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Re: seals orientation and stainless steel garter springs

Craig Briggs
 

Hi Arnold,
I could not find the specification for the exact type of Stainless Spring Steel used for the garter springs so I asked the SKF engineering department. (SKF is perhaps the major supplier of rotary shaft seals worldwide.)

Here is their reply:
"We use a 302 ss spring in our products and it will have slight magnetic qualities."

So if your SS garter spring sticks to a magnet, it may be perfectly fine. Rely on the supplier's spec or on Amel to have the right replacement.
Cheers, Craig


On Sat, Oct 26, 2019 at 02:02 PM, Arnold Mente wrote:
Hi Craig,
 
 have received the seals loosely in the envelope.
1.4301 / V2A / 304 is not seawater resistant. Only 1.4571 / V4A / 316 with 2% molybdenum (is pure austenitic) is seawater resistant and non-magnetic! For example, this is why surveyors use a magnet to test the stainless steel components of a yacht.
Otherwise my education would have been wrong.
I would like to see it differently, but with an austenitic steel one finds no magnetism through the transformation of the structure from ferritic to austenitic. In cheap stainless steel parts for yachts produced in the Far East, it often happens that these are made of 304. I have no intention of questioning the delivery of Amel. But why is the spring magnetic? Shaft seals with 316 springs are also difficult to obtain, as my research has shown so far. With 304 on the oil side, I have no problems but the seawater side worries me.
 
Best, Arnold
 
Am 26.10.2019 um 19:18 schrieb Craig Briggs SN 68 Sangaris via Groups.Io <sangaris@...>:

[Edited Message Follows]

Hi Arnold,
I assume when you say the springs of the Amel supplied lip seals were magnetic you (or your mechanic) concluded they were not Stainless Steel and therefore you replaced them with O-rings. Actually, Stainless Steel is slightly magnetic and the very thin and lightweight Stainless Steel springs in lip seals will "stick" to a magnet - therefore the "test" your mechanic performed was not definitive.

You must rely on the manufacturers specification - there is a Code letter that specifies Stainless Steel Garter Springs. Carbon Steel is usually the default, so you must specifically order stainless steel garter spring. I am sure Amel supplied the correct lip seal and that it did, indeed, have a stainless steel spring. If I recall correctly, Amel ships the lip seals in the manufacturer's box - if so you could check the part number on the box, if you still have it, and see that it indeed is a Stainless Steel Garter Spring.

Cheers, Craig

Arnold Mente

Urbaniweg 12
7000 Eisenstadt 

Tel: +43 660 6699019

arnold.mente@...



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SY Zephyr SM203
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