Double clamping of hoses

I suspect that CapBill is right and it probably is just fly shxit. With certain types of hoses it may be applicable though. But if you want to keep a hose connection from leaking you wouldn't use a clamp like a "U" bolt and most clamps on cars and boats aren't entirely unlike a "U" bolt.

Re the super duper high grade "the best that money can buy" is usually silly, a waste of money, not cost effective and perhaps even pretentious. The slotted band clamps are indeed questionable in strength and could sink one's boat. But if not overtightened and replaced often enough so rust is not an issue they are probably fully serviceable within those stated limits. Mine must be SS (except the little guys in my pic) as I don't see any of them rusting, or rusting enough to be an issue. Good enough is .... good enough.

RickB said:

These work fine for water and wet exhaust hose:

Hydrasearch | Manufacturer of Fluid Systems and Components for Military and Commercial Applications

You can also go with hard piping/tubing and flex sections if you want "the very best."


I think you have that backwards, the high risk / low cost option is to use hose and hose clamps. The installation failures that require rescue are often from the use of cheap hose clamps and rotten rubber hoses.

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I never said said anything about using cheap clamps and rotten or cheap hoses, quite the opposite. You seemed to be advocating going cheap, implying there were good cheap alternatives to clamps, so I apologize if I misread you as you misread me.

George I think you were saying something about using cheap hose clamps. You asked me what my clamps were made of when it's probably obvious they are zinc plated steel. The implication that they were not SS and had no business on a boat. Yes? If not then?
Re the gap below the screw an extension of the band carries over to the other side of the band and can be seen in my pic. Here is a close up for a better view.
I do keep an eye on my plumbing and will replace these when they start to significantly rust.
Edit:
Now that I look at this pic it looks like I overtightened the inbd clamp. Perhaps I had the hose too tight against the hex to start with. And George these clamps are not very strong. They do provide even clamping pressure all around the hose. I tried to get non-barbed fittings but they are hard to find. So I decided light even clamping and the barbed fitting was a good compromise.

The injection pipes on my engine were plain steel (still are) and one developed a pinhole leak from corrosion under cracked paint a few years back.

That atomized fuel could have been one of the most lethal things that could happen on my boat.

I don't think those pipes are available in stainless...yet Lehman owners live with that possibility every time they run their engines....a very hard to detect but very possible issue.

Not everything on a boat has to be stainless if the design and maintenance is there.

All sorts of dangers lurk in engine rooms...even those with constant vigilance. Some items are compromises in materials, designs or uses....rarely is anything without a potential flaw.

Worry is OK.... if not consuming and keeps you on your risk management toes.

The jubilee clip, aka the worm gear hose clamp on this side of the pond, was actually designed by a guy on a naval ship who determined that there was a need for a better pipe to hose connection.

Irony.

SAE recognizes 32 different types of them in J1508.

I have them all over my boat, except the fuel and hydraulic lines.

His design was really a black op to leak the design to the enemy of ALL naval warships....

Recreational boaters!

psneeld said:

The injection pipes on my engine were plain steel (still are) and one developed a pinhole leak from corrosion under cracked paint a few years back.

That atomized fuel could have been one of the most lethal things that could happen on my boat.

I don't think those pipes are available in stainless...yet Lehman owners live with that possibility every time they run their engines....a very hard to detect but very possible issue.

Not everything on a boat has to be stainless if the design and maintenance is there.

All sorts of dangers lurk in engine rooms...even those with constant vigilance. Some items are compromises in materials, designs or uses....rarely is anything without a potential flaw.

Worry is OK.... if not consuming and keeps you on your risk management toes.

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This Lehman 120 owner experienced a cracked steel injection line 20 hours of run time after acquiring the boat. It was a failure that could not have been uncovered in a survey. Just plain bad luck that it did not occur to the PO. The line had been resting against a hose clamp for who knows how long. It could have been for a thousand hours. The vibration apparently work-hardened the metal and it finally cracked spraying diesel fuel 1,600 times per minute. Fortunately, my brother, a Lehman mechanic in a former life, was along for the ride from Palm Coast, FL to our home port near Annapolis and he discovered the problem not long after its occurrence (not a huge amount of diesel had escaped) in doing a routine engine room check. Unfortunately, darkness was approaching and it was obvious that we could not reach our planned destination marina on one engine due to current and the 35 knot wind on our bow.

We tried anchoring but the anchorage that was suggested by the marina was wholly exposed to the wind plus our boat had tremendous windage due to the full canvas enclosure (now mostly gone). We dragged but that may have been to my inexperience. By this time the light was fading rapidly. Fortunately, about a mile off I could see an unlighted face dock. I said to my brother and the Admiral that that was where we are heading. They both said "but we don't have permission". We spent the night at that dock and replaced the offending injector in the morning. We had a full set of spares aboard that came with the boat.

Now, getting that boat tied up that night was another adventure. I mentioned being inexperienced. Imagine an inexperienced captain trying to dock a boat with one engine, a 35 knot wind blowing, and a very swift current along the face dock. We got her tied up but with a tremendous struggle to get the stern against the dock. It sure would have been nice to have known how to employ a spring line to do so.

I have always double clamped, but the tail on the fitting has to be long enough, I'v had to change a few......Noel S

Yes, SS can offer corrosion advantages if your clamps are getting a salt water shower. But SS is not as "strong" as mild steel assuming similar dimensions.

So maybe Eric's galvanized clamp and application is not an issue. Especially if he used quality hose.

My former boss was big on using push lock fittings... not USCG approved and he didn't seen to care as he used them on all the non inspected boats....but seem love a better option than clamps...

Wonder what size they go up to?

Eric, I don't have a problem with you using steel clamps but just in case you're interested, ABA makes the same style in 304 stainless. I use them on small fuel lines.
Scandvik Marine Inc. - Products

To be clear, IMO good stainless clamps are only necessary in below the waterline places exposed to salt water. Even with stainless I spray them with Corrosion X. Crappy "stainless" clamps don't belong anywhere IMO.

That's wonderful Parks.
Need to bookmark this on my computer.
Perhaps they have bigger ones than my current source.
Thank you much.

Cal,
That "Corrosion X" sounds like good stuff to have.

Someone like Eric who keeps an eye on maintenance should be fine with non stainless clamps.
Thanks NS for identifying the clamps as "jubilee" type. My Peugeot dealer/mechanic friend years ago thought they were great clamps applying even pressure, and, as they came on Peugeots...

Eric--- Those are good clamp designs in my opinion. I used the same style for attaching the new sight tubing for our saddle tanks to the upper and lower fittings on each tank. I double clamped, too, but flipped them opposite so the clamp bolt on one is on the other side of the tubing to the other one but with the heads facing the same direction. The flipped thing is a good theory which in practice probably doesn't really improve anything, particularly with this style of clamp.

FWIW, this style of clamp is available in stainless steel if one wants them in that material. We got ours at Fisheries Supply in Seattle.

Some really cool clamps come from oetiker. You need special tools to apply them but they hold. I think a lot of the problems with hose clamps in general comes from inconsistent application. Too tight and they fail. Too loose and they fail. Also, some things need to be retightened after the hose warms up.
It always amazes me that for every hose I have seen leak I have had to cut the same hose off in another instance to get it apart.

"spraying diesel fuel 1,600 times per minute"

WOW! You were cruising at 3200RPM?

FF said:

"spraying diesel fuel 1,600 times per minute"

WOW! You were cruising at 3200RPM?

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Ah, yes, I forgot, it's a four stroke engine. So, 800 times per minute rather than 1,600. Still, that's a lot of spray if not discovered quickly.

My pin hole put out about a pint of diesel rumming all day for several days

We kept smelling it and I would find some in the drip pan...but it would be so fine and dry by the time I would do my end of day checks...didn't find it till maybe the third or fourth day as the mist was more visable.

The second pipe break I had was at the nut right on top of the injector pump. It was easier to find as it looked just like arterial bleeding. A normal sized drop would shoot up an inch or two from the injector pump, but fortunately no atomization danger. I tried tightening, thinking it was loose...but when rock tight.I gused anot her isue and limpedance another hour to the closet marina. It was about a quart in the pan by the time I shut her down.

Old diesel injection is very modest pressure 1500 to 1800 PSI or so.

Even so it is good practice never to stick flesh near the stream.

In the usual 3000 PSI or newer 5000PSI hyd systems a pin hole will puncture the skin , can you say blood poisioning ?

Not sure if a wimpy 1800PSI with a pin hole would puncture , but am not willing to experiment.

FF said:

Not sure if a wimpy 1800PSI with a pin hole would puncture , but am not willing to experiment.

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Fluid injection injuries can occur at pressures as low as 150 psi. If it is diesel fuel or hydraulic oil, the injury can result in severe damage to fingers or hands and may even lead to amputation within a day or two of injury if not immediately treated.

There is no such thing as wimpy when it comes to that stuff! It is a very serious consideration when working around your fuel injection system.

Marin said:

Eric--- Those are good clamp designs in my opinion. I used the same style for attaching the new sight tubing for our saddle tanks to the upper and lower fittings on each tank. I double clamped, too, but flipped them opposite so the clamp bolt on one is on the other side of the tubing to the other one but with the heads facing the same direction. The flipped thing is a good theory which in practice probably doesn't really improve anything, particularly with this style of clamp.

FWIW, this style of clamp is available in stainless steel if one wants them in that material. We got ours at Fisheries Supply in Seattle.

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Marin,
It's nice to find nice things that work.
I didn't "flip them" or install at 180 degrees because I reasoned that w the clamping all the way around flipping wasn't needed. Also relatively low clamping pressure on barbed fittings played a role.

RickB said:

Fluid injection injuries can occur at pressures as low as 150 psi. If it is diesel fuel or hydraulic oil, the injury can result in severe damage to fingers or hands and may even lead to amputation within a day or two of injury if not immediately treated.

There is no such thing as wimpy when it comes to that stuff! It is a very serious consideration when working around your fuel injection system.

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When I was flying C-130s, there was a maintenance technician that lost his hand due to a 3000psi hydraulic leak. Modern common rail engines have fuel pressures in excess of 20,000psi. Imagine what that would do to you.

BlueYonder said:

When I was flying C-130s, there was a maintenance technician that lost his hand due to a 3000psi hydraulic leak. Modern common rail engines have fuel pressures in excess of 20,000psi. Imagine what that would do to you.

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My JD tractor manual has warnings all over the place about hydraulic leaks. They have an 800 number for the doctor to call if one is injured by the pressurized hydraulic fluid. Seems like they really want the ER doc to call them. There are specific warnings about using one's hand to find a leak. I think my tractors hydraulics are 2,000 PSI which is not something to play with at all. I have pinched and cut a hose with the 4n1 front loader bucket and it was not pretty. Scary actually.

Later,
Dan

I am curious, why such crazy high pressures? Why does it take pressures like this to atomize the fuel? Inquiring minds want to learn.

Injection pressures are high because the fuel has to be atomized. The higher the hole the finer the hole size the fuel has to travel thru and thus the better the atomization. The closer to a gas diesel fuel is the easier it is to ignite and the bigger the burn.

I know of an 18yo. apprentice at a BMW workshop who lost an eye due to brake fluid which escaped from the power brake booster. Very sad event, especially for a young man.
We fractured the line from the lift pump to the on engine final filters of one of the Lehmans. It sure sprays out, makes a mess, and quickly.