Alloy C-276 nickel alloy Corrosion Resistance
Alloy C-276 nickel alloy plate is one of the premier corrosion resistant materials that performs exceptionally well in both oxidizing and reducing environments. It resists chloride stress corrosion cracking, pitting, crevice and general corrosion. The alloy is also resistant to carbide precipitation during welding enabling it to be utilized in the as-welded condition.
In chemical processing applications, the alloy has exceptional resistance to sulfuric, hydrochloric, formic, acetic and phosphoric acids. Alloy C-276 nickel alloy plate performs well in environments containing acid chlorides, solvents and acetic anhydride, The alloy is one of the few grades that withstands wet chlorine gas, hypochlorite and chlorine dioxide solutions.
Alloy C-276 nickel alloy plate is highly resistant to concentrated solutions of oxidizing salts including iron and copper chloride. It also performs well in seawater, especially under crevice conditions where other frequently used alloys such as stainless steel, Alloy 400 and Alloy 625 fail.
The operating conditions of flue gas desulfurization systems offer a challenging environment for corrosion resistant materials. Scrubber liquors and gas condensates often contain chlorides. Alloy C-276 nickel alloy plate nickel alloy plate has been shown to withstand higher chloride levels than other grades before the onset of localized corrosion in these systems.
Alloy C-276 nickel alloy plate is used extensively in the recovery and processing of sour natural gas which contains hydrogen sulfide along with carbon dioxide and chlorides. Carbon and alloy steels cannot withstand this corrosive environment. They are subject to failure by sulfide stress cracking or stress corrosion cracking. The rich chemistry of Alloy C-276 nickel alloy plate makes it resistant to sour environments even at high temperatures in deep wells.
Corrosion Tests* in Hydrogen Fluoride Gas.
Test Duration, 36 Hours. Temperature 932-1112°F (500-600°C)
| MATERIAL | Corrosion Rate, mpy (mm/a) | Comments |
|---|---|---|
| Alloy C-276 | 0.3 (0.01) | Iridescent tarnish film |
| Alloy 600 | 0.7 (0.02) | Iridescent tarnish film |
| Nickel 200 | 9 (0.23) | Black film |
| Nickel 201 | 14 (0.36) | Black film |
| Alloy 400 | 13 (0.33) | Adherent dark film |
| Alloy K-500 | 16 (0.41) | Adherent dark film |
| 70/30 Copper-Nickel | 16 (0.41) | Adherent dark film |
* 7 lb HF per hour at 4 psig was passed through a laboratory furnace for hydroflourination of metal oxides
Corrosion-resistance of nickel alloys in four 24-hour tests in boiling acetic acid
| Alloy | Ni | Cr | Mo | W | Nb | N | PREN |
|---|---|---|---|---|---|---|---|
| 316 Stainless Steel | 12 | 17 | 2.2 | — | — | — | 20.4 |
| 317 Stainless Steel | 13 | 18 | 3.8 | — | — | — | 23.7 |
| Alloy 825 | 42 | 21.5 | 3 | — | — | — | 26.0 |
| Alloy G-3 | 44 | 22 | 7 | — | — | — | 32.5 |
| Alloy 25-6MO | 25 | 20 | 6.5 | — | — | 0.20 | 35.8 |
| Alloy 625 | 62 | 22 | 9 | — | 3.5 | — | 40.8 |
| Alloy C-276 | 58 | 16 | 16 | 3.5 | — | — | 45.2 |
| Alloy 622 | 60 | 20.5 | 14 | 3.5 | — | — | 46.8 |
| Alloy 686 | 58 | 20.5 | 16.3 | 3.5 | — | — | 50.8 |
* (Pren) = %CR + 1.5 (%Mo + %W + %Nb) + 30 (%N)
Maximum Pitting or Crevice Attack, mils (MM), in FGD Scrubber Slurrya
| Alloy | Quencher | Absorber | Absorber Outlet |
Outlet Duct |
Bypass Duct |
|---|---|---|---|---|---|
| 316L Stainless Steel | 22 (0.56) | 21 (0.53) | 35 (0.89)b | 35 (0.89)b | 12 (0.30) |
| 317LM Stainless Steel | 20 (0.51) | 22 (0.56) | 29 (0.74) | 33 (0.84) | 29 (0.74) |
| Alloy 825 | 15 (0.38) | 33 (0.84) | 39 (0.99) | 50 (1.27)b | 10 (0.25) |
| Alloy 625 | <2 (<0.05) | 10 (0.25) | 11 (0.28) | 7 (0.18) | nil |
| Alloy C-276 | nil | nil | <2 (<0.05) | nil | nil |
a 6-month exposure at 126°F (62°C), pH 5.5, 5000 ppm chlorides
b Perforated.
