【Q&A】Catalytic Coking Reformate Blending Version 20171011
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Participation: Reward of 3~5 Wealth points； Correct answer: Reward of 10 wealth points ； Note: This post is valid for 48 hours. Question: What measures can be taken to prevent welding deformation? Answer: Anti-deformation method, rigid fixation method, proper welding sequence. Use your fingers to get involved – our ultimate goal is for everyone to acquire knowledge. http://bbs.hcbbs.com/static/image/hrline/1.gif http://bbs.hcbbs.com/static/image/hrline/2.gif The answers will be announced automatically in two days. Petrochemical Zone—“Creative Ideas for Energy Saving” campaign (the second phase is currently in full swing). http://bbs.hcbbs.com/thread-1666758-1-1.html [Daily Question] Summary post for 2017 on the catalytic coking and reforming oil blending topic. http://bbs.hcbbs.com/thread-1811219-1-1.html [Q&A] Summary post for 2017 on the catalytic coking and reforming oil blending topic. http://bbs.hcbbs.com/thread-1826018-1-1.html
There are the counter-deformation method, proper selection of welding sequence, rigid fixation method, and hammering the weld method.
1 Reverse deformation method, 2 Controlling deformation using assembly and welding sequence, 3 Rigid fixation method, 4 Heat dissipation method, 5 Hammering the weld seam method, 6 Heating to reduce stress areas, 7 Preheating before welding and slow cooling after welding, 8 Appropriate welding process methods
1. Pre-deformation. For example, in the case of plate butt jointing, there should be a back tilt angle of 2°. 2. Tooling control. For example, the welding of the chassis for construction machinery vehicles requires the use of tooling for control. This is quite important. 3. Adopt a reasonable welding sequence and direction. (1) For the welds on the welding plane, it is necessary to ensure that the longitudinal and transverse welds (especially the transverse ones) can contract freely. For butt welds, the welding direction should point toward the free end. (2) Weld the joints with greater contraction first; if there are both butt joints and fillet joints in the structure, the butt joints with greater contraction should be welded first. (3) Weld the transverse short welds first. (4) Welds that are subject to high stress during operation should be welded first, in order to ensure a proper distribution of internal stresses. (5) When welding cross-butted joints, a welding sequence must be employed to ensure that defects do not occur at the intersection points. When welding T-joints and cross joints, the weld laid first at the intersection point should be cleaned off, and welding should be carried out in the order shown in the diagram. This allows for more free lateral contraction of the T-joint and cross joint, which helps to prevent cracks from forming at the intersection of the welds
Anti-deformation method, rigid fixation method, proper welding sequence.
(1) Conduct a reasonable welding structure design. (2) Adopt reasonable assembly process measures. (3) Adopt reasonable welding process measures
1. Counter-deformation method 2. Controlling welding deformation using assembly and welding sequences 3. Thermal adjustment method 4. Symmetrical full welding method 5. Rigid fixation method 6. Hammering the weld method
Mainly process measures: counter-deformation method, symmetrical welding, preheating of the welded parts, appropriate welding sequence, and rigid fixation
Anti-deformation method, rigid fixation method, proper welding sequence.
1. Reduce the cross-sectional area of the weld; while ensuring a weld that is complete and free from defects exceeding acceptable limits, use the smallest possible groove dimensions (angle and gap). 2. Use a welding method with low heat input. For example: CO2 gas shielded welding. 3. For thick plate welding, multi-pass welding should be preferred over single-pass welding whenever possible. 4. Where the design requirements are met, intermittent welding can be used for the welding of longitudinal and transverse stiffeners. 5. When welding on both sides, a symmetric groove on both sides should be used, and for multi-layer welding, a welding sequence that is symmetrical with respect to the component’s central axis should be adopted. 6. When the thickness of the T-joint plate is large, a groove-type fillet weld is used. 7. Use pre-weld reverse deformation method to control the angular deformation after welding. 8. Use rigid fixtures to control post-weld deformation. 9. Use the reserved length method of components to compensate for the longitudinal contraction deformation of welds. For example: For H-shaped longitudinal welds, 0.5~0.7 millimeters can be reserved per meter. 10. Twisting of long members. It mainly relies on improving the flatness of the sheets and the precision of component assembly to ensure accurate bevel angles and gaps. The direction or alignment of the arc is accurate, so that the angular deformation of the weld and the longitudinal deformations of the flanges and webs are in line with the length direction of the member. 11. When assembling components with numerous welds or installing structures, a reasonable welding sequence should be adopted. 12. When welding thin plates, the underwater welding method is used. In other words, the molten pool is surrounded by a shielding gas in water, and this gas removes all the water from the vicinity to ensure proper welding. With this method, the metal surrounding the solidification pool is cooled promptly by water, thereby keeping the degree of deformation very low (circular cooling fluid is applied on the opposite side of the welding area to remove the heat generated during welding). 13. Multi-segment symmetric welding, that is, weld one segment, pause for a while, then weld on the opposite side, and pause again
There are the counter-deformation method, proper selection of welding sequence, rigid fixation method, and hammering the weld method.