Stainless Steel Grades

[cas8100]

I'm rebedding everything on the deck of my Catalina 22 and will need a whole slew of new fasteners. A quick forum search doesn't reveal a ton of information on the different types of SS.

Looks like there's a ton of different grades (wikipedia says 150 different types). From what I've read 18/18 and 304 are the same thing. Wikipedia also says that 316 is commonly found on marine applications because of its anti-corrosive properties.

Obviously the different numbers stand for different alloy percentages. Any thoughts from some of the more experienced folks out there? I have to imagine that buying my fasteners at Lowes or Home Depot would be a heck of a lot cheaper than ordering from WM or Jamestown Distributors. But the reduced cost would likely be reflected in a lower quality SS (18/18 instead of 316).

[cas8100]

A similar thread that didn't turn up in my initial forum search: http://www.sailnet.com/forums/gear-m...ess-101-a.html

[AE28]

For what it's worth, I am a buyer of stainless steel food service items.

I have never seen an internationally recognized and accepted specification for stainless steel grades expressed as xx/xx (that's the chrome content/nickel content). In my opinion, the nomenclature was dreamed up by marketing types to confuse folks.

Stainless steel designations such as Type 304 or Type 316 are globally recognized specifications, published by organizations such as AISI (American Iron and Steel Institute).

The best quality steel in the world can be trashed by substandard processing techniques. Conversely, you can't make a silk purse from a sow's ear.

If you plan on keeping this boat and presuming you don't want to repeat this process every few years, I suggest you put the reliability of the vendor at or near the top of your criteria for choosing what and where to buy.

Good luck!
Paul

PS AISI Type 304 is commonly referred to as 18/8 or 18/10 in our industry. It has 18 - 20% chrome and 8 - 11% nickel. AISI Type 316 has 16 - 18% chrome and 10 - 14% nickel.

[whughes]

I was also trying to find out about the differences between Type 302/304 and Type 316 as far as rigging applications go. From what I gather, 302/304 is the commercial grade and 316 has enhanced corrosion protection.

Is the cable used in rigging typically 316? Or could just as well be 302/304?

The reason I ask is they have very different breaking strengths, for example 5/32 302/304 breaking strength is about 2800 lbs and 316 is 3300 lbs.

Thanks,

Warren

[jimq26]

Go to - Stainless Steel Information Knowledge alloys 316 304 18-8

[sigmasailor]

316 is the 'seawater resistent' kind. In Europe nuts and bolts are marked A4 as oposed to A2 for 304.
Try to Google '316 304' and find Stainless Steel Information Knowledge alloys 316 304

[cas8100]

Warren,

I'd double check your breaking strengths... Everything else I can find remarks that 304 is stronger than 316, but at the cost of being more corrosive.

I'm not sure about Home Depot, but I called Lowe's and the sales person I talked to said that ALL fo their stainless supply comes from Hillman. Attached is a document from Hillman about the quality of their steel. I got it from one of my local hardware stores.

Depending on how you read into it, I would take this to mean that you don't get much of a guarantee when you buy stainless from a big box store.... At least not when its going to be used for a marine application.

[whughes]

You're right. My mistake, got 'em reversed. This is from the Loos & Co. website: Loos & Co. Inc. wire rope, steel cable, stainless steel wire rope.

302-304 316
5/32 3/16 5/32 3/16
Breaking Strength 3300 4700 2800 4000

[cas8100]

As I research further, it looks like both West Marine and Jamestown Distributors stock either 316 or 18/8 stainless. They do not specifically offer 304 as an option, just products in the 18/8 family.

West Marine's fasteners are supplied by Fasco
Jamestown Distributor's fasteners are supplied by Eastern Fastener Corp
Lowe's fasteners are supplied by Hillman

All 3 retailers say their stock comes from the 18/8 family. Because the only guarantee is of 18/8 quality (and not 304), for fittings requiring high strength (i.e. chainplates, pulpits, stanchions, sheet tracks) it really makes me wonder if I might as well save some money and head to the local hardware store.

[sailingdog]

Basically, good marine grade stainless steels are the non-magnetic Austenitic grades—304 and 316 being the most common. While 304 is stronger than 316, it is far better to go with 316L, since 304 is far more vulnerable to crevice corrosion and chloride ion stress cracking.

BTW, carrying a magnet with you is a good way to quickly check if the stainless is non-marine grade Martenistic stainless steel, which is magnetic or not. If the magnet sticks, it ain't marine grade stainless. If it doesn't stick, it doesn't guarantee it is marine grade, but it is far more likely.