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Piping and connections
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The tapered thread
The tapered thread is one of the oldest methods of connecting pipe.
Its very simple. Both the male and female threads are tapered smaller at the end of the pipe and the entrance to the fitting, When the the piping is tightened, the threads jam together. As they jam, they sort of meld together.
The thread is not especially smooth, but the jamming tends to close gaps in the thread. The seal is facilitated by using a pipe dope that fills any gaps in the thread and lubricates the joint so that more pressure is applied to the thread jamming than to overcoming the friction between the 2 metals. The tighter the connection, the better the seal.
This type of joint is one of the best sealing methods available.
The video below shows some closeups of the tapered joint.
Its very simple. Both the male and female threads are tapered smaller at the end of the pipe and the entrance to the fitting, When the the piping is tightened, the threads jam together. As they jam, they sort of meld together.
The thread is not especially smooth, but the jamming tends to close gaps in the thread. The seal is facilitated by using a pipe dope that fills any gaps in the thread and lubricates the joint so that more pressure is applied to the thread jamming than to overcoming the friction between the 2 metals. The tighter the connection, the better the seal.
This type of joint is one of the best sealing methods available.
The video below shows some closeups of the tapered joint.
When making connections using wrought iron pipe, the pipe comes with a fitting mounted at one end of the pipe.
Many believe this is a coupling for connecting 2 lengths of pipe.
This is not true. It is only a thread protector. Its threads are not tapered so are not suitable for connections.
Below is a video explaining how this works.
Many believe this is a coupling for connecting 2 lengths of pipe.
This is not true. It is only a thread protector. Its threads are not tapered so are not suitable for connections.
Below is a video explaining how this works.
Another type of fitting is the ferrel connection. This fitting is used in small tubing connections. It is useful only for positive pressure applications. The video below covers how this fitting works.
There is a special type ferrel used on gas pilot tubes. The video below shows how it works and how to install it. This video will be available 2-26-15.
The flare fitting is another method of joining pipe. The video below shows methods of being sure the fitting does not leak.