Stainless steel valves or Marelon valves?

[David M]

I'm going in for a haul out this week. One of the purposes is to pull all the thru-hull valves for inspection.

The boat has an aluminum hull which means that all the thru-hull valves are threaded on to aluminum pipe nipples which are welded to the hull.

The boat used to be a Coast Guard inspected vessel which means metal valves were required. Its now designated an Oceanic Research Vessel (ORV) by the Coasties, so now I can have any kind of valve I want.

Stainless steel of course eventually corrodes the aluminum through electrolysis. I expect to have to change out a few of the aluminum pipe nipples which is pretty normal. The yard manager is recommending that I should go with Marelon valves because that would stop the corrosion. The big downside with Marelon is that the valves jam...and frequently. The boat has 13 thru-hull valves, six of which are intake valves. The rest are discharge valves above the waterline with the exception of the head discharge valve. With 13 valves to possibly replace, its not a minor decision.

What would you do? Keep the stainless steel valves or change them out for Marelon?

[imagine2frolic]

If you notice no problems with the SS then why not keep them? You know already there is a sticking problem with the Marelon......i2f

[MidLandOne]

I say the following not knowing what regulatory or other restraints you may still be under (eg wrt to UL, insurer's requirements, etc).

Plastic industrial ball valves are mostly all fibre reinforced plastic and have non of the difficulties you refer to with respect to the Marelon ones (I am assuming you are referring to the Forespar ones in saying that). Even the ones for normal water service are rated up around 200psi and are able to be disassembled for inspection. They are solidly built of tough materials.

These will, of course, screw straight onto your existing aluminium nipples and there are fibre reinforced plastic fittings to get you to a hose tail or whatever on the inboard side of the valve.

The particular ones we have had for around 12 years now, have fibre reinforced nylon bodies, polypropylene/PTFE balls and have never needed any maintenance whatsoever. The screw that fastens the handle is 316 ss. Our particular ones are rated as resistant to petroleum products (mineral) but one has to be careful with acids (if descaling toilet hoses for example, but that may not be of any concern given the aluminium is likely the same).

Best of all, because they are made for industry they are sensably priced.

You also mention above WL discharges and I would expect you are under no constraint as to any required approvals (UL, etc) for these valves as I have managed new builds going into class with plastic industrial valves in these locations (but in those cases ss below the waterline on aluminium hulls).

[Jentine]

Is it possible to retrofit two manifolds, one intake and one out reducing the necessity for multiple failures. I, personally would rather deal with one seachest and one discharge.

[delmarrey]

Originally Posted by MidLandOne

Even the ones for normal water service are rated up around 200psi and are able to be disassembled for inspection.

I do like the Marelon valves for certain applications but I would have to disagree on this point. If you look at the screwed on end you will find a couple SS pins pressed into the nut, which does not allow you to unscrew the body. And the pins are nearly impossible to get out without damaging the valve.

They can be lubed by closing the valve and adding a silicone grease to each side of the ball, Which requires that you take a dive and pull a hose to get to both side of the ball. Or of course, haul out.

[MidLandOne]

Originally Posted by delmarrey

I'm afraid you have lost me completely because the industrial valves I am familiar with have no such pins. In fact I have just checked the technical manual for the industrial reinforced plastic valves we have to make sure and the only metal item in the whole valve is the ss screw that holds the handle on and that certainly comes out with no problems at all.

I can also confirm that the valve bodies dismantle completely and very easily, no problems at all.

Of course, you may have quoted me in your post by accident or gotten confused between Forespar sea cocks and industrial valves .

[delmarrey]

Originally Posted by MidLandOne

I can also confirm that the valve bodies dismantle completely and very easily, no problems at all.

Of course, you may have quoted me in your post by accident or gotten confused between Forespar sea cocks and industrial valves .

Sorry, my mistake! But I don't believe I've ever seen an industrial reinforced plactic valve on a boat, only the Forespar. So, I made an assumption.

[MidLandOne]

No problem, guessed something like that had happened but I wasn't goin' to let you off the hook easily .

Industrial plastic valves are quite widely used on boats and have seen them in a variety of countries - as I inferred usually for commercial vessels going into class (eg Lloyds, etc) they are more likely used for above waterline overboard discharges. But also commonly used as seacocks on pleasure boats fitted to a through hull fitting or if a metal hull also on welded in nipples.

[David M]

Originally Posted by Jentine

Is it possible to retrofit two manifolds, one intake and one out reducing the necessity for multiple failures. I, personally would rather deal with one seachest and one discharge.

The boat has a rather elaborate system of raw water inlets used for cooling things and for the measuring of a number of different water properties for science. Plus there are three watertight bulkheads that I would have to run hose or pipes through. I really appreciate the idea but it would be a pretty difficult thing to do plus it might even make things more complex.

[David M]

Originally Posted by MidLandOne

I say the following not knowing what regulatory or other restraints you may still be under (eg wrt to UL, insurer's requirements, etc).

Plastic industrial ball valves are mostly all fibre reinforced plastic and have non of the difficulties you refer to with respect to the Marelon ones (I am assuming you are referring to the Forespar ones in saying that). Even the ones for normal water service are rated up around 200psi and are able to be disassembled for inspection. They are solidly built of tough materials.

These will, of course, screw straight onto your existing aluminium nipples and there are fibre reinforced plastic fittings to get you to a hose tail or whatever on the inboard side of the valve.

The particular ones we have had for around 12 years now, have fibre reinforced nylon bodies, polypropylene/PTFE balls and have never needed any maintenance whatsoever. The screw that fastens the handle is 316 ss. Our particular ones are rated as resistant to petroleum products (mineral) but one has to be careful with acids (if descaling toilet hoses for example, but that may not be of any concern given the aluminium is likely the same).

Best of all, because they are made for industry they are sensably priced.

You also mention above WL discharges and I would expect you are under no constraint as to any required approvals (UL, etc) for these valves as I have managed new builds going into class with plastic industrial valves in these locations (but in those cases ss below the waterline on aluminium hulls).

Who are the manufacturers of the valves you describe? I need something that is going to be as tough as the Marelon valves in order to cover my rear end....but don't stick like Marelon valves.

Thanks

[Amgine]

Spartan

Sadly, even with an isolating backing block this probably won't work for your application. But the valves are excellent, can be completely broken down for PMS, and they even offer maintenance kits including lapping. (Of course this may just be misplaced nostalgia for my navy days... ugh.)

[MidLandOne]

Originally Posted by David M

Who are the manufacturers of the valves you describe? I need something that is going to be as tough as the Marelon valves in order to cover my rear end....but don't stick like Marelon valves.

David, sorry but I cannot give any leads regarding typical manufacturers in North America but by way of example these are some that are made in Australia Philmac - Products - Valves . Look for "Blue Handled Ball Valves" on that page and in the Technical library there is a technical manual for valves which a ways into it the technical details of these valves are described, including all materials in them and service conditions/chemical resistance. There is also a technical manual for pipe fittings which includes glass filled fittings - mention that to give an example of what is available in case not known.

These valves and their descriptions may give you a lead as to what to look into there in the US should you wish.

These are real cheap (in price, not construction) valves and widely used here and even sold in most chandleries where at their prices a 1-1/2 inch valve still runs only about the equivalent of US$35. They don't have any of the problems others report for the Forespar valves - personally I have only used their 3 port valves in black water system and wouldn't use them again, going to 3 port plastic industrial instead.

These same valves were used on my own steel boat below the WL when it was professionally built for me in 1996 and I have to say I wondered about them. But as they were both easily swapped out later if they were a problem and the builder was a very well regarded one I kept my mouth shut (quite a job to do at times when it comes to boats ). But they have proven to be fine with no problems at all and no maintenance yet needed (but at the price I would just swap them out) - I would always use plastic again in my own boat. I make the point though that abrasive fouling may be less here due to cooler water temperatures than I expect are found in your home waters.

Obviously, in a power boat one would not use them in an engine room below the WL but while a matter of how relaxed one is about plastic I personally have no issue with using them below the waterline in my own sail boat after experiencing them. Obvious nil corrosion issues for a metal hull - they are certainly stronger than any reinforced plastic through hull fitting is and I suspect if on an aluminium nipple one could destroy the nipple before the valve. Really just leaves exposure to fire and I work on the assumption that in a metal boat if one has a fire of such force down in the bilge outside of a protected compartment then I won't be on the boat, and on a plastic boat - well .

As I said before, for aluminium boats going into class have had similar plastic valves for above waterline overboard discharges and everyone has been happy including the classification society surveyors.

The choice between ss and plastic is difficult for aluminium hulled vessels, I think emotionally driven against plastics and of course ss is much more expensive. If going into class, while I have not tested the acceptability of plastic with any society, one is probably stuck with ss below the WL just as you say it is for USCG. As I know you are well aware of, other parties such as insurers may have a say as far as compliance is concerned.