How many liters of gaz for a car

[Fred_64]

Hi All,

I have to work on an old and very rusty Alfa Romeo (Bertone small coupe).

I know this is quite hard to tell but I need to figure out how many liters of gaz I will need to rebuild the thing.

Would you have in mind some very gross figures for changing sills (ie 2 hours = 2 cubic meters of gaz), floors, etc..

As far as I know (before starting the Makita grinder...);
- both front floors are gone,
- both sills are completely gone (outer at least, maybe the inner as well),
- rear end needs a new mask,
- doors handles are rotten,
- one wheel arch is very "bubbly"

I will need to do a lot of tack/plug welds (not too good for gaz consumption is it ?)
Am I correct in assuming that one cubic meter of gaz will produce about 1 hour, 1hour 1/2 of welding on thin panels ?

I rang a "Air Liquide" today and this opened my eyes on this financial side of "fun welding"; I am not too happy about renting a 4m3 bottle for 3 years.
(Messer in France has a nice deal I believe, 6.8m3 for 216€/3 years, each refill is 85€ all incl. VAT)

 

[langy]

Your answer is "how long is a piece of string" i'm afraid !!!

 

[backpurge]

You will use around 15litres of gas per minute or 0.9 cubic meters per hour of arc on time so the information you got from Air Liquide is about right, don't panic you will deposited a lot of weld in an hour

 

[Fred_64]

Thanks for your replies,

Maybe this methodology could work;
- run a tape on all welds needed (1.5 meters for the top of the sill, another 1.5 for the bottom, so about 3 meters for each sill, etc...)

At the end of my guess work this gives me let's say 8 meters of weld, now I need to know how long it takes to weld 1 meter of thin panels !

Any rule of thumbs from petrol heads ?

Cheers,

Fred

 

[malcolm]

I tend to use maybe 2 size Y bottles in a decent restoration (replacing everything that looks like it used to be made of metal).

Can't remember how many litres are in a size Y. I think it's 10L filled to 200bar which would be 2 cubic meters unpressurised.

 

[Fred_64]

Hi Malcolm,

Roughly how many things did you have to weld on the vehicle, was it a combi or a coupe ?

I assume a Y size is 2m3 (B11 or S11 in France).

Shame is the only one filling bottles at 300 bars in France in Messer, and only on their Megatop B20 range, this gives you 6.8m3 instead of 4.6... and total refill cost is nearly the same (works around 10GBP per cubic meter), and you have to rent it of course...

I will probably go for a 2m3 and start grinding/welding, if I need more I sell the 2m3 bottle and rent a 6.8 m3 Messer one, if I need even more gas I just sell the whole bloody car !!

 

[malcolm]

Here are a couple: http://www.aston-v8.co.uk/ (really complex sills plus some chassis) and http://www.renault4.co.uk/renault-4-restoration.htm (floors, bits of chassis, edges of body). Gas cost is nothing compared to all the other costs.

Never fancied larger cylinders than the one I have - they are too big to move around on the back of a MIG.

 

[Drains]

A wee point Fred - you may use less gas per minute than backpurge suggests, depending largely on the torch/shroud size. If you're on a 500A torch, 15 lpm or more would be the thing, but if you're using a sub 200A torch you can probably use half that amount without any loss of weld quality. Indeed 15lpm might be too much and draw in air.

 

[Fred_64]

Hi All,

Thanks for the replies, I am p.. off as I found out that Air Liquide produces "Albee" tm bottles in the UK and they sell/refill them at a third of their French prices, even using DHL or UPS to France would make economic sense for me !

Anyway, I found info below on the net, hope you will find it useful;

Argon Gas, GTAW (TIG) Process, Average Consumption of 6 LT/MIN
Total welding time with L5 bottle: 2hr 55mins, with L11 bottle: 6hr 23mins

Argon Gas , GMAW (MIG) Process, average Consumption of 15 LT/MIN
Total welding time with L5 bottle: 1 hr 10mins, with L11 bottle: 2hr 33mins

Argon CO2 (15%) Gas, GMAW (MAG) Process, average Consumption of 12 LT/MIN
Total welding time with L5 bottle: 1 hr 36mins, with L11 bottle: 3hr 33mins

And thanks for the links on 4L and Aston, I have printed all these