GB/T 12755-2008Profiled steel sheet for building (English PDF)

8.2 Steel substrate and prepainted steel sheet

8.2.1 The steel substrate and prepainted steel sheet may all directly be shaped by rolling to form profiled steel sheet. The chemical compositions and mechanical properties of the hot- galvanizing steel substrate and hot-dipped aluminium-zinc steel substrate shall comply with the requirements of Appendix A.

8.2.2 According to the yield strength grades, the substrate steels should adopt grade 250 (MPa) and grade 350(MPa) steels. The parameters such as design value of strength may be valued according to the requirements of GB 50018. When backed up by technical economy, higher- strength steels can be adopted for steel substrate of the profiled steel sheet.

8.2.3 In engineering, the nominal thickness of the wall profiled steel sheet substrate should not be less than 0.5mm, while that of the roofing profiled steel sheet substrate should not be less than 0.6mm, and that of the floor system profiled steel sheet substrate should not be less than 0.8mm. The steel substrate thickness (including coating thickness) tolerance shall comply with the requirements of Appendix B, while the plates whose minus deviation exceed those specified in Appendix B shall not be used for processing the profiled steel sheet.

8.2.4 Steel substrate coating (zinc, zinc-aluminium, and aluminium-zinc alloy coating) shall adopt hot dipping method; the coating weight shall be ensured as the delivery item according to the purchaser's requirement and shall be indicated in the purchase contract. If no other requirements asked by the purchaser, cladding weight (both sides) shall not be less than 90/90g/m2 (Hot dip galvanizing steel substrate), 50/50g/m2 (Aluminium-zinc alloy coating alloy steel substrate) 65/65g/m2 (galvanized aluminium steel substrate). The recommended coating weight for different corrosion media may refer to Appendix C, and the classification of environmental corrosive conditions may refer to Appendix D.

8.3 Prepainted steel sheet

8.3.1 The coating type, performance, quality and other technical requirements and inspection methods of the prepainted steel sheet for profiled steel sheet shall comply with the requirements of GB/T 12754. The grades, function, classification and code of the colored pre- painted steel sheet may see Appendix E, and the cladding, coating and durability test shall comply with the requirements of Appendix C.

8.3.2 Coating type and coating structure of the prepainted steel sheet for the profiled steel sheet shall be ensured as the delivery condition of the purchaser and shall be agreed and indicated in the purchase contract. If no other requirements asked by the purchaser, coating structure may be delivered according to the method of two layers on the top side and one layer on the bottom side.

8.4 Others

8.4.1 The profiled steel sheet for building shall not adopt electro-galvanizing steel plate or steel plate (strip) without any cladding and coating.

8.4.2 The profiled steel sheet for composite floor system shall adopt hot-galvanizing steel plate.

8.4.3 When the lower plate of the composite roofing profiled steel sheet is perforated acoustic board, the pore diameter and row pitch of the profiled steel sheet shall be specially designed.

8.4.4 The same roofing engineering or wall engineering's profiled steel sheet should adopt the prepainted steel sheet with the same batch number for the order and the delivery, so as to avoid color difference.

9.1 Packaging

9.1.1 The profiled steel sheet shall be packed by attaching strap or steel strip after the piling up, each bundle of packed weight should not be greater than 10t. When packing the profiled steel sheet, wood block or bubble block shall be used for the shock insulator, and it shall not damage the profiled steel sheet. The package shall be rain-proof.

9.1.2 The length of the profiled steel sheet should be determined by the service and transportation conditions, the packing for those with length of no greater than 3m shall not be less than 2 strips; while for those with length of 3~6m, the packing shall not be less than 3 strips; for those with length of greater than 6m, the packing should not be less than 4 strips.

9.1.3 The content of one packaging piece should be the profiled steel sheet with same model and same length. If packed in mixture, it shall be marked separately, so as to facilitate the recognition and access.

9.1.4 According to the purchaser's demand, refined packing may be adopted if both the purchaser and the supplier agree, and the packing method is determined by both parties through negotiation.

9.2 Marking

9.2.1 Each bundle of profiled steel sheet packed in stacks shall be marked clearly on the package surface.

9.2.2 The marking shall give clear indication of number of specimens, supplier name or emblem mark, raw material grade, color, thickness, product model, batch number, length, number of pieces and bundle number.

9.3 Transportation

9.3.1 The products may be transported by automobile, train, watercraft or container, of which the automobile may be packed, while other transportation means can only be transported in cases.

9.3.2 During the transportation process, reliable support and fixation measures shall be available, so as to avoid compression, mechanical damage and rain wetting.

9.4 Storage

9.4.1 The raw material and finished product shall be stored in dry and ventilated warehouses; when storing them, please ensure to keep away from heat, and shall not contact with the chemical medicine or pollutant objectives; when storing in open air for a short time, reliable rain-proof and moisture-proof measures shall be adopted.

9.4.2 The stock place shall be stable, smooth and unease to accumulate water; the bulk stacking height shall not raise deformation to the profiled steel sheet, the bottom shall be padded with batten and the stow-wood spacing should not be too large.

9.5 Quality certificate Each batch of delivery profiled steel sheet must be accompanied by the certificate to prove that the profiled steel sheet meets the standard requirements and the quality certificate of the order contract. The quality certificate shall include the following content:

a) Standard number;

b) Supplier's name (or emblem mark);

c) Project name, contract number and batch number;

d) Specification (product model, thickness and length), quantity;

e) Material standard number, grade, plating, coating variety and color (prepainted steel sheet) and corresponding quality certificate (including chemical composition and mechanical properties);

f) Marks of supplier's technical supervision department or product certificate;

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Notes and Explanations