Prepping petrol tank for some work???

[alanscottj]

I have had to change my petrol tank due to the carb hitting (see previous post) I would like to keep the original tank so I am thinking of getting somebody to cut a bit out where the carb sits and re-weld it back up.

What is the best way of prepping the tank for this? Obviously it has to be fume free for the cutting and welding, wouldn't want it blowing up - any thoughts on how long it need to be left empty? Can I use something to wash it out?

Many thanks.

[holty]

ive done this before scott, it is dangerous, i emptied it of fuel, connected a hosepipe for 5 mins to give it a good flush out, then ran a hose from my van exhaust to the filler neck and ran the van another 5 mins and then welded it without a problem, i was standing as far back as i could though, petrol fumes linger and can take some flushing out, be careful.

[HxPaul]

I once had a Harley tank welded,I just filled it with water.Most welders use steam to clean out petrol tanks.

[B-Race Tuning]

One of the most hair raising jobs I've done was welding inside an aluminium 45000 litre fuel tanker. The tanks were chemically washed over 24 hours. A certificate of "Gas Free" is issued and then you had a two hour window to complete the job. Metal will hold residue that gets released as it's heated creating the explosive gases.
Cutting up a 47kg Propane cylinder to make a workshop waste wood/ oil heater can be a bit nerve racking too.
By choice these days, any welder worth his salt would use a new tank to start off with if requiring welding due to the low cost of one V a potential explosion.
As Paul says above, thorough steam cleaning may give you a window, that combined with filling with water other than just the area you want welded.
I'd think that your welder of choice would want to do his own prep though.
Simon.

[alanscottj]

Thanks for all the replies - will get in touch with welder this week and leave it to the professionals


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