UL 2420:2016 pdf free download – STANDARD FOR SAFETY Belowground Reinforced Thermosetting Resin Conduit (RTRC) and Fittings.
5.2.1 General
5.2.1.1 The internal diameter of conduit shall not decrease by more than 25% during application of the force specified in Tables 11 and 12 when tested in accordance with Clauses 5.2.2 to 5.2.4. The conduit shall show no evidence of cracking or buckling after removal from the compression machine.
5.2.2 Apparatus
5.2.2.1 The apparatus for this test shall consist of:
a) an inside micrometer or telescopic gauges and a micrometer caliper; and
b) a compression machine having 2 steel platens at least 150 mm (6.0 in) long and 10 mm (0.4 in) thick, and capable of running at a speed within the range of 10 to 15 mm/mm (0.4 to 0.6
in/mm).
5.2.3 Specimens
5.2.3.1 The specimens shall consist of three 150 ±3 mm (6.0 ±0.125 in) lengths of conduit.
5.2.4 Procedure
5.2.4.1 The inside diameter of the specimen shall be measured and recorded. The specimen shall be placed between the plates of the compression machine such that the measured inside diameter is perpendicular to the platens. The machine shall be set in motion until the force specified in Tables 11 and 12 has been applied to the specimen. The machine shall be stopped and the inside diameter re-measured. The percent decrease in the internal diameter shall be calculated and recorded.
5.3 Impact resistance at low temperature
5.3.1 When tested in accordance with Clauses 5.3.2 to 5.3.4, there shall not be any fracture or break in the laminate surface of seven out of ten 200 mm (8.0 in) long specimens of the finished conduit. A fracture or break shall be considered to have occurred where a broken section of the laminate forms a protrusion within the inside diameter or extends beyond the outside diameter of the conduit. The portions of the conduit within 51 mm (2.0 in) from the cut ends of the specimen shall not be examined.
5.3.2 The specimens shall be cut from finished lengths of each trade size of conduit. The specimens, the test apparatus, and the surrounding air shall be in thermal equilibrium with one another at a temperature of -40° ±1°C (-40° ±2°F ) during the test. Each specimen shall be tested separately while resting on a solid, flat steel plate that is at least 13 mm (1/2 in) thick and shall be firmly anchored with its upper surface horizontal.
5.3.3 When it is necessary to remove the specimen from the low-temperature chamber due to handling difficulties, the impact test shall commence as soon as possible and shall be completed within 15 s of the time of removal.
5.3.4 The impact energy shall be provided by a weight of 9 kg (20 Ibs) in the form of a 51 mm (2.0 in) solid, right-circular, steel cylinder with a flat impact face having rounded edges, as shown in Figure 2, falling freely through a vertical guide with the impact force as specified in Tables 13 and 14. The flat face of the weight shall strike the center of the specimen. Provision shall be made for keeping the weight from striking the specimen more than once.
5.4 Water absorption
5.4.1 Conduit shall not absorb water more than 0.25 percent of its weight while immersed for 24 h in distilled water when tested in accordance with Clauses 5.4.2 to 5.4.4.
5.4.2 The cut edges of a specimen shall be sealed with epoxy cement. The cement shall cure at room temperature for 24 h. Specimens shall be preconditioned by drying in a full-draft circulating-air oven at a temperature of 50 ±3°C (122 ±5°F) for 24 h, after which they shall remain in still air at a temperature of 23 ±2°C (73 ±4°F) for 24 h.