The Church of Double Clipping

[Daydream believer]

Jubilee clips aren't so good around by the worm, so alternating where the worm is goes some way to improving on this. At least that is what I have heard in the past. Certainly get some distortion in the pipe sometimes so might be true. Better clips are available.

Well watch the video & suggest a better option please. The one shown is lloyds approved
But of course the term "jubilee" may be a bit like "hoover" , or "jacobs chuck" - distorted from a brand product to indicate a typical pattern, rather than the exact product, which it may not emulate so well.
Another issue is the sizing of the clip. When installing my new engine last year the chap at the hydraulic co was quite careful about matching the clips to the hoses that I purchsed. It was only a small difference on a couple but he insisted on matching them. Something that I apreciate now it is all installed. It is too easy to use a clip a couple of sizes larger. Thus end up with a long sharp tail & as suggested above, a flat spot.

 

[flaming]

Ok, so starting where this thread started, I'll set out my thoughts.

DOUBLE CLIPPING

Looking at this logically from the point of view of someone who makes the things, and uses them on my own boat, here's my opinion on double clipping. And I'll try to be clear where my opinion is just that, and where I have data to back it up.

Firstly, here's what I do on my boat.

I double clip everything that is on either end of a hose that is directly attached to a seacock on the outside of the boat. I single clip everything else, domestic plumbing etc.

The reason for this has nothing whatsoever to do with the sealing strength of the clip. One single, intact, clip made to BS5315, has to withstand as part of testing a pressure of 200PSI for 60 seconds with no loss of pressure (Which gives you a clue how old the standard is!) That's over 13 Bar. And that is the minimum pass mark. A decent clip will go significantly beyond that. We normally burst the hose before we see leakage past the clip. Correctly fitted and intact, you simply aren't blowing a BS5315 compliant clip off in normal use on a leisure boat. I'm also not convinced that double clipping would actually increase the pressure it could withstand, it might increase the time to leak, but once the first clip has failed the second is eventually going to be subject to the same pressure - I don't have any data on this though, that's just my suspicion.

The reason to double clip is because you're fitting them in a corrosive environment, and very often in a part of the boat that you don't inspect as often as you might... It's all about corrosion and peace of mind.

The failures we see in clips in the leisure marine environment are normally due to crevice corrosion, specifically where some water has pooled in the housing and then attacks the band and/or screw. In colder climes this tends to be other leaks, drips that just happen to run down the pipe to the clip, and in warmer climes this is often condensation. I have never, ever, seen a photo of a corroded clip in place without being able to see where the water came from to get to the clip.

Very often when we are sent pictures of clips that have failed even when double clipped and hoses come off, we see that both clips have been affected in the same way, because both have been mounted on the same orientation, so have both caught the same drip running down the pipe. If you are going to double clip, have a look at where water might run down the outside of the hose to the clips from, and then make sure that your clips are orientated in such a way so that the housing of both cannot catch the same drip. Some people advocate using a thick grease to "seal" the housing after installation to prevent any water from pooling there, but I don't feel that is necessary. Worth saying that in the 10 years I've been in the hot seat, the only examples that we've had sent to us of clips failing due to corrosion have all come from the tropics.

 

[Tranona]

Do you have data on how many of the failed clips resulted in the hose coming off - or worse still the hose detaching and the boat sinking?

Suggest the probability of the clip failing to hold because of corrosion is very low and the probability of it leading to the hose detaching even smaller - and that double clipping is unlikely to change the failure rate.

 

[Bouba]

Do you have data on how many of the failed clips resulted in the hose coming off - or worse still the hose detaching and the boat sinking?

Suggest the probability of the clip failing to hold because of corrosion is very low and the probability of it leading to the hose detaching even smaller - and that double clipping is unlikely to change the failure rate.

You can’t place the safety of your craft and occupants on a ‘unlikely’...if ‘almost never’ is only a couple of quid and two minutes effort

 

[Daydream believer]

In my experience it is not always the clip that fails. I have had the hose on the water intake on the saildrive leak. This was double clipped. The hose was slightly too big but not overly so. The reason for this is that each year the boat is lifted. The hose is disconnected the end placed in fresh water & the system flushed through.
By having a loose hose it is still a struggle to get off but easier than it might have been.
After each operation it is re fitted. The clip possibly cutting into the hose, whilst I ensure that it is watertight. This is positioned in a dark difficult place to access. Hence I just ratchet it up.
After 5-6 years the clip cut the hose partly due to engine vibration on the top of the sail drive. I never bothered to turn of the water when leaving the boat for 2 reasons. First because it is difficult to reach. Second so I do not forget to turn the water on next time I use the engine
The small split in the hose started to let a considerable amount of water in to the boat. Fortunately I was on board so I just cut a couple of inches off the end & re fitted it. The split was just at the end of the connection so if it had gone right round it would have fallen off. Unlikely but possible in other situations & with different pipes.ie in a locker with something heavy laying on it, like the outboard etc.

looking round the boat it is clear that over tightening the clips can cause issues. So, although a clip can hold a zillion PSI it may do more damage than good, if torqued up too much. Instructions should accompamy the product me thinks.

 

[Tranona]

You can’t place the safety of your craft and occupants on a ‘unlikely’...if ‘almost never’ is only a couple of quid and two minutes effort

You do it all the time in decision making. There is NO evidence that adding an extra clip stops your boat from sinking. This is a non issue.

 

[flaming]

TYPES OF CLIP

There are 3 basic types of "standard" hose clips. The British type, the German type and the American type.

The British type, originated by Jubilee, is often seen as the "original" and has a good reputation around the world. Good ones are kite marked and made to BS5315. I'm aware of 4 brands that are currently claiming to be kite marked, given where one brand in particular is now being made I have my doubts but they keep getting signed off..... They are recognised by having non perforated bands with the "coining" pressed into the band and 3 different housing/screw sizes depending on the diameter of the clip.

The German type, made to a DIN standard (sorry I don't know the number off the top of my head) also have a good reputation, and are extremely widely used in the automotive industry. They also have non perforated bands, though the "coining" is embossed out of the band, rather than pressed in as the British type have. They have only 2 different housing sizes, and the coining and housing are slightly off centre.
Be aware that if you see what appear to be German style clips in sizes over 25mm at prices that seem too good to be true, that you are probably looking at the automotive variant. These clips use the narrower band that is normally only used on 25mm and less diameter clips in order to cut costs, and frankly put, they're a bit crap. There's a reason that we increase band width as we go up in diameter....

The American type use perforated band. Although widely used globally they are significantly inferior to the British and German type in sealing pressure. They tend to be cheaper though.

All of these types are sold as basically equivalent - i.e general clips suitable for basic hose attachments in normal use. And if we're brutally honest they all generally do the job of keeping a hose attached to a spigot.

Where the differences in brand come in are in the details. Firstly the efficiency of the clip - i.e how much clamping force do you get from a given torque applied to the crew. Next details like the rounding (or not) of the edges which makes a big difference to how much the clip can damage the hose. And little things like the crispness of the screw hex, clarity of the stamped text etc. And then the materials used, and in the case of the mild steel products, the quality of the electroplating.

The good news for the average consumer is that there is in general a really good correlation between the unseen but vitally important clamping efficiency, and the other details like rounded edges, clearly stamped text on the band and housing, nice crisp head on the screw, lack of witness marks on the band.
Naturally I'll tell you that ours are the best, and I have the test data to back that up, but I'll also tell you that your boat is perfectly safe if you've used a clip that complies with the BS5315 standard, or the German DIN standard. By very wary of the US style clips though. There are ok and indifferent ones, and frankly dangerous ones. And unless you know the clip market inside out it's not obvious which is which.

 

[flaming]

Do you have data on how many of the failed clips resulted in the hose coming off - or worse still the hose detaching and the boat sinking?

Suggest the probability of the clip failing to hold because of corrosion is very low and the probability of it leading to the hose detaching even smaller - and that double clipping is unlikely to change the failure rate.

I have some anecdotal evidence that it has happened. I have nothing that I'd call data.

One thing that is generally in our favour is that although the failure of the hose clip due to corrosion often happens over time whilst the boat is not in use, the actual loss of the hose only really occurs in use, so is normally noticed and dealt with by the crew.

 

[flaming]

HOSE CLAMPS

If anyone is left who hasn't been bored to tears by hose clip chat....

So far I've talked about hose clips - our Hi-Grip product and its competitors. Designed for standard hoses doing standard jobs.

We also make Hi-Torque clamps, and they are a totally different beast.

Put simply they are significantly stronger and produce a much higher clamping force, allowing them to seal significantly higher pressures when used with "standard" hose, but more importantly get a seal when used with wire reinforced hose or similar that standard hose clips struggle to squeeze enough to get a seal.
What is frustrating is that many people mistake our Hi-Torque (and to be fair other manufacturer's equivalent product) for the cheap American style clip as they both feature perforated band. But that's really where the similarity ends. The American style feature a simple housing that like a standard clip allows the band to retain its curve as it passes through the housing. This results in variable engagement with the threads of the screw. Hi-Torque products use a 2 part housing that forces the band to travel straight through the housing which results in a much better engagement.

Some competitors make and sell clamps that feature a nut and bolt instead of a worm screw. For example

Looks beefy and strong doesn't it? That's got to be the absolute best there is right?

Well no... The simple fact of the matter is that we have never tested any variant of that style that gets anywhere near the performance of our Hi-Torque product. They can't actually exceed the sealing ability of our Hi-Grip product. See that video for 1 example.
The reasons for this are 2 fold. Firstly, I talked before about the efficiency of the clip, the ability to turn input Torque into clamping force... The nut and bolt clamps are really bad at this.



I've taken out the detail of who's nut and bolt this is, but note that this is comparing a beefy nut and bolt to our standard Hi-Grip product! Some samples that we bought and then just 2 clips from our stores. Note that the recommended working Torque of our Hi-Grip product is 5Nm.

Here is the comparison with Hi-Torque. Again I've taken the brand names out, but both of these are from market leaders who I see recommended on these forums. Brand A is probably the best nut and bolt we have ever tested, brand B is more typical of the type in our experience. Working Torque for our Hi-torque product is 15Nm. The nut and bolt type recommend 20Nm.




So part of the reason that nut and bolt types don't seal very well is shown here - they don't actually generate as much clamping force...

But it's also in how that force is applied. When you tighten a worm screw clip or clamp, the band itself is drawn through the housing so the whole band is tensioned fairly evenly - other than friction with the hose. When you tighten a nut and bolt clamp, you aren't directly shortening the band around a circle, you're shortening a bolt in a straight line, and that's bringing the 2 ears together in a straight line. So in effect you're not closing a circle but pinching across the top of a U. This creates 2 issues, firstly the pressure exerted on the hose is very uneven, and secondly it's quite possible to "ruck" the hose under the bolt and create a gap there. Nicely hidden under the assembly. But even if you avoid that, then you simply don't have even pressure on the hose all the way around, and thus you get a leak path. Which is why even when you do them up to a Torque that is producing the same clamping force as our Hi-Grip does at 5Nm as measured by our test rig, they still don't seal anything like as well. And that's why they are not Lloyds approved.

Some brands, we have found in testing, tend to develop their leak under the bolt, others directly opposite. If I had to guess I'd say this is a function of how proud the bolt is of the band, and also the length of bolt used. Generally the 1st type are the slightly better performing ones. By which I mean I have seen one brand get to 8 Bar before leaking fairly consistently. Still well short of the sealing pressure required by BS5315 on a basic hose clip.... Let alone what we would expect from a Hi-Torque.

And the really good news is that all variants of Hi-Torque, whether ours our our competitors are better and cheaper than the nut and bolt clamps. Naturally I'll tell you that ours are the best, and again I have got the test data for that, but from a practical boat owner point of view, just fit any Hi-Torque type instead of a nut and bolt clamp.

 

[Bouba]

HOSE CLAMPS

If anyone is left who hasn't been bored to tears by hose clip chat....

So far I've talked about hose clips - our Hi-Grip product and its competitors. Designed for standard hoses doing standard jobs.

We also make Hi-Torque clamps, and they are a totally different beast.

Put simply they are significantly stronger and produce a much higher clamping force, allowing them to seal significantly higher pressures when used with "standard" hose, but more importantly get a seal when used with wire reinforced hose or similar that standard hose clips struggle to squeeze enough to get a seal.
What is frustrating is that many people mistake our Hi-Torque (and to be fair other manufacturer's equivalent product) for the cheap American style clip as they both feature perforated band. But that's really where the similarity ends. The American style feature a simple housing that like a standard clip allows the band to retain its curve as it passes through the housing. This results in variable engagement with the threads of the screw. Hi-Torque products use a 2 part housing that forces the band to travel straight through the housing which results in a much better engagement.

Some competitors make and sell clamps that feature a nut and bolt instead of a worm screw. For example

Looks beefy and strong doesn't it? That's got to be the absolute best there is right?

Well no... The simple fact of the matter is that we have never tested any variant of that style that gets anywhere near the performance of our Hi-Torque product. They can't actually exceed the sealing ability of our Hi-Grip product. See that video for 1 example.
The reasons for this are 2 fold. Firstly, I talked before about the efficiency of the clip, the ability to turn input Torque into clamping force... The nut and bolt clamps are really bad at this.

View attachment 173578

I've taken out the detail of who's nut and bolt this is, but note that this is comparing a beefy nut and bolt to our standard Hi-Grip product! Some samples that we bought and then just 2 clips from our stores. Note that the recommended working Torque of our Hi-Grip product is 5Nm.

Here is the comparison with Hi-Torque. Again I've taken the brand names out, but both of these are from market leaders who I see recommended on these forums. Brand A is probably the best nut and bolt we have ever tested, brand B is more typical of the type in our experience. Working Torque for our Hi-torque product is 15Nm. The nut and bolt type recommend 20Nm.

View attachment 173579


So part of the reason that nut and bolt types don't seal very well is shown here - they don't actually generate as much clamping force...

But it's also in how that force is applied. When you tighten a worm screw clip or clamp, the band itself is drawn through the housing so the whole band is tensioned fairly evenly - other than friction with the hose. When you tighten a nut and bolt clamp, you aren't directly shortening the band around a circle, you're shortening a bolt in a straight line, and that's bringing the 2 ears together in a straight line. So in effect you're not closing a circle but pinching across the top of a U. This creates 2 issues, firstly the pressure exerted on the hose is very uneven, and secondly it's quite possible to "ruck" the hose under the bolt and create a gap there. Nicely hidden under the assembly. But even if you avoid that, then you simply don't have even pressure on the hose all the way around, and thus you get a leak path. Which is why even when you do them up to a Torque that is producing the same clamping force as our Hi-Grip does at 5Nm as measured by our test rig, they still don't seal anything like as well. And that's why they are not Lloyds approved.

Some brands, we have found in testing, tend to develop their leak under the bolt, others directly opposite. If I had to guess I'd say this is a function of how proud the bolt is of the band, and also the length of bolt used. Generally the 1st type are the slightly better performing ones. By which I mean I have seen one brand get to 8 Bar before leaking fairly consistently. Still well short of the sealing pressure required by BS5315 on a basic hose clip.... Let alone what we would expect from a Hi-Torque.

And the really good news is that all variants of Hi-Torque, whether ours our our competitors are better and cheaper than the nut and bolt clamps. Naturally I'll tell you that ours are the best, and again I have got the test data for that, but from a practical boat owner point of view, just fit any Hi-Torque type instead of a nut and bolt clamp.

This is all good stuff

 

[flaming]

This is all good stuff

Thanks.

If anyone has any specific questions let me know and I’ll try to answer.
Equally if anyone finds themselves in Suffolk and wants a factory tour just PM me.

 

[Rappey]

If there is an appetite for me to talk about hose clips, then I'm very happy to, but equally I have no wish to stick my nose in where it is not wanted.

There is always an appetite to hear from someone who actually designs and manufactures parts rather than people that only use them.
Cant beat "straight from the horses mouth"

I would certainly take advice from many of our forum professionals over what i can read online as we have the ability to question them or even disagree before reaching a conclusion.

 

[Pye_End]

Suggest you watch the video in post#43 which shows exactly the opposite of "what you have heard in the past".

Apologies - post 43 doesn't come up for me.

There is no support either technically or empirically for "double clipping",

Perhaps you misunderstand - I was not offering an opinion this. I was merely trying to express a possible explanation as to why it has been often recommended that double clips are set in a different orientation, particularly as I can't see that anyone else has provided a reason.

I do not agree as there is no evidence to support your claim or the authority of "what you have heard in the past"

I am not convinced it should be so dismissed. I have had a plastic connector which on installation would not stop weeping. Nipping up did not work, and eventually led to a greater flow. When you took it all apart again you could see the connector had gone D shaped, as that is the shape of a small, tightened jubilee clip. On this occasion there was not enough space to test the theory that a second clip would have solved it, though it may well have. In the end it was only the use of sealant that stopped the weep. Just take a small jubilee clip and keep tightening it - it ceases to become round. Perhaps take this therefore as supportive evidence?

 

[flaming]

I am not convinced it should be so dismissed. I have had a plastic connector which on installation would not stop weeping. Nipping up did not work, and eventually led to a greater flow. When you took it all apart again you could see the connector had gone D shaped, as that is the shape of a small, tightened jubilee clip. On this occasion there was not enough space to test the theory that a second clip would have solved it, though it may well have. In the end it was only the use of sealant that stopped the weep. Just take a small jubilee clip and keep tightening it - it ceases to become round. Perhaps take this therefore as supportive evidence?

What size was the connector?
What size was the clip used, and what brand?

A quality clip used within its adjustment range should not go D shaped. The housing used changes - gets smaller with reduced diameter clips - and the inner radius is also adjusted to suit the size of clip being made.

Normally, to get a D shape on the clip you have to take it well beyond the designed adjustment range. But do that, and absolutely you will get leak paths.

Some brands have, in recent years, changed their production methods from putting only the coining necessary for the stated adjustment range to continuously coining the band. This allows the clip to be tightened far beyond its stated adjustment range and become D shaped.

 

[Daydream believer]

Apologies - post 43 doesn't come up for me.

Perhaps you misunderstand - I was not offering an opinion this. I was merely trying to express a possible explanation as to why it has been often recommended that double clips are set in a different orientation, particularly as I can't see that anyone else has provided a reason.

I am not convinced it should be so dismissed. I have had a plastic connector which on installation would not stop weeping. Nipping up did not work, and eventually led to a greater flow. When you took it all apart again you could see the connector had gone D shaped, as that is the shape of a small, tightened jubilee clip. On this occasion there was not enough space to test the theory that a second clip would have solved it, though it may well have. In the end it was only the use of sealant that stopped the weep. Just take a small jubilee clip and keep tightening it - it ceases to become round. Perhaps take this therefore as supportive evidence?

Perhaps this helps

As for tightening a jubilee clip until it ceases to be round. I am afraid that test is b...x ; simply because the round you are talking about is not the size that the clip is designed for.
If one has a fitting with a plastic tail, then perhaps one should be looking at the tail, not blame the clamp that is being used. better match clamp to tail & if it leaks consider whether the plastic fitting was suitable in the first place

Edit
Overlapped with last post

 

[Pye_End]

What size was the connector?
What size was the clip used, and what brand?

A quality clip used within its adjustment range should not go D shaped. The housing used changes - gets smaller with reduced diameter clips - and the inner radius is also adjusted to suit the size of clip being made.

Normally, to get a D shape on the clip you have to take it well beyond the designed adjustment range. But do that, and absolutely you will get leak paths.

Some brands have, in recent years, changed their production methods from putting only the coining necessary for the stated adjustment range to continuously coining the band. This allows the clip to be tightened far beyond its stated adjustment range and become D shaped.

Looking at my photos it doesn't look particularly oversized. It was either a 25 or a 30. It happened in 2004 so much of my detailed memory of it has gone. At the time I put it down to a lack of strength in the plastic. Clip was probably a decent one at the time from the chandlers, but I couldn't tell you the make.

The lower photo in your post and your comments are interesting. The design doesn't have that edge that the jubilee digs into the hose, and I wonder if tightening (ie rotating) the clip then distorts the hose slightly and then gives you a slightly uneven pressure, whereas the second photo allows more slippage and a more even grip? When you take off a jubilee clip there is a blip where the hose has squashed. I don't know - something caused it. Had to resort to using sealant making the join which has been fine.

Every other fitting or hose on the boat with a (single) jublilee clip I have never had any issue with, Several are now double as that is what the insurance surveyor wanted.

 

[fredrussell]

Once again a forum thread has been infiltrated by someone that actually knows what they’re talking about, instead of it being based solely upon personal opinion and conjecture as is the rightful way of the internet forum. Harrumph.

 

[Roberto]

If anyone has any specific questions let me know and I’ll try to answer.

Thanks for all the explanations, very interesting
As to tightening, a torque wrench is often impossible to use, I usually tighten the clip as much as possible, then take off half a turn: do you reckon it is sensible?
Ps just low pressure hoses, sea water, fresh water etc.

 

[flaming]

Thanks for all the explanations, very interesting
As to tightening, a torque wrench is often impossible to use, I usually tighten the clip as much as possible, then take off half a turn: do you reckon it is sensible?
Ps just low pressure hoses, sea water, fresh water etc.

I wouldn’t take off the half turn.
With a flexible driver keep going until the shaft flexes when you turn it, you’re close enough to the designed working torque then.
With Hi-Torque type clips you need to use either a T-bar driver or a socket wrench. You won’t be anywhere close to the working torque with just a screwdriver.

 

[Roberto]

I wouldn’t take off the half turn.
With a flexible driver keep going until the shaft flexes when you turn it, you’re close enough to the designed working torque then.
With Hi-Torque type clips you need to use either a T-bar driver or a socket wrench. You won’t be anywhere close to the working torque with just a screwdriver.

Thank you Fleming
r.