Impact Testing Exemption Curves for Low Temperature Operation of Pressure Piping

Extension of ASME exemption curves has been accomplished by consistent application of old and new ASME fracture mechanics concepts originally intended for pressure vessels. It is recognized that materials produced by modern means may be deserving of greater credit for toughness and reassignment to different traditional curves or even new curves may be in order. Where there is impact toughness data the mean temperature in the transition region may be estimated and new exemption curves developed. Procedures described were used to adjust exemption curves for thickness where pipe wall is less than the normal Charpy specimen width.