What the hell is TONVAL???

[boatmike]

Without repeating all the stuff on the post about "Marine Brass?" the subject of TONVAL has not been addressed and perhaps should be. Many suppliers are selling skin fittings and valves in this material and the implication is that it is suitable for underwater use. My question is simply this.... Does ANYONE know what it is? I mean specifically? What is its chemical composition? Where does the term come from? Has anyone seen any test data on it or have any reason to believe it is suitable and will resist dezincification? Or are we all just accepting the publicity without question?

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[macd]

Nothing to add that isn't already in the 'Marine Brass' thread, but as boatmike suggests, this is IMPORTANT. Somebody out there must know. But if they don't...well, QED, the stuff's a pig in a poke

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[salamicollie]

Don't know the composition - Tonval ATD is a corrision resistant but may suffer from dezincafication. It is perfectly suited for above the water line and many yachts have it below the waterline without any problems.

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[Roberto]

Taken from a MAIB report

"Tonval ATD: The trade name given to the 60/40 leaded brass used in themanufacture of through-hull fittings. The closest ISO material designation is CW619N and the material symbol designation is CuZn40Pb2Sn.

CW619N: A brass suitable for wrought and unwrought forging with the composition: copper 57-59%; aluminium 0-0.1%; Iron 0-0.4%; Nickel 0-0.3%; lead 1.6-2.5%; tin 0.2-0.5%; remainder zinc (approx. 38-40%).

The trade name Tonval, in the UK, conceals rather than conveys the nature of the material used for the through-hull fittings. To ensure that buyers of these products are fully aware of the nature of the material, such fittings should be clearly described as made of a “brass (not inhibited against dezincification)”."



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[Graham_Wright]

Situation further confused by fittings being described as "moulded" in tonval. Implies plastic.

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[boatmike]

If that's the case Roberto my suspicions are verified. Thanks for the information. Retailers (and there are many) who describe this material as Tonval Bronze are telling lies. It definitely ain't bronze and if, as you say, it is a brass that is not even inhibited against "de-zincing" should, as I originally thought, never be fitted below the waterline.
As luck would have it my new ASAP catalogue just came through the door. In it there are through hull fittings in Gunmetal (excellent) Perko (trade name) fittings in what are called "cast bronze" (lord knows what sort though) 316 stainless steel ones. (should NEVER be fitted below the waterline in my opinion) and guess what? What they call TONVAL BRONZE ones! There are also other fittings such as hose tails that are Lloyds approved in DZR and TONVAL BRONZE ones too. So it's obvious to me that we should NEVER fit tonval anywhere on the boat that comes into contact with seawater. It's also evident that GUNMETAL fittings are still widely available and should be used for this purpose.

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[Roberto]

I just had a saved copy of the report, I found the <A target="_blank" HREF=http://www.dft.gov.uk/stellent/groups/dft_maritimesafety/documents/page/dft_masafety_027359.pdf>original one here </A> anyway





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[boatmike]

Your statement should read "without any problems YET!
These components are safety critical, its like bunjee jumping on knicker elastic.
As it breaks you hear the protest..... I NEVER HAD THIS PROBLEM BEFORE !!!!!>>>>>

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[dickh]

My ASAP catalogue(7th Edition) has the note:-
"Tonval ATD - Has corrosion resistance but is susceptable to dezinctification. Bronze UNI 7.13/8 G-CuSn5ZnSPs - Frequently known as Gunmetal" But no spefic recommendation as to where they should be correctly used.
BUT this note is on the Seaflow Pipe Fitting page, which is 2 pages AFTER the 'Through Hull Fittings/Seaflow Hose Tail Fittings' pages. There should be a definate note concerning Tonval ATD such as "Tonval ATD must NEVER be used underwater"

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I'd rather be sailing... /forums/images/icons/smile.gif

 

[salamicollie]

10 years and counting... Hammer test every year. The point was made on the other thread it depends on the stray currents around - no problem on a swinging mooring, bit of an issue in a marina.

Anyway don't you have hard wood bungs next to the skin fittings - I do even where I have LG2 fittings for the heads!

There is a risk with Tonval but if inspected it is manageable.

PS My Asap catalogue quite clearly states at the top of pages on pipe fittings that it is only corrosion resisting. The problem often is that for pipe fittings you can really struggle to find some combinations in anything else

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[boatmike]

No because they are in fact shell moulded which is a method of casting

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[boatmike]

Yes and it should be called Tonval Brass not Bronze which is entirely misleading

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[boatmike]

"Dont I have hardwood bungs next to the fittings?"
Yes. I also have airbags in my car but I try to avoid them needing to be used.....

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[simonfraser]

still training the monkey to whack them in when i am not present

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[graham]

If you have HARDWOOD bungs probably best to throw them away and replace with softwood bungs which will shape themselves to fit the hole when hammered in rather than splitting it open .

Bungs are really a case of"drinking in the last chance saloon".By the time you locate the correct failed skinfitting or seacock the water is going to be rising fast.

I was on a motorboat where an almost new seacock sheared off due to poor design/installation .Only the fact that it was plumbed in with rigid piework which held it in place .Coupled with better bilge pumps than you will find on 95 /100 boats saved us from some liferaft practice. Wind gusting to 70 knots at the time.

 

[macd]

Tonval isn't funny, but that tickled

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[macd]

Right, that seems to be Tonval sorted. What's next for the copping block?

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[macd]

Right, that seems to be Tonval sorted. What's next for the chopping block?

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[pandos]

Every body should the accident report.

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[ASAP]

As you mentioned our catalogue by name, we thought we ought to add our comments.

We have been selling these fittings for 16 years now. They have been on the market for much longer than that. We have chosen all our underwater fittings from the best suppliers we can find. Almost all our Tonval and Gunmetal items are made by Guidi (Italy) and Perko (USA). We have not chosen for lowest price, we have chosen for quality. Our Perko gunmetal valves are probably the most expensive in the UK - but they are UL Listed, and approved by the US Coastguard for use as underwater through hull fittings. Page 52 of the 7th edition, bottom LH corner has a seacock to beat most of them. The only problem is, NPT threads (UK is mostly BSP) and price. Most people don't want to pay over £50.00+VAT. However, even our less expensive general gunmetal and DZR fittings/valves are chosen for quality and not low price. We always recommend them as the minimum for salt water applications, and have been selling for 12+ years.

Then we have the cause of the post - Tonval ATD. This is a type of brass, however, in the case of Guidi fittings, it is a good quality. We have sold this since we started, and inland boats on fresh water (eg Norfolk Broads) have used these fittings through hull for years before we started, without problems of any sort. There are certainly different grades of material with the same name, but we can assure people, that the cheap stuff ain't coming out of this of warehouse. We publish all the specs we have - we are not trying to disguise cheap brass with a fancy name - Tonval is a specific name - and that's what we sell and have sold since we started.

The problem with ALL of this is not generally the fittings. It is the application of them. The fittings have not changed for years. It is people - many want to build boats for a budget, and through hull fittings can't be seen. People can't show off their 'top of the range' seacock, so the money goes else where. Sorry, but that's the case for many. Boating ain't cheap - let's save a quid and get the fittings at the local boat jumble! Thankfully many are now realising that you don't get something for nothing, and are willing to pay a bit extra for the better materials. They are generally more expensive because they contain more of the metals that make them corrosion resistant - and those metals are expensive!

The comments by 'salamicollie' are some of the best on this string. For certain boats, Tonval is fine, for others not, and mostly the problems with the 'nots' will be down the galvanic action due to marina moarings or incorrectly placed/lack of Anodes. Make sure the anode is in sight of the through hull fitting. Make sure they are all bonded. Check anodes regularly and replace often Visit the MG Duff site - ask for a brochure. They give advice freely, and their high quality anodes are available almost everywhere (as well as from us)

Lastly 'Stainless 316' These fittings are relatively new to the market. Again, for certain vessels they are fine - and can be fitted as underwater fittings. After all, if stainless 316 should not be used, what's the point of making them - and 95% + of you have a stainless 316 propshaft I wager! They should always be assembled completetly 'dry' ie no water or damp around at all. They should NOT be used on a wooden boat. The reason is a complex one, and due to the new nature of the product, is still subject to debate, but stainless 316 needs oxygenated water to form a protective barrier. If this barrier does not form, then the fittings can corrode.

So, if you use the ASAP catalogue, we would like to point out that we have tried extremely hard to offer the very best fittings on the market. We have always tried to offer products that we sell, you fit, and then we all forget (but remember to check!!) We cannot publish specific recommendations for these products - it is such a vast and complex subject. We have a huge water network, and fittings that have lasted for years on a boat moored at point A, may corrode away to nothing in a month when the boat is moved to point B.

They best advise we can offer, is to check, check and double check. If the boat is going into salt water - fit the very best. Don't skimp, especially if you plan to keep and use the boat. If you save a few quid - get two sets - chances are you will need them!!!

Disclaimer. This is not intended to be a sales pitch for ASAP Supplies. Yes, we offer a good range of quality products, but so do many other marine retailers and wholesalers. There are a small few who offer product of a lower grade, but generally the marine trade wants you all to have good experiences when boating and to enjoy yourselves. Maintenance is a pain we know. Most of us offer products that let you enjoy boating. How much you want to pay is up to you.

We do sincerely hope this helps. If you need any other advice or information, please phone and we will try to help as best we possibly can.

A.S.A.P. Supplies



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