Re: PVC Pipe Deflection

While not specifically answering your question, this may be of some use to you:

From: <a href="http://www.ipexinc.com/proppng/ppng2.html">http://www.ipexinc.com/proppng/ppng2.html</a> [Ipex plastic piping design manual]

Adequate support for any piping system is a matter of great importance. In practice, support spacing is a function of pipe size, operating temperatures, the location of heavy valves or fittings, and the mechanical properties of the pipe material.

To ensure satisfactory operation of a PVC piping system, the location and type of hangers should be carefully considered. The principles of design for steel piping systems are generally applicable to PVC piping systems, but with some notable areas where special consideration should be exercised.

1. Concentrated loads (i.e. valves, flanges, etc.) should be supported directly to eliminate high stress concentrations. Should this be impractical, the pipe must then be supported immediately adjacent to the load.
2. In systems where large fluctuations in temperature occur, allowance must be made for expansion and contraction of the piping system. Since changes in direction in the system are usually sufficient to allow expansion and contraction, hangers must be placed so this movement is not restricted.
3. Changes in direction (e.g. 90° elbows) should be supported as close as practical to the fitting to avoid introducing excessive torsional stresses into the system.
4. Since PVC pipe expands or contracts approximately three times that of steel, hangers should not be of the type that will restrict this movement. However, it may be desirable in some instances to use a clamp-type hanger to direct thermal expansion or contraction in a specific direction. When using a clamp-type hanger, the hanger should not deform the pipe when it has been tightened.
5. Since PVC is somewhat notch sensitive, hangers should provide as much bearing surface as possible. Sharp supports or sharp edges on supports should not be used with PVC pipe since these will cause mechanical damage if the pipe moves.
6. Valves should be braced against operating torque.
7. PVC lines must not be placed alongside steam or other high temperature pipelines.

[There is a support spacing chart at the page]

• In PipingDesign@y..., "Phillip P. Joseph" <ppj@w...> wrote:
  > Hi everybody:
  >
  > Can anybody please tell me what are the permitted deflection angles
  for
  > C-900 (4"-12") and C-905 ( >12") PVC pipes/joints used for water
  > transmission?
  >
  > Thanks,
  > Philip