5.3　Materials

5.3.1　For mobilization of high-strength bolt connecting pairs，the batch number，type，variety，specification，quantity，production date and the qualification documents provided by batches shall be checked；moreover，relevant requirements of the design document and the current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures shall be met.The surfaces of the bolts，nuts and gaskets shall be coated with oil for protection，and shall not have rust and shall be free of contamination.And threads shall be free of damage.

5.3.2　Measures of preventing damp，rain and dust shall be taken for storage of the high-strength bolts；moreover，the high-strength bolts shall be stored according to types and specifications and shall not be unpacked randomly before installation.The high-strength bolt connecting pairs shall be collected and distributed according to the construction demand of that day and shall not be collected randomly.After the construction，the residual connecting pairs shall be kept properly according to their batch number，shall not be mixed and shall be free of contamination.And threads shall be free of damage.

5.3.3　For mobilization of welding materials，the variety，specification，performance and quantity，shall be checked；moreover，relevant requirements of the design document and the current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures shall be met.Various welding rods，welding wires，welding flux and consumable nozzles shall be stored in ventilating and dry storehouse having a relative humidity less than 60% according to their variety，specifications and marks，and shall be kept by a special person.The welding materials on the installation site shall be continuously conveyed to a drying room by batches according to the demand.The storage racks in the drying room shall have moist insulation substances similar to wood plates，and should be kept from the wall by no less than 300mm.

5.3.4　Carbon dioxide gas used for gas shielded welding shall meet the relevant requirements of the current national and industrial standard HG/T 2537 Carbon Dioxide for Welding，wherein the carbon dioxide content must not be less than 99.5%（volumetric method）and the water content must not be higher than 0.005%（gravimetric method）.When a cylinder is used，the residual pressure in it must not be less than 1MPa.

5.3.5　After mobilization of the steel products，the steel variety，steel grade，specification，performance，surface quality and quantity shall be checked；moreover，relevant requirements of the design document，the current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures，and the contract appendixes shall be met.

5.3.6　Sampling and recheck shall be conducted on the steel products having one of the following situations and the recheck result shall meet the requirements of the design document，the current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures，and the contract appendixes:

1　Imported steel products.

2　Steel products having mixed batches.

3　Steel plates having a thickness equal to or larger than 40mm or specified by the design document and having Z-direction performance requirements.

4　Steel products with doubted quality.

5　Steel products required recheck by the design document or the contract appendixes.

5.3.7　The thicknesses of the steel plates as well as the specifications and sizes of the profile steel shall be checked by using a steel ruler and a vernier caliper.The depths of the surface corrosion，pocking marks or scratches of the steel products must not be larger than the negative allowable deviation of the thickness of the steel product by 1/2，and shall comply with Class C or above specified in the current national standard GB 8923 Rust Grades and Preparation Grades of Steel surfaces before Application of Paints and Related Products.

5.3.8　Steel plate edges shall be smooth and free of defects including crack，delamination，slag，etc.via observation or using magnifying glass.

5.3.9　Warehousing acceptance procedures shall be handled for warehousing of steel products，and the steel type，steel grade，specification，the qualification documents and the re-inspection report provided by batches shall be checked；moreover，relevant requirements of the design document and the current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures shall be met.Unchecked or unqualified materials shall not be warehoused.Qualified steel products shall be separately piled and stored according to their types，steel grades and specifications.Sleepers or concrete blocks should be stacked on the bottom.

5.3.10　After mobilization of the coatings，the variety，specification，performance，quantity and qualification documents，Chinese signs and inspection reports of the coatings，diluents and curing agents，etc.，shall be checked；moreover，relevant requirements of the design document and the current national standard GB 50205 Code for Acceptance of Construction Quality of Steel Structures shall be met.The coatings overdue shall be sampled and rechecked and shall not be used unless they pass the sampling and rechecking.The sampling method shall meet relevant requirements of the current national standard GB 3186 Paints，Varnishes and Raw Materials for Paints and Varnishes-Sampling.

5.3.11　The coatings shall be stored in a special warehouse which shall be equipped with warning marks for prohibition of fireworks as well as fireproof appliances.The coatings should not be stored in the installation site，and shall be taken charged by a special person for storage and keeping.