1. Subject Matter and Scope This code of practice specifies the technical requirements and precautions for the rolling and fabrication of cylindrical components made of metal plates (including thick-walled rolled tubes). It applies to the rolling of cylindrical sections for pressure vessel products and the fabrication of other cylindrical components made of plates. 2. General Provisions 2.1 This code of practice should be used concurrently with product drawings, standards, relevant process documents, and equipment safety operation procedures. 2.2 Materials for processing shall not be processed unless inspected and found to be合格. 2.3 Applicable to cold rolling processes 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 shall comply with the specifications in the instruction manual. 3.2 Equipment shall be kept in good condition and clean. 4. Rolling Preparation 4.1 Before rolling the cylindrical shell, start the machine for no-load operation to check that all moving parts operate normally with good lubrication, and that electrical switches operate sensitively. Rolling of the cylindrical shell can only be carried out after normal operation. When rolling stainless steel cylindrical shells, the equipment and surroundings shall be kept clean. The roller shafts should be cleaned and surface-rectified, 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 standard 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 same machine. Place the steel plate flat between the upper and lower rolls of the bending machine, ensuring the end face is parallel to the shaft roll, and extends beyond the vertical centerline distance between the upper and lower shaft rolls. Lift and tilt the side shaft roll 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 at any time for the pre-bending radius. Local protrusions or dents can be corrected using steel strips as shims. When pre-bending with a bending machine, the pre-bending should be completed in several stages based on the material's plasticity, thickness, and the size of the curvature. 5.4 After pre-bending the ends of the steel plate with excess pre-bent straight sections, the excess should be cut off. The end (bevel) face and within a range of not less than 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 corrected. The edge of the steel plate's interface must be parallel to the centerline 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 lower step by step to bend the steel plate into a cylindrical shape. The bending machine needs to be activated each time the upper roll is lowered to allow the workpiece to travel back and forth on the bending 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 allow the steel plate to bend back and forth multiple times until the ends of the plate touch 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, the curvature radius should be checked with a template during the bending process to prevent over-bending until the bending radius of the cylindrical section matches perfectly. 5.8 During the rolling process, the steel plate sides should be kept perpendicular to the centerline of the shaft roll, and regular checks should be made 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 cylindrical shell. 5.10 After the thick-walled rolled tube cylindrical shell is formed, use special fixtures to align and flatten the longitudinal seams, align the two ends, and ensure the gap meets the requirements of the drawings and process documents. The longitudinal seam alignment deviation should comply with Table 1. The positioning weld should be done according to the product's corresponding welding process, welding materials, and the "General Code of Practice for Manual Arc Welding."Coil Pipe5.11 Welding: Welding materials and methods must comply with the requirements of the welding process documents. When using test plates, the plates must be flatly connected to the cylinder extension and welded simultaneously. After welding, weld marks should be stamped at the specified positions on the cylinder and test plate. When the test plate is used for A-class confirmation, it should be cut after inspection and confirmation. 5.12 To round the cylinder, it 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 the multi-layer wrapped container should be ≤2mm. It should be measured using an internal or external template with a chord length of 1/6Di and ≥300mm. 5.13 Cylinder roundness (difference e between the maximum and minimum diameters on a uniform cross-section of the cylinder). For heat exchangers and cylinders with internal components, e≤0.5%DN, and when DN≤1200mm, the value should not exceed 5mm, and when DN＞1200mm, the value should not exceed 7mm. Where drawings specify, they should comply with the drawing requirements. For cylinder sections without special requirements, the e value should not exceed 1% of the inner diameter Di and not exceed 25mm. For the inner cylinder of multi-layer wrapped containers, the value should not exceed 0.5% of the inner diameter Di and not exceed 6mm. 5.14 Non-destructive Testing: According to drawing requirements and in compliance with JB4730 standard requirements, and with non-destructive testing marks. 5.15 For cylinders with large diameters, thin walls, and prone to deformation, use a cross-type internal support method to round and rigidly fix the cylinder section to avoid significant deformation during process transfer. 5.16 After the cylinder sections are inspected and confirmed to meet the above requirements (including welding test plates), 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 with design temperatures ≤ -20℃ and stainless steel containers, the following provisions should also be met. 6.1 For cylinders that do not undergo post-weld stress relief treatment, no forced means such as hammering should be used for forming or shaping, and no markings such as material markings and welder 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 seams are not allowed to have undercuts; any undercuts must be repaired. 6.3 Weld spatter must be ground smooth and subjected to magnetic particle inspection or penetrant inspection. 6.4 Surface damage on cylinder sections caused by machining or welding, such as scratches, weld spatter, and arc pits, should all be ground. The thickness after grinding 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 For the weld reinforcement, it should not exceed 10% of the cylinder thickness and not exceed 3mm, with ASME product weld reinforcement not exceeding 2.38mm, and the excess part should be ground.