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Old 05-06-2004, 06:57   #1
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Double Hose Clamps ?

Double Clamping Hoses - A (Controversial) Caution:

I posted the following opinion some years ago (donít recall where), and wonder if anyone has had any luck in locating good hose barbs (& barbed fittings) that have longer stems - long enough to accept the recommended TWO hose clamps?

There has been a lot of discussion concerning the "Good Marine Practice" of
double clamping hoses. Many Marine Surveyors in their "Recommendations" will often (almost always) state, "Double clamp all below water line hoses."

Modern (high quality) hose clamps are a passivated stainless steel strap with stainless steel worm screws (unless one buys the clamps at auto supply or home improvement
stores). Unfortunately, modern hose barbs are too short to accommodate two clamps.

At an ABYC seminar several years ago, Pat Kearns of ABYC said that she could
find no reference to double clamping of hoses, except fuel and exhaust hose.
None of the other thirty-five marine professionals present could cite a reference to double clamping water hoses except those in the CFR (Code of Federal Regulations) which relate to other than recreational vessels.

I surveyed a boat last month that came close to sinking because the owner,
based on the advice of a previous surveyor to double clamp, added an additional clamp. That second clamp was just past the end of the barb and actually pulled the
hose partially off. I was able to wiggle the hose and pull it off the barb
(with the boat high and dry at the time).

Therefore, be extremely careful about double clamping. Only do it when you
are sure that the hose barb is of sufficient length to accept the clamp.
I often install the second clamp loosely on the hose, so that itís immediately available should the prime clamp fail. I also tie (light string) a soft wooden cone plug to each through-hull fitting.

BTW: If you have to remove a hose, it occasionally works to relocate the clamp to
the end of the barb and you may be able to use it as a device to remove the
hose. That doesn't work on an old salted up bronze barb, but often works on plastic fittings.

I look forward to any comment & opinion.
Agree? - Disagree? - Why?

Gord
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Old 05-06-2004, 08:23   #2
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Hose clamps

I only have one hose clamp on my hoses including the exhaust and I have not told anyone until now. My boat came that way from the factory. There is very low pressure on the hoses unlike the radiator in my car which has one clamp. When the taps are open I am on the boat, this seems to be a fairly save practice. I guess a clamp could snap which would be a good reason for having two. As you said there is not enough room for two on a lot of the attachment points. On the exhaust I could not remove the rubber piece after removing the clamp, it had married itself to the metal part. It is a bit like nailing a piece of wood, if one nail is good then two must be better, what about three or four until the wood splits. I think one good clamp is sufficient for next to zero psi. Have a look under the kitchen sink at the lines carrying 40 to 50 psi or the car radiator at about 12 psi. BC Mike C
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Old 05-06-2004, 10:51   #3
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Heavy Duty Hose Clamps

Personally, I don't like the standard hose clamp for anything that is critical. If you tighten them down to their maximum ability. All it takes is a good bump and it'll strips out the teeth on the strap. You might as well have left it loose to start with.

What we use on the paint rigs for street stripping at work is what is usually used on marine exhaust hoses (T-bolt clamps). See link below......

Westmarine sells these and they can be tightened down too tight in some cases. The source where we get them is half the cost of Westmarine. They are from 1" and up. The down fall is that you must get each clamp reasonably close to the size you want, for the adjustment does not have much range and if they are too small they are very difficult to get started. Most of them come with a standard 1/4"-28 SS nut. I usually install a nylock nut for extra security. I have all my exhaust fittings without barbs with these clamps and unable to pull them off. As well all thruhull fittings over 1".


http://www.westmarine.com/webapp/wcs...39446&y=3&x=23

More links to clamps.............

http://www.hosexpress.com/clampsandt...psandtools.htm

http://www.clampco.com/

http://www.breezeclamps.com/tbolt.htm

http://www.centralstateshose.com/hoseclamp.php (with down load to catolog)

.................................................. ............._/)
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Old 05-06-2004, 19:13   #4
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I also use a single 316s/s T-clamp but I always add another s/s nut as a locknut as its not affected by heat and can be reused unlike nyloc nut that should be replaced.
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Old 07-06-2004, 09:40   #5
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I agree with you Gord - double hose clamps are not always possible or necessary.

Better to use one top quality (AWAB) non-perforated clamp than two cheap ones - except at the fuel and exhaust.

One problem is how tight to make them. The manufacturers say about 37 inch/pounds. That is what the average person can produce using a nut driver. Some hose though can't take that much (white sanitation hose for one) so two clamps of lesser torque might be better.
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Old 11-06-2004, 10:36   #6
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...But how do you assemble?

What I want to know, is how to get the frikkin hose on those frikkin fittings. I spent a good 20 frikkin minutes just pushing a 1 1/2" waste hose onto a fitting - I mean trying to... I put waterproof teflon grease on it, and pushed for all I was worth. Used Gord's trick of putting clamps on for better handling. Next step is to use the clamps to hang little pulleys all over the bugger. I doubt that 8-1 purchase will get her on.

What are the secrets? Bought both the hose and the fitting at West, and it starts on, just won't budge past the first bur!!

Of course, these buggers are always in the most outrageous spots to work. A little bit of last year's sewage hanging around helps a lot too. I swear, I was ready to throw myself onto my knife last night.
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Old 11-06-2004, 11:55   #7
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How about sticking the end of the hose in a pan of boiling hot water right before you put it on. This may have the effect of making the hose more pliable and even expanding it slightly.

Of course some polymers and natural rubber actually contract when heated.

Woody
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Old 11-06-2004, 15:19   #8
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I feel your pain. That waste hose is the worst possible stuff to get on. Even boiling water makes little difference. But boiling water will help just slightly and then you just have to fight with every once of strength you have. Of course on the Plus side, it is just as impossible, infact more so, to get the hose back off again. So it isn't going to fall off.
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Old 11-06-2004, 18:43   #9
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I use a heat gun on most of my tight fitting hoses. They don't seem to be any harder to take off.
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Old 11-06-2004, 22:03   #10
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I have also found that a heat gun is definitely helpful
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Old 12-06-2004, 21:48   #11
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Try some K-Y jelly and a little water, after the heat.

Put the K-Y in the hose and some water on the burr.

OK! I know what ya all are thinkin!.........(\_,,,,,,,
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Old 20-06-2004, 08:40   #12
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Got It On!

Well, I found the winning combination. A hair dryer called "Hot Stuff", teflon grease, and a part of the day when I am fresh. I got the hose as hot as my hands could handle, and twisted back and forth. Repeating for 10 minutes got it on.
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Old 28-06-2004, 16:56   #13
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...and it doesn't leak

It doesn't leak. Launched, pooed, flushed, and no steady drip. Boy - that was a leak that took a whole season to find. We're cleaning up the port hull for the last time. Interestingly, we started up the starboard hull, with bleach and cleansers, trying to figure out what went wrong over there. Turned out to be a bottle of Okanagan red wine, well towards the bow. It froze, and left this ruddy, musty trail. What a waste. I am taking this poor boat back before freezing is another issue!!

I recommend all Canadians empty their wine cellars at the end of the season.

Thanks for your advice.
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Old 14-07-2004, 08:50   #14
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The only reason to double clamp is the extra safety in case one fails. And I HAVE had a single clamped exhaust hose fail which promptly filled the bilge with hot salt water and the salon with steam. I just installed a new head and couldn't for the life of me figure out why I would need to double clamp a 3/4'" SUCTION hose. I agree with one poster and double clamp all my exhaust and fuel line fittings and single clamp everything else.

As for using KY Jelly or Vaseline to make the hose easier to slip over the barb, NO NO NO NO! Do NOT do this!!! Use a heat gun to make the hose pliable enough to slip over the fitting. If you HAVE to use something to get it done then use some RTV or Teflon paste as both of these will dry and help seal the hose whereas the slippery goop will just stay slippery and help the hose to slip off the fitting. I know because I did that at work once.
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Old 14-07-2004, 19:34   #15
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K-Y jelly

Actually K-Y is water soluable and dries up in a short period of time or rinses away when wet all the time. That's why I use the stuff on sewer and water lines. Never had a problem with it coming back off. Usually have to cut the hose to get it off!

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