|
UL testing for Electrical Rigid Metal Conduit - Steel
6.1 Tube
6.1.1 At ambient temperature, one specimen of the smallest available trade size shall be capable of being bent into a quarter of a circle around a mandrel, the radius of which is shown in Table 5.5, without developing cracks and without opening the weld.
6.1.2 After being conditioned at a temperature of 0�C (32�F) for 60 min, one specimen of the smallest available trade size of finished tube shall be capable of being bent into a quarter of a circle around a mandrel. The same specimen may also be used to determine compliance with the coating test in Clause 6.2.1.3. Compliance shall be determined by bending the tube with the test apparatus as shown in Figure 4 with a radius as described in Table 5.5. The tube shall not develop a crack and the weld shall not open. The test shall be conducted inside the cold chamber or begun within 15 s of removal from the cold chamber. Tubing that is provided with a nonmetallic alternate corrosion-resistant coating and that is marked with a temperature rating below "0�C" ("32�F") shall be conditioned at the rated temperature. The rated temperature shall be any temperature below 0�C (32�F) in 5�C (9�F) increments.
6.1.3 Compliance of trade size 16 (1/2) and 21 (3/4) ERMC-S with the requirement in Clause 6.2.1.1 shall be determined by bending the tube with a test apparatus as shown in Figure 4. Compliance of ERMC-S larger than trade size 21 (3/4) with the requirement in Clause 6.2.1.1 shall be determined by bending the tube with any suitable bending equipment.
6.2 Protective coatings
6.2.1 General
6.2.1.1 The protective coating used on the interior or exterior of the conduit shall not crack or flake, as visible using normal or corrected to normal vision, when a finished specimen of the smallest available trade size produced by the manufacturer is tested at ambient temperature. Testing shall be performed by bending it into a semi-circle, the center line of which has a radius as described in Table 5.5.
6.2.1.2 Compliance of trade size 16 (1/2) and 21 (3/4) ERMC-S with the requirement in Clause 6.2.1.1 shall be determined by bending the tube with a test apparatus as shown in Figure 4. Compliance of ERMC-S larger than trade size 21 (3/4) with the requirement in Clause 6.2.1.1 shall be determined by bending the tube with any suitable bending equipment.
6.2.1.3 One specimen of the smallest available trade size of finished conduit shall be capable of being bent into a quarter of a circle around a mandrel with the radius as described in Table 5.5 after being conditioned at a temperature of 0�C (32�F) for 60 min. The tube shall not develop a crack and a weld shall not open. The coatings shall not be damaged to the extent that bare metal is exposed or that the coating separates from the metal. The test shall be conducted inside the cold chamber or begun within 15 s of removal from the cold chamber. Conduit that is provided with a nonmetallic alternate corrosion-resistant coating and marked with a temperature rating below 0�C (32�F) shall be conditioned at the rated temperature. The rated temperature shall be any temperature below 0�C (32�F) in 5�C (9�F) increments.
6.2.1.4 The supplementary coating described in Clause 5.3.5 need not comply with Clause 6.2.1.1.
6.2.1.5 For identification of compounds, a nonmetallic material used as an alternate corrosion-resistant or organic coating shall be subjected to the infrared spectroscopy (IR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) tests specified in the applicable standards for polymeric materials. See Reference Item No. 7, Annex A.
6.2.2 Zinc coating
6.2.2.1 A solution of copper sulfate for this test shall be made from distilled water and a reagent grade of cupric sulfate (CuSO4). In a copper container or in a glass, polyethylene, or other chemically nonreactive container in which a bright piece of copper is present, a quantity of cupric sulfate shall be dissolved in hot distilled water. The purpose is to obtain a solution that has a specific gravity slightly higher than 1.186 after the solution is cooled to a temperature of 18.3�C (65.0�F). Any free acid that might be present shall be neutralized by the addition of approximately 1 gram of cupric oxide (CuO) or 1 gram of cupric hydroxide (Cu(OH)2) per liter of solution. The solution shall then be diluted with distilled water to obtain a specific gravity of exactly 1.186 at a temperature of 18.3�C (65.0�F). The solution shall then be filtered.
6.2.2.2 Several 150-mm (6-in) specimens shall be cut from a sample length of the finished zinc-coated conduit. With prudent attention to the risks to health and to the risk of fire, the specimens shall be cleaned with a suitable organic solvent. Each specimen shall then be examined for evidence of damage to the zinc coating, and only specimens that are not damaged shall be selected for use in the test. When a zinc coating is used on the inside and outside of the conduit, half of the specimens shall be longitudinally cut in half to expose the inside surface. If a zinc coating is used only on the outside of the conduit, none of the specimens shall be cut longitudinally.
6.2.2.3 The selected specimens shall be rinsed in water, and all surfaces shall be dried with clean cheesecloth. As much of the water as possible shall be removed in the drying operation because water slows the reaction between the zinc and the solution, thereby adversely affecting the test results. The surface of the zinc shall be dry and clean before a specimen is immersed in the solution of copper sulfate. The specimens shall not be touched by the hands or anything else that can contaminate or damage the surfaces.
6.2.2.4 A glass, polyethylene, or other chemically nonreactive beaker having a diameter equal to approximately twice the diameter measured over the specimen shall be filled with the solution of copper sulfate to a depth of not less than 76 mm (3 in). The temperature of the solution shall be maintained at 18.3 �1.1�C (65.0 �2.0�F). The specimen shall be immersed in the solution and supported on end in the center of the beaker so that not less than 64 mm (2-1/2 in) of its length is immersed. The specimen shall remain in the solution for 60 s, during which time it shall not be moved nor shall the solution be stirred.
6.2.2.5 At the end of the 60 s period, the specimen shall be removed from the beaker, rinsed immediately in running tap water, rubbed with clean cheesecloth until any loosely adhering deposits of copper are removed, and shall then be dried with clean cheesecloth. Again, the hands and other damaging and contaminating objects and substances shall not touch the surfaces that were immersed. The part of the specimen that was immersed shall be examined, considering each broad surface separately and disregarding any threaded area and the portions of the specimen within 13 mm (1/2 in) of the cut ends on sizes 12 - 53 (3/8 - 2) and 25 mm (1 in) for sizes 63 - 155 (2-1/2 - 6) and within 3 mm (1/8 in) of any longitudinal edges cut in the process of preparing the specimen.
6.2.2.6 A record shall be made when the immersed part of the specimen has any deposit of bright, firmly adhering copper, exclusive of any threaded area, and the 13 mm (1/2 in) cut-end portions and any 3 mm (1/8 in) longitudinal cut-edge portions.
6.2.2.7 When bright adhering copper is not found, the process of immersing, washing, rubbing, drying, examining, and recording shall be repeated up to the required number of immersions, or until the presence of copper is noted, whichever comes first, using the same specimen and beaker of solution. After the dips are completed on any one specimen, the portion of the solution of copper sulfate used shall be discarded. A fresh portion of the solution shall be employed for each of any succeeding specimens.
6.2.2.8 A protective zinc coating that provides the sole means of primary corrosion resistance on the exterior of the conduit shall be such that a specimen of the finished conduit does not show a bright, adherent deposit of copper after four 60-s immersions in a copper sulfate solution.
6.2.2.9 A protective zinc coating that provides the sole means of primary corrosion resistance on the interior of the conduit shall be such that a specimen of the finished conduit does not show a bright, adherent deposit of copper after one 60-s immersion in a copper sulfate solution.
6.2.2.10 When it is desired to show the character of the bright metallic copper deposit on an exposed steel surface, prepare a reference standard for comparison as follows. Partially submerge a zinc-coated specimen in strong hydrochloric acid until violent action ceases. Immediately remove the specimen, wash, and wipe it dry. Then dip the specimen, with an area of bare surface thus exposed, including a portion with zinc coating intact, for a few seconds in the copper sulfate solution at a temperature of 16 - 20�C (61 - 66�F), remove it, wash it, and wipe it dry. Prepare this copper-coated reference standard at the time of testing.
6.2.2.11 For an alternate test method to the one described in Clauses 6.2.2.1 - 6.2.2.10 for determining compliance with the evaluation of zinc coating requirements, see Reference Item No. 8, Annex A.
6.2.3 Organic coating
6.2.3.1 Elasticity test
6.2.3.1.1 The organic coating used to protect the interior of the conduit, when applied to a sheet-steel test piece and baked in an oven for 5 h, shall withstand without damage 10 successive bends of the test piece back and forth through an angle of 180 degrees against an edge having a radius of 1.6 mm (1/16 in).
6.2.3.1.2 The apparatus shall consist of flat test pieces of sheet steel 75 by 125 mm (3 by 5 in) long and approximately 0.25 mm (0.010 in) thick, an oven for baking the test pieces, and a vise with jaws at least 75 mm (3 in) wide for holding the test pieces during the bending test. The 75-mm (3-in) edge of each jaw shall be rounded to a radius of 1.6 mm (1/16 in).
6.2.3.1.3 Two test pieces shall be cleaned with a suitable organic solvent to remove any grease and foreign material and shall then be dipped in the organic coating. After air drying for 30 min, the test pieces shall be suspended by means of short wires in the oven. Samples shall be baked for 5 h at the normal baking temperature for the organic in question but, if the normal baking temperature is lower than 135�C (275�F) or the enamel is regularly air dried, the oven temperature shall be maintained at 135 - 150�C (275 - 302�F).
6.2.3.1.4 At the end of 5 h, the test pieces shall be removed from the oven and cooled in still air to room temperature. Each flat test piece shall be secured in the vise, gripped at its free end, and then bent for 90 degrees against one of the 75-mm (3-in) edges of the vise jaws. Each test piece shall then be bent back past its original position through 180 degrees so that it ends bent 90 degrees against the other 75-mm (3-in) edge of the vise jaws. It shall then be bent for 90 degrees in the opposite direction, ending with the test piece in its original position. This cycle shall be repeated 5 times. The organic coating shall not be accepted if any test piece cracks, flakes off, or is damaged otherwise.
6.2.3.2 Warm humid air test
6.2.3.2.1 The test apparatus shall be an insulated specimen chamber with inside dimensions approximately 119 by 71 by 71 cm (47 by 28 by 28 in). It shall contain a temperature-controlled water reservoir, pump, spray chamber for humidifying the air, an air-circulating fan, provision for heating the air, specimen supports, and the necessary means of control.
6.2.3.2.2 The dry bulb temperature of the test chamber shall be maintained at 60 �1�C (140 �2�F) and at 98 � 2% relative humidity throughout the test. The specimens shall be supported in racks at an angle of 15 degrees from the vertical.
6.2.3.2.3 The test shall be conducted for a period of 60 d, at the end of which there shall not be any corrosion of the metal.
6.2.4 Alternate corrosion-resistant coatings
6.2.4.1 A coating other than one consisting solely of zinc, which is to be evaluated for its ability to provide corrosion resistance on the exterior of conduit, shall, in addition to the requirements in Clauses 6.2.4.2 - 6.2.4.10, be evaluated with respect to flame propagation. See Clause 6.2.4.11. Additionally, the conduit, elbow, or nipple shall be subjected to the assembly, bending, resistance, pull, and fault current tests in accordance with Reference Item No. 9, Annex A, with both set-screw and compression-type couplings.
6.2.4.2 The coating shall comply with the salt-spray (fog), moist carbon dioxide-sulfur dioxide-air, and ultraviolet light and water tests after being conditioned in accordance with Clause 6.2.4.5. Corrosion within 13 mm (1/2 in) of cut edges shall be disregarded.
6.2.4.3 Preparation of specimens
6.2.4.3.1 Thirty 152 - 203 mm (6 - 8 in) long specimens, provided with the corrosion-resistant coating, of trade size 2 (53), or the closest trade size manufactured, shall be tested.
6.2.4.3.2 Half of the specimens to be exposed shall be scribed using a rotary tool operating at a speed of 15,000 - 30,000 rpm. The specimens shall be scribed in accordance with Figure 5, using a 1.14 mm (0.045 in) thick fiberglass reinforced cut-off wheel, until bright base metal is exposed. The specimens shall be free of grease or dirt. The coating thickness of each specimen shall be measured prior to exposing it to the test environments.
6.2.4.4 Air oven conditioning exposure
6.2.4.4.1 Six scribed and six unscribed specimens of each coating shall be conditioned for 240 h at a temperature of 100 �2�C (212 �4�F) in an air-circulating oven. Conduit that is marked with a temperature rating above 90�C (200�F) shall be conditioned at the rated temperature plus 10�C (18�F), for which the rated temperature shall be any temperature in excess of 90�C (200�F) at 25�C (45�F) increments. These specimens shall be used for the resistance to salt spray (fog) (Clause 6.2.4.6) and the resistance to moist carbon dioxide-sulfur dioxide-air (Clause 6.2.4.7) tests.
6.2.4.5 Resistance to ultraviolet light and water
6.2.4.5.1 Three scribed and three unscribed specimens shall be exposed to ultraviolet light and water by either of the methods specified in Clauses 6.2.4.5.3 and 6.2.4.5.4.
6.2.4.5.2 As a result of the exposure, the unscribed specimens shall not show any base metal corrosion or any blisters. For the scribed specimens, the average creeping distance of red rust from the scribe shall not be greater than Rating No. 6 (1.6 - 3.2 mm (1/16 - 1/8 in)) as designated in Reference Item No. 10, Annex A, with maximum isolated spot not exceeding 9.5 mm (3/8 in). There shall not be any visual evidence of pitting of the substrate and only the beginning of a buildup of red rust beneath the coating uplifted from the scribe.
6.2.4.5.3 For twin enclosed carbon-arc, the specimens shall be exposed for 360 h to light and water in accordance with Reference Item No. 11, Annex A, using the apparatus designated as type DH. Method 1, continuous exposure to light and intermittent exposure to water spray, with a programmed cycle of 120 min consisting of a 102-min light exposure and an 18-min exposure to water spray with light, shall be used. The apparatus shall operate with a black-panel temperature of 63 �3�C (145 �5�F).
6.2.4.5.4 For xenon-arc, the specimens shall be exposed for 500 h to light and water in accordance with Reference Item 12, Annex A, using the apparatus designated as type BH. Test Method A, continuous exposure to light and intermittent exposure to water spray, with a programmed cycle of 120 min consisting of a 102-min light exposure and an 18-min exposure to water spray with light, shall be used. The apparatus shall operate with a 6500 W, water-cooled xenon-arc lamp, borosilicate glass inner and outer optical filters, a spectral irradiance of 0.35 W/m2/nm at 340 nm, and a black-panel temperature of 63 �3�C (145 �5�F).
6.2.4.6 Resistance to salt spray (fog)
6.2.4.6.1 Six as-received and six air-oven conditioned specimens shall be exposed to the salt spray (fog) for 600 h in accordance with Reference Item No. 13, Annex A. Three of the as-received and three of the air-oven conditioned specimens shall be scribed as described in Clause 6.2.4.6.2.
6.2.4.6.2 As a result of the conditioning, the unscribed specimens shall not show more than a light corrosion beneath the coating system, with no visible pitting of the substrate and only the beginning of a buildup or weeping of red rust. For the scribed specimens, the average creeping distance of red rust from the scribe shall not be greater than Rating No. 5 (3.2 - 4.8 mm (1/8 - 3/16 in)) as designated in Reference Item No. 14, Annex A, with maximum isolated spot not exceeding 9.5 mm (3/8 in). There shall not be any separation of the coating from the substrate as a result of the exposure.
6.2.4.7 Resistance to moist carbon dioxide-sulfur dioxide-air
6.2.4.7.1 Six as-received and six air-oven conditioned specimens shall be exposed to the moist carbon dioxide-sulfur dioxide-air for 1200 h. The apparatus used for this exposure shall consist of a chamber having a volume of at least 0.085 m3 (3 ft3) with a water jacket and thermostatically controlled heater to maintain a temperature of 35 �2�C (95 �3�F). Three of the as-received and three of the air-oven conditioned specimens shall be scribed as described in Clause 6.2.4.3.2.
6.2.4.7.2 As a result of the conditioning, the unscribed specimens shall not show more than a light corrosion beneath the coating system, with no visible pitting of the substrate and only the beginning of a buildup or weeping of red rust. For the scribed specimens, the average creeping distance of red rust from the scribe shall not be greater than Rating No. 6 (1.6 - 3.2 mm (1/16 - 1/8 in)) as designated in Reference Item No. 15, Annex A, with maximum isolated spot not exceeding 9.5 (3/8 in). There shall not be any separation of the coating from the substrate as a result of the exposure.
6.2.4.7.3 The carbon dioxide and sulfur dioxide shall be supplied to the test chamber from commercial cylinders containing the gases under pressure. An amount of carbon dioxide equivalent to 1 percent of the volume of the test chamber and an equal volume of sulfur dioxide shall be introduced into the chamber each working day. Prior to introducing the new charge of gas each day the remaining gas-air mixture from the previous day shall be purged from the chamber. A small amount of water shall be maintained at the bottom of the chamber for humidity. This water shall not be changed during the exposure. The specimens shall be supported in plastic racks at an angle of 15 degrees from the vertical.
6.2.4.8 Tensile strength
6.2.4.8.1 PVC alternate corrosion-resistant coatings shall have a minimum tensile strength of 13.79 MPa (2000 psi) when tested in accordance with Reference Item No. 16, Annex A. Other materials shall be subject to special investigation.
6.2.4.9 Adhesion
6.2.4.9.1 The adhesion of an alternate corrosion-resistant coating that is 0.51 - 1.27 mm (0.020 - 0.050 in) thick shall be greater than the strength of the alternate corrosion-resistant coating itself. This shall be determined by making two 38 mm (1-1/2 in) circumferential cuts 13 mm (1/2 in) apart through the alternate corrosion-resistant coating to the substrate. A third cut shall be made perpendicular to, and crossing, the circumferential cuts. The edge of the alternate corrosion-resistant coating shall be carefully lifted with a knife to form a tab. This tab shall be pulled perpendicular to the conduit with a pair of pliers. The tab shall tear rather than any additional alternate corrosion-resistant coating separating from the substrate.
6.2.4.9.2 The adhesion of an alternate corrosion-resistant coating that is 0.127 mm (0.005 in) thick or less shall be determined in accordance with the relevant standard in Reference No. 17, Annex A.
6.2.4.9.3 The adhesion of an alternate corrosion-resistant coating other than as specified in Clause 6.2.4.9.1 or 6.2.4.9.2 shall be determined by special investigation.
6.2.4.10 Cold impact
6.2.4.10.1 Ten 152 - 203 mm (6 - 8 in) specimens of finished conduit provided with a nonmetallic alternate corrosion-resistant coating shall be conditioned at a temperature of 0�C (32�F) for a period of 60 min. Conduit that is marked with a temperature rating below "0�C" ("32�F") shall be conditioned at the rated temperature, for which the rated temperature shall be any temperature below 0�C (32�F) in 5�C (9�F) increments. The specimens shall then be subjected to an impact of 12.2 J (9 ft-lb) in accordance with Clause 6.2.4.10.2. The coating shall not separate from the metal nor be damaged to the extent that bare metal is exposed.
6.2.4.10.2 The impact test described in Clause 6.2.4.10.1 shall be performed using the Tup B falling mass, using the apparatus and method specified in Reference Item No. 18, Annex A. The test shall be conducted inside the cold chamber or within 15 s of removal from the cold chamber.
6.2.4.10.3 Alternatively, a combination of any height and weight that results in the same impact force specified in Clause 6.2.4.10.1 may be used when the impact face remains unchanged.
6.2.4.11 Flammability
6.2.4.11.1 Vertical specimens of finished conduit provided with a nonmetallic alternate corrosion-resistant coating shall not flame for longer than 5 s following any of three 60-s applications of flame, the period between applications being 30 s. A specimen shall not:
a) Emit flaming or glowing particles or flaming drops at any time that ignite the cotton on the burner, wedge, or floor of the enclosure (flameless charring of the cotton shall be ignored),
b) Continue to flame longer than 5 s after any application of the gas flame, or
c) Have the coating completely consumed during or after any application of the gas flame.
6.2.4.11.2 This test shall be performed on 3 unaged specimens tested separately with each positioned in a 3-sided metal enclosure in an exhaust hood or cabinet. The metal enclosure shall be 305 mm (12 in) wide, 355 mm (14 in) deep, and 610 mm (24 in) high, and the top and front shall be open. A 457-mm (18-in) specimen of finished conduit shall be secured with its longitudinal axis vertical in the center of the enclosure. A flat, horizontal layer of untreated surgical cotton 6 - 25 mm (1/4 - 1 in) thick shall cover the floor of the enclosure. The upper surface of the cotton shall be 229 - 241 mm (9 - 9-1/2 in) below point B, which is the point at which the tip of the blue inner cone of the test flame touches the specimen. This is shown in Figure 6.
6.2.4.11.3 A burner shall conform to Reference Item No. 19, Annex A, having a bore of 9.5 �0.3 mm and a length of 100 �10 mm from the top of the air inlet openings to the top of the mixing tube, or an equivalent burner that meets the calibration requirements of Reference Item No. 20, Annex A shall be used. While the barrel is vertical and the burner is well away from the specimen, the overall height of the flame shall be adjusted to approximately 100 - 125 mm (4 - 5 in). The blue inner cone shall be 38 mm (1-1/2 in) high and the temperature at its tip shall be 816�C (1500�F) or higher as measured using a chromel-alumel (nickel-chromium and nickel-manganese-aluminum) thermocouple. Without disturbing the adjustments for the height of the flame, the valve supplying gas to the burner flame and the separate valve supplying gas to any pilot flame shall be closed.
6.2.4.11.4 The gas used to supply the burner described in Clause 6.2.4.11.3 shall be bottled, technical grade methane or natural gas, approximately 37 MJ/m3 (1000 Btu/ft3) at normal pressure, with a suitable regulator and meter for uniform gas flow.
6.2.4.11.5 A wedge, as shown in Figure 7, to which the base of the burner can be secured, shall be provided for tilting the barrel 20 degrees from the vertical while the longitudinal axis of the barrel remains in a vertical plane. The burner shall be secured to the wedge and the assembly shall be placed in an adjustable support jig. A layer of untreated surgical cotton 6 - 25 mm (1/4 - 1 in) thick shall be placed on the wedge and around the base of the burner. The jig shall be adjusted toward one side or the other of the enclosure to place the longitudinal axis of the barrel in the vertical plane that contains the longitudinal axis of the specimen. The plane shall be parallel to the sides of the enclosure. The jig shall also be adjusted toward the rear or front of the enclosure to position the point A, which is the intersection of the longitudinal axis of the barrel with the plane of the tip of the barrel, 38 mm (1-1/2 in) from the point B at which the extended longitudinal axis of the barrel meets the outer surface of the specimen. Point B is the point at which the tip of the blue inner cone touches the center of the front of the specimen. The specimen shall be adjusted vertically to keep point B from being any closer than 76 mm (3 in) to the lower clamp or other support for the specimen.
6.2.4.11.6 In the absence of a gas pilot light on the burner, the support for the burner and wedge shall be arranged to enable the burner to be quickly removed from and precisely returned to the position described in Clause 6.2.4.11.5 without disturbing the layer of cotton on the floor of the enclosure or the cotton on the wedge and around the base of the burner.
6.2.4.11.7 In instances where the burner has a gas pilot light, the valve supplying gas to the pilot shall be opened and the pilot lit. Where the burner does not have a gas pilot light, the burner shall be supported as indicated in Clause 6.2.4.11.6 in a position away from the specimen and then lit. This operation, and the remainder of the test, shall be conducted under a forced-draft exhaust hood or cabinet operating to remove smoke and fumes without drafts that affect the flame.
6.2.4.11.8 When the burner has a gas pilot light, the valve supplying gas to the burner shall be opened to apply the flame to the specimen automatically. This valve shall be held open for 60 s and then closed for 30 s. This procedure shall be repeated twice for a total of 3 applications of flame to the specimen
UL testing for Electrical Rigid Metal Conduit – Steel end
Welcome to www.UL-UL.com website,this is a free UL information website,and this article mainly introduce UL testing for Electrical Rigid Metal Conduit – Steel. There are some other UL article related with UL testing for Electrical Rigid Metal Conduit – Steel as following:
If you did not find the UL information you need,Feel free to visit UL approval forum powerd by UL Online,our experts will help you.
| 
