The ASME SA336 F11 CL2 Stationary Tubesheet is a chromium-molybdenum (1.25Cr-0.5Mo) alloy steel forging manufactured in accordance with ASME SA336/SA336M — the Standard Specification for Alloy Steel Forgings for Pressure and High-Temperature Parts. This ferritic heat-resistant steel forging serves as the primary pressure-boundary component in fixed tubesheet shell-and-tube heat exchangers, separating shell-side and tube-side fluid circuits.
The Class 2 heat treatment (normalized and tempered, with a minimum tempering temperature of 620°C / 1150°F) delivers mechanical properties superior to Class 1, enabling thinner, more efficient pressure vessel wall profiles under high-pressure service exceeding 50 bar. The material is specifically engineered for maximum continuous service temperatures up to 595 °C (1100°F).
| Element | Requirement (%) |
|---|---|
| Carbon (C) | 0.05 - 0.17 |
| Manganese (Mn) | 0.40 - 0.80 |
| Phosphorus (P), max | 0.025 |
| Sulfur (S), max | 0.025 |
| Silicon (Si) | 0.50 - 0.80 |
| Chromium (Cr) | 1.00 - 1.50 |
| Molybdenum (Mo) | 0.44 - 0.65 |
| Property | Requirement |
|---|---|
| Tensile Strength (min) | 515 MPa |
| Yield Strength, 0.2% offset (min) | 310 MPa |
| Elongation in 50 mm (min) | 20% |
| Reduction of Area (min) | 45% |
| Brinell Hardness | 143 - 207 HB |
| Charpy V-Notch Impact @ -30°C (-22°F) | Avg. 20 J min; single 16 J min |
| Maximum Service Temperature | 595°C (1100°F) |
All ASME SA336 F11 CL2 stationary tubesheets undergo rigorous testing per ASME SA336/SA336M and ASME Section VIII requirements.
| Test Method | Requirement |
|---|---|
| Mechanical Testing | Tensile, yield, elongation, reduction of area per ASME SA336 |
| Impact Testing | Charpy V-Notch @ -30°C (3 specimens) |
| Ultrasonic Examination (UT) | 100% inspection |
| Magnetic Particle (MT) | As required per supplementary requirements |
| Hardness Test | Brinell HBW per specification |
| Dimensional Inspection | Per customer drawing and ASME B16.5 |
| Heat Treatment Verification | Normalized + tempered, min 620°C temper |
ASME SA336 F11 CL2 stationary tubesheets are specified for severe-service heat exchangers and pressure vessels across multiple industries:
Both specifications cover the same 1.25Cr-0.5Mo alloy chemistry. However, SA336/A336 is specifically intended for large forgings for pressure vessels and high-temperature parts, while A182 covers smaller pipe flanges and fittings. For tubesheet applications requiring heavy-section forgings, SA336 is the correct specification.
The maximum continuous service temperature is 595 °C (1100°F). For service above this temperature, creep strength becomes insufficient for long-term operation—engineers should consider upgrading to F22 (2.25Cr-1Mo) or F91 (9Cr-1Mo-V).
