PVC pipe

PVC pipe and fittings is the most common material for spudgun construction. It is cheap, lightweight and availble in a wide range of dimensions and ratings. PVC is usually joined by solvent welding, which is easy to do and requires no special tools. Threaded fittings are also used, but then solvent welded to the pipe. PVC is easy to machine, and parts are sometimes customized to fit a certain purpose.

One of the main disadvantages of PVC is that it becomes brittle in cold weather, which may lead to chamber failure, especially in pneumatic launchers. When PVC fails under pressure it breaks into sharp shards, which are propelled at high velocity. Because of this danger PVC pipe is not rated for use with pressurized gasses, and the use in spudguns is to be regarded as outside of specifications. When proper precautions are taken, it is still very safe to use.

Naming Conventions

Schedule

Schedule is a method of denoting pipe demintions with a standardided set of nominal sizes. Note that this is a size convention, and does not neccessarily denote a pressure rating. Harvel has tables of dimentions for SCH40 and SCH80 pipe sizes.

SDR

SDR (Standard Dimension Ratio) pipe has the same O.D. as Schedule pipe, but with different pipe I.D. All SDR pipe in a series has the same ratio of O.D to wall thickness throughout the sizes, and thus has the same pressure rating. All SDR pipe is rated for pressure, but becuase it often has relatively thin walls, it should be sleeved or otherwise reinforced before use. Harvel has charts of dimentions and pressure ratings for SDR pipe.

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