Power Generation Fastener Alloy Selection Guide

Power generation fasteners operate at extreme temperatures where creep strength rather than tensile strength becomes the controlling design parameter above 540°C. Inconel 718 (1379 MPa tensile, service to 700°C) is the primary alloy for gas turbine combustor bolting and nuclear reactor internals. Inconel 625 extends service to 980°C for exhaust systems and superheater applications. Duplex 2205 and Titanium Grade 2 serve lower-temperature condenser and seawater cooling circuits.

Overview

Power generation environments — gas turbines, nuclear reactors, and steam systems — demand fasteners that maintain structural integrity under sustained high temperatures, cyclic thermal stress, and often corrosive atmospheres. Above 540°C for steel and 650°C for nickel alloys, creep strength becomes the controlling design parameter, not room-temperature tensile or yield strength.

Gas Turbine Fastener Applications

Gas turbine fasteners operate at the highest temperatures in power generation, with combustor sections reaching 700°C and exhaust sections exceeding 980°C. Alloy selection is driven by creep resistance, thermal fatigue life, and oxidation resistance.

Nuclear Power Fastener Applications

Nuclear applications require alloys with dimensional stability under neutron irradiation, resistance to primary water chemistry corrosion, and long-term creep resistance. Inconel 718 dominates due to its combination of high strength, irradiation tolerance, and corrosion resistance in reactor water environments.

Steam System Fastener Applications

Steam system fasteners span a wide temperature range from ambient (condenser circuits) to 760°C (superheater sections). Alloy selection depends on temperature, steam chemistry, and whether the circuit involves seawater cooling.

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