GB/T 39255-2020 in English
VALIDGases and gas mixtures for welding and cutting processes
- Issued on:2020-11-19
- Implemented on:2021-06-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$194.00
《GB/T 39255-2020焊接与切割用保护气体》由TC55（全国焊接标准化技术委员会）归口，TC55SC1（全国焊接标准化技术委员会焊接材料分会）执行，主管部门为国家标准化管理委员会。
Introduction
Analysis of the core content of the standard
| Technical dimension | ISO14175:2008 | GB/T39255-2020 |
|---|---|---|
| Gas classification | 5 major categories | Expanded to 7 major categories (newly added Class Z) |
| Component tolerance | Unclassified regulations | Three levels of control according to content (Table 5) |
| Moisture requirement | Uniform ≤-40℃ | Graded control (inert gas ≤-50℃) |
Key technical requirements
The standard divides the protective gas into single gases and mixed gases such as argon and helium, among which:
- Purity requirement: inert gas ≥99.99%, oxidizing mixed gas ≥99.8%
- Preparation tolerance: ＞5% components are controlled at ±10%, 1-5% components are fixed at ±0.5%
- Dew point index: -50℃/-40℃ graded control (corresponding to moisture content 40-120ppm)
Typical application cases
Case 1: Selection of M12-HeArC-7.5/2.5 mixed gas (7.5% helium + 2.5% CO2 + argon balance), its oxidizing property can improve the fluidity of the molten pool, and helium can enhance the arc penetration.
Case 2: I3-ArHe-30 (30% helium + argon balance) is recommended for aluminum alloy welding, using the high thermal conductivity of helium to prevent pores.
Implementation Suggestions
- Establish a gas acceptance system, focusing on checking the purity certificate and component test report
- When welding key components, it is recommended to control the inert gas dew point below -60℃
- The mixed gas should be left standing for 24 hours before use to ensure uniform components
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