Trial Weld

As in all welding, good root penetration and avoidance of defects are important. In some cases, a trial weld will be required on site. This should be done at the working depth and in the most difficult position required, usually overhead. The specimen weld should be brought to the surface and inspected before the actual welding commences. A visual inspection should be conducted for bead profile and lack of defects. The weld may also be Dye Penetrant Tested (PT) or Magnetic Particle Tested (MT). If neither of these testing methods are available, break the specimen with a sledgehammer to determine how easily it breaks. The weld interior should then be inspected for slag entrapment and/or lack of fusion into the root.

Methods of weld testing and analysis are used to assure the quality and correctness of the weld after it is completed. This term generally refers to testing and analysis focused on the quality and strength of the weld, but may refer to technological actions to check for the presence, position and extent of welds. These are divided into destructive and non-destructive methods. A few examples of destructive testing include macro etch testing, fillet-weld break tests, transverse tension tests, and guided bend tests. Other destructive methods include acid etch testing, back bend testing, tensile strength break testing, nick break testing, and free bend testing. Non-destructive methods include fluorescent penetrate tests, magnaflux tests, eddy current (electromagnetic) tests, hydrostatic testing, tests using magnetic particles, X-rays and gamma ray based methods and acoustic emission techniques.Other methods include ferrite and hardness testing.

References:
Weld quality assurance