TECHNICAL DATA MECHANICAL GRAY PP-RCT PIPES
General Technical Informations
Polymelt PP-RCT (polypropylene random copolymer with modified crystallinity and temperature resistance) uses the “Standard Dimension Ratio” - SDR – method of rating pressure piping and is manufactured to the metric sizes shown in the chart on the following page. Note that for a given size, the outside diameter (OD) does not change, but rather the inside diameter (ID) changes with different SDRs.
All pipe comes in 19 ft. lengths
Socket Fusion Fittings
- Size range ½” to 4”
Butt Fusion Fittings
- Size Range 6” to 20”
Allowable Pressure Rating
PP-RCT Temperature/Pressure Chart
Minimum 50 YEAR LIFE EXPECTANCY For Systems With Constant Operating Parameters. 1) Contact your Polymelt RSM for proper design and installation of systems with temperatures less than 32˚ F. 2) SDR 11 at 180˚ F (25 years) , at 200˚ F (5 years)
With Polymelt PP-RCT, as long as the SDR rating is maintained in a given system, the pressure rating will not change regardless of the pipe size or changes in pipe sizes throughout the system.
Horizontal Support Spacing
The following charts give the center-to-center support spacing for horizontal pipe runs.
- Charts are based on pipes being filled with water. Additional supports may be required for media denser than water.
- The maximum temperature is the highest temperature the pipe will be subject to.
SDR 17.6 Hanger Spacing
SDR 11.0 Hanger Spacing
SDR 7.4 Hanger Spacing
Vertical Support Spacing
Typically, there are fixed vertical supports at each floor, but this is not a hard and fast rule. Please consult our Planning Guide for information regarding how to install vertical supports on your specific project.
Polymelt pipe and fittings are manufactured to metric dimensions, and many metric hanger and support options are available. If you are using IPS or CTS size hangers, the size must be adjusted to accommodate the metric OD of our pipe. Please contact your local Polymelt distributor in this case for assistance.
Remember to always use rubber gaskets when installing metal clamps around hot water pipes, including riser clamps. Never over-tighten metal clamps around Polymelt pipe.
Increased Hanger Spacing
One of Polymelt’s largest markets is retrofitting mechanical HVAC systems. In these types of projects, it is many times advantageous to reuse the existing hangers from the previous steel pipe if possible. Sometimes this can mean that that the existing hangers are outside of the allowable spacing noted in the hanger spacing charts in the previous section. An easy solution for this problem is to use in-line hanger extenders. Example: You are retrofitting a steel pipe system with Polymelt and want to use the existing hangers with a spacing 8’, but the required spacing for Polymelt is 6’. A simple and cost-effective solution is to use 2’ hanger extenders. A 2’ hanger extender would contribute 1’ of additional hanger spacing on each side of the existing hanger, resulting in a new over-all hanger spacing of 6’.
Hanger extenders must:
- be rigid enough to support the pipe filled with water
- have smooth surfaces so as not to damage the pipe
- must not be tight fitting/apply pressure to the pipe
Maximum Pull Force
Maximum safe pull force for MECHANICAL PP-RCT pipe (≤ 68F°;1h).
Bending POLYMELT Pipes
There are instances where it is advantageous to bend a piping run rather than using fittings to maneuver around turns in, for example, trenches, hallway offsets, building riser chases, etc.
Polymelt can be bent using the following formula: R ≥ 100 × D
Where R is the minimum allowable bending radius, and D is the outside diameter of the pipe you are fusing as shown in the following diagram. Laying out your bend on graphic paper is a very quick way to determine if you are within the allowable bending limits. In more complicated situations, have your CAD department layout your proposed bend to determine if you are within the allowable bending limits.
In this hypothetical example, let’s assume that our outside pipe diameter is 6 inches. With this value, our bending radius must be greater than or equal to 50 feet as shown below.
R ≥ 100 × D
≥ 100 x 6 inches
≥ 600 inches or (or 50 feet)
Flange Bolt Torque Values
Insulating POLYMELT PP-RCT Pipes
Polymelt pipe is manufactured to metric dimensions. Some insulation manufacturers, manufacture insulation to match Polymelt’s metric sizes. In the event that you are using standard pipe size insulation, the following chart gives the best IPS (iron pipe size) and CTS (copper tube size) insulation fit.
Pressure Test Procedure
Always consult the required pressure testing procedures of your company and the project specifications. The pressure test outlined below is the minimum standard pressure test recommended for polypropylene pipe.
Compressed air or other gases ARE NOT APPROVED for pressure testing Polymelt piping systems, even for preliminary low pressure leak detection. Water should always be used.
Prepare For Pressure Test
1. Exposure of joints
All joints including fusion joints not previously pressure tested should be left uninsulated and
exposed for examination during the test.
2. Restraint or isolation of expansion joints
Expansion joints should be provided with temporary restraint if required for the additional pressure load under test.
3. Isolation of equipment and piping not subjected to pressure test.
Equipment and piping that is not to be subjected to the pressure test should be either disconnected from the system or isolated by a blank or similar means.
4. Test fluid
The test fluid should be water unless there is the possibility of damage due to freezing or to adverse effects of water on the piping or the process. In that case, another Polymelt approved non-toxic liquid may be used.
5. Provision of air vents at high points
Vents should be provided at high points of the piping system to purge air pockets while the system is filling.
Pressure Test Procedure
1. FILL THE SYSTEM
a.) Fill the piping system to be tested sloly with water while allowing the air in the pipe to escape through high-point air vents. b.) NEVER allow the pressure to rise while filling the system. c.) Always fill the system
slow enough to allow the high-point air vents to expel the air in the pipe system without increasing the pressure in the system.
2. BRING SYSTEM TO STABLE TEST PRESSURE
a.) Once all air is removed, close the air vents, and slowly pressurize the system to 1.5 times the system operating pressure. Do not to exceed the pressures noted in the Maximum Allowable Test Pressures chart on the following page. If you need assistance with your pressure test, please contact your Polymelt Regional Sales Manager. b.) Keep in mind that Polymelt PP-RCT is a thermoplastic and expands and contracts. Pressurizing the system to the desired test pressure may take multiple steps to reach a stable test pressure.
3. PRELIMINARY TEST
Once a stable test pressure is achieved, start a timer for 30 minutes. There should be no more than 9-psi (SDR 11) or 7-psi (SDR 17.6) pressure loss. If you meet this requirement, you can move on to the next step. Otherwise, locate the leaks, repair, and re-test.
4. LOAD TEST
Once the preliminary test has been successfully completed, bring the system back up to a stable test pressure and start a timer for 60 minutes. There should be no more than a 3-psi pressure loss. Otherwise, locate the
leaks, repair, and re-test. Once you have successfully completed steps 1 through 4, you have completed the basic Polymelt pressure test.
Maximum Allowable Test Pressure
- SDR 7.4 --> 400 PSI*
- SDR 11 --> 270 PSI*
- SDR 17.6 --> 160 PSI*
*Maximum test pressures at 68°F