ASME SA 266 Gr.2N Heat Exchanger Tubesheet With Chemical Requirements
ASME SA266 Gr.2N Tube Sheet
ASME SA266 Gr.2N carbon steel tube sheet is the preferred material for conventional heat exchangers and boiler equipment due to its economy, easy processing and medium temperature strength. When selecting, it is necessary to strictly evaluate the corrosiveness of the medium and the temperature and pressure conditions, and use protective coatings or upgraded materials when necessary. For high-risk conditions (such as sour oil and gas, seawater cooling), stainless steel or composite plates are recommended to ensure long-term reliability.
Advantages
High cost performance: low cost, suitable for non-corrosive media (such as water, steam, air).
Convenient processing: good machinability and weldability, matching welding material E7018 (AWS A5.1).
High temperature stability: short-term temperature resistance up to 450°C (stable oxide layer).
Limitations
General corrosion resistance:
Not suitable for Cl⁻, H₂S or acidic media (pH <6), need to be upgraded to stainless steel (SA182 F304) or composite plate.
Limited low temperature toughness:
SA350 LF2 (low temperature carbon steel) is required when the design temperature is below -29°C.
Chemical Composition Requirements
| Item | Chemical Req. for ASTM A266, % | ||
| Gr. 1 & 2 | Gr. 3 | Gr. 4 | |
| C | ≤ 0.30 | ≤ 0.35 | ≤ 0.30 |
| Mn | 0.40~1.05 | 0.80~1.35 | 0.80~1.35 |
| P | ≤ 0.025 | ≤ 0.025 | ≤ 0.025 |
| S | ≤ 0.025 | ≤ 0.025 | ≤ 0.025 |
| Si | 0.15~0.35 | 0.15~0.35 | 0.15~0.35 |
Mechanical Properties
| Tensile Requirements |
Gr. 1 | Gr. 2 & 4 | Gr. 3 |
| T.S min. ksi [Mpa] |
60~85 [415~585] |
70~95 [485~655] |
75~100 [515~690] |
| Y.S min. ksi [Mpa] |
30 [205] |
36 [250] |
37.5 [260] |
| EL. in 2" or [62.5 mm] min. % |
23 [21] |
20 [18] |
19 [17] |
| R.o.A min. % |
38 | 33 | 30 |
Application:
Heat exchangers and condensers:
Fixed tube sheet heat exchangers (TEMA types NEN, BEM), suitable for refineries and chemical plants.
Desalination multi-effect evaporator (MED) tube sheets.
Boilers and pressure vessels:
Fire tube boiler tube sheet, design pressure ≤5 MPa.
Auxiliary feed water heater (AFWH) of nuclear power plant.
Petrochemical equipment:
Hydrogenation reactor (Hydrotreater) inlet distributor tube sheet.
Sulfur recovery unit (SRU) condenser.
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