Replacing Ball Valves Without Replacing Skin Fittings -- Bad Practice?

[Dockhead]

Originally Posted by ramblinrod

Depends how one values their time. As mentioned, it is very difficult to remove valve from thru-hull fitting without special thru-hull tool and second person. Even then, one risks breaking bedding compound seal, so it is prudent to remove the thru-hull, dress the threads, and re-install.

When on the clock, it is less expensive to cut the thruhull head off with a cutting wheel on an angle grinder, and pull the kit and kaboodle into the boat, to
Discard, and replace all with new.

If attempting to preserve thru-hulls cause another day of yard fees, it may also be cheaper for DIY to cut and replace.

When time is not valued, and tinkering on the hard is preferred, with yard fees paid anyway, by all means, save the cost of the new thru-hulls, by removing, cleaning and rebedding originals if still serviceable.

That sounds like good advice.

If I had known what I would find when I got into it, I would have organized professional labor and would have done them all in one swell foop.

But as it is, there was no way to hire anyone on such short notice.

I've only had one of the skin fittings turn on me, so I will be rebedding that one, but the other 6 were fine, very well bedded as part of the original build, did not turn, have never leaked. So I think I'll be OK, but I think the lesson is that it's best not to do things like this piecemeal -- once one or two are starting to go bad it's best just to do all of them, skin fittings at all. And this kind of work I definitely prefer giving to one of the highly skilled professionals in Cowes, to doing it myself.

You just have to watch their choice of hardware. I had one ball valve replaced some years ago by one very good guy here, but I did not specify what kind of ball valve to use. It turns out he used an inferior kind of DZR ball valve -- screwed to my bronze skin fitting. It's now quite deteriorated -- more so after 6 years or so than my original gunmetal bronze ones at 17 years old. It's remarkable how much longer quality underwater fittings last; cutting corners here is false economy.

[Rorzech]

Please don't take my word for it ! Maybe do a little research on your own, like email the manufacturer. Decades of pipe fitting doesn't squat if you've never learned the science behind it from the beginning.

[OS2Dude]

Love a good quality Butyl tape for sealing my deck hardware. I've not ever used it for below water.

[Compass790]

Originally Posted by Rorzech

Please don't take my word for it ! Maybe do a little research on your own, like email the manufacturer. Decades of pipe fitting doesn't squat if you've never learned the science behind it from the beginning.

Trouble is cobber science means squat if the stuff works as a sealer. Many times people find uses for things that may not be their original design use. Trust me, if you do pressure pipe work & it leaks no-one is happy so you soon find find out what works or not. After all science said the world was flat once. Anyway you use what you like & I'll continue to use what works. Sealer combined with thread tape is better than thread tape alone if necessary tho, just experience tells me it's unnecessary on very low pressure fittings.

[jtsailjt]

Last week we hauled out for bottom painting and I wanted to replace 2 ball valves because one was stuck in position and the other would move but nut that secures handle was badly rusted so couldn’t be removed. In order to have more room to work I decided to remove the handle of a nearby ball valve. The valve moved freely but after removing the nut the handle was difficult to slide out along the threaded shaft and as I attempted to work it off the shaft broke off about 1/4” inside the ball valve. This one that broke was about 6” above waterline and was the outlet from the rarely used forward shower sump. So I decided to replace it with a Marelon valve. I installed the Forespar Marelon valve and was screwing in the 90 degree black marelon hose barb and needed to turn it about 90 more degrees to align with the hose. It was in a tight spot under the forward head sink so difficult to apply much pressure. But as I hand tightened it those last few degrees the whole top of the valve cracked and came off! It turns out that the threaded portion of the 90 degree barb was slightly longer than the depth of the threaded portion in the ball valve so it bottomed out and exerted an upward force which popped the top of the valve off. My previous boat had all Marelon valves and skin fittings and I never had a problem with them. But even though I understand how I broke this one I’m unimpressed with the fact that it was possible while using so little force. It was a 3/4” valve that cost about $60 and I wasn’t even using a wrench, just hand tightening using the 3” moment arm of the barb. So I bought a replacement Groco bronze valve and all was well. I’m sort of glad that it failed so catastrophically because if it had just slightly cracked I might not have noticed it until it failed at sea.

Of the 3 valves I removed, I only had to remove one skin fitting and that was because cabinetry wouldn’t allow valve removal unless it was first pushed outward. The removed bronze fitting seemed to be in good condition but the cost to replace it was relatively small and I didn’t want to take the time to clean the old one properly. I managed to remove the other 2 valves without turning the skin fittings so saw no need to replace them.

[Kenomac]

Originally Posted by Dockhead

You're got them backwards. It's Naval Bronze which is 40% zinc and is unsuitable for underwater fittings. 85 5 5 5 Gunmetal Bronze is what all of the best underwater fittings are made of, including Spartan, Groco, etc., and it's what Moodys always had, and what new Oysters and Discoveries have, and certainly not anything made of Naval Bronze. Gunmetal is only 5% zinc and it has unlimited life in sea water so long as it has not been subjected to stray currents or galvanic action. The surveyor pronounced my skin fittings fit for another 17 years of service.

A key issue with sea cocks, often overlooked, is being damned sure that there is no galvanic incompatibility between any metal parts in contact. That means that skin fitting, valve, and hose tail must all be the same material. If you screw a DZR valve into a bronze skin fitting or use a brass hose tail (as I have seen very often), you are asking for your boat to sink. I am using not only the same material but the same Italian manufacturer (Maestrini) for everything. The Maestrini fittings are actually a slightly different gunmetal formulation (I got a test certificate with them) with only 4% zinc. Like Spartan and Groco sea cocks made of the same material, they will last as long as the boat as long as you don't do something dumb like screw a brass fitting into them. They are very beautiful and it is a pleasure to see them installed in the boat. Cast and machined in Italy and not stenciled branded Chinese fittings like almost all others these days.

Naval bronze is what is commonly referred to as 85-5-5-5 and has 4% zinc content not 40% as your post indicates, it's intended use is for below waterline fittings in seawater as the name implies. Its been around for many years. Gunmetal bronze is for what it's name implies. Suit yourself, but please look up your metallurgy.

Gunmetal Bronze:

Gunmetal, also called G Metal, variety of bronze, formerly used for ordnance. Modern admiralty gunmetal is composed of 88 percent copper, 10 percent tin, and 2 percent zinc and is used for gears and bearings that are to be subjected to heavy loads and low speeds. It withstands atmospheric, steam, and seawater corrosion and is suitable for valves, pump parts, and steam fittings.

[Wotname]

Hmm... I can't find many authoritative references for Naval Bronze but plenty for Naval Brass.

[Copacabana]

Dockhead, if you've inspected your skin fittings and they checked out OK, I see no reason to change them. I just did the same thing last month with my boat on the hard (changed all the ball valves). One thing I did that you may want to do as well is get a marker (felt pen) and put a few lines on the edge of the skin fitting and hull. That way, if the skin fittings move just the slightest bit when you are unscrewing the valves (and breaking the seal), you'll know (the lines won't be alingned). I use white plumbing tape and PFTE paste (pipe dope) on mine- mostly to make them easier to unscrew in the future. As they have many threads engaged, I don't really worry about them unscrewing on their own.

[ramblinrod]

Originally Posted by Dockhead

So I think I'll be OK, but I think the lesson is that it's best not to do things like this piecemeal -- once one or two are starting to go bad it's best just to do all of them, skin fittings at all.

So true.

Bedding compound typically has a life expectancy of 15 +/-5 years.

If any fitting, above or below the waterline, is more than 10 years old, and begins leaking, it is wise, if at all practical, to remove and rebed everything, ASAP.

If practical, at the same time, it is wise to resin pot all mounting holes in cored composites, so the next time bedding fails, no core moisture ingress, and possible damage, ensues.

The "if it ain't broke don't fix it" mantra, flies in the face of "preventative maintenance".

Rebedding only the fittings that start leaking, is like replacing brake pads on the wheel that wears out soonest. How long before the next one?

[Dockhead]

Originally Posted by Kenomac

Naval bronze is what is commonly referred to as 85-5-5-5 and has 4% zinc content not 40% as your post indicates, it's intended use is for below waterline fittings in seawater as the name implies. Its been around for many years. Gunmetal bronze is for what it's name implies. Suit yourself, but please look up your metallurgy.

Gunmetal Bronze:

Gunmetal, also called G Metal, variety of bronze, formerly used for ordnance. Modern admiralty gunmetal is composed of 88 percent copper, 10 percent tin, and 2 percent zinc and is used for gears and bearings that are to be subjected to heavy loads and low speeds. It withstands atmospheric, steam, and seawater corrosion and is suitable for valves, pump parts, and steam fittings.

Ken, arguing is your favorite pastime, isn't it?

20 seconds of Googling is not enough to get up to speed on this subject. You need at least 40 seconds in order to know that there are a number of different alloys called "Gunmetal", and not only the one you mentioned, which is "G Bronze" or C90300. If you had only just read the entire Wiki article, you would see another type of Gunmetal mentioned:

Red brass is used to produce pipes, valves, and plumbing fixtures and is considered to offer a good mixture of corrosion resistance, strength and ease of casting.[7] It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc.

https://en.wikipedia.org/wiki/Gunmetal


I actually happen to know a little about this because I helped a friend write a business plan for producing quality underwater fittings in Estonia. He did a ton of research on materials and came to the conclusion that LG2 Gunmetal AKA Leaded Red Brass AKA C83600 AKA 85 5 5 5 Gunmetal Bronze is the optimum material for metal underwater fittings, as used by Groco, Spartan, Maestrini, and others. Its advantages include resistance to dezincification, resistance to galvanic degradation, lack of stress cracking, and easy to work (due the lead content) and easy to cast (due to the zinc content).

The OEM supplier to Oyster and Moody for years was the Italian firm Guido -- here is their data sheet:



They are made of "LG2 Gunmetal".

Later Oyster switched to Maestrini, which is the type I'm using to replace my old ones. They are made of the same material, also referred to as "LG2 Gunmetal". I got a test certificate with my new Maestrini fittings:



More on 85 5 5 5 Bronze:



"Naval Bronze" is occasionally used to refer to Naval Brass, which is actually 40% zinc with only 1% tin. This is not suitable for underwater fittings.

"NavY Bronze" is a variety of Gunmetal, namely C90300, usually known as "Navy G". The "G" stands for "Gunmetal". It's not used in yacht fittings as far as I know. It has higher tin and zinc and no or little lead, so it's very difficult to machine.

The words "brass" and "bronze" don't have much meaning and can be confusing. Brass was copper and zinc; bronze was copper and tin, but all these materials we are discussing are neither -- they all have some zinc and some tin and so many are referred to as both brass and bronze. Actually they are all just different copper alloys.

[Cadence]

Originally Posted by Dockhead

Ken, arguing is your favorite pastime, isn't it?

20 seconds of Googling is not enough to get up to speed on this subject. You need at least 40 seconds in order to know that there are a number of different alloys called "Gunmetal", and not only the one you mentioned, which is "G Bronze" or C90300. If you had only just read the entire Wiki article, you would see another type of Gunmetal mentioned:

Red brass is used to produce pipes, valves, and plumbing fixtures and is considered to offer a good mixture of corrosion resistance, strength and ease of casting.[7] It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc.

https://en.wikipedia.org/wiki/Gunmetal


I actually happen to know a little about this because I helped a friend write a business plan for producing quality underwater fittings in Estonia. He did a ton of research on materials and came to the conclusion that LG2 Gunmetal AKA Leaded Red Brass AKA C83600 AKA 85 5 5 5 Gunmetal Bronze is the optimum material for metal underwater fittings, as used by Groco, Spartan, Maestrini, and others. Its advantages include resistance to dezincification, resistance to galvanic degradation, lack of stress cracking, and easy to work (due the lead content) and easy to cast (due to the zinc content).

The OEM supplier to Oyster and Moody for years was the Italian firm Guido -- here is their data sheet:

Attachment 169343

They are made of "LG2 Gunmetal".

Later Oyster switched to Maestrini, which is the type I'm using to replace my old ones. They are made of the same material, also referred to as "LG2 Gunmetal". I got a test certificate with my new Maestrini fittings:

Attachment 169344

More on 85 5 5 5 Bronze:

Attachment 169345

"Naval Bronze" is occasionally used to refer to Naval Brass, which is actually 40% zinc with only 1% tin. This is not suitable for underwater fittings.

"NavY Bronze" is a variety of Gunmetal, namely C90300, usually known as "Navy G". The "G" stands for "Gunmetal". It's not used in yacht fittings as far as I know. It has higher tin and zinc and no or little lead, so it's very difficult to machine.

The words "brass" and "bronze" don't have much meaning and can be confusing. Brass was copper and zinc; bronze was copper and tin, but all these materials we are discussing are neither -- they all have some zinc and some tin and so many are referred to as both brass and bronze. Actually they are all just different copper alloys.

A good write-up. I always suspected brass and bronze were about synonymous. Maybe not to a metallurgist or a machinist but few of us are.

[Kenomac]

Originally Posted by Dockhead

Ken, arguing is your favorite pastime, isn't it?

20 seconds of Googling is not enough to get up to speed on this subject. You need at least 40 seconds in order to know that there are a number of different alloys called "Gunmetal", and not only the one you mentioned, which is "G Bronze" or C90300. If you had only just read the entire Wiki article, you would see another type of Gunmetal mentioned:

Red brass is used to produce pipes, valves, and plumbing fixtures and is considered to offer a good mixture of corrosion resistance, strength and ease of casting.[7] It typically contains 85% copper, 5% tin, 5% lead, and 5% zinc.

https://en.wikipedia.org/wiki/Gunmetal


I actually happen to know a little about this because I helped a friend write a business plan for producing quality underwater fittings in Estonia. He did a ton of research on materials and came to the conclusion that LG2 Gunmetal AKA Leaded Red Brass AKA C83600 AKA 85 5 5 5 Gunmetal Bronze is the optimum material for metal underwater fittings, as used by Groco, Spartan, Maestrini, and others. Its advantages include resistance to dezincification, resistance to galvanic degradation, lack of stress cracking, and easy to work (due the lead content) and easy to cast (due to the zinc content).

The OEM supplier to Oyster and Moody for years was the Italian firm Guido -- here is their data sheet:

Attachment 169343

They are made of "LG2 Gunmetal".

Later Oyster switched to Maestrini, which is the type I'm using to replace my old ones. They are made of the same material, also referred to as "LG2 Gunmetal". I got a test certificate with my new Maestrini fittings:

Attachment 169344

More on 85 5 5 5 Bronze:

Attachment 169345

"Naval Bronze" is occasionally used to refer to Naval Brass, which is actually 40% zinc with only 1% tin. This is not suitable for underwater fittings.

"NavY Bronze" is a variety of Gunmetal, namely C90300, usually known as "Navy G". The "G" stands for "Gunmetal". It's not used in yacht fittings as far as I know. It has higher tin and zinc and no or little lead, so it's very difficult to machine.

The words "brass" and "bronze" don't have much meaning and can be confusing. Brass was copper and zinc; bronze was copper and tin, but all these materials we are discussing are neither -- they all have some zinc and some tin and so many are referred to as both brass and bronze. Actually they are all just different copper alloys.

In other words, we’re both talking about the same 85-5-5-5 alloy under different names. We’re both right as I referenced Italian and high quality US bronze in my first post.

BTW: My expert is my father who worked as a lab metallurgist for forty years. Regarding your comment on arguing being my favorite passtime... YOU seem to enjoy it more than anyone. I’m actually trying to give this forum another chance, as I was quite happy and productive having not been on it for the past 4-5 months.

[Dockhead]

Originally Posted by Kenomac

In other words, we’re both talking about the same 85-5-5-5 alloy under different names. . . .

Sure, except that "Naval Bronze" is NOT one of the many names of this alloy.

But now I trust everything is clear.


While we're discussing materials for underwater fittings -- I think someone above asked about it in a more general way.

I have limited experience with DZR Brass, which has become very popular. This material is said to be pretty decent. But my experience with it was terrible. I wonder if that is because it was screwed to a gunmetal skin fitting, which is more noble? Anyone have long-term experience with these?

As to Marelon -- there are a lot of arguments in favor of this. Would be great to simply forget about corrosion of all kinds. What I like less is the prospect of swelling nylon which seems to jam them from time to time.

[Kenomac]

Dockhead,

LG2 Gunmetal alloy was not mentioned until post #55, you only referred to your skin fittings as having been made from “gunmetal bronze,” a big difference.

I’m attempting to get back into this forum discussion stuff to help others like yourself who come on here asking for advice, but I really don’t understand why you and several other regulars post questions, then like to argue with and make snide remarks towards members who’re trying to help.

[Scott Berg]

I'm always concerned when I hear of people removing valves from thru hull fittings. Almost all thru hulls are straight threads and most ball valves are tapered pipe threads. While they may seem to go together they don't (see ABYC H-27). Compass Marine has a GREAT piece on this so I won't retype it all (see link below). A SEACOCK is a valve that is flange mounted to the hull. It doesn't 'unscrew' off. A THRU HULL is a threaded skin fitting that screws into the mounted (usually thru bolted) thru hull. Just because some builders take short cuts doesn't make right or even compliant with accepted industry practices. See: https://marinehowto.com/seacock-thru-hull-primer/