Differences in between ERW Welded Pipe and Saw Welded Pipe 1. Comparison of approach traits and quality efficiency of several steel pipes:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     ERW Pipe is divided into induction welding and contact welding in accordance to diverse welding strategies. Making use of scorching-rolled wide strip steel coils as raw supplies, by means of pre-bending, steady forming, welding, heat treatment method, sizing, straightening, cutting and other processes, compared with spiral welded pipes, it has shorter weld seams, large dimensional accuracy, uniform wall thickness and surface good quality Excellent, with the positive aspects of higher stress, but the disadvantage is that only small and medium-caliber thin-walled pipes can be made, and the welds are susceptible to gray spots, unfused, and groove-like corrosion defects. At current, the most broadly utilized locations are city gas, crude oil and refined oil transportation.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     Spiral submerged arc welded pipe (SSAW) is a strip steel coiled pipe whose advancing course has a forming angle (adjustable) with the center line of the forming pipe. It is welded although forming, and its weld is spiral. The benefit is that the identical specification of strip steel can be produced Steel pipes of numerous diameters have a massive selection of raw materials. The welding seam can avoid the principal anxiety and the tension is better. The disadvantage is that the geometrical size is poor. The length of the weld Welding defects such as slag inclusion and welding deviation, the welding tension is in the state of tensile pressure. The general layout code for lengthy-distance oil and fuel pipelines stipulates that spiral submerged arc welded pipes can only be utilised in Group three and Category four regions. In foreign countries, this process is enhanced and the raw material is modified to steel plate to separate the forming and welding. Right after pre-welding and precision, and cold growth soon after welding, the welding quality is close to U0E pipe. At existing, there is no this kind of process in China. It is a spiral pipe in my country. The direction of plant improvement. The spiral steel pipe used in the "West-East Gasoline Pipeline" is nonetheless produced in accordance to the standard technology, but the pipe finish has been expanded in diameter. The United States, Japan and Germany generally reject submerged arc welding and believe that submerged arc welding is not suitable for the main line Canada and Italy use submerged arc welding in some components, and Russia utilizes submerged arc welding in a tiny volume, and they have formulated quite strict supplementary problems. Due to historical causes , Most domestic trunk lines even now use submerged arc welding.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     Longitudinal submerged arc welded pipe (LSAW) is created by employing a single medium and thick plate as the raw material, pressing (rolling) the steel plate in a mold or forming machine into a tube blank, utilizing double-sided submerged arc welding and expanding the diameter. The modern JCO molding machine is a stepping compression molding machine managed instantly by a personal computer. Throughout the complete forming approach, the movement of the upper and decrease molds with the feeding and discharging mechanism is managed by a laptop. The reduction sum, reduction force and the steel plate feed amount can be immediately adjusted in accordance to distinct steel grades, wall thicknesses, and plate widths. At the very same time, the upper and reduced molds have The deformation compensation function effectively avoids the adverse results of mold deformation on the forming and assures the flatness of the complete length of the steel plate for the duration of the pressing approach. The feeding stage is uniform in the course of forming, ensuring the roundness of the tube blank and the flatness of the welding edge. The finished solution has a broad range of specs, and the weld has good toughness, plasticity, uniformity and compactness. It has the rewards of large pipe diameter, pipe wall thickness, substantial strain resistance, reduced temperature resistance and strong corrosion resistance. In the building of higher-strength, high-toughness, higher-good quality prolonged-distance oil and fuel pipelines, most of the steel pipes essential are big-diameter thick-walled LSAW steel pipes. In accordance to API specifications, in large-scale oil and fuel pipelines, when passing by way of Class 1 and Class two locations this kind of as alpine areas, seabeds, and densely populated urban regions, LSAW pipe is the only designated applicable pipe sort.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         2. Comparison of ERW and Submerged Arc Welding(Noticed) Method                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               A) ERW Pipe has rapidly heating pace, extremely concentrated heat and no filler metal. It is not achievable to use wire flux to include alloying factors to compensate for the burning of alloy components in the welding procedure like submerged arc welding, and it are not able to properly enhance the structure and efficiency of welded joints like submerged arc welding (microalloying is to refine the grain The main way, grain refinement is the only way to simultaneously enhance power and toughness).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     B) ERW does not kind a welding pool, so the welding dross potential is poor. check out this site If there is slag inclusion on the edge of the raw material, it can only continue to be in the weld and become a high quality threat. Since submerged arc welding varieties a welding pool, it is beneficial for slag inclusions to float in the slag.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     C) There is no slag/fuel safety throughout ERW welding (submerged arc welding has slag protection formed by flux), and the welded joint framework at higher temperature is simply oxidized, which tends to make the welded joint have a tendency to embrittlement.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     D) ERW has the traits of large nearby heating temperature and quick cooling time. The welding temperature discipline has a big gradient, which is susceptible to hardening phase and huge welding tension. The plasticity and toughness of the welded joint are not excellent. As a result, all ERW steel pipes in the nation call for submit-weld heat remedy (Q+T or Q+N), but domestic the submit-weld heat treatment method procedure is not yet mature.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     E) In contrast with submerged arc welding, the ERW welding pace is also quick, the edge quality of the raw materials are not able to be tested by NDT, and the NDT check of the weld soon after welding is also difficult to guarantee the high quality.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     F) Given that ERW is welded by pressing molten metal, it is tough to use NDT for efficient inspection. Therefore, incomplete fusion and gray spots are the problems of ERW steel pipes, which have been hard to properly solve for decades. The ditch corrosion in ERW pipeline failure is primarily induced by unfusion. (Refer to Welded Pipe "Oil and Gasoline Transmission Pipeline Failure Accidents and Typical Instances")                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     G) ERW will inevitably kind far more T-joints in the course of pipeline development, even though submerged arc welding will not. As we all know, the T-joint is the place where the pressure is the most concentrated, which minimizes the fatigue lifestyle of the welded joint.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  

Forum Role: Blocked

Topics Started: 0

Replies Created: 0