Technical Details

Recommended supports for PVC-U ASTM Plumbing Pipes :

The PVC-U ASTM Plumbing pipes are best when used for water up to 230C. As the temperature of the water increases, its working pressure goes on reducing e.g. if the working pressure is 100% at 230C temperature, it will be 50% at 450C temperature and only 22% at temperature and at 600C temperature.




Thermal expansion of PVC is roughly 4.5 to 5 times more than metallic pipes. As long as PVC-U ASTM plumbing pipes are buried & are used for conveying cold water, thermal changes do not have any adverse effect on the durability. But in case of exposed lines & for high fluid temperatures, thermal expansion & contractions need to be considered.

The change in the length of a pipeline can be calculated as:

δl = α × L δt

Where δl : Change in length in mm

α : Coefficient of linear expansion of PVC

L : Length of pipe in mm (at Ambient Temperature)

δt  : Difference between ambient temperature & maximum operating temperature.

To accommodate this thermal expansion & contraction, following methodology can be applied.


    1. Expansion Loop: This is most common method used to compensate for thermal changes in a pipeline. A typical expansion loop is shown below.



Length of the loop offset ‘X’ can be calculated as

X = 1.44 x d x δl

Where d : Outside diameter of the pipe in mm.

δl : Change in length in mm.

Also Y = X/2.


  1. Fixed & Sliding points: Combination of these two types of anchoring compensates changes due to thermal expansion & contractions.


Recommended distances between supports in meters:

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Joining of Finolex PVC-U Plumbing Pipe and Fittings Threaded


    • Threading at the site should be carefully carried out. Ensure a proper square cut to the pipe end.
    • Insert support from inside and wet the threading operation by spraying water continuously.
    • Provided adequate cushion between the jaws of the pipe wrench and pipe while holding the pipe for threading.
    • For perfect process, threads should be made in one pass.
    • High quality Teflon tape must be used as a sealant of joints.
    • Avoid over tightening of the joint.
    • All the pipe lines should be supported approximately at a distance of 1m for horizontal service and 1.5m for vertical service with pipe clips or with nut bolts.
    • The system should be pressure tested before concealment.


Joining of Finolex PVC-U Plumbing Pipe and Fittings by Solvent Cement


  1. CUTTING:- Measure and cut the pipe length as per the requirement with the help of a plastic pipe cutter or hacksaw blade.
  2. DEBURRING:- Burrs and filings should be removed from pipe with the help of pocket knife or a file suitable for this. Provide slight bevel at the end of pipe for easy insertion during assembly.
  3. CLEANING AND FITTING PREPARATION:- Use a clean, dry rag to wipe dirt and moisture from the pipe and from inside the socket fittings.
  4. CHECK DRY FIT :- Pipe should easily go into the socket to around 1/3 to 2/3 of its depth. This is commonly referred as inference fit. If the pipe goes to the bottom without any reference, check it the fitting is the correct size. If it is not correct size get another fitting. To make the task easier mark the socket depth on the pipe with the marker.
  5. SOLVENT CEMENT APPLICATION:- Use only Finolex solvent cement that meets the ASTM D-2564 standard otherwise the joint can fail. Apply a heavy and even coat of solvent cement to pipe end and thin solvent cement coat inside the fittings socket. Excess solvent cement during jointing may cause clogged water ways so you need to be sure you put the right amount. Recommended applicator for Pipe over 90mm is a Brush 1/2 the Pipe Diameter. All Brass and Plastic threaded fittings must be used with suitable Sealant to ensure leak proof joints. Teflon or equivalent tape is the preferred as thread sealant. Always remember Do Not Over Tighten.
  6. ASSEMBLY:- Push and assemble the pipes quickly into fittings socket, rotate the pipe by using the 1/4 to 1/2 motion while inserting which confirm even distribution of solvent cement within joints. Cement should be fluid while joining for uniform application
  7. SETUP AND CURING:- To create a perfect joint of pipe and fittings hold together for 60 seconds. Solvent cement requires 10 to 20 minutes to set. The joint needs a minimum of 24 hours to cure. Pressure test pipes only after the joint is fully cured.


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  • The joint should not be pressure tested until it has cured, the exact curing time varies with pipe size, temperature and humidity
  • For relative humidity above 60%, allow 50% more curing time
  • Use above details as a guideline only


Guide Line For Pressure Testing of Plumbing System:-



        • Select the section of pipe line to be tested.
        • Check the support system and ensure that open ends are fitted with plugs.
        • The piping system should be sufficiently anchored to limit movement during testing
        • Keep all the valves in open position
        • The Pressure tests must be conducted with water only
        • The piping system should be slowly filled with water this allows entrapped air to escape.
        • The pipes should be subjected to one and half times the rated working pressure.
        • However, ensure that pressure does not exceed the working pressure of the lowest component in system like unions, valves, threaded parts etc.
        • The pressure test should not exceed more than one hour.
        • Any leaking pipe or joints must be repaired or replaced and line recharged.
        • Retest using the same procedure.


Solvent Cement for Plumbing Applications



To form joints with the Finolex pipes & fittings the Finolex Plumbing Solvent Cement is recommended. It meets ASTM D-2564 standards. According to the sizes of pipes and fittings there are two types of Solvent Cements.  Solvent joints makes pressure bearing capacity around two times than that of threaded joints.
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