1. Subject Matter and Scope: This code of practice specifies the technical requirements and precautions for the rolling and fabrication of metal sheet cylindrical components (including thick-walled rolled tubes). It applies to the rolling of cylindrical sections for pressure vessel products and the fabrication of plate cylindrical components for other products. 2. General Provisions 2.1 This code should be used concurrently with product drawings, standards, relevant process documents, and equipment safety operation procedures. 2.2 Materials for processing must be inspected and must meet quality standards; untested or substandard materials are not allowed for processing. 2.3 It is applicable to the cold-rolling process for cylindrical shells on three-roller and four-roller plate bending machines. 3. Equipment and Installation 3.1 The equipment precision and capability of the plate bending machine should comply with the specifications in the manual. 3.2 Equipment should be kept in good condition and kept clean. 4. Rolling Preparation 4.1 Before rolling the cylinder, start the machine for no-load operation to check the sound of all rotating parts, which should be normal, well-lubricated, and the electrical switches should operate sensitively. Rolling the cylinder can only be performed after the machine operates normally. When rolling stainless steel cylinders, the equipment and surrounding area should be kept clean. The roller shafts should be cleaned and surface dressed, and wrapped with adhesive tape or paper that does not contain iron ions. 5. Rolling 5.1 During three-roller rolling, the ends of the steel plate should be pre-bent using a general pre-bending mold on a press. The pre-bending length should be greater than half the distance between the centers of the two lower rolls of the three-roller bending machine. Within the pre-bending length, the pre-bending arc and the gap h≤1mm with the check template, and the nominal size of the check template's curvature radius should be 0.5-1mm smaller than the nominal size in the drawing. 5.2 When pre-bending and rolling on a four-roller bending machine, the pre-bending of the steel plate ends can be done on the machine. Place the steel plate flat between the upper and lower rolls of the bending machine, ensuring the end faces are parallel to the shaft rolls and extend beyond the vertical center line distance between the upper and lower shaft rolls. Lift the side shaft rolls and tilt them upward to bend one end of the steel plate while moving it forward a certain distance, thus pre-bending the plate end. Similarly, pre-bend the other end of the steel plate. The pre-bending length should be determined based on the structural dimensions of the bending machine, and the quality of the pre-bending arc should meet the requirements of 5.1. 5.3 During pre-bending, the pre-bent section of the steel plate should be checked with a template for the pre-bending radius at all times. Local bulges or dents can be corrected using steel strips as shims. Pre-bending using the bending machine should be done in several stages based on the material's plasticity, thickness, and the size of the curvature. 5.4 After pre-bending, the excess material on the ends of the steel plate with pre-bent straight sections should be cut off. The end (bevel) face and the area within 20mm on both sides must be cleaned of oil, rust, and scale. 5.5 The steel plate to be rolled should be placed in the middle of the length direction of the shaft roll, and the position of the steel plate should be adjusted so that the edge of the joint is parallel to the center line of the shaft roll. 5.6 During rolling, the steel plate should be gradually bent into shape. 5.6.1 When rolling with a three-roller bending machine, the upper roll should be adjusted to move down in stages to bend the steel plate into a cylinder. Each time the upper roll moves down, the bending machine must be activated to make the workpiece travel back and forth on the machine one or two times. 5.6.2 When rolling with a four-roller bending machine, the side shaft rolls should be adjusted multiple times to tilt upward to make the steel plate bend back and forth multiple times until the ends of the plate contact and align. 5.7 After each adjustment of the upper roll on the three-roller bending machine or the side shaft rolls on the four-roller bending machine, check the curvature radius with a template to prevent over-bending until the bending radius of the cylinder section matches perfectly. 5.8 During the rolling process, the steel plate sides should be kept perpendicular to the center line of the shaft roll, and regular checks should be performed to prevent misalignment, causing misalignment of the end faces. 5.9 The shaft rolls of the bending machine should be adjusted to maintain parallelism to avoid the formation of a conical shape in the rolled cylinder. 5.10 After the thick-walled rolled tube cylinder is formed, use special fixtures to align the longitudinal seams flat and align the ends, ensuring the gap meets the requirements of the drawings and process documents. The alignment deviation of the longitudinal seams should comply with Table 1. Spot welding should be done according to the product's corresponding welding process, welding materials, and the "General Code of Practice for Manual Arc Welding."Coil Rolling5.11 Welding: Welding materials and methods must comply with the requirements of the welding process document. When carrying a test plate, it must be flatly connected as an extension of the cylinder and welded simultaneously. After welding is completed, weld marks must be stamped at the specified positions on the cylinder and the test plate. When the test plate is used for A-class confirmation, it should be cut after being inspected by the supervisor. 5.12 The rounding of the cylinder should be done on a rolling machine. The edge angle at the longitudinal weld of the container should be E≤0.1δn+2mm and ≤5mm, and the edge angle formed at the A-class welding joint of a multi-layer wrapped container should be ≤2mm. It should be measured using an inner or outer template with a chord length of 1/6Di and ≥300mm. 5.13 Cylinder roundness (the difference e between the maximum and minimum diameters on a uniform cross-section of the cylinder). For heat exchangers and cylinders with internal parts, e≤0.5%DN, and when DN≤1200mm, the value should not exceed 5mm; when DN＞1200mm, the value should not exceed 7mm. If the drawings have specific requirements, they should comply with the specifications. For cylinders without special requirements, the e value should not exceed 1% of the inner diameter Di and not exceed 25mm. For the inner cylinder of a multi-layer wrapped container, the value should not exceed 0.5% of the inner diameter Di and not exceed 6mm. 5.14 Non-destructive Testing: As required by the drawings and in accordance with JB4730 standards, and with NDT marking. 5.15 For cylinders with large diameters and thin walls that are prone to deformation, use a cross-type internal bracing method to support the cylinder into a circular shape and rigidly fix it to avoid significant deformation during the process flow. 5.16 The cylinder should be inspected and confirmed to meet all the above requirements (including the welding test plate), and after witnessing the longitudinal seam inspection, proceed to the next process. 6. For cylinder sections of carbon steel and low-alloy steel low-temperature pressure vessels designed with a temperature ≤ -20℃ and stainless steel containers, the following provisions should also be met. 6.1 For cylinders that are not subjected to post-weld stress relief treatment, no forced means such as hammering should be used for forming or shaping, and no markings such as material marks or welder's stamps that may cause notch sensitivity effects should be scratched or struck on the cylinder sections. All markings should be recorded in detail. 6.2 Weld edges are not allowed, and any weld edge must be repaired. 6.3 Weld scars must be ground smooth and subjected to magnetic particle inspection or penetrant inspection. 6.4 Surface damage on the cylinder section caused by machining or welding, such as scratches, weld scars, and arc pits, should all be ground. After grinding, the thickness should not be less than the calculated thickness of the cylinder plus the corrosion allowance, and the grinding depth should not exceed 5% of the nominal thickness of the cylinder, and not exceed 2mm. 6.5 The weld bead height should not exceed 10% of the cylinder thickness and not exceed 3mm, and the ASME product weld bead height should not exceed 2.38mm. The excess height should be ground.