Hose Jubilee clips Grade of SS

Intend to put double on each hose.

Are these Jubilee clamps stamped 304 or 316? As they were the most expensive I assumed that 316 was the best choice but how do I know they have supplied the right grade?
 
I cannot understand any reason why 316 hose clips would be needed for internal fittings, especially ones not in full view. The hose clips on most engines, certainly those on my Bukh, Yanmar and BMC, are only galvanised steel, i.e. not stainless at all, and have lasted for many years, still in useable condition. 304 is perfectly good for the job but it is important to check with a magnet to ensure that the screw is made from a 300 series steel. The hose clip will not fail even if the screw is ferrous but it will become increasingly difficult to release, ultimately impossible.

There is a premium attached to 316, for example RS describe it as 'special', but it is close to a waste of money for fittings that are not immersed.
 
vyv_cox said:
I cannot understand any reason why 316 hose clips would be needed for internal fittings
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I'm glad you said that :)

I was thinking the same thing, but with so many people seeming so sure of themselves and me not having any hard facts to point to, I didn't want to stick my oar in.

I've always looked for stainless screws rather than mild steel, but not worried about the precise grade of stainless.

Pete
 
prv said:
I'm glad you said that :)

I was thinking the same thing, but with so many people seeming so sure of themselves and me not having any hard facts to point to, I didn't want to stick my oar in.

I've always looked for stainless screws rather than mild steel, but not worried about the precise grade of stainless.

Pete
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I was tempted to launch into one of my pet hates, which is this insistence on double clipping. Why? There are billions of hoses throughout the world containing pressures of up to 8 bar and probably loads more, yet they are only single clipped. Automotive heating systems at 12 psi or so are universally single clipped. And yet on a boat, with an internal pressure of a few inches of water, the 'experts' say they have to be double clipped. However, I won't start on it. :)
 
vyv_cox said:
I cannot understand any reason why 316 hose clips would be needed for internal fittings, especially ones not in full view. The hose clips on most engines, certainly those on my Bukh, Yanmar and BMC, are only galvanised steel, i.e. not stainless at all, and have lasted for many years, still in useable condition. 304 is perfectly good for the job but it is important to check with a magnet to ensure that the screw is made from a 300 series steel. The hose clip will not fail even if the screw is ferrous but it will become increasingly difficult to release, ultimately impossible.

There is a premium attached to 316, for example RS describe it as 'special', but it is close to a waste of money for fittings that are not immersed.
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My suggestion for 316 is based on my experience of cheaper stainless where the screw is not stainless - and the difficulty of cutting a seized up clip in an inaccessible location. I have also had experience of cheap clips where the worm wears and the clip will not tighten properly.

In theory you are right, but to my mind it is worth the extra expense to buy the best clips you can.

BTW agree with you about this obsession with double clipping.
 
vyv_cox said:
I was tempted to launch into one of my pet hates, which is this insistence on double clipping. Why? There are billions of hoses throughout the world containing pressures of up to 8 bar and probably loads more, yet they are only single clipped. Automotive heating systems at 12 psi or so are universally single clipped. And yet on a boat, with an internal pressure of a few inches of water, the 'experts' say they have to be double clipped. However, I won't start on it. :)
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I agree.
Many fittings are probably less secure with an extra clip squeezed on.
I think it often increases the stress on the hose near the end of the fitting.
Doubling things up because you don't trust them is no substitute for using stuff that you can trust, and looking at it from time to time.
 
>I cannot understand any reason why 316 hose clips would be needed for internal fittings, especially ones not in full view.

316 is marine grade stainless so it they get damp/wet they won't rust, I wouldn't use anything else.

Agree about doubling up and remember to tighten them occasionally as the hose compresses.
 
KellysEye said:
>316 is marine grade stainless so it they get damp/wet they won't rust, I wouldn't use anything else.
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The only difference between 304 and 316 is that the latter contains an additional 2% molybdenum over the standard 18/8 Cr/Ni. It's the chromium that prevents rusting, the molybdenum is there to reduce pitting (and crevice) corrosion. Pitting is unsightly on an exposed fitting and could ultimately lead to failure but highly unlikely in a hose clip used inside a boat.
 
I think that double clipping is a bit "belt, braces and a bit of string" when in fact in many cases where a hose has to be heated up to fit the tail, then shrink fits on is nearly sufficient in itself. Add a decent pinch clip - 304 is fine IMO for inside the boat - and you'd snap/tear the hose, before it would leak or come off the tail. Having said that, if there is room and for the price of an extra clip, perhaps it is worth it for piece of mind - bit like the old life-raft for coastal sailing debate.
 
I think the double-clipping thing may be surveyor driven... When we sold our boat last year the surveyor for the purchaser put under "Recommendations" that all hoses should be double-clipped where possible. The purchaser's insurers then mandated that this was done...
 
MikeBz said:
I think the double-clipping thing may be surveyor driven... When we sold our boat last year the surveyor for the purchaser put under "Recommendations" that all hoses should be double-clipped where possible. The purchaser's insurers then mandated that this was done...
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I think you are right. The same thing seems to be happening with gas installations, where rules to comply with inland waterways requirements are being imposed by surveyors on sea-going craft and of course the insurers are not going to speak against them. In the case of gas installations this is probably a good thing, but not for double clipping and no doubt other examples.
 
Double clipping also comes up regularly in magazine boat "tests" - usually as a criticism when it is not done!

Typical example of "moral panic" - if enough people say it is the case, then it is. Problem is that there is no technical reason why it should be the case, nor any reliable empirical evidence, so it never gets challenged.

Or maybe it was just a marketing ploy started by manufacturers who had so little faith in their products such that they believe you should use two of them rather than one. Or am I being cynical?
 
vyv_cox said:
I was tempted to launch into one of my pet hates, which is this insistence on double clipping. Why? There are billions of hoses throughout the world containing pressures of up to 8 bar and probably loads more, yet they are only single clipped. Automotive heating systems at 12 psi or so are universally single clipped. And yet on a boat, with an internal pressure of a few inches of water, the 'experts' say they have to be double clipped. However, I won't start on it. :)
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Cosequences come into play. Car hose fails, you stop, boat hose fails you die?
 
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