Strength of Seacocks, Are Yours Strong Enough?

[onecoolair]

If you stick with "plastic" valves I would recommend the OEM 93 Series. Once you know your sizes any chandler that sells Forespar can order them. I've got some more testing to do so may just grab a white valve with red handle to see how it does....

Hey....that test would be interesting to see. Make sure it is stamped as upvc plus find a cpvc they also come in gray. And depending manufacture come with different colored handles blue,yellow etc. besides red...Most upvc valves will have a octagonal shape to them and most are slightly off color. While the standard pvc will usually be totally rounded and are not stamped as such but just maybe have the size stamp on it.
http://answers.yahoo.com/question/index?qid=20090525055147AA4UQ9H


Right now I am not happy with the way any of my thru hull fittings are attached at the hull. Nor am I satisfied that hull would not fail first before the thru hull fittings. Plus hunter located one fitting. The masacrator pump discharge in such a location that the only way to reach it is to climb on to the swim platform and open hatch exposing the chance that a wave hitting the back of boat just the right way while hanging up side down in side storage locker. Not to mention thru hull is exposed to any thing rolling lose in that space. That Thru hull will be removed and glassed over when I do the next haul out.

 

[anchorclanker]

Re: Strength Testing A Seacock/Thru-Hull To Failure

My respects, and I apologize beforehand, but I see nothing at all here that looks anything like the drawing. In the drawing, the ball valve has a heavy integral flange as part of its casting, through bolted to the hull, with a pipe nipple threaded from outside the hull, into the female end of the ball valve flange.

In all these other pictures, I see only a threaded nipple coming through the hull, and a common female thread ball valve threaded onto the nipple.

In the drawing, the entire ball valve casting is through bolted to the hull, with a backing plate for added strength. The nipple, threaded through from outside, primarily only offers sealing protection, the primary strength is carried by the flange and through bolts.

with only a threaded nipple coming through, and the valve threaded onto it so far from the hull, it would have many time less strength to torque loads than what is described in the drawing. You need a flanged ball valve with female threads at the flange as well as the opposite end, to match the fitting in the drawing.

The fitting described in the drawing would rip out of the hull before it broke.

 

[anchorclanker]

Re: Strength Testing A Seacock/Thru-Hull To Failure

I would also argue that high quality manganese bronze is not at all brittle, but is in fact quite malleable and has as much tensile strength as mild steel. Thats why they make propellers out of it. You can hit rocks and stumps and rather than snap off a blade it will plow right through.

Some of the fittings coming out of China are not manganese bronze, but more often aluminum bronze, and of low quality to boot.

A good manganese bronze nipple would not just snap off, but would deform and bend before failing.

 

[mitiempo]

While most propellors are manganese bronze (up to 39% zinc) bronze through hulls and seacocks like Groco or Conbraco are made with 85-5-5-5 bronze, only 5% zinc. Very different materials.

 

[Maine Sail]

My respects, and I apologize beforehand, but I see nothing at all here that looks anything like the drawing. In the drawing, the ball valve has a heavy integral flange as part of its casting, through bolted to the hull, with a pipe nipple threaded from outside the hull, into the female end of the ball valve flange.

In all these other pictures, I see only a threaded nipple coming through the hull, and a common female thread ball valve threaded onto the nipple.

In the drawing, the entire ball valve casting is through bolted to the hull, with a backing plate for added strength. The nipple, threaded through from outside, primarily only offers sealing protection, the primary strength is carried by the flange and through bolts.

with only a threaded nipple coming through, and the valve threaded onto it so far from the hull, it would have many time less strength to torque loads than what is described in the drawing. You need a flanged ball valve with female threads at the flange as well as the opposite end, to match the fitting in the drawing.

The fitting described in the drawing would rip out of the hull before it broke.

The whole point is that hundreds of thousands of boats shipped from manufacturers with a valve threaded onto a thru-hull, not a "proper" seacock.

Even if installed in this manner if it is strong enough to pass the ABYC test then it meets the ABYC standard provided other criteria are also met. In larger sizes, such as 1.5", 2" and up they do meet the 500 pound test. In smaller sizes they do not.

Many builders, even today, still slap a ball valve onto a thru-hull fitting while also claiming to be ABYC / NMMA compliance built vessels.

That drawing, while showing a "proper" seacock, is the ABYC test whether it is a proper seacock or a valve threaded directly to a thru hull. There is no requirement for a "flanged" valve or flanged seacock just that any installed sea valve meet the strength standard.

Any thru-hull penetration below the max heeled waterline needs to withstand 500 pounds, at the innermost hard piping, for 30 seconds to meet the UL/ABYC standards. There are thousands upon thousands of boats out there that DO NOT meet this standard or even come close, this is why I posted what I have.

There is no requirement to through bolt, or even to have a flanged valve just that the installed sea-valve, as installed, can handle the load & meet the corrosion standards of UL & the ABYC...

 

[Maine Sail]

I would also argue that high quality manganese bronze is not at all brittle, but is in fact quite malleable and has as much tensile strength as mild steel. Thats why they make propellers out of it. You can hit rocks and stumps and rather than snap off a blade it will plow right through.

Some of the fittings coming out of China are not manganese bronze, but more often aluminum bronze, and of low quality to boot.

A good manganese bronze nipple would not just snap off, but would deform and bend before failing.

UL Marine valves & thru-hull fitting do not use manganese bronze.. The bronze used is an 85-5-5-5 (eighty five, three-five) bronze.. In Europe they use DZR-1 which is a "dezincification resistant BRASS" it is quite poor in comparison to what we use in the US which is 85-5-5-5 bronze. Of course in Europe the standard only requires a 5 year service life...... I have seen 70 year old 85-5-5-5 bronze seacocks still in perfect working order.

 

[anchorclanker]

Re: Strength Testing A Seacock/Thru-Hull To Failure

Main, I think were both on the same page, I was simply pointing out the basic construction of the drawing. Even poor quality brass would be quite strong if the parts and assembly were as per that drawing.

I will also mention that we need to be careful where we buy materials. Many things we buy today are made in china and the materials are not always the spec they say they are. Old fittings, even real old fittings, can usually be cleaned up and reused. I would rather buy and use an old flange type ball valve, and install it as per that drawing, than anything I have seen otherwise. Even if it leaked a bit, at least you would know its not going to just "break".

 

[Maine Sail]

Main, I think were both on the same page, I was simply pointing out the basic construction of the drawing. Even poor quality brass would be quite strong if the parts and assembly were as per that drawing.

I will also mention that we need to be careful where we buy materials. Many things we buy today are made in china and the materials are not always the spec they say they are. Old fittings, even real old fittings, can usually be cleaned up and reused. I would rather buy and use an old flange type ball valve, and install it as per that drawing, than anything I have seen otherwise. Even if it leaked a bit, at least you would know its not going to just "break".

This is why you buy only seacocks, valves or thru-hull fittings from manufactures who have tested the fittings and carry the Marine UL label. Groco, Conbraco/Apollo, Buck Algonquin or Forespar/Marelon.. If it does not carry a Marine UL approval DO NOT buy it...

 

[Maine Sail]

This test has little to do with anything but drilling and tapping the backing block rather than drilling entirely through the hull of the boat for the seacock flange. Some boaters are adamant they don't want any more holes in the hull so I offered this option.

I originally posted this as; " Alternative Method Backing Blocks" on my web site for those who do not want to drill yet more holes entirely through the hull. On my site I recommend using 5/8" GPO-3 or 5/8" G-10 polyester/fiberglass or epoxy/fiberglass sheet.

For this test I used 1/2" GPO-3 polyester/fiberglass sheet. This stuff is VERY strong and G-10 is even stronger.

One reader emailed me, with concern, that if you hit something and lost the thru-hull the bolts would simply pull right out of the fiberglass sheet and you would sink. His take was that the bolts are a weak link. Having tested this, before I ever recommended it, as an "alternative" option, I knew that to not be the case..

To mimic this event I did not install the thru-hull and instead relied solely on the three 1/4" X 20 machine screws to hold the seacock into the GPO-3 board.

So which was stronger a 3/4" Marelon tri-flange seacock or the 1/4 X 20 machine screws tapped into the 1/2" fiberglass sheet?

Disclaimer: It should be noted that the thru-hull is an integral part of the strength of the seacock assembly. The video below is an "unfair" representation of the failure point of the Marelon tri-flange seacock because the thru-hull fitting was not installed. I do plan to destroy another valve identical to this one, only with the thru-hull installed. My guess is that it will meet the 500 pounds for 30 seconds.

Here we go:

 

[Maine Sail]

New test:
This test has three parts.

1- To test the strength of drilling and tapping directly into a 1/2" fiberglass board to see if it meets the ABYC standards.

2- To test a 3/4" Marelon ball valve to ABYC strength standards.

3- To test the strength of a Groco flanged adapter in 3/4".

Disclaimer: In fairness to Forespar this was an early Marelon valve that already had the handle fail. Why ruin a brand new valve, right? Still, in my opinion, the strength of the valve body should not have been compromised by the missing handle. With the video viewed frame by frame the valve failed & slipped the first thread at 253 pounds.. The ABYC standards call for 500 pounds at the innermost hard piping or male adapter for a period of 30 seconds. This particular valve, an older model, did not meet the standard but this is not to say a newer version would act the same.

 

[Maine Sail]

Test #6 is up:

 

[onecoolair]

Maine Sail...Thanks For the testing very informative..BUT IT'S........UPVC...That's....UPVC......You tested a pvc valve. It would be interesting to see the correct valve tested. Again UPVC.
Okay now that I made myself clear on that discrepancy.
Next....
??...So what ever I do I will need to install for each fitting at least a 1/2"x 12"x 12" backing plate to inside of hull and then mount the thru hull fittings in the center of each 12"x 12" backing plate. For if one was to preform this test on a factory installed fitting that was installed in the hull of my boat I would have a huge hole ripped out! So it sounds and looks like I have got some major factory defects to correct. No matter what type of ball valve I now have.

 

[Maine Sail]

Maine Sail...Thanks For the testing very informative..BUT IT'S........UPVC...That's....UPVC......You tested a pvc valve. It would be interesting to see the correct valve tested. Again UPVC.
Okay now that I made myself clear on that discrepancy.
Next....
??...So what ever I do I will need to install for each fitting at least a 1/2"x 12"x 12" backing plate to inside of hull and then mount the thru hull fittings in the center of each 12"x 12" backing plate. For if one was to preform this test on a factory installed fitting that was installed in the hull of my boat I would have a huge hole ripped out! So it sounds and looks like I have got some major factory defects to correct. No matter what type of ball valve I now have.

Umm I did test a uPVC valve. That valve is un-plasticized PVC and NSF61 rated. NSF rated valves apparently can't contain plasticizers, I learned something new. I had my distributor look it up for me. I also grabbed one identical to the one you showed that is also uPVC. Just have not uploaded the video... They fail at well below the minimum ABYC standard.

Basically the guys at the plumbing wholsaler cleared up the confusion. Any "PVC" valve sold as NSF rated is an un-plasticized PVC or uPVC or as some manufactures refer to it PVC-U. Spears one of the largest PVC valve makers states that all their valves are uPVC yet are referred to as simply PVC.


You'd be surprised how strong a hull is with a 6" dia backing plate...

 

[onecoolair]

You need to check again I bet that was a standard pvc valve. The valves I have are shaped slightly different have a slightly thicker construction and are stamped as being upvc. The standard color is gray but can be made in white most come out as an off white. To the casual observer, there's little difference between the PVC valve and a uPVC valve. Beyond the superficial similarities, the two types of valves are manufactured differently and thus have different properties and different applications such as in industrial uses etc......PVC is softer as much more flex does not have a uv rating and were as uPVC is much harder. I am really curious how a true uPVC valve does against that marelon valve you had already tested. If at least if it beats or matches the marelon I will sleep a little easier till I can fix the situation. BTW...All my thru-hull fittings are bronze just do not know type. And its the way that they are not properly back plated that is a concern. And Its the bronze valves that the manufacture installed that have nearly all failed.

At least at this point if I had to deal with a failure it would be the valve and not a much larger hole being ripped out of the hull from the factory installed thru-hull fittings. After seeing your test the hull would be the first to give way making for a much larger problem.
So for now I will have my wood plugs always at the ready and a few extra valves that can be simply screwed on temporarily in an emergency.

This has got me somewhat worried because of all the extra cost involved that I will have endure because of a manufactures half ass construction shortcut.

 

[Maine Sail]

Here's the uPVC valve:

I could not get it to hold steady because once it hit 200+/- the threads began deforming then the line would slack and I had to apply more pressure. It failed at roughly 275+/- pounds below the minimum ABYC requirement for a seacock.

 

[onecoolair]

Yep that's it! u-PVC....In the other video showing the marelon it looked like just a standard pvc valve that you were showing. Thanks for the video. At least it looks like it did about as well as the marelon in my opinion. Right now the u-PVC valve I was forced to use in an emergency when the first factory installed valve failed (handle broke) off about 8 years ago and water started pouring in is in a protected area so I doubt it will ever have to be put to such pressure. Right now in my opinion...because manufacture did not properly back plate any of my fittings and used questionable product, I feel that if I had fittings installed as you recommend without the proper backing my hull would fail before thru hulls or valves would give way. Which would create a much larger problem...Even over the ones that are in place now.
Sorry if I have been a pain.
Thanks again for the test videos it not only helps me but I am sure others as well.

 

[SaltyHog]

Sorry to bring up an old thread, but I think my situation is relevant. I'm replacing the thru-hulls and valves on my boat. The existing setup had ball valves threaded on the ends of the thru-hulls. I think most agree this is not a good plan going forward. The plan is to make G10 backers and install either flanged adapters or seacocks. The issue I'm having is this: several of the thruhulls are in locations with little room above. The existing install had a street elbow on the end of the thruhull and a ball valve on the street elbow. I was planning to use Groco tri-flange adapter to a street elbow and then to a ball valve. But then I saw Maine Sail's testing and I got to thinking that this might not be much better than what is there now. The tri-flange adapter will certainly be much stronger than the tail of a thru-hull, but the street elbow fitting into the the ball valve is a potential weak point. Am I over thinking this? I might be able to fit a tri-flange seacock with short 90 degree NPT to hose adapter, but it will be tight. Which method would be better? Also, Buck Algonquin seems to have the lowest profile seacocks. Are these a good quality part? There was at least one mention of someone having a problem with corrosion of the ball. Any pros or cons to Buck Algonquin seacocks?

 

[Maine Sail]

Sorry to bring up an old thread, but I think my situation is relevant. I'm replacing the thru-hulls and valves on my boat. The existing setup had ball valves threaded on the ends of the thru-hulls. I think most agree this is not a good plan going forward. The plan is to make G10 backers and install either flanged adapters or seacocks. The issue I'm having is this: several of the thruhulls are in locations with little room above. The existing install had a street elbow on the end of the thruhull and a ball valve on the street elbow. I was planning to use Groco tri-flange adapter to a street elbow and then to a ball valve. But then I saw Maine Sail's testing and I got to thinking that this might not be much better than what is there now. The tri-flange adapter will certainly be much stronger than the tail of a thru-hull, but the street elbow fitting into the the ball valve is a potential weak point. Am I over thinking this? I might be able to fit a tri-flange seacock with short 90 degree NPT to hose adapter, but it will be tight. Which method would be better? Also, Buck Algonquin seems to have the lowest profile seacocks. Are these a good quality part? There was at least one mention of someone having a problem with corrosion of the ball. Any pros or cons to Buck Algonquin seacocks?

Even with the 90 degree elbow the flanged adapter will be considerably stronger than a valve/thru-hull. This option will also allow for easy future replacement of valves when, not if, they do need replacing. The flanged adapter could virtually outlast the boat but the ball valves won't..

I have a 1" tri-flange/bronze street ell /valve for our engine intake. No other option for this location. So long as it is protected you'll be fine. The actual lever arm is not that much further away when adding a street 90. If I had to guess it would easily meet the ABYC standards. Be sure to use an 85-5-5-5 street ell Groco has them and Perko may still have them too.......

 

[SaltyHog]

Even with the 90 degree elbow the flanged adapter will be considerably stronger than a valve/thru-hull. This option will also allow for easy future replacement of valves when, not if, they do need replacing. The flanged adapter could virtually outlast the boat but the ball valves won't..

I have a 1" tri-flange/bronze street ell /valve for our engine intake. No other option for this location. So long as it is protected you'll be fine. The actual lever arm is not that much further away when adding a street 90. If I had to guess it would easily meet the ABYC standards. Be sure to use an 85-5-5-5 street ell Groco has them and Perko may still have them too.......

Maine Sail -- Thanks! Great videos and explanations. Reveals a lot. I guess the wall thickness of the tapered male portion of a 90 street elbow is enough to meet strength/impact requirements. That was my main concern My situation is exactly yours; the engine raw water intake. I may increase the size from 3/4" to 1" to add some strength and reserve capacity.
-Tom