Gauge Psi Kpa

Gasketed PVC pipe is now very popular throughout North America for underground water lines and sewage force mains. As is the case for all pipelines, regardless of material, after the building inspection is generally required to ensure that all new lines were installed correctly.

A test of the joint for gasketed Such as PVC pipe is the combined "leakage and pressure" test. This test is both the pressure capacity and joint tightness of the piping system while . Check

The method of this test is to remove one section of the line filled with water. Next, additional water into the line, until the section increased to a desired test pressure is pumped. The system is then closed and held for a certain trial period usually 2 hours.

During these 2 hours, it is possible that the system pressure can decrease. When the pressure drop when tested quickly, it is likely that a significant leak is present in the system. This could be attributed most of the incorrect assembly of appurtenance, pipe joints, or service connection.

However, assuming that proper installation and assembly were carried out, it is possible to have a very low pressure drop over the 2 hours. To a limit of acceptable pressure loss, was a table "Accepted leakage volumes created '. This table shows the maximum volume of water allowed to be added back to the system after a Pressure / leak test has indicated a low pressure drop. (The actual table of values can be found in IPEX PVC pressure pipe installation manual or AWWA C605).

For example, for 1000 m of 300 mm gasketed PVC water pipe, a maximum volume of 7.6 L of make-up water (in theory, the leakage during the test) is allowed for a test in 1035 kPa (equivalent to 2.0 U.S. gal are added. for 3300 ft. 12 "pipe tested at 150 psi). If large quantities of water it takes to be a failure, the test will locate and repair the installation program needs and deficiencies of each system.

As a result of this table of "leakage" Certificates have many individuals, a perception that is always leaking joint PVC sealed to some degree. In reality, properly assembled, PVC pipe bottle tightly.

This claim is checked out by the strict tests on the sealed joint at the production site. Seals made of PVC pressure joints, the CSA B137.3 to be certified and meet ASTM D 3139, must be one of the following two tests:

(A) 60 minutes at 2.5 times the pressure stage of the pipeline (ie 588 psi for DR18)

(B) 60-70 seconds at 3.2 times the pressure stage of the pipeline (ie, 755 psi for DR18)

Both of these tests are performed, during the joint to its maximum recommended angle to simulate a worst-case-box state. No leakage is permitted at the joints during these tests. The consistency and coupled precision found in the extrusion of PVC pipe, with the very strict dimensional tolerances is to ensure that sealed the joint are fully as reliable in the field as demonstrated in the plant.

An example of joint tightness PVC's was recently a project outside of Vancouver in Delta, British Columbia completed shown. B & B Contracting of Surrey was commissioned to construct 4,500 meters (15,000 feet) of 400 mm (16 ") PVC water pipe-DR18 as a supply mainly to the newly built Delta Port Container Terminal.

After the installation supervisor Rollie Knackstead showed enormous confidence in the processing of his crew, and the tube by its decision to print the entire 4500 meters Test tube at once. The results were extraordinary. B & B line successfully tested at 200 bar for 2 hours not a drop of leakage. The meter did not move from the 200 psi level. The bottle-tight joints of PVC contributed to an already successful installation at a very successful overall project.

If during a pressure leak test on PVC, the pressure drops slightly (the maximum supply water volumes), ie this mean that it detected leaks? Perhaps, but the factory testing of PVC pipes and numerous case studies, such as B & B Contracting Project in Delta, seem to point out, that properly assembled PVC pipe is not leaking.

So why does it sometimes have small amounts of make-up water after a pressure test? Here are 4 possible Reasons:

(A) air inclusions

(B) Relocation of tees or elbows before joint function restrictions

(D) radial expansion of the PVC pipe

In fact, radial expansion of such a important factor for a further thermoplastic piping material (HDPE) that its test limit specifically identified as an "extension Allowance, but noted as a "leakage allowance." It is also interesting that if you have a comparison, the actual values of the allowable make-up water are found be considerably higher with butt fused HDPE than those for gasketed PVC pipe for equivalent pipe sections and test pressures.

In summary, the reader is that recommended many times a correct term for "leakage" is Apparent leakage 'or' Make-Up Water Allowance 'in the analysis of test results from a PVC pressure pipe. Evidence that properly assembled gasketed PVC pipe is virtually zero leakage. The fact that PVC is not the time from corrosion attacks will be weakened to ensure that the bottle-tight joints of today will come to stay that way for many years.

Gordon Lefort is a Professional Engineer (Mechanical) employed with IPEX Inc., Canada’s largest plastic pipe manufacturer and has over 20 years experience with the design and installation of underground plastic pipelines.

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