Fig. 10.90 Alloy 72 overlay superheater tubes in a sootblower lane after 6 years of service. Original weld bead ripples are still clearly visible. Source: Ref 87 More

Fig. 11.3 Melting of the deposits formed on the superheater tubes as a function of the value of (Na + S)/V ratio (in atomic percent) in the fuel oils used in firing a boiler (375 MW) producing superheated steam of 570 °C (1060 °F). Source: Ref 8 More

Fig. 11.19 Corrosion of Type 321 superheater tubes with and without Mg(OH) 2 injection in an oil-fired boiler. Source: Ref 8 More

Fig. 12.5 Alloy 625 overlay superheater tubes (on 15Mo3 steel substrate) after 4.5 years of service in a superheater producing 405 °C (760 °F)/42 bar (609 psi) superheated steam, showing no evidence of corrosion or erosion/corrosion. Source: Ref 24 More

Fig. 12.30 Carbon steel superheater tubes protected by metallic tube shields awaiting installation at one WTE plant. More

Fig. 13.23 Type 310 overlay superheater tubes (a) and in close-up (b) after 2 years of operation in the boiler at a mill in South America. Source: Ref 31 More

Fig. 12.29 Alloys 72 overlay superheater tube (a) and alloy C276 overlay superheater tube (b) after 7200 operating hours (10 months) in a RDF unit. The windward side of the tube, where the flue gas impinged upon the tube surface was the top side of the tube cross section as shown in the figure More

Fig. 6 Thick-lip “fishmouth” failure of a 2-in.-diam superheater tube. The tube bent away from the fracture due to the reaction force of the escaping steam. The material was ASME SA-213 T22 (0.15 maximum C, 1.90–2.60 Cr, 0.87–1.13 Mo). Hardness was 96–98 HRB. Scale about 0.012 in. thick More

Fig. 6.131 Superheater tube cut by steam leaking from an adjacent tube More

Fig. 5.2 Grain size measurement on final superheater tube sample More

Fig. 5.5 Cross section of superheater tube sample that has undergone decarburization Location Decarb depth, μm 1 384.7 2 397.5 3 394.9 4 359.3 5 361.8 Avg 379.6 More

Fig. 5.6 Variation in scale thickness on flue gas side of a superheater tube Location Scale thickness, μm 1 583.5 2 575.8 3 524.9 4 675.2 5 537.6 Avg 579.4 More

Fig. 5.14 EDS spectrum for outer surface of a superheater tube sample More

Fig. 6.23 Failed superheater tube (a) showing 180° bending and (b) opposite end view showing a burst opening with disordered contours More

Fig. 6.36 Close-up views of a superheater tube at the failure location More

Fig. 6.137 Portion of a failed superheater tube showing failure location More

Fig. 18 Type 321 stainless-steel (ASME SA-213, grade TP321H) superheater tube that failed by thick-lip stress rupture. (a) Overall view of rupture. (b) Macrograph of an unetched section from location at arrows showing extensive transverse cracking adjacent to the main fracture (at right More

Fig. 10.72 Cross section of a superheater tube made of Type 304SS suffering coal-ash corrosion attack. Note the wastage flats on both sides of the tube surface where the flue gas impinged at the 90° location (i.e., facing the ruler in the photo). Courtesy of Welding Services Inc. More

Fig. 12.16 Alloy 622 overlay superheater tube after 225 days of exposure in a boiler. (a) Cross section of the overlay showing slight pitting attack. Micrograph (a) also shows the fusion boundary and substrate carbon steel. (b) Higher-magnification micrograph showing surface corrosion More

Fig. 12.17 Alloy 625 overlay superheater tube after 152 days of exposure in the superheater platen next to the alloy 622 superheater tube, which is shown in Fig. 12.16 . (a) Cross section of the overlay showing slight pitting attack. Micrograph (a) also shows the fusion boundary and substrate More