Page 65 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

PIPING 2.15

existing metallic pipe specifications and others are unique to the plastic pipe industry. The
following is an explanation of the terms used in various standards:
SDR. The standard dimensional ratio is the most commonly accepted measure for provid-
ing a pipe wall thickness category and constant mechanical properties for many plastic pipe
materials. Used for solid homogeneous pipe, the SDR is found by dividing the average outside
diameter of a pipe by the wall thickness. This designation has resulted in a series of preferred
industry standard numbers that are constant for all sizes of pipe. It is possible for a pipe to have
different SDRs depending on whether the I.D. or O.D. is the controlling factor.
DR. The dimensional ratio is often incorrectly used interchangeably with SDR. The
DR is found in the same manner as above and means the same thing, but is used when
the product does not have the preferred SDR number established by other prevailing
standards. Pipe manufactured to pressure ratings for AWWA C-900 series standards
uses this designation.
O.D. controlled. This designation is used when the outside diameter of the pipe is the
controlling factor in the selection of the pipe.
I.D. controlled. This designation is used when the inside diameter of the pipe is the
controlling factor in the selection of the pipe.
P.R. Pressure rated is used when the pressure rating is the controlling factor in the
selection of the pipe rather than the dimensions of the pipe itself.
PS. Pipe stiffness is used only for sewer pipe. This designation is in PSI. The higher
number has a thicker pipe wall.
Schedule. This designation is used to match the standard dimensions for metallic pipe
sizes. The pressure rating of the pipe varies with pipe size. Some standards use iron pipe
size (IPS) instead of schedule to keep the wall thickness consistent with iron pipe.
PSM. This is an arbitrary designation for products having certain dimensional charac-
teristics unique to a very specific product.
The AWWA has several proprietary dimensional standards that are used to specify plas-
tic pipe used only for pressurized potable and fire water main distribution and transmission
systems. The composition of the plastic piping material is referenced to ASTM standards.
Since plastic pipe connects to or replaces cast iron and ductile iron pipe, these standards are
O.D. controlled for use with O-ring gasketed joints only and are dimensionally compatible
with these joints. These standards are:
AWWA C-900 = 4 to 12 in PVC
AWWA C-901 = 1/2 to 3 in PE
AWWA C-902 = 1/2 to 3 in PB
AWWA C-903 = Deleted
AWWA C-904 = Fittings for C-900 pipe
AWWA C-905 = 14 to 36 in PVC
AWWA C-906 = Larger diameter PE pipe
Trade laws allow import of Canadian pipe materials into the United States. The Canadian
Standards Association (CSA) has standards of their own, but many of them have not been
completely coordinated with the U.S. standards for similar products. At this time, using
CSA standards as reference for plastic products is not recommended.
There are three designations used in plastic drainage pipe standards: DWV, sewer, and
drain. All standards are O.D. controlled and are non-pressure-rated. The only differences
between identical materials with different designations are dimensions. Different materials
with the same designations have the same dimensions.

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