mechanical connectors [3]
Pipes joined using nuts and threaded metal parts; a gasket is inserted to tighten them, thus preventing leakage.
flare joint 
Threaded part over which two tubes having bell-shaped ends can be tightened by a nut.
tube end 
Flared end of a pipe.
connector 
Threaded part joining two pipes.
nut 
Metal part used to tighten the end of a tube onto the fitting.
pipe B 
pipe A 