Kestrahl 6 Posted July 12, 2011 Share Posted July 12, 2011 Seems this is what we have and the ball valves are showing some surface rust. Is this caused by the different metals? I could change to the fiber reinforced plastic skin fittings but they will have the heavy S/S ball valves hanging off them.. Link to post Share on other sites
wheels 543 Posted July 12, 2011 Share Posted July 12, 2011 No Bronze will not cause the SST to rust. Rust on SST comes from two sources. The grade of SST as in how much Iron and Chrome content there is or contamination, which is the most likely. You only have to touch SST to a ferrous surface of anything and that little transfer is enough to start the process. Easy to clean off by using some Phosphoric acid. A lower grade of SST like 304 (does not mean it is a poor grade, just less Chromium) will tend to rust easier than 316. So that can be a possible also. 304 is often used because it is easier to machine than 316. Once again a bit of acid will wipe the rust away. Link to post Share on other sites
Steve Pope 243 Posted July 12, 2011 Share Posted July 12, 2011 Why not change to Hansen (glass filled plastic?) marine valves, at the same time they have marine certification. No rust, corrosion, electrolysis, and not heavy etc. etc. well priced as well. Link to post Share on other sites
Kestrahl 6 Posted July 12, 2011 Author Share Posted July 12, 2011 They are 316, and the rust is the bottom half, I took one off today and gave it the wire brush treatment, skin fitting looks okey. Interestingly the engine water intake skin fitting/valve is connected to a zinc and doesn't have rust like the others, but it could just be a coincidence. I would replace them with plastics if money and time were no object, but trying to only replace necessary items Link to post Share on other sites
wheels 543 Posted July 12, 2011 Share Posted July 12, 2011 If you wire brush, make sure it is a good SST bristle, or you will just be contaminating the valve and it will rust again. When you say bottom half, do you mean the square "nut" area that mabe a spanner...a metal spanner...may have tightened it up originally?? It is unlikely the Zinc has portected the other valve as the Zinc and Valve must be both under the same piece of water to work as a circuit. The Zinc is portecting the Skin fittings on the other side of the Hull. Which if you have one connected, you should really have them all connected. Either all or nothing, or yuou could have an issue wiuth the Bronze on the water side of the hull. Give em a clean with Phosphoric acid, as in a Rust neutralizer and then connect them all together with an earth wire so they are all at the same common potential and you will be sweet. Link to post Share on other sites
Guest Posted July 12, 2011 Share Posted July 12, 2011 They are 316, and the rust is the bottom half, I took one off today and gave it the wire brush treatment, skin fitting looks okey. Interestingly the engine water intake skin fitting/valve is connected to a zinc and doesn't have rust like the others, but it could just be a coincidence. I would replace them with plastics if money and time were no object, but trying to only replace necessary items after wirebrushing any stainless fittings you should use a descaling paste to remove ferrous deposits, more importantly, try a magnet against your so called 316 valve/ fitting you'd be stunned at just how magnetic cast stainless is and also how porous it can become in a very short timeframe, hansen are a well enginered , reliable easy operating inert valve that are hard to go past Link to post Share on other sites
Kestrahl 6 Posted July 13, 2011 Author Share Posted July 13, 2011 After looking at the price of hansen plastic ones, they don't seem like a bad idea.. Here is a photo of the issue, two others are worse and rust up into the body, the other one connected to the zinc is fine. Link to post Share on other sites
wheels 543 Posted July 13, 2011 Share Posted July 13, 2011 Not a problem. Get some acid on them. The green on the bronze is due to the interaction. The acid will clean them up as well. But that bronze is the item I would be inspected most carefully. Also inspect the inside of the valve on the Ball. If it is pitted that is the thing that will leak when shut. Biff them if they are pitted. If you then have to replace, either replace with Bronze valves (hard to get pure Bronze) or replace with Marlon (reinforced fibre Valves) and I would look at removing the bronze through hull and replace the thru hull and valve with Marlon. Link to post Share on other sites
Guest Posted July 13, 2011 Share Posted July 13, 2011 After looking at the price of hansen plastic ones, they don't seem like a bad idea.. Here is a photo of the issue, two others are worse and rust up into the body, the other one connected to the zinc is fine. rust on the valve body would suggest corrosion to female thread, remove and if the female thread is black or pitted discard, also check with magnet if magnetic at all discard, sealing stainless can also be a bitch for crevice corrosion Loctite stainless pipe sealer works very well, Link to post Share on other sites
Kestrahl 6 Posted July 19, 2011 Author Share Posted July 19, 2011 def replaceing with plastic valves now. But the big question is do i want to replace the bronze skin fittings? they seem okey but still need a clean up.. Any opinions? Link to post Share on other sites
PaulR 3 Posted July 20, 2011 Share Posted July 20, 2011 I'm knot a metal expert but top photo 514 looks in better condition than the lower photo 515, which has more rust around it. Are the threads the same because 514 looks like it has longer and better threads. Before replacing, get a boat builder or surveyor to inspect, get written report for Insurance purposes. Then follow their advice or treat as the others have suggested. What is each skin fitting used for? Where are tyey located in the hull? Link to post Share on other sites
Battleship 100 Posted July 20, 2011 Share Posted July 20, 2011 Bottom one looks bad, no expert either but from what I understand pink discolouration on bronze is the zinc coming out and the bronze is turning into copper. If it were me I would replace it while I had the chance and sleep alot easier. Link to post Share on other sites
Kestrahl 6 Posted July 20, 2011 Author Share Posted July 20, 2011 The top one has been cleaned up, bottom one hasn't. The red inside the 2nd one is the red anti foul, as I think it is Brass that turns red when the zinc disappears as opposed to bronze?. From further research on the net it was mentioned that in cold climates metal skin fittings with plastic valves isn't a good idea as they have different expansions and can cause the valves to crack.. But maybe not the new fiber reinforced plastic. who knows! Link to post Share on other sites
idlerboat 116 Posted July 20, 2011 Share Posted July 20, 2011 Hi Ya, firstly I am assuming that your hull is glass ? Having dissimilar metals in contact with the possibility of any electrical current making a circuit will make the most noble start to corrode. As a metal boat owner it is one of the biggest problems with my type of boat. Bronze through hulls have been used through the ages. I would not recomend them to anyone now. The reason is simple. Our modern boats contain a mass of electronics and metals other than bronze. It is an indisputable fact that if you have dissimilar metals and an electrical current...the most noble metal gives its self up....hence noble. You have three choices......either have metals of all the same nobility...a good start but even that dosnt get you a perfect solution becuase even so called "the same" metals can have slightly differant quantities of metas. Have no electrical "movement" or current travel through your boat....impossible !! Because current can come from outside your boat. Even in a "perfect" situation the dirt and salt on the inside of a hull can provide a current path. Provide the noble warrior !! that is of course an annode. An annode is chosen simply becuase out of all your metals it will give up of itself before the others start to corrode. Stainless steel is many things dependant on what type it is and where it is used. It has its own little problems , one of which is crevise corrosion. A very nasty little problem that has big rigs on big boats fall down !! I wont go in to all of that here, but my suggestion is first make a desion.....all isolated or all bonded. That is with all isolated, you have to make as much as possible every part of your boat that has metal in contact with the water and meatal that has contact with electrical components....electricaly isolated. AND get rid of disimilar metals in contact with each other. In a fiberglass boat this is possible and normal. Get rid of your bronze through hulls and go to an all 316 ss solution. Through hulls and valves . You could go to bronze valves....but why would you ? That red colour is a big danger sign...if it goes to a light pink you will find that you can scratch it off with your finger nail. OR all bonded...that is everything (or the things that matter like through hulls and other essential pieces are electricaly bonded to an annode.(s)... It is still much better to not have disimilar metals in contact. Plastic through hulls are a good solution as long as they are super strong. If they are connected to a ss valve and you kick the valve and snap the through hull thread off you are ....well ....in deep trouble. If you go that way...Protect the through hull with some kind of physical barrier. (remember you still need to get to it in an emergency) Finaly to all the timber boat smarties...electrolisis attacks the celular structure of timber ...and turns it to mush especialy around through hulls...so take your annodes very seriously. sorry about my crap spelling tonight cheers martin ps have hundreds of pages and web sites (industry and scientific) on this issue. if anyone has specific questions that i can point them towards people who know much better than me. But for everyone this is a solid start on the issue of wet corrosion. http://www.sandvik.com/sandvik/0140/int ... 490032613D Link to post Share on other sites
idlerboat 116 Posted July 20, 2011 Share Posted July 20, 2011 ....it would be remiss of me...for metal boat owners, www.metalboatbuilding.org go to the section on galvanic protection. Link to post Share on other sites
wheels 543 Posted July 20, 2011 Share Posted July 20, 2011 Having dissimilar metals in contact with the possibility of any electrical current making a circuit will make the most noble start to corrode. Your post is very correct IB. It is the reason why any metal skin fitting should be bonded. Although a steel boat, the Hull does that for you. While Pink in Bronze is a colour to be concerned with, this pink is actually just surface. Once the bronze has been cleaned, if the Pink is in spots actually in the bronze itself, then that is cause for concern. Admralty Bronze is one metal that can be used against SST, as long as it is protected ofcourse. Think of your bronze shaft bearing assembly etc. Willow, Bronze through hulls are safe (as long as they look OK ofcourse) as any material, but you do need to bond them all. However, for ease of not having to bond them, and if you are not sure of the quality anbymore, then replacement with a Marlon material would give piece of mind. A Marlon (that's the material of fibre reinforced Resin type plastic looking fittings) fitting is strong and will last for many years with no issues. I would not use a plain plastic material. The hardest part is knocking the old one out of the hull, hut a good clout with a mallet should knock it free. Make sure you seal the new one in with a good polymer ADHESIVE/sealant. DO NOT use Silicon. Link to post Share on other sites
rigger 47 Posted July 20, 2011 Share Posted July 20, 2011 The hardest part is knocking the old one out of the hull, hut a good clout with a mallet should knock it free. Make sure you seal the new one in with a good polymer ADHESIVE/sealant. DO NOT use Silicon. When removing old bronze skin fittings I did not 'knock them out'. I undid the nut then used poly grips to turn the skin fitting and unscrewed it from the inside first then when I could get a grip on the outside finished the job from there. Once I did knock one out and did a bit of damage to the surrounding hull material so would rather take a bit more time and reduce the isk of damage. Link to post Share on other sites
Guest Posted July 27, 2011 Share Posted July 27, 2011 After many years of selling bronze & SS fittings, there are some hard and fast rules. 1. Bronze and SS don't mix. Real bronze made for marine underwater is best but there are very few reliable manufacturers. 2. Avoid SS underwater, it is more likely to cause trouble than bronze. Even the best quality SS will bleed if anaerobic or if you used a ferrous spanner on it. 3. Be sure of your source. Metal from one country in particular is almost never what it says it is. Don't use Naval bronze underwater. 4. SS needs the presence of oxygen otherwise it pits quickly. I saw quite a few boats sunk where the SS skin fitting bedding compound - normally epoxy, let water in osmotically, and very quickly the pitting began. It looks like the SS had a toredo worm attack. 5. Very few plastic valves and fittings have the orifice size that is the thread standard. If you take out a bronze 1 1/2" BSP fitting (which has a 1 1/2" flow orifice, you need to go to 2" or 2 1/2" plastic to get the same flow orifice. 6. Plastics are hydroscopic. The least so is UHMWPE which is NOT suitable for valves. Nylons glass filled, are the preferred but are quite hydroscopic - meaning they expand. Once again be sure of your source. One more thing......Better to use fittings with BSP threads as this is the standard in NZ, Europe, UK, most of Asia and easiest to find replacements for. The USA has NPT. Link to post Share on other sites
Steve Pope 243 Posted July 27, 2011 Share Posted July 27, 2011 If you are (and you should) going to fit "plastic" valves Hansen make v/v's that are survey approved. Made in Whangarei !!! Link to post Share on other sites
Kestrahl 6 Posted July 27, 2011 Author Share Posted July 27, 2011 Think we are going with tru design skin fittings and valves, i guess the next question is what to bed them in with.. Epoxy sounds like the norm. Link to post Share on other sites
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