Finite-element creep damage analyses of P91 pipes

Review of weld repair procedures for low alloy steels designed to minimise the risk of future cracking

Weld repair practices without post weld heat treatment for ferritic alloys and their consequences on residual stresses: A review

Prediction of creep failure life of internally pressurised thick walled CrMoV pipes

Aging of power plants and competitive pressures to operate and maintain (O&M) these plants at reduced costs have heightened industry interest in life assessment and management technologies. Piping and tubing systems carrying high-pressure steam at temperatures exceeding 1000°F (530°C) have notably been the center of focus of many of these activities. Enormous progress has been made in understanding mechanisms of damage and their rate of evolution. Progressive application of improved calculational, nondestructive and destructive techniques have enabled optimum utilization of components at reduced costs. In addition, the efficacy of weld repair techniques to extend the lives of aged components has been investigated in detail. This paper will review the damage mechanisms encountered in fossil power plant boiler pressure parts and then describe in more detail life management tools that have been developed.

Life management of high-temperature piping and tubing in fossil power plants

This article documents the results of an industry survey of weld repair practices and describes the results of experimental evaluations performed on service-aged 21/4 Cr-1Mo steel piping using SMAW with both conventional postweld heat treatments and temper bead repair techniques. The overall results of this program provide substantial evidence that service-aged piping systems can be successfully weld repaired with and without postweld heat treatments and that life extension by several decades is achievable under the right design and repair conditions. Weld repairs performed on degraded exservice welds resulted in restoration or improvement of tensile and creep properties. Microhardness test results within the heat-affected zone of each weldment indicated that the temper bead weld repairs produced only slightly higher peak hardness values than those measured for the fully postweld heat treated repairs. Finally, in terms of toughness, temper bead weld repairs consistently produced higher impact properties than those measured for the postweld heat treated weldments. Gas tungsten arc weld repairs with postweld heat treatment resulted in the best combination of tensile strength, uniform microhardness distribution across the weld, Charpy toughness, and creep rupture life.

D. W. Gandy

Papers

Performance of repair welds on aged Cr-Mo piping girth welds