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SOLUTIONS: Stainless Steel Austenitic stainless steel has the following characteristics: • Non-magnetic.

• Cannot be hardened by heat treatment, but can be hardened by working.

• Can easily be welded • Grade: 304 (most used), 310 (for high temperature), 316 (for better corrosion resistance), 317 (for best corrosion resistance).

Avoid welding mild steel to stainless steel.

2.06

• Unified Numbering system UNS: 30400, S 31000, S 31600, S 31700.

Some limitations:

Austenitic stainless steel has some limitations: • The maximum temperature under oxidizing conditions is 925°C. • They are suitable only for low concentrations of reducing acid.

Crossed weld joints are undesirable. In general welds must not be located too close to one another.

• In crevices and shielded areas, there might not be enough oxygen to maintain the passive oxide film and crevice corrosion might occur (Duplex are available in these situations).

• Very high levels of halide ions, especially the chloride ion can also break down the passive surface film.

Flange ring made by hammering back the pipe end (mechanical working) must be avoided.

Flange ring welded on gives less stress set up in the material.

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