Orbital welding
Orbital welding-The pipe or tube to be welded is held while the welding arc rotates (in “orbit”) around the workpiece. Welding parameters are set by a microprocessor, so settings can be saved and reused, ensuring a highly reproducible process.
Orbital welding is the automatic or mechanized welding of pipes and tubes using an electrode that rotates (or rotates) 360 degrees around the workpiece. Orbital welding of pipes or tubes can be done using filler metal or fusion welding.
In the 1950s, the aerospace industry developed orbital welding, which replaced compression fittings and hand welding. This type of welding is classified as TIG (tungsten inert gas) welding.
Orbital welding can be performed using either consumable or non-consumable electrodes. The former uses the energy of a wire feeder to drive the metal into the arc, while the latter uses the sealed electrodes and inert gas inherent in orbital welding systems. Made of tungsten.
Since the 1980s, an industry has developed that manufactures fittings, pressure gauges, regulators, valves, and other high-purity orbital welding products. Welded pipes for high purity applications require the use of fully enclosed welding heads.
To achieve perfect repeatability, it is also important to evaluate the weld head to ensure that internal parts are not scorched by carbon deposits that can short circuit current flow. Welding heads require cleaning and maintenance to prevent parts from wearing out over time.
Although it is a highly automated process, engineers must operate the machinery effectively. Even if welding parameters are entered into the welder, variable constraints may require the welder to take corrective action. This includes regularly checking samples or coupons for differences in weld penetration. These coupons are typically prepared at the beginning of a welding shift and whenever adjustments or changes are made. These coupons must continue to demonstrate full penetration and consistent joint width.
The quality of orbital welding is determined by the quality of the materials used. 316L stainless steel tubing is often used with argon sources as shielding and support gas and has a minimum purity of 99.9995% for industrial applications.
The quality of the weld depends on factors such as arc length, welding current and pulse frequency, welding speed, type of core and filler wire materials, shielding gas, and thermal conductivity and weld preparation. Understanding and adjusting these various parameters will greatly improve the quality of your weld.
What is orbital welding?
Orbital welding is a method in which the welding tool rotates 360° around a stationary workpiece. It was originally developed to solve the problem of operator error in tungsten inert gas (TIG) welding (also known as gas tungsten arc welding (GTAW)) and to provide uniform welds around pipes and tubes that are difficult to achieve by welding. Manual welding. process.
The orbital welding process uses computers to produce high-quality, repeatable welds that require little or no intervention from the welding operator. This process is used for two main applications. Pipe-to-pipe joints, pipe-to-pipe joints and pipe-to-tube sheet joints.
The process was originally developed in the aerospace industry by Roderick Rohrberg of North American Aviation in 1960 to repair fuel and hydraulic fluid leaks on the X-15 rocket research aircraft. In the 1980s, improvements in control systems, portability, and power supplies allowed orbital welders to be moved between construction sites
What are the 5 main types of welding?
There are five main types of welding.
- MIG – Gas Arc Welding (GMAW),
- Tungsten Inert Gas Welding (TIG),
- Gas Tungsten Arc Welding (GTAW),
- Shielded Metal Arc Welding (SMAW),
- Flux Cored Arc Welding (FCAW) and
- Plasma Arc Welding (Surface Active substance).
Stages of the orbital welding process of welded pipes or tubes
1.Cut
Before aligning the ends of the pipe or pipes, you must first cut them to the appropriate length. Orbital saws are often used for cutting plumbing and thin-walled pipes. Orbital cutters rotate 360 degrees around tubes and tubes to make clean, precise cuts. It can be adjusted to different sizes without deforming. Cutting can be completed in approximately 20 seconds.
- Chamfer or chamfer
After cutting, use a pipe end tool to remove burrs and other imperfections. This will be important later during fitting. If you want to add wire in the case of a thick-walled structure, you need to take a pipe or pipe with a bevel. - Clear
This step is especially important when hygienically welding stainless steel. Cleaning removes potential contaminants such as oil and grease, increasing the likelihood of a successful weld. Use gloves, alcohol spray and a dry cloth to remove surface dirt. - Insert consumables – tungsten and wire.
Electrodes are needed to create an arc. Here it will be 2% cerium tungsten. Please note that tungsten is different for manual and orbital welding. To achieve repeatable welds, tungsten must be produced consistently according to application specifications, such as the welding head used and the outside diameter of the pipe or tube. - Alignment
When it comes to weld penetration, fit is very important. Align the joint of the two parts using a tungsten electrode. - Cleaning
Once aligned, use argon or a shielding gas mixture to remove oxygen from inside the tube or line. This prevents tanning on the back of the weld and prevents indentation of the weld. When saccharification does occur, it can be very problematic for many industries, especially process piping where bacteria can thrive in such conditions.
For tubes:
Purge plugs allow oxygen to be removed while distributing the gas mixture evenly.
In less critical cases, argon gas tapes and lines can be used.
For pipes:
Purge chambers are used when large outside diameter pipes are used or when there are elbows or tees that need to be purged.
Nylon dowels are a suitable tool for blowing out smaller outside diameter pipes.
- Program
Modern power supplies are equipped with automatic programming technology. Simply enter the welding head you are using, the material to be welded, the outside diameter size and the wall thickness into the power source. Then the power supply will generate a pre-developed program. In many cases, minor adjustments are required to create an accurate welding program. - Welding
Once you have completed all these steps and your program is ready, you are ready to start vaping. Click the Start button to launch the program. Follow the automatic process:
Pre-purge – First, pre-purge for a certain period of time.
travel delays
During a motion delay, also called a rotation delay, the tungsten remains in place while the weld puddle is formed. This will help adjust the arc and achieve the required penetration.
For thick-walled pipes and tubes, the operation delay may increase depending on the thickness of the base material. Once the puddle is created, add the wire before the electrode begins to move.
Ripple
The electrode moves around the workpiece and delivers both the main (high) and background (low) pulses. This current and the pulse duration within the welding program determine the overlap of the weld. The speed of movement is determined by the program, and the current strength also changes depending on the position on the level.
Insertion and descent
After the electrode moves 360 degrees and returns to its original position, it continues to move another 10 degrees to “join” or overlap the weld.
Decay then begins as the head slowly reduces the output power of the amplifier, giving the weld pool a teardrop or dovetail effect. This seals puddles and prevents sagging and defects in the weld. In most cases, the operating time is from 4 to 12 seconds, depending on the outer diameter of the pipe.
Post-cleaning
Once the descent is complete, the arc goes out and the head sprays gas for 15–30 seconds. This helps improve the color of the metal and the cooling process. After this, the welding is considered complete.
After the first test weld, you can change the program to suit the needs of your application.
Advantage
Orbital welding has many advantages over other welding methods, including:
Increased productivity. Orbital welding equipment is mechanized and allows welding sequences to be repeated easily and reliably, increasing productivity compared to manual TIG welding.
Consistent weld quality: Once welding parameters are set and entered, welding cycles can be repeated with a high level of accuracy and consistency. Most orbital welding equipment allows for real-time monitoring, allowing you to create a complete weld report and save it for future reference.
Operator Skill Level: After training, a qualified mechanic can operate orbital welding equipment. Labor costs are also lower because the skill level is lower than with manual welding.
Environmental Conditions: Orbital welding can be performed in harsh environmental conditions and in areas with limited access or poor visibility. Once the welding head is in place, you can use the video feed to check the weld and complete the job from a safe distance.
Improved security. Orbital welding can improve safety by removing the welder from the workspace and allowing him to monitor the process from a safe distance.
Constraints
Despite its advantages, orbital welding also has many limitations. Firstly, not all objects can be welded in orbit. Secondly, welding different objects requires different welding heads.
Additionally, the cost of orbital welding equipment can be 5 to 10 times the initial capital cost of traditional welding.
Necessary equipment
The main components of an orbital welding system are the power source (including built-in computer control), the welding head and, optionally, the wire feed system. Additionally, some part sizes and materials also require the use of water/cooling systems.
Programmable power supply: The programmable power supply allows you to set various parameters such as amperage, pulse frequency, shielding gas flow, welding head speed and wire feed settings. Ideally, the power supply should be light enough to be carried by one person, capable of operating at least 4 axes, and compact.
Head for orbital welding: Different applications may require different sized heads, but in each case, the welding head holds the electrode in place, controls the welding current, maintains the optimum temperature, and supports the welding process. Pressure must be applied to parts that are touched.
Wire Feeder: The wire feeder can be additionally welded to the head of the device or can be part of a separate system.
Water/Air Cooling Systems: Air or water cooling systems prevent welding equipment from overheating and protect welding operators from the thermal effects of the process.
QUALIFICATION STUDY FOR VISUAL INSPECTOR
