Nickel is highly resistant to various reducing chemicals and is unexcelled in resistance to caustic alkalies.
Nickel 200 (UNS N02200/W.Nr. 2.4060 & 2.4066) is commercially pure (99.6%) wrought nickel.
Nickel 200 is normally limited to service at temperatures below 600°F (315°C). At higher temperatures Nickel 200 products can suffer from graphitization which can result in severely compromised properties. For service above 600°F (315°C), Nickel 201 is preferred.
Nickel, (UNS N02200), from a corrosion standpoint, is the best material for caustic piping up to 600°F. Nickel is used extensively to convey higher temperature and product grade caustic where low metals pickup (particularly iron), is a requirement.
The main factor contributing to the outstanding performance of Nickel 200 in highly concentrated caustic soda is a black protective nickel oxide film that forms during exposure. The nickel oxide film results in a marked decrease in corrosion rates over long exposure under most conditions.
Following is a typical specification for class 150 Nickel piping 140 psig @ 270° F
Pipes
- 1" & below------Nickel, Schedule 40, stress relieved or annealed, per ASTM B161.
- 1½" thru 6" -----Nickel, Schedule 10S, stress relieved or annealed, per ASTM B161.
- 8" thru 12" ------Nickel, Schedule 10S stress relieved or annealed per ASTM B161 (seamless) or ASTM B-725 (welded, 100% X-ray of joint to be specified).
Fittings
- Butt weld fittings to ASTM B366 Grade WPN (UNS N02200). Wall thickness same as pipe.
Flanges
- Lap joint flange ASTM A105 with stub end. Stub end material to ASTM B366 Grade WPN (UNS N02200).