Fireside corrosion can be a serious problem in oil-fired boilers and in refinery furnaces fired with low-grade fuels. This chapter provides an overview of fireside or oil-ash corrosion and the problems it can cause in utility power boilers and petrochemical refinery furnaces. It explains how oil-ash corrosion affects waterwalls, superheaters, and reheaters as well as metal tube supports and hangers.

This chapter focuses on creep-rupture failure, or more precisely, the time required for such a failure to occur at a given stress and temperature. It begins with a review of creep-rupture phenomena and the various ways creep-rupture data are presented and analyzed. It then examines a large collection of creep-rupture data corresponding to different alloy designations and heat treatments, identifying key relationships, similarities, and differences. It also presents a test method developed by the authors in which twelve materials are tested over a range of temperature, stress, and time in order to determine multiheat constants that are then used to fit multiheat data from other materials and thus estimate rupture times.

This chapter discusses two damage mechanisms in which stress plays a major role. In the one case, stress causes cracks in the oxide scale on metals, leading to preferential corrosion attack. An example from industry of this type of failure is the circumferential cracking that occurs on the waterwall tubes of supercritical coal-fired boilers fired under low NOx combustion conditions, conducive to the production of sulfidizing environments. In the other case, stress contributes to brittle fracture in the form of intergranular cracking. The phenomenon, which is known by various names, typically occurs at the lower end of the intermediate temperature range and has been observed in ferritic steels, stainless steels, Fe-Ni-Cr alloys, and nickel-base alloys, as described in the chapter.

Boilers are often classified based on the maximum operating temperature and pressure for which they are designed. Classifications, in ascending order, are subcritical, supercritical, ultra-supercritical, and to advanced ultra-supercritical. At each higher operating point comes greater efficiency, as well as greater demand on construction materials. This chapter discusses the primary requirements for boiler tube materials, including oxidation and corrosion resistance, fatigue strength, thermal conductivity, and the ability to resist creep and rupture. It also provides information on various steels and alloys, covering cost, engineering specifications, and ease of use.

Liquid metals are frequently used as a heat-transfer medium because of their high thermal conductivities and low vapor pressures. Containment materials used in such heat-transfer systems are subject to molten metal corrosion as well as other problems. This chapter reviews the corrosion behavior of alloys in molten aluminum, zinc, lead, lithium, sodium, magnesium, mercury, cadmium, tin, antimony, and bismuth. It also discusses the problem of liquid metal embrittlement, explaining how it is caused by low-melting-point metals during brazing, welding, and heat treating operations.

This chapter compares and contrasts the high-temperature behaviors of metals and composites. It describes the use of creep curves and stress-rupture testing along with the underlying mechanisms in creep deformation and elevated-temperature fracture. It also discusses creep-life prediction and related design methods and some of the factors involved in high-temperature fatigue, including creep-fatigue interaction and thermomechanical damage.

Containment materials used in power generating applications are subject to molten salt corrosion. This chapter reviews the data relevant to corrosion problems in molten salt environments. It describes the corrosion behavior of steel, aluminum, nickel, and titanium alloys in molten chlorides, molten nitrates, molten fluorides, molten carbonates, and molten sodium hydroxide.

This chapter presents the primary considerations and mechanisms for corrosion and how they are involved in the selection of materials for process equipment in petroleum refineries and petrochemical plants. In addition, specific information on mechanical properties, corrosion, sulfide stress cracking, hydrogen-induced cracking, stress-oriented hydrogen-induced cracking, hydrogen embrittlement cracking, stress-corrosion cracking, velocity-accelerated corrosion, erosion-corrosion, and corrosion control is provided.