IEC 60981-2019 pdf download.Extra heavy-duty electrical rigid steel conduits.
4 General requirements
4.1 Tests Tests according to this document shall be type tests. Unless otherwise specified, the tests shall be carried out at an ambient temperature of (20+5) °C. Unless otherwise specified, each test shall be carried out on two new samples. If a sample tested in accordance with this document fails, two additional samples shall be tested, both of which shall comply with all the requirements of this document.
4.2 Circular cross-section An EHDERS conduit shall have a circular cross-section sufficiently accurate to- pormit allow the cutting of threads in accordance with Figure 1.
4.3 Wall thickness The wall thickness shall comply with the dimensions given in Table 1.
4.4 Surface condition
4.4.1 General Surfaces of a conduit shall be free from slivers, burrs, scale and other defects likely to cause damage to conductors or cables. Compliance shall be checked by visual inspection of the external and internal surfaces. 4.4.2 Locallzed surface Imperfections Localized surface imperfections shall not exceed a depth of 12.5 % of the nominal wall thickness given in Table 1. Compliance of localized surface imperfections shall be checked by measurement.
4.5 Welding The welding of all seams shall be continuous and carried out in a workmanlike professional manner. Compliance is checked by visual inspection.
4.6 Cleaning The conduit shall be adequately cleaned before the application of the protective coating. The cleaning process shall leave the exterior_ and interior surfaces of the conduit in such a condition that the protective coating will be firmly adherent and smooth, as defined in 4.4.
4.7 Protective coating(s)
4.7.1 Primary coating(s) The exterior surface shall be thoroughly and evenly coated with either a metalic zinc or an alternative corrosion protection coating applied directly to the surface of the steel so that metal-to-metal contact and galvanic protection against corrosion are provided. Zinc coatings or alternative corrosion protection coatings having a zinc component shall be in metal-to-
metal contact with the steel.
The interior surface shall be protected by a zinc or organic or other suitable corrosionresistant coating.
4.7.2 Secondary coating(s)
When (an) additional coating(s) is(are) applied to enhance the primary coating, the evaluation for- its each additional coating’s degree of corrosion protection shall be optional.
5 Dimensions
5.1 Dimensions The dimensions and mass of the EHDERS conduit shall be in accordance with those given in Table 1 ,
5.2 Threads
5.2.1 General The pitch and the length of the threaded portion at each end of each length of conduit, nipple, and elbow shall be as indicated in Figure 1 and shall be compatible with IEC 61950. The complete thread shall be tapered for its entire length, and the taper shall have a ratio of 1 to 16.
5.2.2 Pitch form The form of the thread profile, the dimensional relationships for the form of the thread and the general notation are shown in Figure 2.
5.2.3 Angle of thread The angle between the sides of the thread, measured in the axial plane, shall be 60°. The line bisecting this angle is perpendicular to the axis.
6 Protective coatings
6.1 Interior coatings 6.1.1 Zinc The presence of a zinc coating on the interior surface shall be verified. Compliance shall be checked by the method described in Annex A for one test cycle only.IEC 60981 pdf download.