Copyright Goodheart-Willcox Co., Inc. Chapter 18 Weld Inspection and Repair 275 Weld Integrity Inspections Many weldments require destructive tests in addition to nondestructive examination to verify the weld quality. These tests may be imposed as part of the qualifi cation test program, or an additional test may be conducted during or after the manufacturing cycle. The test requirements are usually a part of the fabrication specifi cation. Pressure Test Pressure tests subject a vessel, tank, piping, or tubing to internal pressure. Pressure tests can use either air or a liquid. If a liquid is used, the test is called a hydrostatic test. The test program may require a number of cycles to be performed, simulating the use of the part in actual service. During the test, the part will expand. This expansion should not be restricted with tools, or undue stresses will build within the part. When conducting a pressure test, be alert to the possible failure of the unit. Before beginning the test, make sure the test procedure ensures the safety of everyone in the testing area. Hardness Test Hardness tests involve pressing a test probe into the surface of the weld. The amount of pressure required to deform the surface of the weld metal is an indication of the hardness of the weld or weldment. If the weldment has been heat-treated (annealed, hard- ened, tempered, etc.) after fabrication, the hardness test will determine the effect of the heat treatment. A hardness tester is shown in Figure 18-19. Hardness test results can also be used to determine the ultimate tensile strength of the material. The test results can be compared with standard tables. (Refer to the hardness conversion table included in Chart R-9 in the reference section of this book.) Weldment designs that include areas such as fl anges and extensions can be tested by portable hardness testers as shown in Figure 18-20. Weldment designs that do not have clear areas for testing must have test bars of the same material (welds if required) submitted with the weldment during the heat-treating cycle. The bars are then tested on a stationary tensile machine, as shown in Figure 18-14, for the hardness results. Round tensile test bars are shown in front of the tester in Figure 18-21. A fl at tensile test bar is being tested in Figure 18-22. Corrosion Test Corrosion tests measure the ability of a weld to resist corrosion by a specifi c material. These tests are usually performed on test weldments. The test Figure 18-19. Rockwell hardness testing machine for bench testing. (Mark Prosser) Figure 18-20. Portable Rockwell hardness tester for flange testing. (Qualitest International LC, www.WorldOfTest.com, info@qualitest-inc.com)