing.