Straight pipe fittings(Adapters) are used to connect two straight sections of pipes in a straight line without any change in direction. Ensure that the pipe ends are clean, smooth, and free from any burrs or debris before installing the fitting. Apply a suitable pipe thread sealant or thread tape on the male pipe threads to create a leak-free seal. Hand-tighten the straight fitting onto the pipe until snug, and then use a pipe wrench to make a final quarter to a half turn to ensure a secure connection. Avoid over-tightening the fitting, as it may damage the threads or cause leakage. Check for any visible leaks after installation and make necessary adjustments if required.