Quality Control - Stainless?

[ssullivan]

Quite a few hoseclamps I up on last year have begun to show evidence of rust. Has anyone else seen problems with stainless hoseclamps lately? Any tricks to reduce the corrosion?

[Doghouse]

My hunter has the same problem on the steering cable clamps. Supposed to be stainless, but the nuts are rusting so I am replacing them . Don't want those to break on you!

[Euro Cruiser]

Sean, I've counted carefully and there are about 3 Bazillion different types of "SS" hose clamps out there. Many of them rely on steel screws. This is one of those products one should buy based on quality and by brand name, not price, and with a magnet in your pocket when heading for the store.

Also, particularly if you are seeing rust around the screw and its housing, work the clamp with a socket rather than a screwdriver. You can put a lot more tension on the fastener that way, not only making sure it's tight but also 'testing' its integrity. Removal and inspection is the more conservative approach.

Jack

[s/v 'Faith']

Sean,

Describe the rust. Even 316 can rust where it is worked, especially if worked with a carbon steel tool. For instance, you can have a 316 stainless screw develop surface rust where it was screwed in. If you use steel wool on stainless the particles of steel wool will not only corrode on the surface, but encourage corrosion in the stainless. Stainless also needs air to remain stainless, if there is high moisture in the vicinity of the clamp that could be causing the problem.

That said, mild steel screws in stainless clamps are not uncommon. Usually found in hardware stores.

and with a magnet in your pocket when heading for the store...

Not sure what for, stainless steel is ferrous just like mild steel...?

[Greg S]

Hummm, I do use the magnet if I buy them from anyplace except a quality chandlery. It should tell you if the screw is something other than stainless, or do I have that wrong!??

[s/v 'Faith']

Originally Posted by Greg S

Hummm, I do use the magnet if I buy them from anyplace except a quality chandlery. It should tell you if the screw is something other than stainless, or do I have that wrong!??

Stainless steel is ferrous just like mild steel. The magnet would stick to either one so I don't know that the magnet would help. A magnet is good for testing things like chrome plated steel vs chrome plated pot metal.. or chrome steel vs chrome bronze if you are buying something like a cleat, but not so much for telling the difference between satinless and mild steel (and would not help in telling 304 from 316 stainless).

Here are a couple links on the topic.

Here is a good link on Corrosion problems associated with stainless steel

The basic resistance of stainless steel occurs because of its ability to form a protective coating on the metal surface. This coating is a "passive" film which is resistant to further "oxidation" or rusting.

Wiki on Stainless steel

wiki on Contact corrosion in stainless steel

Contact corrosion
Contact corrosion is a combination of galvanic corrosion and crevice corrosion, occurring where small particles of suitable foreign material are embedded to the stainless steel. Carbon steel is a very common contaminant here, coming from nearby grinding of carbon steel or use of tools contaminated with carbon steel particles. The particle forms a galvanic cell, and quickly corrodes away, but may leave a pit in the stainless steel from which pitting corrosion may rapidly progress. Some workshops therefore have separate areas and separate sets of tools for handling carbon steel and stainless steel, and care has to be exercised to prevent direct contact between stainless steel parts and carbon steel storage racks.

[colemj]

The 304/316 grades of stainless most used for clamps (or at least desired) are not ferromagnetic like mild steel and will not be attracted to a magnet. If you want to test this, just try to stick a magnet to your standing rigging. Some grades of stainless are ferromagnetic (401?), but these are not typically found in common parts like hose clamps and fasteners. 304/316 stainless can become ferromagnetic if it has been worked hard or been mistreated in a certain way, so if the magnet does stick to your rigging, you should probably consider immediate action.

So a magnet is always a good thing to take with you when shopping for stainless stuff. Especially in bins, where non-stainless pieces can find their way into the wrong place. I have even bought sealed boxes of stainless fasteners that have had a couple of non-stainless screws in them.

Mark

[Pblais]

Here is a good alternative:

Titanium Hose Clamps

Hose Clamps from Titan are 100 Percent Titanium

They can run into a little money so you might want to pick and choose where you use them. Ordinary small ones about $6 on up to $12 for a 5 1/2 inch. If you replace a few all the time it might be worth it to try one.

I found this link on Google there are a few more so you can shop around for perhaps a better deal closer to home port. They will never ever rust but they could break. Titanium has a better strength to weight ratio but steel is stronger than Titanium. A SS 304 clamp is stronger than a SS 316 clamp so long as it does not rust. Hardware store grade SS clamps are usually 304 and really the best choice around the house not aboard.

[Pblais]

so if the magnet does stick to your rigging, you should probably consider immediate action.

A big problem with rigging is the same foundries that make SS cable also make a whole lot more regular steel cable. There really is no large demand for the type of SS cable we all use on our rigs so it tends to be made in small batches until it is sold out.

The iron dust in the foundry can become impregnated inside the SS cable if it sits around a long time. This problem can lead to premature failure due to rust. Most serious rigging outfits do track the lot numbers and dates of SS cable to avoid this problem. Since they buy wholesale through distributors they have a better way to track it than you or I do.

[ssullivan]

And... dare I say it... what about plastic hose clamps? Has anyone had experience with these?

Obviously, they won't be quite as powerful in clamping as the stainless, due to the screwing action, but they won't rust out over the years, which might make them more safe.

Just thinking outside the box a little bit, and remembering my Marelon seacocks, which have held up flawlessly for 20 years.

I bought my current corroding clamps at West Marine last year.. spent the extra money and everything. But, given that the freshwater supply line ones are subject to moisture from sweating, they develop corrosion quickly where they meet the tubing.

[Jon D]

There is a line of clamps made by scandvik avail in both 304 and 316. way more expensive than the generic west marine, etc. stainless but way better clamps..

[Alan Wheeler]

Here's a different take on the topic. If you are buying a standard hose clamp, the one with the worm drive type screw action, then do NOT buy all SST. Buy ones that have a SST clamp band and a plated screw. Don't panic about the corrosion. They will still last for years. But the screw will NEVER come lose. An all SST clamp loosens with vibration and you need to constantly run around tightening them as a maintanace routeen. Double clamps are a must.
If you want a good all SST clamp, the only clamp you should use is one that has a straight bolt that pulls the clamp together. The name escapes me right now, but I will find it. They are far heavier made, will not come loose and the clamping pressure is far higher. They are slightly more expensive, but because they are far supperior, you don't need two and they will last far longer.

[Sunspot Baby]

Somehow I get by with stainless clamps purchased at Lowes. Corrosion hasn't been a problem. Neither has loosening.

George

[Greg S]

Come to think of it, the last ones I had to replace because of rust were an absolute bear to get off. (You know, ones in that teeny, tiny area under the head) Seems the scew had become one with the clamp. Had to get the dremel in there to cut them off. That rust works just like a weld, until they fall off, of course!

[Vasco]

Originally Posted by Greg S

Come to think of it, the last ones I had to replace because of rust were an absolute bear to get off.

Greg,

Just wait till you have to remove one on a head hose which was put in before the deck half was put on. The genius that built mine (or worked on the head) put the screw part of the hoseclamp up against the hull on a hose that was in a corner and already nearly touching the hull. Maybe they do this for fun at the factory, after all it must get kind of boring. They must think, " wait till the sucker tries to get this one off, ha".