A necessary work before giving its approval to the construction of a reservoir testing program for welding of the geomembrane, for this there are different ways to do it.
Once the welding and before cutting the specimens for destructive testing of welds tightness should be checked by NDT. There are basically three types of nondestructive testing for checking the tightness of the joints.
1. Vacuum chamber: It is on the welds. Consists of submitting the entire weld to a vacuum pressure which will vary depending on the thickness of the geomembrane. If you wish you can visit a previous post where we talk about this type of testing.
2. Test electrical spark (spark gap): This test can only be used spark if prior to the placement of the geomembrane is left a thread of copper wire. If so, the test is performed with the igniter machine, this machine is passed over the weld, and if it detects a pore or a fault in the welding emit an electric spark visible because they have electrical continuity with copper wire we have placed above.
3. Air Testing: This type of testing is to introduce pressurized air through the channel which lies between the two welds, and check that there is no pressure loss, that we mark the check gauge accessory.
If you want you can click here and watch all the accessories such checks.
Unlike non-destructive tests, which aimed to determine the tightness of all welds, destructive tests are used to check the quality of the welds. The tests are performed on samples cut directly from the newly welded geomembrane, either hot wedge or extrusion. The assays can be in two different ways.
1. Court: This involves subjecting the weld between the plates of the specimen to an effort that is made to a certain speed. For this test, the ends are fixed to the jaws of the tensiometer, they are moving and stretching to cause the cut. The machine will record the maximum resistance and indicate if the break has occurred in the sheet or in the weld.
2. Tear: The procedure is almost identical to the cutting test method. The difference is that for causing the tearing of the weld, the ends to be put into the jaws of the tensiometer blades are located at the same end of the weld. The tear must have the same strength or higher than the supplier’s specifications.
Click here and see information available tensiometers.