Alloy 800HT
UNS N08811Alloy 800HT material
Key Engineering Metrics
Instant specifications summary for Alloy 800HT
General Specifications & Standard Data
Alloy 800HTMinimum Design Metal Temperature rules for impact testing exemption under ASME B31.3 paragraph 323.2.2.
Mechanical Properties
Room Temp (20°C / 68°F)Allowable Stress Data (ASME B31.3 Table A-1)
asme-b31-3Allowable Stress vs Temperature
ASME B31.3 / BPVC Section II Part D Reference Curve
| Temperature (°C) | Allowable Stress (MPa) | % of Room Temp Rating |
|---|---|---|
| 38 | 137.9 | 100% |
| 100 | 137.9 | 100% |
| 150 | 137.9 | 100% |
| 200 | 131.0 | 95% |
| 250 | 122.0 | 88% |
| 300 | 115.0 | 83% |
| 350 | 112.0 | 81% |
| 400 | 108.0 | 78% |
| 450 | 105.0 | 76% |
| 500 | 102.0 | 74% |
Chemical Composition (% Weight)
Heat & Product Analysis🛡️ Service Compatibility
Exceptional resistance to hydrofluoric, hydrochloric, and hot sulfuric acids.
Maintains mechanical strength and oxidation resistance up to 1000°C (Inconel 600/625, Alloy 800H).
Immune to SSC, HIC, and pitting in extreme sour oilfield environments.
Zero pitting or crevice corrosion under stagnant or high-velocity seawater.
🔥 Welding & Heat Treatment
None required. Strict cleanliness required (remove all sulfur, oil, grease, paint to avoid hot cracking). Interpass temp < 150°C.
PWHT not required. Thermal stress relief at 870°C recommended only for Monel 400 in hydrofluoric acid service.
Exempt down to sub-zero temperatures per ASME B31.3.
Material property data provided is for preliminary engineering reference. Always verify properties against the latest ASME BPVC Section II, ASTM material specification, and Material Test Report (MTR/MTC).