BS 12814-2:2021 pdf download – Testing of welded joints of thermoplastics semi-finished products Part 2: Tensile test
7 Cutting of test specimens
The tensile test specimens shall be cut with parallel sides as shown in Figures 1 and 2. During cutting,
heating of the test specimen shall be minimized.
Cutting of the test specimen shall not produce notches.
After cutting, a visual examination of the weld according to EN 13100-1 shall be carried out and recorded.
8 Mechanical testing
Test specimen shall be conditioned to a temperature of (23 ± 2) °C and unless otherwise specified, the test shall be carried out at a room temperature of (23−25 ) °C.
The test speeds and tolerances shall be in accordance with EN ISO 527-1.
For all materials the test speed shall be chosen to ensure that the test is terminated in about one minute.
Examples of test speeds for some relevant thermoplastics materials are listed in Annex B.
At least five test specimens shall be tested for each welded and unwelded test piece.
Welded and unwelded test specimens shall be of the same geometry and shall be tested at the same speed with the same distance between the clamps.
If all welded test specimens fracture or yield within the calibrated length, but outside of the weld (L w ), the unwelded test specimen do not need to be tested, and the short-term tensile welding factor shall be taken as 1.
In order to achieve a failure in the weld, the test specimens shall be as described in ISO 13953 (Type A only,for thickness less than 25 mm) or in Annex C.
9 Test equipment
The test equipment shall conform to the requirements given in ISO 5893.
The crosshead displacement shall be continuous, uniform and in accordance with Clause 8.
10 Determination of the short-term tensile welding factor
In order to determine the short-term tensile welding factor, welded and unwelded test specimens shall be tested.
The short-term tensile welding factor is determined from the arithmetic mean values of the fracture stresses of the welded test specimens, σ w , and the unwelded test specimens σ r , where:
At least ten test specimens (five welded and five unwelded) shall be used in the evaluation of the shortterm tensile welding factor. No test specimen shall be disregarded unless failure occurs in the clamps.
In the case of the type 1 test specimens, failure within a distance of 1 times specimen width b, from the clamps shall be regarded as failure in the clamp.
If type 1 test specimens consistently fail in the clamps then type 2 test specimens shall be used.
In the case of type 2 test specimens, failure outside of the calibrated length (L O ) shall be regarded as failure in the clamp.
In the case of the whole tube tensile test, failure within a distance of 1,5 D n from the clamps shall be regarded as failure in the clamp.
11 Test report
The test report shall include at least the following information:
1) description and identification of the test piece and test specimens;
2) appearance of the test pieces before the test:
a) visual examination of weld;
b) beads removed or not;
3) weld type;
4) maximum width of the weld bead, if applicable (L w );
5) nominal outside diameter of the tube, if applicable (D n );
6) number of test specimens;
7) appearance of all surfaces of the test specimens, (e.g. flaws, scratches, visual imperfections);
8) thickness of test specimen (a);
9) type of test specimen;
10) appearance of all surfaces of the test specimens, (e.g. flaws, scratches, visual imperfections);
11) thickness of test specimen (a);
12) width of calibrated and parallel length (b);
13) calibrated and parallel length (L 0 );
14) total length of the test specimen (L);
15) width of the test specimen shoulder, if applicable (b 1 );
16) radius of shoulder (r);
17) distance between the clamping jaws;
18) temperature of the test specimen (°C);