Stainless Bolts

[goboatingnow]

Originally Posted by boatpoker

"galvanized steel" .. which of the several hundred available grades are you referring to ?

100 micron + hot dip or spun. To ISO 1461

Dave

[Cheechako]

Originally Posted by Stumble

Just as a FYI.

Magnetic testing of stainless DOES NOT DETERMINE GRADE.

While the conventional wisdom is that 304 is magnetic, while 316 isn't, this is just wrong. All a magnet can tell you for sure is that the material is either non-cold worked of either grade, or if it was cold worked that it has been thru a stress relief process.

This may be enough of a test for many things, but it is not really all that definitive. The only way to know what you have is a molybendium testing kit which start at around $250.

yep, especially in shapes like flat bar etc , which normally have a final cold pass in manufacture. The littel bit of Moly in 316 has nothing to do with magetic. It's about grain oreintation and the amount of iron in the mix.

[Exile]

Originally Posted by MarkSF

For a reputable supplier, I've never had problems with McMaster Carr. The stuff they sell is what they say it is!

Do they say where their nuts, bolts, etc. are made?

[delmarrey]

Originally Posted by Exile

Do they say where their nuts, bolts, etc. are made?

Actually, Mc Master-Carr does not carry "Structural Bolts" in SS, only cap screws, which are fully threaded. So, it doesn't matter. They are only useable for thin materials as far as shear is concerned.

[Cheechako]

Originally Posted by delmarrey

Actually, Mc Master-Carr does not carry "Structural Bolts" in SS, only cap screws, which are fully threaded. So, it doesn't matter. They are only useable for thin materials as far as shear is concerned.

Actually they carry fully threaded and partially threaded: McMaster-Carr
Check the table under "316 SS"

[delmarrey]

Oops! Missed it some how. But I'll bet their made in India.

[Lagoon4us]

Originally Posted by Cheechako

yep, especially in shapes like flat bar etc , which normally have a final cold pass in manufacture. The littel bit of Moly in 316 has nothing to do with magetic. It's about grain oreintation and the amount of iron in the mix.

Pick a 304# bolt, washer or nut from your kit, also grab a 316# now place a magnet on them and for some unknown reason only the 304#'s will attract.

As i stated it is a quick test to show what isn't 316#.

We are talking fasteners here.

Cheers.

[Jim Cate]

Originally Posted by Lagoon4us

Pick a 304# bolt, washer or nut from your kit, also grab a 316# now place a magnet on them and for some unknown reason only the 304#'s will attract.

As i stated it is a quick test to show what isn't 316#.

We are talking fasteners here.

Cheers.

The point is this: 304 is more likely to be magnetic due to cold working than 316 is, but it is not ALWAYS magnetic. So, it is possible that using your magnetic discriminator would falsely identify a 304 item (one of the non-magnetic ones that really do exist) as being 316.

Probably not life threatening in teh short term, but a potential problem.

Cheers,

Jim

[Cheechako]

I seriously doubt if alot of fasteners use on boats in the past were 316 anyway. I could be wrong of course, but it seems the whole 316 discussion has started since the mid to late 90's. My guess is that the difference in service is pretty marginal and that 304 SS will work just fine. Probably more important to manage how they are installed to eliminate trapped wet areas than which alloy. Of course we all want to use the best when we can, as the labor is usually more cost or more tedious, than the cost of materials. JMHO of course. The Taiwan built boats with their reportedly "cheap" 18-8 stainless seem to do as well as most any.

[Lagoon4us]

Jim it's a hell of a lot cheaper than using a test kit and i've not once been let down by discarding the 304# where i particularly wanted 316# out of the pile of fasteners in the corner of the shed.
The point is 316# is Austenitic and the 394# isn't.

Duralac forever Cheechako....

Cheers.

[Cheechako]

Originally Posted by Lagoon4us

Jim it's a hell of a lot cheaper than using a test kit and i've not once been let down by discarding the 304# where i particularly wanted 316# out of the pile of fasteners in the corner of the shed.
The point is 316# is Austenitic and the 394# isn't.

Duralac forever Cheechako....

Cheers.

Even if the test aint perfect, I suppose it narrows the odds a lot!

The point is 316# is Austenitic and the 394# isn't.
If you meant to say 304... all 300 series is called austenitic SS.

Whats the Duralac story? I know nuttin'.....

[sabray]

Originally Posted by Cheechako

I seriously doubt if alot of fasteners use on boats in the past were 316 anyway. I could be wrong of course, but it seems the whole 316 discussion has started since the mid to late 90's. My guess is that the difference in service is pretty marginal and that 304 SS will work just fine. Probably more important to manage how they are installed to eliminate trapped wet areas than which alloy. Of course we all want to use the best when we can, as the labor is usually more cost or more tedious, than the cost of materials. JMHO of course. The Taiwan built boats with their reportedly "cheap" 18-8 stainless seem to do as well as most any.

+ on how they are installed and maintained. If its wet and soggy mush that they are bedded in wont matter much. Check the bedding plates if you have them. Prefer 326L if stainless.

[Lagoon4us]

Originally Posted by Cheechako

Even if the test aint perfect, I suppose it narrows the odds a lot!

The point is 316# is Austenitic and the 394# isn't.
If you meant to say 304... all 300 series is called austenitic SS.

Whats the Duralac story? I know nuttin'.....

Have a look at the attached, this is a very good compound, i've never seen a failure with it over 40 years that i've used it from mast building to underwater bolting of prop brackets etc, it's good stuff!

:: Llewellyn Ryland :: Bringing Colour To Life ::

Cheers

[lateral]

Just another stainless to throw in the mix. I have just machined my keel bolts. They were magnetic before and still are after. Duplex 50/50. Twice the yield of std 316 & significantly more corosion resistant. (Chloride) They came with a heat sheet & price tag. The bumax nuts were $7 each. I only get one go at it.
2205=22%,5%,3% Cr,Ni,Mo + specfic heat.

[Cheechako]

Originally Posted by lateral

Just another stainless to throw in the mix. I have just machined my keel bolts. They were magnetic before and still are after. Duplex 50/50. Twice the yield of std 316 & significantly more corosion resistant. (Chloride) They came with a heat sheet & price tag. The bumax nuts were $7 each. I only get one go at it.
2205=22%,5%,3% Cr,Ni,Mo + specfic heat.

Any job that big should use the best materials available. Shame on the boat manufacturers for choosing to save just a few bucks on something like keel bolts. I've often wondered why they didnt use Bronze in the past.... Lead and bronze dont mix well?