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IEC 60981
Edition 3.0 2019-08
INTERNATIONAL
STANDARD
colour
inside
Extra heavy-duty electrical rigid steel conduits
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IEC 60981
Edition 3.0 2019-08
INTERNATIONAL
STANDARD
colour
inside
Extra heavy-duty electrical rigid steel conduits
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.10 ISBN 978-2-8322-7310-4
– 2 – IEC 60981:2019 © IEC 2019
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General requirements . 8
4.1 Tests . 8
4.2 Circular cross-section . 8
4.3 Wall thickness . 8
4.4 Surface condition . 8
4.4.1 General . 8
4.4.2 Localized surface imperfections . 8
4.5 Welding . 8
4.6 Cleaning . 8
4.7 Protective coating(s) . 8
4.7.1 Primary coating(s) . 8
4.7.2 Secondary coating(s) . 9
5 Dimensions. 9
5.1 Dimensions . 9
5.2 Threads . 9
5.2.1 General . 9
5.2.2 Pitch form . 9
5.2.3 Angle of thread . 9
6 Protective coatings . 9
6.1 Interior coatings . 9
6.1.1 Zinc . 9
6.1.2 Organic coatings. 9
6.2 Exterior coatings . 10
6.2.1 Zinc . 10
6.2.2 Alternative corrosion-resistant coating . 10
7 Threading and chamfering . 13
8 Couplings . 14
8.1 General . 14
8.1.1 Corrosion protection . 14
8.1.2 Chamfering . 14
8.1.3 Dimensions . 14
8.2 Coupling threads . 14
8.2.1 Thread form . 14
8.2.2 Dimensions . 14
9 Elbows and nipples . 14
10 Ductility . 14
10.1 Bending properties . 14
10.2 Ductility of zinc coating . 14
11 Marking . 15
11.1 General . 15
11.2 Required information . 15
Annex A (normative) Test for thickness of zinc coating on extra heavy-duty electrical
rigid steel (EHDERS) conduits . 24
A.1 Requirement . 24
A.2 Solutions required . 24
A.3 Preparation of samples . 24
A.4 Specimen surface condition . 24
A.5 Test method . 24
A.6 Results . 25
Annex B (normative) Tests for evaluating alternative exterior coatings applied on extra
heavy-duty electrical rigid steel (EHDERS) conduits . 26
B.1 Alternative corrosion-resistant coatings . 26
B.2 Preparation of specimens . 26
B.3 Air oven conditioning exposure . 28
B.4 Resistance to ultraviolet light and water exposure . 29
B.5 Resistance to salt spray (fog) exposure . 29
B.6 Resistance to moist carbon dioxide-sulfur dioxide-air exposure . 29
Bibliography . 30
Figure 1 – Dimensions of threads for EHDERS conduits . 18
Figure 2 – Basic form of taper thread . 19
Figure 3 – Limits on crest and root truncation of external and internal threads . 20
Figure 4 – Dimensions of a ferrous metal coupling . 21
Figure 5 – Dimensions of wedge . 22
Figure 6 – Essential dimensions for flame test . 23
Figure B.1 – Alternative corrosion program flowchart with sample requirements . 27
Figure B.2 – Scribe pattern . 28
Table 1 – Dimensions and mass of EHDERS conduits . 16
Table 2 – Dimensions of couplings . 17
Table 3 – Dimensions of 90° elbows . 17
– 4 – IEC 60981:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXTRA HEAVY-DUTY ELECTRICAL RIGID STEEL CONDUITS
FOREWORD
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