The Xiris Blog

Using Cameras When Welding Spiral Pipe Part 2: Helical Sub Arc Welding

Posted by Peter Serles on Tuesday, October 03, 2017 @ 08:15 AM

One-step Helical (or Spiral) Submerged Arc Welding (HSAW) processes do not use GMAW/GTAW systems to tack the material into pipe form like two- step processes, but rather perform full inner welds using a sub arc welder during the initial forming stage.

This one-step process is advantageous in that it requires less equipment, and therefore less shop floor space, but it results in significantly lower processing speeds compared to the two-step process.

Both one- and two-step HSAW processes use dual-system submerged arc welding with flux recovery systems to perform the complete welds, with a preliminary weld on the inner diameter and a secondary weld on the outer diameter. Using two HSAW systems in parallel allows the weld penetration depths to meet, providing a strong weld in wall thicknesses as large as 1”.

cross-section-dual-sub-arc-welded-seam.pngCross section of Dual Sub Arc Welded Seam [1]

The quality of these welds is paramount to the success of the pipe. With applications in the transportation of oil, natural gas, water, and other flammable and nonflammable liquids, a small defect in the weld seam affects not only the density of the weld—causing higher risk of leaks—but also becomes a major point of corrosion-induced wear. Porosity, thermal cracking, undercut, and insufficient penetration are all critical defects caused by relatively common circumstances during the submerged arc welding process.

Detecting Defects Sooner With HDR Weld Cameras
Various standards organizations such as the American Society of Testing and Materials or the American Water Works Association prescribe hydrostatic testing to 2800 psi / 193 bar, as well as ultrasonic or radiography testing, to ensure the quality of the weld seam for its service life. But these tests determine the quality of the seam in a retroactive way, after the defects have already propagated throughout the tube.

The Xiris Weld Camera for Sub Arc applications, the XVC-S, is an affordable turnkey solution for monitoring the sub arc welding process. The XVC-S features an out-of-the box solution with integrated lighting, graphical-overlay-producing crosshairs, and a rugged housing suitable for the welding environment.

With on-screen monitoring tools, operators can easily identify and correct any deviations from standard operating procedures, including insufficient flux supply, misalignment of the torch or seam, and damage to the weld tip. The remote viewing monitor can display multiple processes, allowing a single operator to monitor the quality of the inner and outer sub arc welding processes simultaneously.

operator-remote-monitoring-sub-arc-welding-process.jpgOperator remotely monitoring a sub arc welding process

The small size of the XVC-S camera allows it to be easily integrated into an existing sub arc welding mount and the high-voltage and high-temperature resistant design, combined with the built-in solid-state lighting, allows high-quality images to be produced even in the harshest environments. By ensuring the quality of the weld during the sub arc welding process itself, defects can be caught sooner and corrected before the quality of the entire pipe length is compromised—saving time, money, and resources to provide an overall more-efficient process.

[1] RIBEIRO, Anderson Clayton Nascimento; HENEIN, Hani; IVEY, Douglas G. and BRANDI, Sergio Duarte. Evaluation of AH36 microalloyed steel welded joint by submerged arc welding process with one and two wires. Mat. Res. [online]. 2016, vol.19, n.1 [cited 2017-06-22], pp.143-152.

Topics: High Dynamic Range, Tube and Pipe welding, submerged arc welding

Using Cameras When Welding Spiral Pipe: Processing and Tacking

Posted by Cameron Serles on Wednesday, August 16, 2017 @ 10:18 AM

Helical (or Spiral) Submerged Arc Welding (HSAW) allows for larger, thinner-wall welded pipe, but this benefit has a cost—a higher chance of welding defects.

By enabling greater visibility and control during processing and tacking, high dynamic range (HDR) weld cameras are a powerful tool to counter this risk.

The Advantages of HSAW

HSAW has a unique capability for producing large diameter pipes for flammable and nonflammable liquid transportation. While longitudinal pipe welding is limited to approximately 42” (1.1 m) outer diameter due to the size of the feedstock sheet, helical pipe welding is only limited by the size of the equipment, allowing pipes as large as 140” (3.6 m) outer diameter to be manufactured.  

Helically welded pipe also has a distinct advantage over longitudinally welded pipe because the radial stress in the weld seam is not concentrated along a single axis but instead rotates around the circumference of the pipe, creating a more-even stress distribution. This advantage allows for thinner tube wall construction using more economical, non-high-strength materials.

Limiting Defects with HDR Weld Cameras

Spiral welded pipe is made using either one-stage or two-stage weld processing.  While both processes begin with the incoming skelp coil of material being unwound, flattened, trimmed, squared, and then fed into the forming  stage, in one-stage processing, the forming process is immediately followed by simultaneous inside and outside Submerged Arc Welding.

In two-stage processing, the material is formed and tack welded into the pipe body shape by a gas metal welder prior to the Submerged Arc Welding process. The tack welding stage is critical for the quality of the pipe because misalignment of the initial tack will cause defects when further processed during the Submerged Arc Welding stage. Numerous factors can cause misalignment, including defects in the metallurgical properties of the feedstock, gaps between sheets, misalignment of the welding heads, or dull tooling during the processing of the skelp coil.

With the latest in camera and software technology, the Xiris XVC-1000e high-dynamic-range weld camera permits the operator to see the spiral pipe feedstock,  the weld head, and torch location relative to the weld seam during the welding process. By monitoring the images directly, an operator can make adjustments to the material inputs or torch position to quickly correct the fault before the defect propagates throughout the length of the weld.  The camera’s robust, IP65-rated enclosure allows it to survive the harsh environments of HSAW pipe mills.

Additionally, the XVC-1000e can be used with Xiris’ seam tracking software, as shown in the figure below. The seam tracker software identifies the location of the welding head and the arc contact with the material and the material seam, detecting fluctuations in alignment. With such software, out-of-alignment conditions can automatically alert the operator to make process-control adjustments or even provide closed-loop feedback to automatically move the torch back into position.

XVC-1000e with Seam Tracker Software

Summary

Adding a Xiris XVC-1000e weld camera to an HSAW pipe mill can help operators monitor the feedstock material forming process and alignment to the welding torch, ensuring that minimal defects occur during the preliminary material processing and forming stages. In so doing, pipe weld quality can be improved, reducing the risk that weld defects will propagate down the pipe mill and make it to the customer.

Topics: Tube and Pipe welding, submerged arc welding, weld seam alignment

XVC-S for Subarc Weld Monitoring: A Case Study

Posted by Catherine Cline on Tuesday, July 19, 2016 @ 02:00 AM

The Xiris XVC-S Weld Camera system was recently profiled in a Subarc Welding case study by LJ Welding Automation of Edmonton, AB.

The XVC-S camera system was chosen as “a key component for remote viewing and easy, safe and efficient adjustment of welding head during set up and welding; laser pointers and cross-hair output on monitor included to make seam following easy for operator “

See the XVC-S in action here: 

 

For more information on how Xiris Weld Cameras can enhance the quaity and economy of your Subarc and Open Arc welding processes, visit Xiris.com

Topics: Xiris, welding, High Dynamic Range, Sub Arc welding, weld monitoring, submerged arc welding

Improved Productivity in Submerged Arc Welding using a XIRIS Weld Camera

Posted by Cameron Serles on Tuesday, October 27, 2015 @ 02:21 PM

The problem

A large fabricator in Mexico employed welding operators high atop their welding manipulators to monitor the process of Submerged Arc Welding (SAW) of large steel pressure vessels.

Each time an operator needed to come down from their monitoring perch (eg: break time, equipment malfunction, end of shift, etc.), approximately 15 minutes of production time was lost.  Not only did the  equipment need to be stopped and the path down secured, auxiliary personnel at the base station were needed to provide safety backup to move the manipulator out of the way and lower the boom for the welding operator to climb off the machine at ground level.  Another 15 minutes were lost while the path was re-secured, the operator returned to the monitoring perch and the manipulator was realigned in order to resume production. Each of these 30 minute cycles represented a significant loss of productivity for the company.

The Solution

The fabricator needed a solution to improve their productivity.  Recognizing that a 30 minute delay, 2-3 times per shift was uneconomical and, in the long run, unsustainable, the fabricator was able to rationalize the purchase of a Xiris XVC-S Sub Arc Camera.  The improvement in productivity alone was sufficient to justify the acquisition.  Once a sub arc weld camera was installed at the weld head and the machine controls, along with a new monitoring screen, were moved to the machine's base platform at ground level, operators were no longer required to be stationed high above the shop floor.

The Result

Now, when an operator needs to leave the machine, it is a simple matter of putting the machine on pause and walking away.  Since the manipulator remains in place and safety backup is no longer required, the time and productivity lost to a production interruption has been dramatically reduced to just a few minutes.

 An additional benefit of this set-up is that operators, monitoring the weld process remotely, at the ground level control station, are far less fatigued during their shift.  They no longer have to climb up and down from their workstations nor must they lean out over the weld head to monitor the proceedings.

For more information on how Xiris Weld Cameras can help monitor your weld processes, visit Xiris.com 

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Topics: remote monitoring, weld camera, productivity, submerged arc welding

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