Tests for Medium Voltage Graded Pipes

 Tests for Medium Voltage Graded Pipes

Virtual test of columns before galvanizing

- The virtual test is done before the galvanizing process, reviewing dimensions, assembly, finishing, and removing impurities.

The tested columns are excluded from the supplied quantity after they are destroyed.

- It is necessary to weigh the columns before galvanizing and after galvanizing and to ensure that they conform to the specifications and conditions booklet.

Load testing of medium voltage listed pipe poles before galvanizing

- The load test of the columns (by means of a tensile testing device at the factory, provided that the calibration of the device is from an approved body and that the calibration certificate is valid during the date of the test) under the influence of the design loads for each model, taking into account the safety factor and according to what is shown in the following table.

The following steps are applied to carry out the loading and tensile tests:

* The column is installed at a distance of 1.8 meters from the base of the column (the depth of the column in the concrete base) and the column is carried at a distance of 30 cm from the top of the column.

* The tensile test is carried out on a ratio of 4 per thousand of the number of manufactured columns.

* Sudden loading of the column is carried out until it reaches the design load for a period of two minutes, then suddenly descends, according to the values ​​mentioned in the following table.

* The column is gradually loaded 50 kg or 100 kg until we reach the design load in the following table multiplied by the safety factor, then the load is gradually reduced at the same rate of increase (50 kg or 100 kg) until it reaches zero and the deviation is calculated so that it is less than 5% of the maximum deviation of the maximum tension The mechanism of the column reaches for each column being tested.

Tests for columns of medium voltage listed pipes after galvanizing

- Virtual inspection of columns.

The surfaces of galvanized parts shall be free from any stains, rust, or loose or brittle deposits.

Galvanizing thickness test 

The thickness of the galvanizing is measured using precise measuring devices to determine the thickness of the galvanizing layer, and the minimum acceptable thickness of the galvanizing layer for any part of the column is 85 microns (inside and outside the column). As for screws and nuts, the minimum thickness of acceptance is 43 microns.

- The galvanizing layer is tested with the surface to be tested by subjecting it to mechanical shocks using a hammer (smooth) weighing 250 kg and the test has been passed in the absence of any signs of cracks or peeling.

- The distribution company’s engineers have the right to check the quality and thickness of the galvanizing inside and outside the column (and a hole is made to be determined by the distribution company’s engineers in place and size in the test column to check the layer and thickness of the galvanizing inside the column).

Table (3)

Design load table for medium voltage graded pipe poles

Pole model 2 minute sudden load

(kg) Design load (kg)      Coefficient of safety    Maximum tensile strength of the column

Medium voltage pipe column length 12m         300          300     1,35                  405