1 General Provisions
1.0.1 This Code is formulated with a view to ensuring overhead transmission line project construction quality as well as standardizing quality control requirements and acceptance conditions for construction process.
1.0.2 This Code is applicable to construction, extension and renovation projects of 750kV overhead transmission line.
1.0.3 750kV overhead transmission line project must be constructed according to approved design documents as well as design and construction drawings jointly reviewed by the parties concerned.
1.0.4 This Code is also 750kV overhead transmission line design and project supervision basis.
1.0.5 New technologies and processes can be adopted only after they are confirmed meeting the requirements of this Code through test, testing and experiment verification.
1.0.6 Overhead transmission line construction and acceptance as well as raw materials and apparatus inspection shall not only comply with this Code but also meet the requirements of the current relevant standards and codes of the nation. The requirements higher than relevant standards listed in design documents or construction contracts shall be implemented according to design or contract requirements.
1.0.7 Instruments, meters and measuring tools used for overhead transmission line project measurement and inspection must be made of qualified products and be used within calibration validity period.
2 Raw Materials and Apparatus Inspection
2.0.1 Raw materials and apparatus used in overhead transmission line project must meet the following requirements:
1 They shall be provided with outgoing quality inspection certificates of this batch of products;
2 They shall be provided with various quality inspection data in conformity with the current standards of the nation;
3 As for the raw materials such as sandstone without quality inspection data, they shall be sampled and inspected by qualified inspection organizations, and only qualified ones can be put into service;
4 As for the products with doubtful inspection results, they shall be re-sampled and inspected by qualified inspection organizations, and only qualified ones can be put into service.
2.0.2 Proposed new raw materials and apparatus must experience test and technical assessment conducted by the departments concerned, after which they can be used only when their quality is confirmed meeting the requirements of design and this Code.
2.0.3 Raw materials and apparatus shall be re-inspected if any of the following conditions exists, and then their usage or degradation usage shall be determined according to inspection results:
1 Retention period exceeding the specified one;
2 Potential deterioration due to poor storage;
3 Sampling failing to conform to the requirements of the standards or test samples not representative.
2.0.4 Gravel and crushed stone for precast concrete member and on-site casted concrete foundation shall meet the relevant requirements of the current national standard "Technical Requirements and Test Method of Gravel and Crushed Stone for Ordinary Concrete" (JGJ 53).
2.0.5 Sand for precast concrete member and on-site casted concrete foundation shall meet the relevant requirements of the current national standard "Standard for Technical Requirements and Test Method of Sand and Crushed Stone (or Gravel) for Ordinary Concrete" (JGJ 52). In particular areas, local standards can be complied with.
Sea sand shall not be used.
2.0.6 Cement must comply with the national standards related to the current national standard "Portland Cement and Ordinary Portland Cement" (GB 175) and their variety and strength grade shall meet the design requirements. Cement shall be indicated with ex-factory date. When cement has left factory for more than 3 months or is not properly stored even though leaving factory less than 3 months, strength grade test must be carried out again, and cement shall be used according to the actual strength grade after the test.
Cement shall be prevented from moisture during storage. Cement of different grades, manufacturers and batch numbers shall be stacked separately and marked clearly, which shall not be used together.
2.0.7 Concrete casting water shall meet the following requirements:
1 Drinking water should be used for precast member and on-site casted concrete, otherwise clean river water or pond water can be used. Unless there are special design requirements, only visual inspection can be carried out and chemical examination can be omitted. Water shall be free from lipid; no hazardous compound flows into water from the upstream; chemical examination shall be carried out where water composition is uncertain;
2 Sea water shall not be used.
2.0.8 Where it is allowed to mix boulders in cast-in-place concrete foundation in the design, the mixed boulders shall be free from any crack or interlayer, and their strength shall not be lower than concrete stone criteria. Average diameter of boulder should be 150~250mm and crushed stone should not be used.
2.0.9 Processing quality of reinforcement, foundation bolt, and inserted angle steel, etc. for precast concrete member and cast-in-place concrete foundation shall meet the requirements of design and relevant standards. Steel shall meet the requirements of the current standards of the nation and steel surfaces shall be free from blemish.
2.0.10 Such welding consumables as electrodes and fluxes of steel shall be suitable for weld metal on the aspects of model and attribute.
2.0.11 Processing quality of angle steel tower shall meet the requirements of the current national standard "Transmission Line Tower - Technical Requirements for Manufacturing" (GB/T 2694). Steel tube tower processing quality shall meet the design requirements and the relevant requirements.
2.0.12 Model, specification, manufacture quality, inspection, test and packaging of conductor shall meet the requirements of the current national standard "Round Wire Concentric Lay Overhead Electrical Stranded Conductors" (GB/T 1179).Model, specification and manufacture quality of inlet conductors shall meet the standards selected during design.
2.0.13 Where galvanized steel strand is adopted as overhead ground wire, model, specification and manufacture quality of galvanized steel strand shall meet the requirements of the current national standard "Zinc-coated Steel Wire Strands" (YB/T 5004); where good conductor is adopted as overhead ground wire, model, specification and manufacture quality of good conductor shall meet the requirements of corresponding current standards and codes of the nation; where Optical fiber composite overhead ground wires are adopted, domestic products shall meet the requirements of the current national standard "Optical Fiber Composite Overhead Ground Wires" (DL/T 832); imported products shall meet the standards selected during design.
2.0.14 Fittings manufacture quality shall meet the requirements of current national standards "General technical Requirements for Electric Power Fittings" (GB 2314) and "Manufacture Quality Specification for Electric Power Fittings" (DL/T 768) as well as other related current national standards and codes. Acceptance, marking and packing shall meet the requirements of the current national standard "Acceptance Inspection, Marking and Packing for Electric Power Fittings" (GB/T 2317.4).
2.0.15 Precast stay wire foundation shall meet the following requirements:
1 Members shall be free from any longitudinal or transverse crack;
2 The surface shall be even without obvious defects;
3 Machining permissible deviation shall be in accordance with those specified in Table
