Final answer:
To prevent leakage with flanged pipe joints, gaskets are the primary sealing method, and clean flange faces are crucial for a secure seal.
Step-by-step explanation:
To prevent leakage with flanged pipe joints, gaskets are used between the flanges. Additionally, it is important that the flange faces must be very clean to ensure a good seal. While Teflon tape is commonly used for threaded pipe joints, it is generally not used with flanged joints. Welding the flanges together would make the connection permanent, which is not desired in all applications. A sealant compound can be used for added security, but the primary sealing mechanism is the gasket.