Alloy 20 Tubing
Alloy 20 Tubing
Alloy 20 is an austenitic, nickel-iron-chromium-molybdenum alloy with the addition of copper. This combination makes it preferable in applications involving sulfuric, phosphoric, and nitric acids. The chromium and molybdenum content provide good pitting and crevice corrosion resistance. This grade exhibits exceptional resistance to stress corrosion cracking (SCC) induced by chlorides. Alloy 20 can be utilized in a wide variety of chemical process environments and has good performance in most acids, alkalines, salts, and seawater.
Product Specifications
ASTM B729, B464, B468 / ASME SB729, SB464, SB468 / NACE MR0175
Size Range
Outside Diameter (OD) | Wall Thickness |
.250"–.500" | .035″–.065″ |
Cold finished and bright annealed tube.
Chemical Requirements
Alloy 20 (UNS N08020)
Composition %
C | Mn | P | S | Si | Ni Nickel | Cr Chromium | Mo | Cu | Nb + Ta Niobium + Tantalum | Fe Iron |
0.07 max | 2.00 max | 0.045 max | 0.035 max | 1.0 max | 32.00–38.00 | 19.00–21.00 | 2.0–3.0 | 3.0–4.0 | (8.0xC) - 1.0 max | 35.0 max |
Chemical Requirements
Alloy 20 (UNS N08020)
Composition %
C | Mn | P | S | Si | Ni | Cr | Mo | Cu | Nb + Ta | Fe |
0.07 max | 2.00 max | 0.045 max | 0.035 max | 1.0 max | 32.00–38.00 | 19.00–21.00 | 2.0–3.0 | 3.0–4.0 | (8.0xC) - 1.0 max | 35.0 max |
Dimensional Tolerances
OD | OD Tolerance | Wall Tolerance |
.250” | ± .005” | ± 15% |
.375” | ± .005” | ± 15% |
.500” | ± .005” | ± 15% |
Mechanical Properties
Yield Strength: | 35 ksi min |
Tensile Strength: | 80 ksi min |
Elongation (min 2"): | 30% |
Fabrication
The chemical composition of alloy 20 allows excellent formability for bending and flaring, and the addition of Niobium provides minimal carbide precipitation during welding.
Industry Applications
Chemical Process
Alloy 20 has a higher nickel content which, combined with chromium, molybdenum and copper, makes it the austenitic stainless steel of choice for chemical processes involving higher concentrations of sulfuric acids.
Fabrication
The chemical composition of alloy 20 allows excellent formability for bending and flaring. End-use applications in the fabrication industry include storage tanks, mixing tanks, agitators, pump and valve parts, food processing equipment, fasteners, and fittings.
Food & Beverage
In the food and beverage industry, alloy 20 offers unparalleled resistance to corrosion in the handling of food preservatives including phosphorus oxychloride and phosphorus trichloride.
Oil & Gas
Alloy 20 offers great performance in refining processes that include sulfuric, phosphoric and nitric acids, which are seen in the oil and gas industry.
Power Generation
Alloy 20 can be found in many areas of power plants such as in heat exchangers, steam condensers, flue gas desulphurization systems where its pitting and chloride ion corrosion resistance offer a longer equipment life.
Pulp & Paper
Alloy 20 tubing offers good performance in sulphuric acid services in the pulp and paper industry where temperatures are too high for alloy 316/L.