Seamless teel pipes are widely used in our lives, and there are more and more types of materials on the market. Now everyone trusts galvanized seamless steel pipes. Galvanized steel pipes have better corrosion resistance among seamless steel pipes. It is welcomed by many consumers. Next, the
PMC carbon steel pipe manufacturer & supplier will introduce how to connect the galvanized seamless pipe and the control method of the welding process.
1) How to connect the galvanized steel pipe?
There are three main connection methods when connecting
galvanized seamless pipes, namely wire type, welding type and rolling groove type.
1. Wired connection
(1) Random buckle: The pipe hoop and the threaded buckle cannot be completely contacted and loosened.
(2) The threaded thread of the steel pipe does not match the threaded thread of the pipe hoop and cannot be connected. The pipe hoop should be replaced or the equipment should be re-threaded.
(3) Leakage after steel pipe threading: measure whether the wall thickness of the steel pipe can meet the standard thickness requirements of the threaded pipe.
2. Welded connection
(1) There is a problem that the seamless pipe mouth is not in a straight line and the steel pipe has a bevel after butt jointing. It is recommended to cut off a small section of the steel pipe head before processing.
(2) After the steel pipe nozzles are docked, the two pipe nozzles are not tightly connected, resulting in uneven thickness of the weld joints; and the steel pipes are oval due to their own reasons or transportation bumps. It is recommended to cut off a small section of the steel pipe pipe head before for processing.
(3) After the pipe nozzles are butted, trachoma appears at the nozzle part: 1. It is caused by technical reasons during welding; 2. There are zinc tumors at the pipe nozzle, which causes welding difficulties and trachoma problems. Simple inspection of excessive zinc tumors and excessive pipes zinc tumor removal treatment.
3. Roll groove connection
A. Roll groove weld cracking:
1. Grind the welding ribs on the inner wall of the grooved part of the nozzle to reduce the resistance of the rolling groove.
2. Adjust the axis of steel pipe and rolling groove equipment, and require the level of steel pipe and rolling groove equipment.
3. Adjust the speed of the grooving, the forming time of the grooving should not exceed the specified time, and the force should be applied evenly and slowly.
B. Roll groove steel pipe fracture:
1. Grind the welding ribs on the inner wall of the steel pipe nozzle pressure groove to reduce the resistance of the rolling groove.
2. Adjust the axis of the steel pipe and the rolling groove equipment to require the level of the steel pipe and the rolling groove equipment.
3. Adjust the speed of the groove, the speed of the groove cannot exceed the specified, and the force is applied evenly and slowly.
4. Check the width and type of the support roller and pressure roller of the grooving equipment, and check whether there is any bite phenomenon caused by the size mismatch between the two rollers.
5. Use a vernier caliper to check whether the groove of the steel pipe is specified.
C. The groove formed by the rolling groove machine should meet the following requirements:
1. The surface from the pipe end to the groove section should be smooth without unevenness and rolling marks.
2. The center of the groove should be concentric with the pipe wall, the width and depth of the groove should meet the requirements, and check whether the type of the clamp is correct.
3. Apply lubricant to the rubber sealing ring and check whether the rubber sealing ring is damaged. The lubricant must not be oil lubricant.
2) Welding process control
The pre-weld preparation of galvanized steel pipe is the same as that of ordinary low carbon steel. It should be noted that the groove size and the nearby galvanized layer should be carefully handled. For penetration, the groove size should be appropriate, generally 60-65°, and a certain gap should be left, generally 1.5-2.5mm; in order to reduce the penetration of zinc into the weld, before welding, the galvanized Solder after the layer is removed.
In the actual supervision work, centralized beveling, no blunt edge process is adopted for centralized control, and the two-layer welding process reduces the possibility of incomplete penetration. The welding rod should be selected according to the base material of the galvanized pipe. For general low carbon steel, it is more common to choose J422 because of the ease of operation.
Welding method: When welding multi-layer welded seams, try to melt the zinc layer and make it vaporize, evaporate and escape the weld seam, which can greatly reduce the liquid zinc remaining in the weld seam.
When welding fillet welds, try to melt the zinc layer and make it vaporize and evaporate to escape the weld. The method is to move the end of the electrode forward about 5-7mm. Get back to the original position and continue to weld forward.
In horizontal welding and vertical welding, if short slag electrodes such as J427 are selected, the tendency of undercutting will be small; if the forward and backward transport technology is used, defect-free welding quality can be obtained.
The above is all the knowledge about how to connect galvanized steel pipes and welding process control methods introduced to you today, I hope it can help you.
Go here to learn more about " Welding Characteristics and Process of Galvanized Steel Pipe"
