The Babcock & Wilcox Company

7-22 Steam 41 / Metallurgy, Materials and Mechanical Properties

to enhance creep strength. A new family of Ni and Ni-Cr-Co alloys is also available, specifically for advancedsupercritical and advanced supercritical boiler designs.

Fuel ash corrosion considerations might dictate theuse of higher alloys at lower temperatures. This iscommon in process recovery and refuse-fired boilerswith very corrosive flue gas and ash. For example, SB-407-825 (42Ni-21.5Cr-3Mo-2.25Cu-0.9Ti-bal Fe) isused in the highly corrosive regions of refuse boilersuperheaters, even at temperatures below 1000F(538C). In extreme cases, bimetallic tubes, with a core

of a Code material for pressure retention and a clad-ding of a corrosion resistant alloy, are used for bothfurnace wall and superheater applications. Some com-mon combinations are SA-210A1/304L, SA-210A1/Alloy 825, and SB-407-800H/50Cr-50Ni.

Selection factors

Many factors influence material selection in a su-perheater. These include cost as well as performancefactors (heat transfer surface area required, finalsteam temperature, total mass flow through the tubes,

Table 1Boiler Materials and Typical Applications (English Units)

Min Min High Heat Other Furn SH Unheated Headers Recomm

Nominal Product Tensile, Yield, Input Furn Walls and RH Conn Pipe and Pipe Max Use

Specification Composition Form ksi ksi Walls Enclosures Econ <10.75 in. OD >10.75 in. OD Drums Temp, F Notes

SA-178A C-Steel ERW tube (47.0) (26.0) X X X 950 1,2SA-192 C-Steel Seamless tube (47.0) (26.0) X X X X 950 1SA-178C C-Steel ERW tube 60.0 37.0 X X 950 2SA-210A1 C-Steel Seamless tube 60.0 37.0 X X X X 950SA-106B C-Steel Seamless pipe 60.0 35.0 X X 950 3SA-178D C-Steel ERW tube 70.0 40.0 X X X 950 2SA-210C C-Steel Seamless tube 70.0 40.0 X X X 950SA-106C C-Steel Seamless pipe 70.0 40.0 X X 950 3SA-216WCB C-Steel Casting 70.0 36.0 X X X X 950SA-105 C-Steel Forging 70.0 36.0 X X X X 950 3SA-181-70 C-Steel Forging 70.0 36.0 X X X X 950 3SA-266Cl2 C-Steel Forging 70.0 36.0 X 800SA-516-70 C-Steel Plate 70.0 38.0 X X 800SA-266Cl3 C-Steel Forging 75.0 37.5 X 800SA-299 C-Steel Plate 75.0 40.0 X 800SA-250T1a C-Mo ERW tube 60.0 32.0 X X 975 4,5SA-209T1a C-Mo Seamless tube 60.0 32.0 X X X 975 4SA-250T2 1/2Cr-1/2Mo ERW tube 60.0 30.0 X X X 1025 6SA-213T2 1/2Cr-1/2Mo Seamless tube 60.0 30.0 X X X 1025 6SA-250T12 1Cr-1/2Mo ERW tube 60.0 32.0 X X 1050 5SA-213T12 1Cr-1/2Mo Seamless tube 60.0 32.0 X X X 1050SA-335P12 1/2Cr-1/2Mo Seamless pipe 60.0 32.0 X 1050SA-250T11 1-1/4Cr-1/2Mo-Si ERW tube 60.0 30.0 X X 1050 5SA-213T11 1-1/4Cr-1/2Mo-Si Seamless tube 60.0 30.0 X X X 1050SA-335P11 1-1/4Cr-1/2Mo-Si Seamless pipe 60.0 30.0 X X 1050SA-217WC6 1-1/4Cr-1/2Mo Casting 70.0 40.0 X X X X 1100SA-250T22 2-1/4Cr-1Mo ERW tube 60.0 30.0 X 1115 5SA-213T22 2-1/4Cr-1Mo Seamless tube 60.0 30.0 X 1115SA-213T23 2-1/4Cr-W-V Seamless tube 74.0 58.0 X X 1115SA-335P22 2-1/4Cr-1Mo Seamless pipe 60.0 30.0 X X 1100SA-217WC9 2-1/4Cr-1Mo Casting 70.0 40.0 X X X 1115SA-182F22Cl1 2-1/4Cr-1Mo Forging 60.0 30.0 X X 1115SA-336F22Cl1 2-1/4Cr-1Mo Forging 60.0 30.0 X 1100SA-213T91 9Cr-1Mo-V Seamless tube 85.0 60.0 X 1150SA-335P91 9Cr-1Mo-V Seamless pipe 85.0 60.0 X X 1150SA-217C12A 9Cr-1Mo-V Casting 85.0 60.0 X X 1200SA-182F91 9Cr-1Mo-V Forging 85.0 60.0 X 1150SA-336F91 9Cr-1Mo-V Forging 85.0 60.0 X 1150SA-213T92 9Cr-2W Seamless tube 90.0 64.0 X X 1200SA-213TP304H 18Cr-8Ni Seamless tube 75.0 30.0 X 1400SA-213TP347H 18Cr-10Ni-Cb Seamless tube 75.0 30.0 X 1400SA-213TP310H 25Cr-20Ni Seamless tube 75.0 30.0 X 1500SB-407-800H Ni-Cr-Fe Seamless tube 65.0 25.0 X 1500SB-423-825 Ni-Fe-Cr-Mo-Cu Seamless tube 85.0 35.0 X 1000

Notes:1. Values in parentheses are not required minimums, but are expected minimums.2. Requires special inspection if used at 100% efficiency above 850F.3. Limited to 800F maximum for piping 10.75 in. OD and larger and outside the boiler setting.4. Limited to 875F maximum for applications outside the boiler setting.5. Requires special inspection if used at 100% efficiency.6. Maximum OD temperature is 1025F. Maximum mean metal temperature for Code calculations is l000F.