mechanical connectors [1]
Pipes joined using nuts and threaded metal parts; a gasket is inserted to tighten them, thus preventing leakage.
union 
Formed by using a nut to tighten a male union nut in a female union nut; leakage is prevented by placing a gasket where the two tubes meet.
union nut 
Threaded on the outside so it can be inserted into the female union nut.
gasket 
Flexible washer placed where two tubes meet to prevent leakage.
pipe B 
pipe A 
ring nut 
Part that enables a male union nut to be screwed into a female union nut.
union nut 
Threaded on the inside so that a male union nut can be screwed into it.