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HAYNES® Alloys

Thermocouple Protection Tubes and Thermowells

When it comes to finding a thermocouple protection tube material to withstand aggressive environments or high stress at elevated temperatures, turn to HAYNES® alloys for the long-term performance that means a cost-effective solution. A full range of alloys is available to solve those problems which force stainless steels, nickel-chromium alloys, and iron-nickel-chromium alloys into an “early retirement”. Whether the application is in a chemical waste incinerator, a forging furnace, a brick kiln or a gas turbine - there’s a HAYNES alloy suited to the application. Look to 214®, 230®, or 556® alloys for all your T/C tube needs.

Stress Rupture 1800°F/2.0 ksi

(980°C / 14 MPa)

Stress Rupture Life (Hours)

1800°F (980°C) Sulfidation Resistance

Average Metal Affected, µm*

Average Metal Affected, Mils*

215 hour exposures in H2S-bearing reducing environment test gas at 1800°F (980°C).
*Wastage + internal attack.

Resistance to Combustion Gas Environment 2000°F (1095°C) for 500 Hours

Alloy Metal Loss Maximum Metal Affected**
- mils µm mils µm
214® 0.5 13 1.8 46
230® 2.2 56 5.7 145
RA330 10.9 277 13.6 345
600 17.2 437 20.7 526
Type 310 21.2 538 24.1 612
601 10.7 272 >24.0 >610

Nominal Composition wt. %

Alloy Ni Fe Co Cr Mo W Si Mn Al C Other
230® Balance 3 max. 5 max. 22 2 14 0.4 0.5 0.3 0.10 0.015B, 0.01La
214® Balance 3 2 max. 16 - - 0.2 max. 0.5 max. 4.5 0.04 0.01Y, 0.1 max.Zr
556® 20 Balance 18 22 3 2.5 0.4 1 0.2 0.10 0.2N, 0.6Ta, 0.02La, 0.017Zr

Product Description

HAYNES 230 alloy combines excellent high-temperature strength, outstanding resistance to oxidizing environments up to 2100°F (1150°C) for prolonged exposures, premier resistance to nitriding environments, and excellent long-term thermal stability. It is readily fabricated and formed. Other attractive features include lower thermal expansion characteristics than most high-temperature alloys, and a pronounced resistance to grain coarsening with prolonged exposure to high-temperatures.

HAYNES 556 alloy combines effective resistance to sulfidizing, carburizing and chlorine-bearing environments at high temperatures with good oxidation resistance, fabricability, and excellent high-temperature strength. It has also been found to resist corrosion by molten chloride salts, moltenzinc, and other aggressive environments.

HAYNES 214 alloy is the most oxidation-resistant, carburization-resistant, and chlorination-resistant alloy available as a fabricable material. Its effective use temperature limit is in excess of 2200°F (1204°C) for prolonged exposure, and up to 2400°F (1316°C) for shorter exposures.

Typical Tensile Properties (Plate)

Test Temperature Ultimate Tensile Strength 0.2% Yield Strength Elongation
ksi ksi %
°F °C 230® 556® 214® 230® 556® 214® 230® 556® 214®
70 21 124.9 118.1 145.0 56.9 59.5 82.0 48 48 37
1200 649 97.2 85.4 120.0 39.0 32.8 85.0 55 52 31
1400 760 84.9 68.5 102.0 41.2 32.0 79.0 46 49 15
1600 871 58.3 47.6 60.0 32.4 28.6 47.0 59 53 15
1800 982 32.5 28.0 15.0 17.3 15.5 8.0 71 63 72
2000 1093 17.3 14.8 8.3 8.2 8.0 3.9 50 55 99
2100 1149 11.4 - 4.5 5.6 - 2.0 40 - 99
2200 1204 8.0 - 4.4 3.7 - 1.4 31 - 99
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