Will it catch fire?

[DODO``]

Trying to cut an existing gas tank bracket and weld new bracket and wanted to be cautious and see if anyone had a similar experience.

*it's used gas tank so it did have gas in it before.
*its been empted and dried around 1 week.
*Welding point are here (see pic) & away from the tank.

*even though the tank is dry it still smells of petrol very very faintly.
*I will wrap the tank with wet towel when I'm doing it to protect paint.

Would it be ok to proceed? Or should I clean it right out with water or something?
What would be an indicator that there is no fume?

thanks for your advice.

[caseye]

OK, is there a reason the tank cant simply be taken off?
Most tanks slip on or off front mounted rubbers and have a single bolt or clip holding therm in place.
Otherwise a couple of wettish towels covering the tank and the filler in particular would most definitely be advised.
Should be OK at that distance, but do disconnect your battery and don't hold on the work for too long, heqat build up is rapid on thin walled steel.
Thinking on it a bit more, if you are going to refill the tank soon,(with petrol that is), I'd probably opt to fill it full of water while I was welding the bracket, you can't be too careful around combustables.

[DODO``]

OK, is there a reason the tank cant simply be taken off?
Most tanks slip on or off front mounted rubbers and have a single bolt or clip holding therm in place.
Otherwise a couple of wettish towels covering the tank and the filler in particular would most definitely be advised.
Should be OK at that distance, but do disconnect your battery and don't hold on the work for too long, heqat build up is rapid on thin walled steel.
Thinking on it a bit more, if you are going to refill the tank soon,(with petrol that is), I'd probably opt to fill it full of water while I was welding the bracket, you can't be too careful around combustables.

Hi thanks for your reply I appreciate it!
I'm customizing my bike with new tank and this is the tank I want so no it can't be taken off

Got a welder coming to do the job. he will tack it in couple spots to get the position right first, then take the whole tank off the bike to do the rest of the welding. and yup will dis connect the battery.

if I fill it with water, would fuel pump work as normal when the petrol goes back in? or would I need to dry them out too?

[caseye]

Safest is to remove the tank away from the area to be welded. All tanks come off their original frames, one way or another, if this can't be done, then plan B as in first post.
If you can't get the tank off the frame, you'd be advised not to fill it full of water, because, NO the fuel pump won't work again after it's had a drink of water, not petrol.
Your welder perosn should have a good understanding of the risks and may not think too much of what you want to do, on the other hand they might just do it and wonder what all the fuss was about.
Thier call.

[Graystone]

It won't catch fire, it'll either explode or do nothing.

As strange as it sounds, it may be safer to fill it to the brim with petrol (water would be safer still but then you have to remove it all) to reduce the vapor area and chance of explosion (only do this if you can seal the tank vent though).

Also bear in mind the tank should be opened if it is going to be heated up due to the welding.

[jato]

If much heat gets to the actual tank it will generate a potentially explosive vapour (quite a few people have been killed welding tanks - even one i know of that had been empty for months) so if you can stop heat getting to the tank you may not need to do the water thing. Perhaps 5 to 10 seconds of welding and then let it cool before another 5 to 10 seconds...

[DODO``]

Safest is to remove the tank away from the area to be welded. All tanks come off their original frames, one way or another, if this can't be done, then plan B as in first post.
If you can't get the tank off the frame, you'd be advised not to fill it full of water, because, NO the fuel pump won't work again after it's had a drink of water, not petrol.
Your welder perosn should have a good understanding of the risks and may not think too much of what you want to do, on the other hand they might just do it and wonder what all the fuss was about.
Thier call.

oh you ment the tank to be off the bike while working? if thats the case, yes it can be taken off!

so how do you fill the tank and keep the water inside with the fuel pump off? the water will just drible down the bottom.

[AllanB]

if I fill it with water, would fuel pump work as normal when the petrol goes back in? or would I need to dry them out too?

Take the fuel pump out.

A. so it does not fill with water if used.

B. because it is probably that any residue fuel will be retained in the filter.

[DODO``]

It won't catch fire, it'll either explode or do nothing.

As strange as it sounds, it may be safer to fill it to the brim with petrol (water would be safer still but then you have to remove it all) to reduce the vapor area and chance of explosion (only do this if you can seal the tank vent though).

Also bear in mind the tank should be opened if it is going to be heated up due to the welding.

wowee.. it really does sound strange..

If much heat gets to the actual tank it will generate a potentially explosive vapour (quite a few people have been killed welding tanks - even one i know of that had been empty for months) so if you can stop heat getting to the tank you may not need to do the water thing. Perhaps 5 to 10 seconds of welding and then let it cool before another 5 to 10 seconds...

wow again,, scary.. !

[DODO``]

Take the fuel pump out.

A. so it does not fill with water if used.

B. because it is probably that any residue fuel will be retained in the filter.

ok thanks for this, how would water stay in the tank while the pump is out and theres hole at the bottom of tank?

[AllanB]

ok thanks for this, how would water stay in the tank while the pump is out and theres hole at the bottom of tank?

[FJRider]

The safest method is actually ... connect a hose from the exhaust pipe of a car and poke it into the fuel tank (take the tank off First) and run the exhaust fumes into the tank for about an hour. This dries out the interior and removes ALL petrol fumes.

[eldog]

Suggest removal of battery if your welding onto the bike frame, away from sparks, H2 will explode.

[DODO``]

The safest method is actually ... connect a hose from the exhaust pipe of a car and poke it into the fuel tank (take the tank off First) and run the exhaust fumes into the tank for about an hour. This dries out the interior and removes ALL petrol fumes.

Long time no chat,
Yup will do this thank you sir!

[FJRider]

Long time no chat,
Yup will do this thank you sir!

Prior to painting the outside of the tank ... it pays to put a sealer coat on the inside to stop rust issues later.