Heating radiator technical standards

The material of the radiator shall comply with the provisions of GB 13237, and the thickness of the water pipes shall be 1.5 mm.
Radiators should undergo water pressure testing group by group, with a pressure resistance capacity of no less than 1.6 MPa.
The inlet and outlet pipes of the radiator are both located at the bottom of the radiator, with no inlet or outlet pipes installed on the sides. The center-to-center distance between the inlet and outlet pipes is 120 mm, with an allowable tolerance of no more than ±5 mm.
The radiators are high-quality, cold-rolled low-carbon steel pipe radiators. In the room, they feature an oval-tube, double-lap design, with water passages measuring at least 15 mm in diameter. Inside the radiator tubes, there must be at least one uniform, dense protective layer that is acid-resistant, alkali-resistant, and capable of withstanding high temperatures while effectively blocking oxygen penetration. Additionally, detailed construction procedures, installation methods, and inspection reports for this internal cavity protection layer must be provided.
The threaded connections of the radiator pipe fittings shall comply with the provisions of GB/T 7303. The threads must ensure 3 to 5 complete, defect-free turns, and protective caps should be provided at the threaded sections of the connecting pipes. Each radiator unit is equipped with one manually operated air vent valve.
The welding of radiators shall comply with the provisions of GB/T 985 and GJB481. Weld seams must be straight, uniform, neat, and aesthetically pleasing, with no defects such as cracks, porosity, incomplete penetration, or burn-through. Spot welds should have evenly spaced weld points, with adjacent points no more than 40 mm apart, and must not exhibit defects like burn-through. Additionally, the welding between heat dissipation tubes and water supply pipes must ensure a secure and tight fit.
The outer surface of the radiator should undergo proper pretreatment before being coated with an electrostatic powder-spraying process. The resulting paint film must be smooth, flat, and uniform, free from bubbles, buildup, sagging, or missed spots. Additionally, the primer thickness must not be less than 15 μm, and the total paint film thickness should meet or exceed 60 μm. The adhesion of the paint film must satisfy the Grade 1–3 requirements specified in GB/T 1720, while its impact resistance must comply with the provisions outlined in GB/T 1732.
The material used to coat the surface of radiators should be non-toxic and odorless, must not release substances harmful to human health at high temperatures, and should also maintain the material's original physical properties.
The inlet and outlet pipes, air vents, and end caps of the radiator all have a nominal diameter of DN15. The number of brackets supplied with the radiator must not be fewer than the quantity specified for the T22 type in L90N92-49, and each bathroom radiator must be equipped with at least 4 brackets.
The bathroom radiator is an oval steel-tube basket-style model equipped with a towel rack, delivering a heat output of at least 685W per unit when the inlet and outlet water temperatures are 80°C/60°C. The center-to-center distance for the vertical pipe of the bathroom radiator is 570mm, with a height not exceeding 1 meter. The radiator should feature a visually appealing ratio of length to width, and it must include an equipotential bonding device, complete with designated equipotential bonding terminals.
The radiator must not have any obvious deformation, scratches, dents, or burrs.