What are the two main categories of manufactured pipe?

The correct answer points to the two primary types of manufactured pipe, which are welded and seamless.

Welded pipes are created by taking flat sheets of metal and welding them together to form a hollow tube. This manufacturing method tends to be more cost-effective and allows for a wider variety of pipe sizes and thicknesses. Welded pipes are commonly used in various structural applications and can be produced with specific properties tailored to their intended use.

Seamless pipes, on the other hand, are made from a solid round steel billet that is heated and then pushed or pulled over a form until the pipe is the desired diameter. This manufacturing process yields a pipe that does not have a seam, making it stronger and more durable in situations where the integrity of the pipe is critical. Seamless pipes are often preferred in high-pressure applications.

The other options presented refer to different types of joints or fittings rather than categories of pipes themselves. For example, soldered and flanged or brazed options involve joining methods or specific types of connections rather than the basis on which the pipe is manufactured. Thus, the distinction between welded and seamless represents the essential manufacturing processes for producing these types of pipes.