When fitting up two pipes, what are two important considerations?

When fitting up two pipes, ensuring proper alignment and addressing the gap between them are critical to achieving a secure and leak-proof connection. High-low refers to the positioning of the two pipes in relation to each other; if one pipe is higher or lower than the other, it can lead to issues during installation such as misalignment or stress on the joints. The gap is equally important, as too much space between pipes can lead to weak connections, while an insufficient gap can cause problems during expansion or contraction due to temperature changes.

In contrast, while length and diameter are important for matching pipes, they do not focus specifically on the fit-up process that emphasizes joint integrity. Sealing and alignment are more directly related to how the pipes come together. Material type and temperature are also significant considerations, especially for certain environments, but they don't specifically address the immediate challenges of fitting two pipes together for a secure connection.