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GB 18280 consists of the following parts under the general title Conduit systems for cable management:
——Part 1: General requirements
——Part 2: Particular requirements
? Part 21: Particular requirement for rigid conduit systems
? Part 22: Particular requirement - Pliable conduit systems
? Part 23: Particular requirement - Flexible conduit systems
? Part 24: Particular requirement - Conduit systems buried underground
? Part 25: Particular requirements for conduit fixing devices
This is Part 21 of GB/T 20041.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB20041.21-2008 Conduit systems for cable management - Part 21: Particular requirement - Rigid conduit systems. The following main technical changes have been made with respect to GB 20041.21-2008:
——The Clause "Normative references" is added (see clause 2);
——The requirements for routine test items are added (see 5.101);
——The requirements of marking the number of this part are added (see 7.1.101);
——The requirements on thread of metallic conduit are added (see 8.1)
——The requirements on size of metallic conduits are added (see 8.101, 8.102, 8.103, 8.104, 8.105 and 8.106);
——The structural requirements of metallic conduits are added (see 9.101, 9.102, 9.103, 9.104, 9.105, 9.106, 9.107 and 9.108);
——The requirements on degree of protection and resistance against corrosion of metallic conduits are added (see clause 14);
——Figure 101 is added;
——Annex C (normative) “Routine tests” is added.
This part has been redrafted and modified in relation to IEC 61386-21: 2002 Conduit systems for cable management - Part 21: Particular requirements - Rigid conduit system.
The technical differences between this part and IEC 61386-21: 2002 as well as the reasons are as follows:
——The adjustment in "Normative References" of this part has technical differences to meet the technical specification in China; the adjustment situations are embodied in a concentrated way in Clause 2 - "Normative references" and the specific adjustments are as follows:
? IEC 61386-1 is replaced by GB/T 20041.1-2015;
? The reference documents GB/T 192, GB/T 196, GB/T 4208 and GB/T 17194 are added.
——The subclause 5.101 is added to guide the manufacturer's production and inspection.
——The requirements of marking the number of this part are added in 7.1.101.
——According to the situation of metallic conduit systems in China, the clauses related to conduit size requirements are added, such as 8.101, 8.102, 8.103, 8.104, 8.105 and 8.106.
——According to the situation of metallic conduit systems in China, the clauses related to conduit structure requirements are added, such as 9.101, 9.102, 9.103, 9.104, 9.105, 9.106, 9.107 and 9.108.
——According to the application environment of metallic conduit systems in China, the clauses related to the degree of protection and to resistance against corrosion of conduits are added, such as 14.101 and 14.102.
——Annex C “Routine tests” is added.
——Figure 101 is added.
The following editorial changes are made in this part:
——In accordance with the requirements of GB/T1.1-2009, the content in clause 1 “Scope” is modified as “This part of GB/T 20041 specifies technical requirements for marking and documentation, dimensions, constructions, mechanical properties, electrical properties and thermal properties of rigid conduit systems. This part is applicable to rigid conduit systems”.
——As Figure 101 is added, the number of figures is adjusted according to the order in which the figures are mentioned in the text.
This part was proposed by China Electrical Equipment Industrial Association.
This part is under the jurisdiction of SAC/TC67 National Technical Committee on Electrical Accessories of Standardization Administration of China.
The previous editions replaced by this part are as follows:
——GB/T 14823.1-1993 and GB/T 14823.2-1993;
——GB 20041.21-2008.
Conduit systems for cable management -
Part 21: Particular requirement for rigid conduit systems
1 Scope
This clause of GB/T 20041.1-2015 is replaced by:
This part of GB/T 20041 specifies technical requirements for marking and documentation, dimensions, constructions, mechanical properties, electrical properties, and thermal properties of rigid conduit systems.
This part is applicable to rigid conduit systems.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 192 General purpose metric screw threads - Basic profile(GB/T 192-2003; ISO 68-1: 1998, MOD)
GB/T 196 General purpose metric screw threads - Basic dimensions(GB/T 196-2003; IS0 724: 1993, MOD)
GB/T 4208 Degrees of protection provided by enclosure (IP code)(GB/T 4208-2008; IEC 60529: 2001, IDT)
GB/T 17194 Conduits for electrical purposes - Outside diameters of conduits for electrical installations and threads of conduits and fittings (GB/T17194-1997; eqv IEC423: 1993)
GB/T 20041.1-2015 Conduit systems for cable management - Part 1:General requirements (IEC 61386-1: 2008, MOD)
3 Terms and definitions
This clause of GB/T 20041.1-2015 is applicable.
4 General requirements
This clause of GB/T 20041.1-2015 is applicable.
5 General conditions for tests
This clause of GB/T 20041.1-2015, after adding the following provisions, is applicable.
5.101 Routine test items are given in Annex C.
6 Classification
This clause of GB/T 20041.1-2015 is applicable, except as follows:
6.1.1.1), 6.1.2.1), 6.1.3.2), 6.1.3.3), 6.1.3.4), 6.1.4.1) and 6.1.5.1) are not applicable.
7 Marking and documentation
This clause of GB/T 20041.1-2015 is applicable after the following modifications are made.
Addition:
7.1.101 The conduit shall be marked in accordance with 7.1 along its entire length at regular intervals of preferably 1m but not longer than 3m and each length shall be marked at least once. The number of this part shall be marked on each conduit, for example, GB/T 20041.21.
Compliance is checked by inspection.
7.1.102 The manufacturer shall document for the system the minimum inside diameter and the classification in accordance with clause 6.
Compliance is checked by inspection.
8 Dimensions
This clause of GB/T 20041.1-2015 is modified as follows:
8.1 Thread and outside diameters shall comply with GB/T 17194.
The thread of metallic conduit shall be neat, smooth and free of cracks. Black skin is allowed on the thread at the weld of steel conduit, but the reduction of thread cross-section height shall not exceed 15% of the specified height, the total length of broken thread or incomplete tooth profile shall not exceed 10% of the specified length, and the same part of two adjacent threads shall not be broken at the same time.
Compliance is checked by inspection and by means of the gauges specified in GB/T 17194.
8.2 Threadable conduits and threadable conduit fittings, except terminating conduit fittings, shall comply with those specified in Table 101. Non-threadable conduit fittings, except fittings which are part of a conduit system declaring tensile strength, shall comply with those specified in Table 2. The minimum inside diameter of the conduit system shall be as declared by the manufacturer.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 General conditions for tests
6 Classification
7 Marking and documentation
8 Dimensions
9 Construction
10 Mechanical properties
11 Electrical properties
12 Thermal properties
13 Fire hazard
14 External influences
15 Electromagnetic compatibility
Annex A (Normative) Classification coding for conduit systems
Annex B (Normative) Determination of material thickness
Annex C (Normative) Routine tests
Figure 101 Gauge for checking the minimum outside diameter of the conduit system
Figure 102 Gauge for checking the minimum inside diameter of the conduit system after impact, bending, collapse and resistance to heat tests
Figure 103 Bending apparatus for metallic and composite conduits
Figure 104 Bending apparatus for non-metallic and composite conduits
Figure 105 Arrangement for collapse test
Table 1 Thread lengths
Table 2 Maximum entry diameter and minimum entry length details
Table 3 Size of outside diameter and wall thickness of non-threadable metallic conduits
Table 4 Size of outside diameter and wall thickness of threadable metallic conduits
Table 5 Minimum outside diameter gauge size of metallic conduit
Table 6 Minimum inside diameter size of metallic conduits after bending
