You turn on the Acetylene and ignite it, you start to add oxygen via the control valve. You will see the colour changes from yellow to blue. There are two shades of blue, one is slightly darker than the other. Once the inner blue cone is down to a nice roaring bright light you are more or less set up to weld. Get your Filler wire (welding rod) put on your welding goggles and lower the flame to the piece of metal you wish to weld. You will start to see the metal heat and become molten. The next part takes practice. Once the metal has turned molten immediately start to add the filler wire; keeping the torch at about 45º move along the metal adding the wire at a constant steady rate. Insufficient filler wire will result in either undercut or the pool dropping through. Too much wire or moving to fast will result in either a poor weld or no weld at all. Speed and angles do not need to be 100% correct find what is comfortable for you.
Remember Gas welding is Extremely Dangerous and you should take courses in it before attempting it.
I will add a couple of links for you to get a more detailed idea lower in the page under related, source links.
One method of removing a specimen of weld is by using a cutting torch, which employs high-temperature flames to melt and separate the weld metal from the base materials. This technique is efficient for thick welds, as it allows for precise control over the cut. Alternatively, mechanical methods like grinding or machining can be used, where the weld is physically removed by abrasion or cutting tools. Each method's choice depends on the weld's size, location, and the desired level of precision.
You can order cutting torch and accessories at www.homedepot.com. Beleive it or not you can also find torches and accessories at www.amazon.com.
Oxygen Acetylene torch will get to 5800-6300 degrees Fahrenheit easily.
A cutting torch can be used on any material though it was made mainly for cutting metals. The heat generated may damage other materials such as wood or plastic.
By cutting them with a cutting torch so that the receiver is in at least 3 pieces.
Last time I did it was with a cutting torch.
The type of weld bead formed by moving the torch or electrode from side to side as the weld progresses is known as a "weave" pattern. This technique helps to distribute heat more evenly and can create wider welds, improving penetration and fusion with the base materials. Weaving is commonly used in various welding processes, such as MIG or TIG welding, to enhance the quality and appearance of the weld bead.
A cutting torch is one answer.
Please see the link.
oxygen supports the combustion of the gas that one uses in the welding/cutting torch. Acetylene combined with Oxygen produces the hottest flame.
A good brand for cutting torch is rigid at home depot. They make quality products that lasts and have good warranties if the item should break or malfunction on you.
with a cutting torch of course