Key Differences Between TC1 and TC2 Grades in Nondestructive Testing of Steel Pipes
Date:2025-08-06
In the steel pipe manufacturing and quality control fields, nondestructive testing (NDT) is a critical step in ensuring product performance and safety. Ultrasonic testing (UT) and eddy current testing (EDT) are the two most widely used methods. To regulate the rigor and scope of testing, international and industry standards (such as the European standard EN 10246 series and ISO 10893 series) define different testing levels. TC1 and TC2 are the most common and frequently compared of these levels, representing different testing requirements and quality standards.
Key Differences:
1. Inspection Scope and Area:
TC1: Typically, 100% automated ultrasonic testing is performed on the weld area of the steel pipe. Its primary focus is on continuous defects in the weld itself and its heat-affected zone. For the pipe body (base metal), TC1 typically does not require 100% automated testing or requires a lower standard (for example, it may only require manual spot checks or testing of specific areas).
TC2: Requires 100% automated ultrasonic testing of the entire surface of the steel pipe (weld + pipe body). This means not only the welds require rigorous inspection, but the pipe body (base metal) also requires full coverage, high-sensitivity defect scanning. The goal is to detect potentially harmful defects anywhere on the pipe.
2. Detection Sensitivity:
TC1: Its detection sensitivity is relatively low. Its calibration and acceptance references are typically larger artificial defects (such as notches or drill holes). This means it primarily targets larger, more detrimental defects.
TC2: Its detection sensitivity is significantly higher. Its calibration and acceptance references are smaller artificial defects. This means TC2 can detect smaller and more subtle potential defects, and imposes more stringent product quality requirements.
3. Acceptance Criteria:
TC1: Its acceptance criteria are relatively relaxed. The permitted defect signal amplitude or indication length (based on the reference artificial defect) is higher. In other words, some smaller defects that may be rejected under TC2 may be acceptable under TC1.
TC2: Acceptance criteria are very stringent. The permitted defect signal amplitude or indication length limits are even lower. Any defect indication exceeding these strict limits typically results in pipe rejection or the requirement for repair/removal.
4. Applications and Requirements:
TC1: Typically suitable for applications with relatively low safety requirements, low operating pressures or stress levels, or slightly higher defect tolerance. Examples include:
Certain structural pipes
Some general fluid transport pipes (non-high-pressure, non-hazardous media)
General-purpose steel pipes for cost-sensitive and manageable risks
TC2: Suitable for critical applications with extremely high safety, reliability, and integrity requirements. Examples include:
Oil and gas line pipes (especially high-pressure trunk lines)
Boiler pipes, pressure vessel pipes
Chemical pipes (transporting corrosive or hazardous media)
Subsea pipelines
Key components for high-strength structures
