Yes, compression fittings can be used on brake lines. Compression fittings are commonly used to repair or replace a damaged section of brake line. They consist of a nut, a sleeve, and a ferrule. When the nut is tightened, it compresses the sleeve onto the brake line, creating a leak-proof seal. Compression fittings are designed to be used with soft steel or copper brake lines, and are available in different sizes to fit various brake line diameters. When using compression fittings on brake lines, it's important to make sure that the fittings are tight and secure, and that the brake line is properly flared before installing the fittings. Additionally, after repairing or replacing a section of brake line, it's important to bleed the brakes to remove any air that may have entered the system. If you're unsure about using compression fittings on brake lines, it's best to contact a professional mechanic for assistance. This type of repair should only be performed by a professional as it requires a high level of expertise and can be dangerous if done incorrectly.