CRA Weld Overlay Inspection Using NDT
Increasingly, industries are seeking various ways to enhance productivity and remove waste in their process. Flaw detection in the early stages of production can prevent long-term economic and productivity damage.
In industries like manufacturing, petroleum, as well as military and defense that deal with metals or steel surfaces, corrosion can be a big issue. During the welding process of such materials, corrosion-resistant alloy (CRA) can be introduced to the weld to reduce the risk of corrosion. However, to detect any underlying issues, it is important that the CRA overlay be inspected using nondestructive testing (NDT). In this article, we discuss the need for inspection of CRA weld overlay and the suitable NDT methods to use.
Challenges Presented by CRA Weld Overlay
Corrosion-resistant alloy is widely used for its propensity to resist corrosion. A CRA layer is welded onto steel or other metal surfaces to provide a corrosion-resistant barrier. This CRA welding process is often sought after in industrial applications that are exposed to corrosive environments such as oil and gas pipelines, heat exchangers, and pressure vessels. Besides corrosion protection, CRA also improves the mechanical properties of the metal, increases their service life, and can reduce the need for maintenance for such critical applications.
However, certain operating conditions or anomalies in the CRA weld overlay process can create vulnerability in the final weld overlay. The damages like porosity, cracks, or weld inclusions may occur as a result of:
- Incomplete or improper fusion of metal surfaces
- Improper handling
- Incompatibility of CRA material with the base material
- Non-conducive operating environment
These flaws can reduce the effectiveness of CRA weld overlay and develop conditions where corrosion can take hold and damage the entire system. In order to identify these flaws in the CRA weld overlay, NDT inspection is crucial.
Inspecting CRA Weld Overlay With Ultrasonic NDT
Ultrasonic testing (UT) is considered the most effective nondestructive testing method for inspecting CRA weld integrity as compared to other NDT techniques such as eddy current testing. Phased array ultrasonic testing instruments, scanners, and probes are an ideal solution for their effective corrosion detection and mapping ability as compared to conventional ultrasonic testing. The PAUT probes use multiple transducers to emit beams which can be steered and focused along the span of the weld for volumetric scanning. The focusing ability can be used for different weld thickness and angles. The reflected beams can be used to analyze if there are any fractures or pores present in the weld which may allow corrosion into the system. The data can also be analyzed to identify the changing pattern of material thickness which may be an indication of corrosion in the system.
NDT provides validation of a successful CRA weld overlay and ensures its quality. As the inspection of the components is performed long before they are placed in service, it helps in preventing long-term damage to the integrated system and minimizes the risk of losses incurred for the remediation purpose.
Improving Efficiency With Nondestructive CRA Weld Overlay Testing
Many industries commonly use CRA weld overlays to increase safety and improve the service life of their components. The use of specialized phased array ultrasonic products can effectively examine any flaws developed during the welding process. With ultrasonic NDT, technicians can easily detect the flaws and analyze the integrity of the weld. The data can be analyzed to find the potential problem in the weld system for future welding operations. The process also assists industries in reducing operational risk and maintenance cost and time, potentially increasing their process efficiency.
Zetec is a leading provider of equipment and software solutions for your ultrasonic non-destructive testing solutions for corrosion-resistant alloy (CRA) weld overlay inspections. To find more about the suitable ultrasonic testing solution that best suits the need for your application, contact Zetec today!