316 Stainless Steel

Don't panic. It's normal for SS to mildly attract magnets. Some of the metallurgical wizards can tell you which ones are most likely to do this, I don't remember, exactly and don't have time to look it up.

First turn off your caps lock.

Stainless steel will attract magnets depending on the purity of the steel and strength of the magnet.

As for the longevity of the steel components you would need to check manufacturer specs.

The austenitic SSs (300 Series) are usually non responsive to magnets. Howver some times severe cold work may disturb the microstructure (breaking the austenites) and make them a bit magnetic. However the more stable austenited 316 (Higher Ni/Cr ratio) should not usually show this behaviour, more common in lower grades eg 304 etc.

If you want these to become non magnetic, heat treat them to above the curie point say 700-800 deg C (though must be careful to avoid the carbide precipitation) or solution anneal.

Ensure the materials are 316. The ferro-magnetic property (unless these are magnetised) may not introduce corrosion in them, not likely in water lines. But I will be a bit surprised, if the magnetic attraction is strong and the material is SS316

<...G.R.P WATERTANK PLEASE LET US KNOW TILL WHAT TIME IT WILL RESIST FOR CORROSION...>

Please turn off Caps Lock, as many forum readers consider it to be akin to SHOUTING, and rather rude. Politeness will encourage rather more rational and useful responses.

The resistance to corrosion of metals in water depends upon the mixtures of metals present in other parts of the system and the electrical connections between them. Sea-going vessels and outboard motors, for example, often use a piece of magnesium as a sacrificial anode so as to protect them against corrosion. It is not possible to predict the corrosion rate for 316ss on the basis of the information proivided so far.

• What is the pH of the water?
• What is the minimum thickness of the wetted part?
• What is the nature of any suspended solids that may intruduce aggressive scour?
• What other metals are present that might introduce galvanic corrosion?

For example.

ss can become magnetic after cold working or other treatments if they develop a martensitic phase. you can restore the properties of ss with a stress relieving.

Stainless Steel - Magnetic Properties

http://www.azom.com/Details.asp?ArticleID=1140

regarding the resistance of SS in water it depends on many factors like temperature, water chemistry (chloride conc) flow velocity... usually a safe limit for SS 316 is approx 500-1000 ppm of chlorides.

http://www.stainless-steel-world.net/pdf/11003.pdf

hope this help

S.

corrosion & rust prevention