Welding Tests

WELDING TESTSObjectivesThe student understand the types of testing done on weldsThe student will show Knowledge of the tests carried outThe student will be able to name one test of each type.

Introduction Welding tests are done to correctly identify if the weld has reached the correct specification and level of effectiveness.This can be check by three specific types of testing.Visual Inspection Non-Destructive testingDestructive testing

Visual InspectionVisual inspections can be done by the eye alone or can be enhanced by using magnifiers and microscopes.

Equipment available for inspection are mirrors (to check inside of pipes) and gauges to assess the weld profile and uniformity.

What is need for visual inspection is a clean comfortable environment with adequate lighting, The test piece should be free of all protective coatings, spatter and arc marks.

Visual inspection is a test in itself but it also overlaps into the non-destructive testing, as once it is done a visual analysis is needed to determine if the weld has passed the test.

Non-Destructive TestingNon-destructive testing is a method of testing that does not destroy or impair the usefulness of a welded item. These tests disclose all of the common internal and surface defects that can occur when improper welding procedures are used. A large choice of testing devices is available and most of them are easier to use than the destructive methods, especially when working on large and expensive items

Dye-Penetration Testing

Destructive testsIn destructive testing, sample portions of the welded structures are required. These samples are subjected to loads until they actually fail. The failed pieces are then studied and compared to known standards to determine the quality of the weld. The most common types of destructive testing are known as free bend, guided bend, nick -break, impact, fillet welded joint, etching, and tensile testing. The primary disadvantage of destructive testing is that an actual section of a weld must be destroyed to evaluate the weld. This type of testing is usually used in the certification process of the welder

Types of Destructive TestingFree bend test. This test is used on butt welds. It is designed to measure the ductility of the weld deposit and the heat-affected area adjacent to the weld.

Guided bend testYou use the a guided bend test to determine the quality of the weld metal at the face and root of a welded joint. This test is mainly used on butt weld joints. A jig is usually made to bend the test piece to the correct angle.

Nic break test The nick break test is a useful test for determining the internal quality if the weld metal, this test will reveal various defects with in the weld, such as slag inclusions, gas pockets, lack of fusion. To accomplish this you need to break the weld through its face to the root.

Macro Etch testing