If you need to join an exhaust pipe without welding, there are a few options. You can use a high-temperature silicone sealant, which will create a tight seal that will hold up under heat and vibration. You can also use exhaust clamps, which are designed to hold the pipes together without welding. Another option is to use a slip joint, which is a type of coupling that allows the pipes to slide together so they can be joined without welding.