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There are many types of fittings that are available to connect PVC pipes. Pipes and fittings can be either threaded or unthreaded. Fittings that join pipes must correspond, i.e. a threaded pipe can only connect to a threaded elbow, not an unthreaded one. Here are some of the main fittings to be familiar with:
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Name
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Image
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Notes
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Coupling
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Elbow
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Adapter
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Bushing
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Cross
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Wye
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Cap
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Flange
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Union
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Nipple
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Check out this Wikipedia guide that explains the different types of pipe fittings.
Sealing PVC Pipe Fittings
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