Ultrasonic flaw detection standard of LSAW steel pipe

In the domain of non-destructive testing for LSAW (Longitudinally Submerged Arc Welded) steel pipes, a variety of techniques are employed to ensure the quality and integrity of the welds. These include ultrasonic testing, radiographic testing, and visual inspection methods. The selection of the testing approach is tailored to the specific characteristics of the weld seam, such as its thickness and width.

Key Techniques in Flaw Detection:

Single-Sided Dual-Side Flaw Detection: Ideal for welds that require a comprehensive scan from a single access point.

Dual-Sided Dual-Side Flaw Detection: Provides a thorough examination from both sides of the weld, suitable for critical applications.

Single-Sided Single-Side Flaw Detection: A more streamlined method for less critical welds or where access is limited.

Adaptation of Flaw Detection Methods: The choice of flaw detection method is influenced by the wall thickness and weld seam width of the LSAW steel pipe. Thicker and wider weld seams benefit from more rigorous inspection techniques such as single-sided dual-side or dual-sided dual-side flaw detection.

Standards for Inspection:

GB11345-89 and GB/T11345-2013: 

These documents outline the protocols for non-destructive testing, emphasizing the importance of primary and secondary inspections. For structural piping with less stringent requirements, a tiered inspection approach is advocated.

Post-Manufacturing Evaluation: 

Once the LSAW steel pipe is fabricated, it must pass a series of mechanical tests, including flattening and flare tests, to verify its structural integrity. A critical component of this process is the pressure test at 2.5Mpa, which ensures the pipe's ability to withstand the specified pressure without leakage for a continuous minute.

Innovative Testing Alternatives: 

In lieu of traditional hydraulic pressure testing, the eddy current method offers a viable alternative. This technique involves attaching a probe to a scanning frame and maintaining a precise distance of 3 to 5 mm from the weld seam. The pipe is then scanned rapidly, allowing for a detailed examination of the weld seam without the need for physical contact.

This enhanced protocol aims to provide a more robust and adaptable framework for the inspection of LSAW steel pipes, ensuring that each method is chosen based on the specific needs and requirements of the weld seam being examined.