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

[Cadence]

Originally Posted by sailorchic34

I suspect the older bronze through hull fittings are superior to the new ones. Reason is many countries are limiting lead in bronze castings and substituting aluminum instead.

Gunmetal bronze use to be 85% bronze, 5% tin, 5% lead and 5% zinc. Newer bronze ingots are replacing the lead with Aluminum. Which means in seawater after the 5% zinc dezinc's the aluminum will go next.

Overly simplistic as there are many different formulations of bronze.

I did have a discussion with Hopcar ages ago about newer bronze. He contacted a manufacturer, who did confirm that they were using aluminum instead of lead in their bronze formulation.

My old spartan seacocks and throughhulls are original (46 years old) and still look very good (no pink at all)

I found some in circa 78 that were from 56. Totally crystalline, for lack of a better term. Taped with a wrench fell apart. I can not speak to electrolysis as the cause, they looked good. For what it is or isn't worth..

[Compass790]

Originally Posted by Dockhead

Thanks, Gord. That's what the local experts are telling me, too.

Another question -- is there a consensus that PTFE sealant AND PTFE tape is the best way to seal the threads?

Mine are all BSP, so there are no NPT/NPF issues.

Have done decades of pipework & can tell you with confidence it's fine to use to use PTFE tape & sealant. Hemp & heldite sealant works well too but is messy. I like Loctite hydraulic pipe sealant if you are worried but find on boat seacocks thread tape alone is sufficient as they arent under much pressure. Seen much older bronze skin fittings than yours that were still ok but if replacing them I'd use fibre reinforced nylon skin fittings & v/v's

[thunderhoof]

I have to agree with donradcliffe in that there is no guarantee that the hull fittings will not turn, or worse yet be weak internally due to corrosion or defect. I suggest you do this work with some spare through hulls handy and a diver ready to stop any catastrophic leaks. I take it that putting the boat on the hard is not an option.

[jgbrown]

Originally Posted by stormalong

Never use locktite for this purpose. It requires heat above 400 degrees Fahrenheit to remove. Do you really want a blowtorch in your bilge?

As for through hull sealant use 3M 5200. I know this will start a heated discussion but it will hold the through hull from spinning and yes, it will be a pain to remove but it will not fail. I have had 5200 sealant in my Marelon through hull fittings since the boat was built. When I went to change one after 20 years to put on a strainer both the Marelon and the sealant were as good as new.

As for replacing through hulls so that you know what material they are made of don't be too sure. Just because they are new does not mean that the alloy is correct. That is the main reason I like Marelon - no potential for electrolysis.

I have thirteen Marelon seacocks in my 32 Y.O. boat. About two thirds of them original and they all work fine.

I prefer 3m 4000UV. Better sealant, less runny too.

[Dockhead]

Originally Posted by thunderhoof

I have to agree with donradcliffe in that there is no guarantee that the hull fittings will not turn, or worse yet be weak internally due to corrosion or defect. I suggest you do this work with some spare through hulls handy and a diver ready to stop any catastrophic leaks. I take it that putting the boat on the hard is not an option.

Boat IS on the hard. All the skin fittings have been scraped down and carefully inspected. They are gunmetal bronze and there are no signs of deterioration. But one of them did turn, and will have to be rebedded. This one is an Isotherm SP fridge condenser skin fitting, so will not be replaced.

[Alita49DS]

I can contribute a cautionary tale. When I replaced a number of seacocks with Trudesign ones I also replaced all the skin fittings: bar one.


The one was because I foolishly listened to the person doing the work. He said the skin fitting was fine. No it was not. In fact it is the one that leaked since I have had the boat but I could not see that as it was also where the water collected. The component might have been fine but the bedding was not.


I am now going to have to lift the boat again to replace that fitting. A very expensive way to put in place a part that I already had at the time of the original decision.


A short cut can end up as a very tiresome long cut.

[Kenomac]

Gunmetal Bronze? I’d be changing those out for high quality Italian or US manufactured Naval Bronze. There’s been several lengthly threads on this subject. Manufacturers back around 2000 and onward including Oyster were experimenting with installing skin fittings of various alloys. Oyster returned to Naval bronze after just a couple of years, and has been installing Italian naval bronze ever since. But it’s your boat, do as you see fit.... We changed all the skin fittings on our 53 five years ago following a failure, another friend owning a 53 did the same. The degeneration can’t always be seen by scratching the surface, only by cutting through the metal or after a failure. Our head waste fittings suffered more degeneration than the others.

From wiki:

Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Proportions vary by source,[1][2] but 88% copper, 8–10% tin, and 2–4% zinc is an approximation. Originally used chiefly for making guns, it was eventually superseded in this department by steel. Gunmetal, which casts and machines well and is resistant to corrosion from steam and salt water,[3] is used to make steam and hydraulic castings, valves, gears, statues, and various small objects, such as buttons. It has a tensile strength of 221 to 310 MPa, a specific gravity of 8.7, a Brinell hardness of 65 to 74, and a melting point of around 1,000 degrees Celsius.

[a64pilot]

Originally Posted by stormalong

Never use locktite for this purpose. It requires heat above 400 degrees Fahrenheit to remove. Do you really want a blowtorch in your bilge?
.

Only the red requires heat and or excessive force. Green and Blue don’t.
Reason I’d look at a thread locker, is that with straight threads, nothing but the friction of the sealant is preventing rotation of the valve, unless you bottom out the threads of course. If you do that, you have to accept the orientation of where the valve ends up.
Thread locker is also an excellent sealant, and in some applications, that is its primary function.

[Dockhead]

Originally Posted by Kenomac

Gunmetal Bronze? I’d be changing those out for high quality Italian or US manufactured Naval Bronze. There’s been several lengthly threads on this subject. Manufacturers back around 2000 and onward including Oyster were experimenting with installing skin fittings of various alloys. Oyster returned to Naval bronze after just a couple of years, and has been installing Italian naval bronze ever since. But it’s your boat, do as you see fit.... We changed all the skin fittings on our 53 five years ago following a failure, another friend owning a 53 did the same. The degeneration can’t always be seen by scratching the surface, only by cutting through the metal or after a failure. Our head waste fittings suffered more degeneration than the others.

From wiki:

Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Proportions vary by source,[1][2] but 88% copper, 8–10% tin, and 2–4% zinc is an approximation. Originally used chiefly for making guns, it was eventually superseded in this department by steel. Gunmetal, which casts and machines well and is resistant to corrosion from steam and salt water,[3] is used to make steam and hydraulic castings, valves, gears, statues, and various small objects, such as buttons. It has a tensile strength of 221 to 310 MPa, a specific gravity of 8.7, a Brinell hardness of 65 to 74, and a melting point of around 1,000 degrees Celsius.

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.

[Dockhead]

Originally Posted by Alita49DS

I can contribute a cautionary tale. When I replaced a number of seacocks with Trudesign ones I also replaced all the skin fittings: bar one.


The one was because I foolishly listened to the person doing the work. He said the skin fitting was fine. No it was not. In fact it is the one that leaked since I have had the boat but I could not see that as it was also where the water collected. The component might have been fine but the bedding was not.


I am now going to have to lift the boat again to replace that fitting. A very expensive way to put in place a part that I already had at the time of the original decision.


A short cut can end up as a very tiresome long cut.

Thanks; it's a useful tale and of course there is always a risk.

I did have one skin fitting turn on me, so I will be taking that out and rebedding it -- big PITA.

The others are well bedded in, have never leaked a drop, and didn't turn under intentional stress test, so to save a couple of days of work I don't have time for, I will take the calculated risk with them. Fingers crossed.

[fallingeggs]

Originally Posted by Dockhead

The surveyor pronounced my skin fittings fit for another 17 years of service.

Sabre installed all Spartan seacocks and through hulls and they are going strong after 35 years, so I'm in the camp of the surveyor.

[ramblinrod]

Originally Posted by Dockhead

I'm changing a bunch of sea cocks on my boat. Some of them are original to the build, so 17 years old. Others were changed 7 or 8 years.

I changed the previous ones because they were frozen and/or shaft broken -- neglect by the previous owner. But I exercise and lubricate my sea cocks, and always turn them off when I leave the boat overnight, so the rest of them have not suffered from this problem. I've had some external green corrosion but the bronze has otherwise held up just fine. I have tested them in different places and there is no pink.

However, my bilges are damp (keel stepped mast) and the f-ng handles of these ball valves are plated mild steel! They eventually rust, and the shafts are steel too and rust . I have bought new bronze ball valves made in Italy with stainless handles and bronze shafts and plated bronze balls.

Here is my question -- is it bad practice to replace the ball valves without replacing the skin fittings?

My skin fittings seem to be absolutely fine -- not the slightest pink color anywhere. I have wire brushed them and checked them everywhere. They have remained well bedded in their places and I don't see any reason to change them.

What say ye?

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.

[donradcliffe]

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.

+1 With Rod's method, its possible for two guys to replace 12 thru hulls in 8 hours.

[Rorzech]

Teflon tape is not a sealer. It's purpose is to lubricate the threads during installation .

[Compass790]

Originally Posted by Rorzech

Teflon tape is not a sealer. It's purpose is to lubricate the threads during installation .

Dunno who told you that but after decades of pipework I can tell you it's a very good sealer.