weld inspection, Tube and Pipe welding, defects, tubedefects

Detecting Hairlike Scratches on Coated Tubing

Aishani Mehra
Written by Aishani Mehra on June 18, 2021

Several industries, such as automotive, oil and gas, and agriculture, use coated precision tubing for key applications. The protective coatings provide additional abrasion and corrosion protection for the tubing in the field, which is crucial in preventing damage and equipment failure. 

The Problem 

Plastic protective coatings are usually extruded on to the welded tube as part of the final step in the process.  The extrusion dies wear out over time or can pick up impurities, so it is possible for surface imperfections to appear on the extruded material.  The imperfections can appear as a type of scratches that can run the length of a tube. Coated tubes are used in applications such as fuel transport where they are coupled to other components via a pressure fit. If the pressure fit component ends up being applied to a coated tube with surface variations, a leak path could result. This can create potentially hazardous conditions. To ensure coated tubes meet the exacting needs of their customers, the manufacturer must monitor the quality of the coated tube for the presence of any surface variations greater than 0.015 mm in width or depth that may occur. These scratches can be extremely hard to detect. Often, once detected, it is too late to correct the source of the surface defects on a tube production line, and a section of the tube must be scrapped. 

The Solution 

The only way to properly detect surface related issues on a coated tube is to use a laser-based surface inspection system such as the WI-2200 - 360° Scratch Inspection SystemUsing such systems are the only way that features as fine as 8µm, such as hairline-like scratches on a surface, can be detected. The image below is from a screenshot of an inspection where surface defect has been detected and highlighted to the user.  This allows the user to take proper action to address the issue before it worsens.  Because the scratches could happen anywhere around the tube, measurements have to happen all the way around the tube, which the WI-2200-360 does offer 

Detected Defect Highlighted on Tube

Fig. 1: Partial Screen Shot Showing Part of the Surface Inspections with a Detected Defect Highlighted 

The WI-2200 - 360° Scratch Inspection is Xiris’ newest innovation that provides our customers with high precision, high quality inspection systems to ensure 100% on-line quality. To learn more, download our free datasheet or request a one-on-one consultation with our experts. 

Better Images. Better Decisions. Better Process Control. 

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