GB/T 34370.10-2020 in English

The standard puts forward clear performance indicators for magnetic memory detector:

• Magnetic field measurement error: ≤±5%
• Measuring range: ≥±1000A/m
• Resolution: ≤1A/m
• Probe characteristics: Must be equipped with displacement sensor and dual magnetic field measurement unit

Before testing, an adjustable standard magnetic field of 40-2000A/m must be used for calibration to ensure measurement traceability.

The standard innovatively proposes a dual-parameter evaluation model:

1. Magnetic field gradient value K: reflects the local stress concentration intensity, calculated by the formula K=ΔH/ΔL
2. Gradient factor m: eliminates the influence of environmental noise, m=(K_i-K_avg)/σ

When K>10(A/m)/mm and m>2, it is determined to be a significant stress concentration area, which needs to be verified by visual inspection, magnetic particle inspection and other methods.

Case of roller coaster track weld inspection: During the annual inspection of a theme park, the EMS-2003 magnetic memory detector was used to find that:

• An abnormal signal of K=15.2(A/m)/mm appeared at the track butt weld
• Magnetic particle inspection confirmed that it was a micro crack initiation zone
• The fatigue damage development was warned three months in advance

This case verifies the technical advantage of the early warning in the standard.

Recommendations for different application scenarios:

1. New equipment: Magnetic memory benchmark data should be established during the first acceptance
2. Equipment in use: Comparative inspection should be carried out in combination with the overhaul cycle
3. High-risk areas: The inspection cycle should be shortened for roller coaster track welds and spindles

Inspectors should pay special attention to the influence of geomagnetic field interference, and a 20mm lift-off calibration should be performed before inspection.