Backing in welding
A backing (strip) is a piece of metal that is placed on the backside of a weld joint to prevent the molten metal from dripping through the open root (burn through). It helps to ensure that 100% of the base metal’s thickness is fused by the weld (full penetration). The backing may be either left on the finished (cofferdam or void space closing welds without both-sides accessibility) weld or removed following welding (Ceramic backing, Copper strips). If the backing is to be removed, the letter R is placed in the backing symbol. The backing is often removed from a finished weld … Continue reading Backing in welding
Groove Design & Bevel Preparation
Weld preparation Preparation for making a connection where the individual components, suitably prepared and assembled, are joined by welding or brazing. The dimensions below can vary depending on WPS. Angle of bevel The angle at which the edge of a component is prepared for making a weld. For an MMA weld on carbon steel plates, the typical angles is: 25-30 Deg. for a V preparation. 8-12 Deg. for a U preparation. 40-50 Deg. for a single bevel preparation. 10-20 Deg. for a J preparation Note: The value is only for reference, the angle and groove type is depending on structure design type, welding processes, and … Continue reading Groove Design & Bevel Preparation
WPS/PQR – JOINT DESIGN
Definitions: Welding Groove Design & Bevel Preparation What is Backing in welding What is Back gouging in welding What is Retainer in welding What is CJP, PJP in welding What is Buttering in welding, In Situ Buttering AWS D1.1: Non-Tubular vs Tubular and how to prepare the PQR WPS Codes/Specifications references for crosscheck the essential variables applied to write WPS/PQR: AWS D1.1: WPS variables – Joint design ASME IX: WPS variables – Joint design EN ISO 15614: WPS variables – Joint design API 1104: WPS variable – Joint design End Product Design Codes Notes on Welding WPS: ASME 31.3 (Process … Continue reading WPS/PQR – JOINT DESIGN
Welding Work Clamp (Return line)
Work Clamps The work clamp must be the correct size for the current being used, and it must clamp tightly to the material. Heat can build up in the work clamp, reducing welding efficiency. Power losses in the work clamp are often overlooked. The clamp should be touched occasionally to find out if it is getting hot. In addition to power losses due to poor work lead clamping, a loose clamp may cause arcing that can damage apart. If the part is to be moved during welding, a swivel-type work clamp may be needed, It may be necessary to weld … Continue reading Welding Work Clamp (Return line)
Welding Cable or Lead set-up
The terms welding cables or welding leads are used to mean the same thing. Cables used for welding must be: 1- Flexible 2- Well-insulated 3- Correct size for the job. Most welding cables are made from stranded copper wire. Some manufacturers sell a newer type of cable made from aluminum wires. The aluminum wires are lighter and less expensive than copper. Because aluminum as a conductor is not as good as copper for given wire size, the aluminum wire should be one size larger than would be required for copper. The insulation on welding cables will be exposed to hot … Continue reading Welding Cable or Lead set-up
What is Duty Cycle in Welding
The duty cycle is the percentage of time a welding machine can be used continuously. Most SMA welding machines cannot be used 100% of the time because they produce some internal heat at the same time that they produce the welding current. SMA welders are rarely used every minute for long periods of time. The welder must take time to change electrodes, change positions, or change parts. The duty cycle of a welding machine increases as the amperage is reduced and decreases as the amperage are raised. Most SMA welding machines weld at a 60% rate or less. Therefore, most … Continue reading What is Duty Cycle in Welding
Welding Arc Blow Causes & Remedies
Arc Blow is the deflection of arc from its normal path because of magnetic forces. When electrons flow, they create lines of magnetic force that circle around the path of flow. These lines of magnetic force are referred to as magnetic flux lines. They space themselves evenly along a current-carrying wire. If the wire is bent, the flux lines on one side are compressed together, and those on the other side are stretched out. The unevenly spaced flux lines try to straighten the wire so that the lines can be evenly spaced once again. The force that they place on the wire is usually … Continue reading Welding Arc Blow Causes & Remedies
Typical Welding operating Voltage
Operating, welding, or Closed-circuit voltage, is the voltage at the arc during welding. Operating voltage is much like the water pressure observed as the water hose is being used. The operating voltage will vary with arc length, type of electrode being used, type of current, and polarity. The welding voltage will be between 17 and 40 V. What if Operating Voltage is too High? –> See:Welding Voltage & Arc Length Relationship Continue reading Typical Welding operating Voltage
What is OCV Open Circuit Voltage Maximum value
Open Circuit Voltage Open circuit voltage is the voltage at the electrode before striking an arc (with no current being drawn). The open-circuit voltage is much like the higher surge of pressure you might observe when a water hose nozzle is first opened. It is easy to see that the initial pressure from the garden hose was higher than the pressure of the continuous flow of water. The open-circuit voltage is usually between 50 and 80 V. The higher the open-circuit voltage, the easier it is to strike an arc because of the initial higher voltage pressure. Additional question? What is … Continue reading What is OCV Open Circuit Voltage Maximum value
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