Hanger Support Spacing
It is necessary to adequately support any piping system. Correct spacing and support selection depend upon several factors including but not limited to, weight loading (pipe and its contents), bending stress, effects of thermal expansion/contraction (operating temperatures and temperature range), location of heavy valves and fittings, and the material properties of rigid PVC and CPVC.
It is important to ensure that the hanger selected has enough weight bearing surface contact with the pipe. Rigid PVC and CPVC materials are notch sensitive therefore, hanger surfaces must be smooth with no rough or sharp edges. Rough surfaces and /or sharp edges can damage the piping. It is recommended that weight-bearing surfaces in contact with the pipe be a minimum of 2 inches in width. Listed below are some basic rules to follow while installing and hanging PVC and CPVC piping systems:
Thermoplastic piping systems will move due to the effects of thermal expansion and contraction. This must be considered when choosing the correct type of hanger selection; a hanger that does not “squeeze” or compress the pipe or restrict axial movement is required for both vertical and horizontal systems.
Placement – Support Spacing
Placement of supports when installing a system is critical so that system damage can be prevented. It is recommended that supports be placed within 2 feet of a joint (couplings, unions, flanges, etc.) or change in direction (elbows, tees, etc.). Valves will require close support, or if possible, independently supported, due to the extra weight a valve adds to the system and the operational torque of valves. An additional factor to consider is if the fluid being pumped contains any particulates. Accumulation of particulates will add additional weight to the system. Maximum system operating temperature will determine the required horizontal support spacing in a system. Consult pipe manufacturer and local code authority for proper spacing. Supports should not restrict axial movement. Vertical load should be the determining factor for vertical support placement. Vertical piping must be supported properly. Thermal expansion/contraction must be assessed when designing system support.
*Local plumbing codes may differ but generally most (plumbing codes) have the same requirements for supports spacing. However, always consult with the local Authority of Jurisdiction.
Minimum Spacing in Feet
Model Plumbing Codes
4; Allow for expansion every 30 feet3
1 inch and smaller
1¼ inch and larger
Base and each floor;
Provide mid-story guide; provide for expansion every 30 feet
Provide mid-story guide
IPC Note B: For sizes 2 inches and smaller, a guide shall be installed midway between required vertical supports. Such guides shall prevent pipe movement in a direction perpendicular to the axis of the pipe.
IMC Note C: Mid-story guide.
UPC Note 3: Support at each horizontal branch connection
*Note- other factors such as operating system temperature and heavy components such as valves may necessitate closer spacing and/or independent support.
In some applications, using protective sleeves or pads between the pipe and the hanger to distribute the stress loads over a greater surface area may be required. Piping surfaces must be protected when in contact with abrasive surfaces. High temperature may deform plastic pipe and fittings. Appropriate shielding should be utilized to protect pipe and fittings from high temperature producing equipment and/or components. Contact with heat producing sources should be avoided.
Anchors and Guides
Anchors direct piping movements by completely restraining movement at key locations in the system.
Anchors can used to manage the effects of the following:
Guides are necessary to direct movement between anchor locations as they allow axial movement but do not allow transverse or lateral movement. Anchors and guides should be engineered and installed so that they perform satisfactorily without point loading the system causing damage.
Hanger Support Recommendations
The following charts show recommended support spacing according to nominal size, schedule (40 and 80) and a range of operating temperatures. Do not restrict axial movement of the pipe. Allow for movement by thermal expansion/contraction and/or pressure changes. Continuous support may be more economical if short spacing is required.
The information in the following chart applies to an un-insulated straight run with a fluid having a specific gravity of 1.00 or less. Concentrated/point loads are not a factor in the charts.
Nominal Pipe Diameter (in.)
PVC Schedule 40
PVC Schedule 80
CPVC Schedule 80
*Note: Always abide by local and state code, and consult with the Authority of Jurisdiction.