SSM/ABI Technology Background and Accomplishments
The accuracy, reliability, and easy field applicability of the SSM system to test pipeline materials with unknown properties have been demonstrated on samples and pipe sections from several pipeline companies and on many pipelines and their welds worldwide. In 1996 the portable/in-situ SSM version received an R&D 100 Award and in 2008 the SSM system received the Pipeline Advanced Technology Award at the International Pipeline Exhibit.
The ABI® test is based on progressive indentation with intermediate partial unloadings until the desired maximum depth (maximum strain) is reached, and then the indenter is fully unloaded. The indentation load-depth data are collected continuously during the test using a 16-bit data acquisition system. The nonlinear spherical geometry of the tungsten carbide indenter allows increasing strain as the indentation penetration depth is increased. Hence, the incremental values of load (at the end of each progressive loading cycle) and plastic depth (associated with each partial unloading cycle and the upper part of the final full unloading data) are converted to incremental values of true-stress and true-plastic-strain values according to established elasticity and plasticity theories.