Your typical household tools will not cut a metal pipe. To cut a metal pipe, you’d need more specialized tools like a pipe cutter or circular saw. Do not attempt to use these tools without taking proper safety precautions and wearing safety gear. It’s usually safer to let a pro cut a metal pipe, especially if you’re not confident in your skills with a heavy-duty saw.

The best thing to cut metal pipe is a durable pipe cutter that is made for metal. You may want to measure the diameter of the pipes before purchasing a pipe cutter to ensure it will be able to cut your metal pipes. Opt for a heavy-duty option to cut through metal like steel or cast iron.

You should not do your own welding unless you have the proper training and experience. Most home electrical systems can only handle MIG welding, which creates weaker bonds than TIG welding and won’t work on certain metals or metal thicknesses. Both welding forms usually require the use of shielding gas, which can be dangerous to store at home. Additionally, welding machines create temperatures of over 3,000 degrees, and the sparks can blind you if you don’t have the proper equipment. As such, it’s usually better to hire a professional welder for your welding projects.

Cutting rectangular ductwork requires careful measurements and the right technique. Use a measuring tape and pencil to mark the cutting lines accurately. Tin snips are excellent for straight cuts on smaller ducts. For more extensive or thicker rectangular ducts, a reciprocating saw with a metal-cutting blade is effective. 

Ensure the duct is well-supported and secure while cutting to prevent wobbling and maintain precision. After cutting, use a metal file to smooth any sharp edges, ensuring safety during installation.