Petrol and solder?

[Maker]

This is the fuel tap I made for dad's Lister after the original died. It's made from a brass steam valve with new threads soft soldered on. This worked for a few months until the joint broke.

Should I solder it back on or am I doing anything wrong? Any clue why it broke?

It didn't break while the handle was being turned, it was just leaking one morning and upon closer inspection had came apart.

 

[gaz1]

you could braise it instead of soldering it

 

[colnerov]

Hi, It's the ethanol in the petrol which attacks among others things the solder.

http://www.stationary-engine.net/forum/archive/index.php?t-32849.html

Colin

 

[rikrobson]

I doubt very much that alcohol would attack solder.

 

[MattF]

Likely you just didn't get enough heat into the pieces for it to flow and bond properly, when you soldered them.

 

[penfold]

A butt joint is also asking quite a lot of solder; cutting a small spigot to give an overlap, sleeving the joint or a swap to silver solder may help. Cleanliness when making the joint is essential whichever way you use, bright metal degreased then fluxed generously and solder applied opposite the heat source.

 

[rtbcomp]

Solder is used on petrol tanks, some were even made from terne plate, effectively solder plated steel.

 

[awemawson]

What solder did you use? The original 60/40 tin lead or the modern lead free? The lead free solder crystallizes and fractures with vibration which is why it is banned in aerospace and other mission critical applications

 

[piman]

Hello all,

I understand that ethanol is a problem with soldered joints, but I forget all the details, the FBHVC ran a report on it and I would imagine that details could be obtained from their website? Materials that were common with older fuels are now failing with modern ethanol fuels, especially if over 5%.

Alec

 

[hunter27]

I have seen gas and plumbing joints like that, usually caused by movement in the joint before the solder has cooled properly. they looks tinned but the joint not secure.
Pete

 

[Maker]

I have seen gas and plumbing joints like that, usually caused by movement in the joint before the solder has cooled properly. they looks tinned but the joint not secure.
Pete

Now you mention it, I think I know what happened. I nudged it to see if it was cool and it wasn't, I didn't think it would cause any problems.

I''ll clean and redo it, if it fails again I'll be back.

 

[brightspark]

I have seen gas and plumbing joints like that, usually caused by movement in the joint before the solder has cooled properly. they looks tinned but the joint not secure.
Pete

hit the nail on the head a clean break on a joint and it would still be shiny that's dull through out due to movement or not enough heat or not cleaned and fluxed enough

 

[The_Yellow_Ardvark]

If petrol does it attack the solder, then why did the old Suffolk Punch lawn mowers have brass fuel taps solder together from 3 different parts.
But looking at the joint, not enough heat in one or both parts.
I have heard about the modern solder not being used in crucial parts etc. But I have seen something interesting when old Radio kit has bean repaired.
My friend is a very keen "Radio Ham" and collects old kits.
Some we have repaired, and one Korean war age USA radio kit. We used modern solder, and as we put it back together we noticed the repair joints, well 4 out of 7 had, for a want of better words, miniature pine tree growing out of them. Couple mm high, the new solder had crystallised.

But I digress.
Clean all the old solder off.
Re-tin with fresh solder.
Clamp the part so it can not move.
Heat the parts, you will see the solder run. You can dab some more on, but use the stored heat or the gas flame to help the solder run.
That's should do it.

 

[rikrobson]

Like all metal bonding processes the metal has to be clean. If you are usimg a flux apply this as it will make the solder wick into the joint. Tinning the parts will help as the solder will melt together. The heat should wander in through the metal from the iron or the flame and not come dorectly from the source as this just melts the solder without getting the part to the correct temperature.

The problem with the "new" solder is that its like the "original" solder before the added the lead. Tin will grow wiskers, which has kill at least one satellite. Lead mitigates this process. Also tin has two allotropes that have a transition to 13 degrees C
Grey tin has no metalic properties and will crumble whereas white tin is whet we are used to. again alloying with lead stops the grey allotope forming.

 

[500e]

Does not look as if it was tinned all over, tin both pieces flow solder over all surface & I used a 1\4 inch brush dipped in bakers to wipe the face while still flowing do this on both parts you should have a completely clean tinned surface re heat & deposit solder on one side place second part & heat till solder flows, make sure there is a flow all around the edge you can use the brush\flux to help flow & cool

 

[rikrobson]

To Reply to your original question, The joint looks like its didn't join correctly in the first place.

I'd clean it up with a file. make sure the parent metal is clean and shiny. If you can get leaded solder all the better amd use some flux too. coat both sides with the flux and hold together in the final position.

Apply heat to both parts but not the joint itself. let the applied heat transfer to the joint you will see the flux start to boil away. keep the parts hot and apply the slodet to the edge of the join. you should see the solder melt and get wicked into the joint by capillary action with the help of the flux. keep applying heat to the parts and add enough solder untill its stops getting wicked into the joint. then remove any head and allow to cool. don't be tempted to touch the parts to se iff has frozen as it will ruin the joint of there is still liquid or soft metal there.

The alternative is to tin both sides then put together and reapply heat to melt the two surfaces again dont be tempted to touch until its cool.

 

[piman]

Hello TYAD,

"then why did the old Suffolk Punch lawn mowers have brass fuel taps solder together from 3 different parts."

The clue is in the word 'old, there was no ethanol in petrol in that era, there is now, and possibly there will be a larger percentage if the E.U. gets it's way?

Alec

 

[The_Yellow_Ardvark]

Odd you mention of not using alcohol in old engines, but my grandad add an Austin in WW2 as part of his Home guard duties and that was running on Ethanol Mix.

Until about 1998 we still had the car, ran it with no issues, on a methanol/unleaded mix.. Well the metal moth was a ongoing battle.

I also make Bi fuels from old deep fat frying oil. Part of the blend we have to add Methanol and/or Ethanol. This will gives us a correct burn.

To get this we built from old hot water tanks, cooper pipe fittings all held with solder. No issues at all.

We get the Alcohol from brewing a mash up of woody green garden waste, it does help Mrs Vark used to work in a brewery, so was able to advise us. When the brewery closed we borrowed the lab all copper distillation still, nice bit of kit.

I have spoken to a friend who does the petrol pump servicing and it is not the alcohol added to fuel blends what give issues. But the chemical additives. Classic example is we could not run my friends Merc van on the bio fuels as the alcohol we added would/ could damage the seals in the fuel pump. So we striped it down and added the Bio fuel approved seals from Canada, were bio fuels are more common.