# ISO 9969:2016 pdf free

**ISO 9969**:2016 pdf free.Thermoplastics pipes一Determination of ring stiffness

The pipe of which the ring stiffness is to be determined shall be marked on its outside with a line along one generatrix over its entire length. Three test pieces, a, b and C, respectively, shall be taken from this marked pipe such that the ends of the test pieces are perpendicular to the pipe axis and their lengths conform to 6.2.

The length of each test piece shall be determined by calculating the arithmetic average of three to six measurements of length equally spaced around the perimeter of the pipe, as given in Table 2. The length of each test piece shall conform to 6.2.2, 6.2.3, 6.2.4 or 6.2.5, as applicable.

Each of the three to six length measurements shall be determined to within 1 mm.

For each individual test piece, the smallest of the three to six measurements shall not be less than 0,9 times the largest length measurement.

For pipes that have nominal diameters equal to or less than 1 500 mm, the average length of the test pieces shall be (300±10) mm.

For pipes that have nominal diameters larger than 1 500 mm, the average length of the test pieces in millimetres shall be at least 0,2 dn.

Structured wall pipes with perpendicular ribs, corrugations or other regular structures shall be cut such that each test piece contains a whole number of ribs, corrugations or other structures. The cuts shall be made at the mid point between the ribs, corrugations or other structures.

The length of the test pieces shall be the minimum whole number of ribs, corrugations or other structures resulting in a length of 290 mm or greater or, for pipes greater than 1500 mm, 0,2 dn or greater.

For each test piece, attach the deflection gauge and check the angular position of the test piece in relation to the upper plate.

Position the test piece with its longitudinal axis parallel to the plates and with its middle point vertically under the centre-line of the load cell.

In order to obtain the correct reading from the load cell, it is necessary to position the test piece so the expected resulting force is approximately in line with the axis of the load cell. ISO 9969 pdf free.