How a Weld Inspection NDT Crawler Improves Inspection Time and Quality

Welding can be a highly complex process. When disparate components are welded together, there’s a chance that the connections can come apart—quickly or slowly, due to the presence of tiny fractures or flaws. The possibility of a structural issue being present increases when the length of a weld extends, such as in long, multipass welds. 

Nondestructive testing (NDT) is vital to the detection of these flaws. Any technician inspecting long welds, welds in harsh conditions, or welds on irregular-shaped-and-sized materials knows how difficult it can be to ensure testing is comprehensive, accurate, and time-efficient.  

Having a consistent and reliable scanning process can save time, money, and help to ensure high-quality welds. It is especially beneficial if weld inspection can be efficiently conducted during and after manufacture, as well as after the weld has entered the field and been in use. The right tool for versatile and efficient weld inspection is an NDT crawler scanner. 

The Challenges Present During Multipass Weld Production

The larger scale the project, such as in long seam welds, the more challenging weld production may become. These challenges are amplified in multipass welding projects. The more the materials are altered, the more the chemical composition opens itself up to micro flaws. 

One study described this chemical process and analyzed how the engineering of multipass welds can be improved to enhance structural integrity. The study revealed that in multipass welding, the weld’s metal and the associated heat-affected zone are subjected to repeated thermal cycling from the successive deposition of filler metals. This repeated process can result in deformation of the weld, causing variably distributed residual stress through the thickness and across the weld. In addition to the challenges created by this process, the area where metals are fused together may also present an opportunity for flaws to be present. If these flaws aren’t detected and addressed before these materials leave their production facility, they may end up causing larger problems once they’re put to use. 

Multipass welds are often used in large-scale operations and need to be engineered to withstand the pressures that come with above-ground storage tanks, high-pressure vessels, and heavy-duty piping. Welds used for these purposes:

• likely have to withstand extreme pressures and harsh elements; 
• are not always easy to reach; and
• may be irregular in size and consist of complex geometries. 

Because of these qualities, inspection in the field may be difficult. This makes it especially important to identify and remedy any discontinuities before multipass welds are placed into service. 

The solution: an NDT crawler scanner. 

What To Look for in an NDT Crawler

An NDT weld crawler scanner is a flexible product that can be set up in minutes. It is versatile, easy to adjust, and provides comprehensive scans that can identify flaws in a wide variety of welds. 

In essence, advanced NDT crawlers can have five main operating parts: 

1. magnetic wheels
2. break system and lever
3. embedded ruler
4. onboard camera
5. laser pointer

The crawler can be placed over a weld and transverse the length of the seam, taking images the entire time. It coordinates with software and instrumentation to create an accurate picture of the weld, identifying any flaws. 

There are a number of key features and benefits of leveraging an advanced NDT crawler for weld inspection, these include:

• remote operation capabilities
• the ability for a user to transform the circumferential weld scanner into an axial weld scanner for welded pipes in minutes, without any tools
• the ability to accommodate a wide range of pipe diameters 
• very low clearance for tight and confined spaces
• the ability to handle welds up to six inches thick

All of these benefits are important on their own. But taken together they offer something crucial: efficiency. One scanner, with the slightest and quickest of adjustments, can inspect a variety of welds. Its remote operation also allows for quicker inspections. 

Perhaps most importantly is how this efficiency is combined with effectiveness. The scans are comprehensive and fast, giving users a near-real-time image of the weld, with the ability to identify any micro-corrosion cells or flaws. 

With the accuracy and efficiency of an NDT crawler, inspection times are improved and flaws can be detected before a weld is placed in a field for use. 

NDT Crawling Solutions Simplify the Complexity of Weld Production

Welding is a matter of complex chemistry, and weld inspection is performed to detect any flaws created by this process. Inspecting these complex structures can be challenging but is necessary for successful and safe operations. 

Weld inspection efforts can be simplified with an NDT crawler scanner designed to be accurate and efficient.   

Zetec is a leading provider of NDT solutions for welding inspections in all industries. Contact us to find a solution right for you.