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New American Petroleum Institute specifications for line-pipe steels has prompted an evaluation of testing machines available to perform the Battelle drop-weight tear test (DWTT). This evaluation indicated a need for a machine of new design that would be safe, accurate, require little maintenance, and be acceptable as an industry-wide standard. The machine preferred was the pendulum-type machine rather than a vertical drop-weight type because of low maintenance, operator comfort, and accuracy of fracture-energy determination. Therefore, a pendulum-type machine was designed and built by the U.S. Steel Applied Research Laboratory. This new machine has a 6300-ft∙lb capacity and is capable of testing both the Battelle 12-in.-long DWTT specimen for line-pipe steels and the Naval Research Laboratory 18-in.-long dynamic-tear-test specimen for ship-plate steels. The pendulum head and anvil are designed to prevent interference between the broken sections of the test specimen and the pendulum after impact. The frame structure is designed to prevent vibration within the structure. The machine is operated by compressed air-mechanical devices, and the control circuit is designed to provide fail-safe operation by one man. Performance testing, strain analysis, and high-speed photography indicate that this machine fulfills the desired design goals. In the interest of standardization, the design is being proposed for industry-wide use.
design, pendulum, dynamic tests, drop-weight tests, tear tests, machine, line pipe, ship plates, steels, fracture toughness, fracture energy, evaluation, tests
Section supervisor, Applied Research Laboratory, U.S. Steel Corp., Monroeville, Pa.