3 Inspection of Raw Material and Equipment
3.0.1 DC overhead transmission lines of±800 kV and below must be constructed in accordance with approved design documents and construction drawings jointly reviewed by relevant parties.
3.0.2 New technology，techniques and materials can be used only after they are proved through tests and verifications to meet the design requirements and specifications of this code.
3.0.3 The construction and acceptance of overhead transmission lines as well as the inspection of raw materials and equipment shall be not only in accordance with the relevant terms in this code，but also the terms of the relevant current national standards and specifications.
3.0.4 Instruments，apparatus and gauges used for construction survey and inspection must be qualified products within validity period.
3.0.5 Raw material and equipment used for projects must meet the following requirements:
1 Ex-factory quality inspection certificates for the batch of products shall be provided.
2 Quality inspection information required by current national standards shall be provided.
3 Raw materials such as sand and stones without quality inspection data shall，before application，be sampled and tested by qualified inspection units.And the materials can be used only after proved to be eligible.
4 If there is any doubt about the test results，the sampling and testing procedure shall be repeated by the qualified inspection test units and the materials can not be used until being qualified.
3.0.6 Raw materials or equipment must be re-tested if the following conditions appear，and use of the material and equipment is subject to the results of the test.
1 Expiration of storage period；
2 Possibility of deterioration due to poor preservation；
3 Samples was not taken in accordance with standards or not representative.
3.0.7 Crushed stones and cobbles used in concrete foundations or protection facilities shall comply with the current national standard JGJ 52.
3.0.8 Sand used for cast-in-site concrete shall comply with the following provisions:
1 Sand used in concrete foundations and protection facilities shall comply with relevant provisions of JGJ 52.In special regions，local standards may be accepted.
2 Sea sand is forbidden.
3.0.9 Cement must be satisfied the requirement of relevant national standards（including GB 175）.The brands and grades shall conform to the strength rating specified by design，which shall be marked with exfactory dates.When the cement left the factory more than 3 months or exposed to poor storage conditions in 3 months，the additional strength grade test must be done，and the actual strength is determined by the test.
Cement shall be protected against moisture during storage，and cement of different brands，grades，or different factories shall be separated with clear identifying labels to prevent mishmash.
3.0.10 Water used for concrete casting shall comply with the following requirements:
1 Drinking water should be used for cast-in-site concrete，or if unavailable，clean river water or pool water may be used instead.Visual inspection is enough unless chemical test is required by design documents.The water shall be free of oil/grease and there shall be no chemical pollution sources at the upstream stretch.If any suspicions，chemical test shall be done.
2 Seawater is forbidden.
3.0.11 If stone blocks are permitted to used in cast-in-site concrete foundations，they shall be free of cracks and laminations，with strength no lower than the requirement by relevant specifications.The average diameter of stone blocks should be 150mm-250mm，and cobble should not be used.The amount of stone blocks shall not exceed the design limit.
3.0.12 Reinforcement bars，anchor bolts，inserted angles and groundings used for concrete foundations shall be fabricated in accordance with the requirements of design documents and relevant standards，with no dirt on their surfaces.The steel shall comply with requirements of relevant national standards.
3.0.13 Ready-mixed concrete purchased from third parties shall satisfy the strength requirements of design documents as well as the quality requirements of GB 14902.
3.0.14 Welding electrodes and welding reagents used for steel members shall comply with relevant standards and their brands and characteristic shall be compatible with the metals to be welded.
3.0.15 Angle steel tower shall be fabricated according to the quality requirements of GB 2694，and steel tube tower shall be fabricated according to quality requirements of design documents and relevant regulations.
3.0.16 The quality of the conductor shall be consistent with the design requirement.The fabrication quality，inspection，test and packing of conductors shall be consistent with current national standards GB/T 1179.Imported conductors or the non-GB conductors shall comply with design selection criteria for models，sizes and fabrication quality.
3.0.17 If galvanized steel strands are used as overhead ground wires，the models，sizes and fabrication quality of the wire shall comply with the current standard YB/T 5004；and if good conductors are used as ground wires，the models，sizes and fabrication quality of the wire shall comply with the current standard.For optical fibre composite overhead ground wires，the domestic products shall comply with the standard DL/T 832，and the imported products shall comply with design selection criteria.
3.0.18 The quality of accessories should be consistent with the current national standard GB 2314，DL/T 768 and other relevant technical standards.Their acceptance，marking and packing shall comply with GB 2317.4.For new or non-standard accessories，the acceptance，marking and packing shall comply with relevant design and technical requirements.
3.0.19 Insulators and insulator strings:
1 The quality of cap and pin type suspension porcelain and glass insulators shall comply with technical requirements of GB 1001.1，GB 7253 and JB/T 9678.
2 The quality of organic composite insulators（also known as composite insulators）shall comply with technical requirements of DL/T 810.
3 Long-rod porcelain insulators shall comply with technical requirements of design documents and relevant technical standards.
4 New or non-standard insulators shall comply with design document and relevant technical requirements.
3.0.20 The quality of bolts used for assembling steel tower shall comply with quality requirements of DL/T 764.4.The types and models of locking bolts shall meet the requirements from the construction unit，and the quality and material of locking nuts shall meet the relevant standards.