ASTM A266 GR.2 Heat Exchanger Tube Sheet
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What is ASTM A266 Gr.2 heat exchanger tubesheet?
ASTM A266 Gr.2 heat exchanger tubesheet is a pressure vessel component made from carbon steel forgings that provides a rigid connection for piping within heat exchangers and other pressure equipment. Grade 2 material offers excellent strength and toughness, making it suitable for high-pressure and high-temperature applications.
The tubesheet is so called because the tubes are carefully arranged in a specific pattern and penetrate the tubesheet at multiple locations, allowing fluids within the tubes to flow into and out of the heat exchanger. These tubesheets can also be made into "clad" sheets, where a layer of a different material (such as stainless steel) is bonded to the carbon steel for enhanced corrosion resistance. These tubesheets are most commonly used in heat exchangers in refineries and large chemical plants.
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 |
*The tabulated values are applicable to heat analysis. Further, nickel ≤ 0.25%, Cr ≤ 0.20%, and Mo ≤ 0.08%. Carbon equivalent CE = C + Mn /6 + ( Cr + Mo + V ) / 5 + ( Ni + Cu ) / 15. The carbon equivalent shall not exceed 0.45 for Grade 1 or 0.50 for Grade 2 or 4.
Heat Treatment
After forging and before reheating for heat treatment, the forgings in accordance with ASTM A266 shall be cooled in such a manner as to prevent injury and to accomplish transformation. All the ASTM A266 forgings shall be heat treated by one of the four processes: annealing, normalizing, normalizing and tempering, or liquid quenching and tempering. When tempering is performed, it shall be at a subcritical temperature, but no less than 1100°F [595°C].
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 |
*T.S: tensile strength; Y.S: yield strength; El.: elongation; RoA: reduction of area.
| ASTM A266 Grade |
Brinell Hardness HBW |
|---|---|
| 1 | 121~170 |
| 2 | 137~197 |
| 3 | 156~207 |
| 4 | 137~197 |
Testing and Inspection
A plurality of testing and inspection shall be performed on forgings conforming to ASTM A266. It includes heat analysis, tensile test, hardness test, hydrostatic test, magnetic particle examination, liquid penetration examination, macro-etch test, as well as Charpy impact tests.
