GB/T 35361-2017 in English

National Standard of the People's Republic of China GB/T 35361—2017 Ultrasonic Testing and Quality Grading of Titanium Alloy Butt Welds for Submersibles

Scope of Application of the Standard

This standard is applicable to the ultrasonic testing of titanium alloy butt welds for submersibles with an outer diameter of not less than $500~\mathrm{mm}$ and a wall thickness of $10~\mathrm{mm} \sim 110~\mathrm{mm}$. Ultrasonic testing of titanium alloy structural welds for other ships can be used as a reference.

Comparison of standard frameworks

Testing equipment requirements

Performance indicators of flaw detectors:

• Working frequency range: $1~\mathrm{MHz} \sim 10~\mathrm{MHz}$
• Horizontal linear error: ≤1%
• Vertical linear error: ≤5%
• Dynamic range: ≥26 dB

Probe selection and use

Table 1 Selection of probe parameters

Quantitative detection of defects and quality rating

Table 3 Quality classification table of welded joints when the defect reflection amplitude is in zone II

Implementation Recommendations

In order to ensure that the ultrasonic testing of titanium alloy butt welds of submersibles achieves the expected results, it is recommended:

• Staff training: The inspectors need to be familiar with the properties of titanium alloy materials and welding processes, and hold relevant qualification certificates.
• Equipment calibration: Regularly check the performance of the flaw detector and probe to ensure that the sensitivity margin meets the requirements.
• Testing environment: Control surface roughness and coupling agent use to reduce interference factors.
• Record management: Record the testing process and results in detail and properly save the original data.