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Old 05-12-2012, 05:17   #121
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Re: Brass Seacocks -

Quote:
Originally Posted by Bill_E View Post
I managed to find the DIN standard. It’s actually DIN 3357-4 for nonferrous ball valves. It turns out that in the sizes of interest to me, there are three possible threads, including NPT. I will just have to get some pipe and see if it’ll thread easily into the ball valve in place. I hope it’s NPT because I’m going to have a hell of a time finding the others.

Regarding wall thickness, Thanks to MaineSail!! I understand that when you cut the thread you reduce the wall thickness of the starting pipe. I suppose that when buying thruhulls one should look for those with a “thick” wall and suffer the loss in ID. Better to have some flow restriction than a weak system.

Now, what is the downside to using an NPS tap and cutting the thread in the ball valve to match the NPS thruhull? It doesn’t seem that this would drastically reduce the wall thickness because the ball valves already have pretty thick walls. I guess this falls into the category of “good enough” until I haul out and redo everything according the best practices.


Bill
The first couple of threads in the ball valve are the same size as the parallel thread, by running a parallel blind or plug tap all you are doing is making the thread the same size.

It is a common thing to do, a parallel thread is far better of holding pressure than a tapered one hence hydraulic's etc prefer. Compound like Loctite Pipe sealant is the go!

A properly made/cast thru hull will have maximum thickness so as to not be an issue.
Remembering a caulked boat relies on putty and cotton so what you are doing here is not a weakness :-) (a joke before the boat police comment).

Cheers
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Old 05-12-2012, 08:37   #122
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Quote:
Originally Posted by goboatingnow

BSP parallel and taper threads are designed to go together and regularly do in all forms of plumbing , The tapered thread is designed to provide the sealing unlike parallel thread joints where some other sealing is required.
I'm not a plumber and you may be, but I have always heard the opposite. Tapered threads are for joining and sealing and straight threads are only for joining.
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Old 05-12-2012, 08:41   #123
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Re: Brass Seacocks -

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Originally Posted by PamlicoTraveler View Post
I'm not a plumber and you may be, but I have always heard the opposite. Tapered threads are for joining and sealing and straight threads are only for joining.
Plumbing and boats are different trades, i'm a boat builder and my position is a parallel thread matching a parallel thread with sealant is the optimum solution short of a flange other wise you will bind on the threads and that will be the the extent of the seal..... Not on my watch!
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Old 17-05-2019, 08:39   #124
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Re: Brass Seacocks -

Beneteau Responds to Seacock Query

Beneteau wrote a detailed response to our (Practical Sailor) recent query from a reader regarding seacocks in his Beneteau (“Seacock, Through-hull Caution” Mailport, PS July 2017). We are continuing to look at seacocks and seacock materials. The last Practical Sailor in-depth report on seacocks was in 1994, so this is long overdue. If you have a relevant seacock story to share, send it to the editor at practicalsailor@belvoir.com.

Here is Beneteau’s statement.

“As they are distributed throughout the world, all Beneteaus are built to the stringent standards of CE certification. CE is the most widely recognized official global standard, and one that is mandated as legally necessary by dozens of countries. The CE directives and legal requirements are used as the reference for the materials and systems needed in order to build Beneteaus.

“CE carries the weight of law in many jurisdictions, and Beneteau observes these; along with the legal requirements of governing bodies such as the US Coast Guard for the North American markets.

“For well over a decade, Beneteau has been installing through-hulls and valves made of a duplex brass alloy which is approved for use in sea water, and which are sourced through a respected supplier.

“Prompted by interest from a BoatUS member, Beneteau recently sent samples of the through-hulls and valves to be tested to confirm that they exceed the specific CE requirements of ISO 6957, the rule governing such items for corrosion issues. The testing was performed by the independent scientific laboratory of CETIM, and the positive results prove the examples met the ISO standard.

“As with many materials submerged in seawater, over years brass alloys may deteriorate due to chemical or electrical reaction (electrolysis), sometimes at an advanced rate due to external forces. Electrolysis may also be caused by stray current coming from the boat’s electrical system or from shore side sources (such as docks or surrounding boats).

“Electrolysis may also be the product of dissimilar materials in the water that create an electrical current that results in corrosion (batteries, metal bulkheads, etc).

“To our knowledge based upon over a hundred thousand boats produced, serious corrosion on through-hulls is episodic, and in our experience the incidence of failure is very, very rare. And those limited episodes can normally be traced to some key contributor; such as stray current, improper wiring, failure to inspect on an annual basis, lack of maintenance, etc.

“Beneteau confirms that it is mandatory to have a competent professional perform a thorough annual inspection of all underwater appendages, items and surfaces for function, integrity or performance, and that includes through- hulls and valves. The inspection of the through-hulls should be undertaken from both the inside and the outside of the hull looking for any color change.

“We also require that there must be regular replacement of the protective zincs anodes (or magnesium if in fresh water). In the case of rapid deterioration of anodes, the cause of such activity must be investigated and a fix for stray current or the exceptional presence of dissimilar metals must be addressed. In some extreme cases it is not uncommon to have anodes erode within a matter of a few weeks. Those examples require extra anode protection or more serious remedies, and expert professionals should be consulted in such instances.

"In some cases it may be necessary to replace through-hulls after years of use, which in those occurrences are considered by Beneteau to be normal maintenance. There are also examples of through-hulls which, due to standing condensation or a leaking connection, visually appear to be severely degraded on the surface, only to find that after a short minute or so of polishing they are fully structurally sound, functional, and visibly improved. With proper maintenance and vigilance, through-hulls and valves will remain reliable and secure.

"As a general reminder, it is recommended that boaters close all through-hulls upon leaving any unattended vessel."

Wayne Burdick

President, Beneteau Inc.

https://www.practical-sailor.com/iss...y_12456-1.html
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