The Xiris Blog

Post Scarf Inspection of Automotive Fuel Line Tubing

Posted by Cornelius Sawatzky on Wednesday, June 14, 2017 @ 04:00 AM

Fuel line tubing is typically manufactured on an ERW welding mill similar to traditional seam welded tubing.  Once the tube has been welded, it moves down the mill for further in-line processing that may include reducing, sizing, annealing and coating processes to meet the customer’s needs.

Fuel line tubing must be perfectly round in order to create a good seal when compression fittings are applied to it. The tube surface must be free from longitudinal scratches, grooves or beads in order to prevent a leak path from developing at the interface point of the fittings.

Immediately after the fuel line tube has been welded and before any further in-line processing is done, the weld bead must be scarfed (the process whereby the weld bead is cut off with a knife).  Unfortunately, the scarfing process can be the primary contributor to creating a leak path on a compression fitting because:

1. Insufficient scarfing can leave a small portion of the weld bead protruding from the     surface of the tube. This may be on either one or both sides of the weld bead where scarfing tool positioning is critical.

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Insufficient Scarfing

2. Excessive scarfing may look perfectly round to the human eye however a non-uniform wall thickness may be lurking below the surface. What is not always apparent and usually only observed during thorough end cut inspection is a thinned portion of the tubing wall that may compromise the integrity of the tube. The reducing process applies enough external force to the tube that the tube may buckle or collapse, causing a deep surface groove.


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Excessive Scarfing

3. A mismatched setup may also be a contributor to a non-uniform wall thickness. The scarfing tool may cut the bead on the outside diameter so that it looks perfectly round to the human eye, disguising the compromised wall thickness below the surface. Sufficient mismatch conditions will most certainly cause the tube to split on end forming later in the fabrication process.

June 14 Image 3.jpgMismatched Defect, Post Scarfing

The Xiris WI2000/3000 Weld Inspection System uses laser-based imaging techniques to continually monitor the scarf zone for any variations in the scarf height, seam mismatch and possible scarf tool wear or chips that may cause a longitudinal line on the tube. By detecting and responding to these conditions proactively, a mill operator is able to reduce the chance of a leak path on the tube and avoid an unplanned stoppage to the mill due to a tube collapse during the reducing process.

For more information on how a Xiris Weld Inspection System can enhance your scarfing processes visit Xiris.com 

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Topics: quality control, Tube and Pipe welding, laser-based monitoring, scarfing, productivity tools, automotive

Checking Tube Welds Before and After Scarfing

Posted by Cameron Serles on Wednesday, December 07, 2016 @ 10:01 AM

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The process of tube welding requires several variables to be in check for efficient and stable production and to meet the quality demands of the industry.  Mill dynamics, from setup to production, have an impact on the stability of these variables.  Measuring and monitoring these variables is the first step in controlling them and improving weld quality for tube fabricators.

In response, tube fabricators employ laser based weld inspection systems to monitor a variety of geometrical features around the weld area of the tube and to provide early warning of quality issues related to the welding and forming process.  Traditionally placed right after the weld box on a tube mill, where the majority of tube forming and weld bead measurements can be made, such systems provide the operator with an early warning of weld related process variations that could lead to quality defects.  

While most tube mill customers use the system right after the weld box where the most as-weld related information is available, some fabricators use it after scarfing to check for quality issues related to the scarfing process: does the scarfing tool cut too deeply, or not enough?  Is the tool damaged?  Is the scarf cut a consistent amount?  All these questions can be addressed by installing a weld system after scarfing.

Now, Xiris has developed a double head laser based weld inspection system that allows for one head to be placed immediately after the weld box and one head immediately after scarfing.  In this way, tube fabricators can monitor their tube production before scarfing for weld related defects; and after scarfing for potential scarf related issues.

 

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WI2000 Double Head Configuration: One Head Post Weld, One Head Post Scarf

 With a double head configuration, tube fabricators can better control their process and improve quality by monitoring the tube profile, weld bead geometry and final scarf cut, all controlled from a single system. 

 

For more information on how Xiris Weld Cameras can help monitor your weld processes, visit Xiris.com or sign up to receive the Weld Video of the Month 

Topics: quality control, weld camera, weld inspection, Xiris, Tube and Pipe welding, scarfing, weld seam

Post Scarf Inspection on Tube and Pipe Mills

Posted by Cameron Serles on Tuesday, June 30, 2015 @ 09:54 AM

Scarfing is a process of removing excess weld bead on a pipe or tube to create a desired shape.  It is done by planing longitudinally welded tubes or pipes right after the welding process.  If it is done perfectly, the resulting profile will match the ideal shape of the parent material.  However, if the scarf tool is set to plane too much material, or not enough, the resulting profile could appear too deep or leave a weld bead above the parent material.

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Result of a Scarf Tool Cutting Too Deeply
 
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Result of a Scarf Tool Not Cut Deep Enough
 

Detecting if the scarf tool is properly adjusted is a difficult task to do on a continuous basis.  In particular, some thick walled tube and pipe mills make precision end products using multiple scarf cuts using scarfing tools operating sequentially.  If not correctly adjusted, the tube or pipe could end up with an incorrect profile shapes where the scarf occurred.  A way to make sure that the right amount of material is removed from the welded tube is important.  If placed after the scarfing process on a tube mill, the Xiris WI-2000p can measure the scarf width and bead height left behind after a scarfing process to provide quality control of the scarfing process itself.

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Image of an Ideal Scarf Zone from the WI-2000p from Xiris

 

In the above image taken from a WI-2000p system, a laser profile is shown of a welded tube, post scarf.  The area of the scarfing does not reflect the laser line as well, so the scarfed area can be easily detected and measured.  As the scarf cuts deeper into the material, the scarf width will increase, as it cuts shallower, the scarf width will decrease.

Conclusion

Measuring the scarf area of a tube or pipe with a device such as the WI-2000p Weld inspection system from Xiris is a quality control tool to ensure that the scarfing process has been set properly and not cutting too little or too much of the parent material away.


 

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

Topics: weld inspection, Tube and Pipe welding, scarfing, WI-2000p

Monitoring Tube and Pipe Production to Find SCARFING Defects

Posted by Cornelius Sawatzky on Tuesday, June 17, 2014 @ 12:53 PM

Recent advancements in machine vision technology have made a new type of inspection able to see defects related to the forming and welding area of a tube or pipe.  The result is improved quality assurance and process control on the production line.  The new type of inspection device is a laser-based triangulation system that measures the outside contour of a tube or pipe in the vicinity of its weld. 

Typically NDT systems are placed at the end of a production as a final check.  However, the laser inspection system can be placed directly after the weld box.  This system can let operators know what is changing in their welding process, allowing them to perform corrective action before significant scrap occurs. This capacity is especially helpful for one of the most common defects found across all types of Tube manufacturing: Tube Scarf defects.

 

The Scarfing Width

In certain situations on ERW/HF tube and pipe production lines, there is not enough space to perform the Non Destructive Inspection (NDI) measurements right after the weld box because the scarf tool (used to remove excessive bead from the tube) is placed directly after the weld box.  In such situations, the measurement process must be made after the scarfing tool, measuring the flat area of the tube where the scarf has occurred. On some production lines, this measurement is essential to identify the shape and profile of the tube, and to understand how it is travelling through its forming process.

Known as the scarf width, this measurement is defined as the length of the “flat” portion of the tube that appears after the weld bead has been removed by scarfing.  Scarf width measurement changes quickly during production, so it is best averaged over a number of inspections in order to make the measurement stable.

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The Scarf Width, where “w” = the width of the defect.

How the WI2000p System Measures the Scarf Width

Xiris Automation Inc. has developed a non-destructive inspection system called the WI2000p Weld Inspection System. The WI2000p includes a laser line and a camera whose optical axis is offset to the axis of the laser line by an “offset angle”.  The WI2000p creates a visible cross-section of the tube by projecting the laser line on to the tube and capturing an image of the line using the camera.  The resulting image shows a profile of the tube surface as if it were cut in cross section.  If a tube is ideally round, the laser image will represent a section of an ellipse and any anomaly such as a freeze line defect can be mathematically detected. 

The WI2000p bases all of its measurements on the differences between the actual laser profile line seen by the camera, and the ideal mathematical profile based on the tube parameters.  By knowing the position of the actual laser profile, the ideal profile, and the size of the pixels in the image, the WI2000p can detect weld bead profile defects that often escape detection by other quality tools such as Eddy Current testing, or Ultrasonic Testing techniques

 

Conclusion

Overall, laser-based 3D imaging systems, such as the WI2000p from Xiris, offer an excellent measurement option for tube mill owners/operators who want additional, real-time monitoring of weld features. They can be used in a proactive manner, warning operators what is changing in their welding process so that they can perform corrective action before significant scrap occurs And by measuring the outside contour of a weld, laser-based 3D imaging systems can operate on any type of material, regardless of its reflectance or magnetic properties, using a single head to perform the measurement.

Topics: quality control, weld camera, weld inspection, Laser welding, image processing, High Dynamic Range, Tube and Pipe welding, laser-based monitoring, Pipe Cladding, welding defect, scarfing