What did you do to or for or with your Laverda today?

Haven't gone out into the shed to check, but I think the half open end is the main top tube that comes down from the headstock. Yes, pretty clean in there, but strangely enough I found a lot of rust inside one of the small tubes that form the pillion rear triangle - should be totally sealed. That's part of another of the many frame jobs on my list. Getting close to weld time - I'm excited!

 
Dellortoman said:
It won't rust if the tube is sealed and air can't get in.
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Air can't get out either. Unless they fill the tube with an inert gas there will always be air inside it, sealed or not. Perhaps you mean the ingress of moisture?
 
Davo said:
Perhaps you mean the ingress of moisture?
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Well, er ... no. I did actually mean air. This is what was going through my brain at the time ...

Rust is iron oxide (mostly Fe2O3) so oxygen has to be present to make rust. Air is about 21% oxygen. In a sealed tube there's a finite supply of oxygen and not all of it will dissociate into ions to be available to react with the iron in the steel. The oxidation reaction will proceed until it reaches equilibrium and then stop as the available O-2 ions are depleted.  I'd guess that the amount of rust produced would barely be noticeable.

It's true that the rust reaction is greatly assisted by the presence of liquid water as a medium in which the oxygen can dissolve (ionise), but I think it's safe to assume there wouldn't be any liquid water sloshing around inside a frame tube. It may be present as vapour in the encapsulated air, but water vapour only makes up around 2% of air, so the oxygen in the water vapour wouldn't play a big part in the rust reaction.

Someone who knows chemistry will come along in a minute and tell me I've got it all wrong.  ::)
 
The RGS runs... The ride home from Wolfgang's 3 years ago was more of a limp home, terrible MPG rough running ...I was guessing the 35 year old coils were the problem, the parts were ordered but the bike was parked, since I was working away from home.
After three years of sitting the bike needed a full service, so the list was created and the tasks performed. No real drama; still waiting for my shared shim kit to adjust #1 Ex and IN.  New gas and push the starter button - the RGS has never been a quick stab and go, but I fitred right up and I would say it runs as good as ever, who would expect anything less... Mileage after 35 years of ownership is under 35k and there are some tasks still on the list to clean 'er up but the smile still remains...Now on to the SF2...
 
Dellortoman said:
Well, er ... no. I did actually mean air. This is what was going through my brain at the time ...

Rust is iron oxide (mostly Fe2O3) so oxygen has to be present to make rust. Air is about 21% oxygen. In a sealed tube there's a finite supply of oxygen and not all of it will dissociate into ions to be available to react with the iron in the steel. The oxidation reaction will proceed until it reaches equilibrium and then stop as the available O-2 ions are depleted.  I'd guess that the amount of rust produced would barely be noticeable.

It's true that the rust reaction is greatly assisted by the presence of liquid water as a medium in which the oxygen can dissolve (ionise), but I think it's safe to assume there wouldn't be any liquid water sloshing around inside a frame tube. It may be present as vapour in the encapsulated air, but water vapour only makes up around 2% of air, so the oxygen in the water vapour wouldn't play a big part in the rust reaction.

Someone who knows chemistry will come along in a minute and tell me I've got it all wrong.  ::)
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So that is why they store dead planes in the desert?

From Wiki and my chemistry memory - "Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture."


 
steam pipe does not have to be seamless, it depends on the pressure, too high and yes you need seamless, as in boiler tubes, but distributing service steam pipes are merely a heavy grade of BS1387. The joints do not always have to be welded, far from it.

What Cam was trying to say is that its the air that carries the moisture, and if the tube is sealed the amount of air trapped inside will rust the surface very slightly, but to no measurable effect, unless a continual supply of air is arriving and bringing moisture with it.

If you look at a correctly designed and installed central heating system using steel panel radiators, they are filled with water but rusting should not occur, because the initial charge of water will carry with it oxygen to create rust, but once heated and cooled several dozen times, that capability is lost. ie the elements that cause rust are used up, UNLESS fresh water is introduced. Fernox Sentinel and other rust preventers are masking what is a common design/install error.

CLEM
 
had the Jota out on the weekend..... some smart cunt yelled 'bloody Hansen voter' whilst at the servo.  ???    Its not easy being Orange!!  :-[  Glad its not Yellow or Green!
 
sweetas said:
had the Jota out on the weekend..... some smart cunt yelled 'bloody Hansen voter' whilst at the servo.  ???    Its not easy being Orange!!  :-[  Glad its not Yellow or Green!
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What are you talking about?
 
Please explain!  probably should have been in Oz section...  Australian Politics - we have a federal election in two weeks;  You are either red, blue, green, yellow or orange.  Orange is run by a rather outspoken Right Wing Senator - Pauline Hanson.  :-[
 
CLEMTOG said:
steam pipe does not have to be seamless, it depends on the pressure, too high and yes you need seamless, as in boiler tubes, but distributing service steam pipes are merely a heavy grade of BS1387. The joints do not always have to be welded, far from it.


CLEM
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In Australia, distribution steam pipes, from say the battery to (let?s say a number of retorts) must be seamless, slagged, lines. The pressure from boiler to retort, in this case remains the same, once the retort valves are closed. Let alone any water hammer that may be generated, which is indeed worse than the pressure, if allowed to continue.

Even the blow-off lines on our boilers are sesamless, as are the steam fed pre-heated water tanks, which have almost zero pressure. Our joints are welded boltable flanges, or, pressure tested welds.

Boiler fire tubes, or water tubes, depending on the type of boiler, are of course, seamless.

Sorry, to hear that my statement wasn?t described as an international standard, which I wasn?t aware of.

 
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