L51578 Drop-Weight-Tear-Test Equipment Energy Calibration Program

The Drop-Weight-Tear-Test (DWTT) energy absorption has not previously been considered as a measure of fracture toughness from this test. The DWTT was originally planned to define the fracture appearance transition temperature of line pipe. The test has been very successfully used for this purpose for the past 20 years. During this period of DWTT usage, the need for a toughness measurement to control ductile fracture propagation has seen the application of a Charpy shelf-energy in addition to a DWTT or Charpy shear area requirement in the specification of line-pipe properties. The purpose of exploring energy measurements in the DWTT is to determine if both fracture appearance and toughness can be obtained from a single test. To this end, a number of individual steel companies and gas-transmission companies have been examining the use of a DWTT energy measurement.

The objective of this program is to obtain reference steels that are uniform and of varying energy levels so that reference specimens can be supplied to a laboratory to assess the accuracy and precision of their DWTT energy measuring equipment. The major result is that three plates have now been calibrated and are available for energy verification measurements on DWTT testing equipment. The procedure that has been established for the calibration of machines is based on accuracy and precision tolerances of 5 percent.