GJB 9579-2018 in English

Analysis of standard technical framework

Key technical requirements

1. Material preparation control

The specification clearly requires the use of a vacuum consumable arc furnace for at least two smeltings, and the vacuum degree in the final smelting stage must be maintained at ≤5Pa, and the use of tungsten inert gas welding electrodes is prohibited. This rigorous smelting process can effectively control the content of interstitial elements such as oxygen and nitrogen to ensure material purity.

2. Mechanical properties matrix

Implementation Suggestions

1. Material Selection Decision Tree

• Conventional Pipeline:TA2 Pipe (Cost Advantage, 440-620MPa Strength Range)
• High Pressure System:TA22/TA24 Pipe (600-730MPa Strength, Containing Mo/Zr Alloying)
• Special Parts:TC4 Pipe (α+β Dual-Phase Structure, Strength ≥895MPa)

2. Key Points of Quality Control

1. Smelting Batch Number Traceability: Complete Smelting Process Records Must Be Retained
2. Ultrasonic Testing Parameters: The Artificial Defect Standard for TA22 Pipe is 10% of the Wall Thickness
3. Surface Treatment: α Contamination Layer Detection is Required After Pickling (GB/T 23603)

Analysis of Standard Evolution

Compared with the civil GB/T 3624 standard, GJB 9579-2018 has added:

• TA22/TA24 and other special alloy grades for ships
• 350℃ high temperature performance indicators
• Correlation requirements between pipe surface roughness and non-destructive testing
• Electrical lettering marking specifications (for pipes with outer diameter＞120mm)