I guess you are up pretty early in Italy since it is almost 10 PM here on the East Coast. The difficulty I have with the welder information you have shown is that I am not familiar with metric specifications. My guess is that you should have no problem using it is a 230 V system but I think most of Europe is that way anyhow?
As for the valves on the side of the tank, the large ones that were big enough to pass two fingers through, I just plugged them with a hole plug. The smaller holes, of which there were three, I left open and use them to pass thermometer probes through without getting the wiring crushed by the smoker doors. I wrap a small piece of nomex gasket around the wire to keep it relatively airtight. The remaining holes I left open were about 10 mm in diameter. Since they were tapped for pressure gauges and a pressure switch they are threaded. I can always close them with a bolt. Remember that you will need to have a bottom drain, you might try to position the tank to allow one of those holes to be at the center of the bottom so you can just fit in a ball valve to allow drainage when you clean it.
With regards to your perfect cube firebox, you might consider shifting those dimensions slightly to make the firebox taller and may be not as wide. The taller firebox will make it easier for you to load the wood into especially that the fire basket will be elevated from the floor several inches and you will need this to accommodate the damper on the side of the firebox or the front, depending on where you place. But having the intake air infiltrate the firebox from below the fire is an advantage.
All three of my steel smokers were cut using a hand grinder. I do not know of the wattage. They are however 4 1/2 inches and from the conversion I just tested that would be about 114 mm.
You might post the dimensions of your tank. Particularly the diameter and the length. The doors will probably fit nicely in between the welded seams of the endbell on the tank. Are you using one door or two? With the position of your tank as it lies on the ground I cut my door at about 1 o'clock and 4 o'clock position. This seems to have worked for me but I did change plans in the middle of the build and utilized square doors by building the cut out opening to fit square doors. If you search the website here you will see several smokers utilizing the same style.
There are many great builders here on the site that will have greater knowledge on your metric specifications. My sons in-laws live near the Adriatic Sea in Bari Italy. As for your English... Seems pretty perfect to me!
Make no mistake, there ain't no powder in this Puff ! And... I'm not really a crazy person but I play one in real life
Hello Ras,
First let me say that i am no expert ok but here is what i have learned any 230V wire welder will work especially welding less than 1/4 inch thick steel. You will want to use .035 Flux core or if your using gas with it use non-Flux.
To your original question about door cutting with an angle grinder yes that will work i can tell you it was easier to use a circular saw with a metal cutting blade, this is because if you are not practiced with a angle grinder you will break allot of blades. If you can keep a steady straight hand then the angle grinder will work great.
As for the position of the doors they are normally placed Top 1 inch prior to the 12 o'clock and Bottom at the 9 o'clock position. i would set the cylinder so one set of the valves are at the bottom, one of the valves will make a great pre-drilled drain hole. the others will either need to be cut off and patched or capped if patching is to much trouble. Just depends on what you want the look to be like.
After you get the doors cut build a large fire inside and it will burn the exterior paint off nicely.
Anyways it is a fun process invest in good welding gloves and leather work gloves, get a respirator of some sort, breathing grinding dust sucks. Also, get a auto darkening welders helmet you can get one cheap that has variable shades from 1-10 for like 50 bucks.