I. Core Performance Indicator Verification
1. Pressure Control Accuracy
The cross-sectional area of the hydraulic cylinder must be clearly marked (e.g., 10 cm²), and the matching of the drag pressure (Pdrag) and the welding pressure (P1 = Pdrag + P2) must be verified. The pressure error should be ≤±5%.
Fully automatic welding machines must have real-time pressure monitoring and alarm functions to prevent parameter violations.
2. Temperature Uniformity
The surface temperature difference of the heating plate must be ≤±3°C. The heat absorption temperature of PE80/PE100 must be controlled at 210±10°C and 225±10°C, respectively (national standards).
Gas pipeline welding requires a digital constant temperature display (e.g., 450°C) and regular calibration.
3. Time Parameter Accuracy
The heat absorption time and cooling time must be calculated based on the pipe diameter (e.g., SDR11 pipe diameter/11×10). For pipes with diameters between 90-315mm, the cooling time should be 11-35 minutes.
The hydraulic cylinder should move slowly during the switching phase to avoid high-pressure collisions that could cause false welds.
II. Equipment Structure and Function Inspection
1. Mechanical Stability
The number of slip layers should be ≤ 3 (as required by national standards) to reduce cumulative errors.
The hydraulic system must be stable to prevent pressure fluctuations from affecting hemming quality.
2. Intelligent Functions
The system must support temperature compensation, real-time pressure monitoring, and data storage (e.g., 500 welding records).
Welding records must be tamper-proof and support on-site printing and traceability.
III. Welding Quality Inspection Methods
1. Non-destructive Testing
Visual inspection of the weld ring: The width (0.35-0.45 times the wall thickness) and height (0.2-0.25 times the wall thickness) must be symmetrical and uniform, with no bubbles or dents.
Ultrasonic Testing: Use pulse echo or time-of-flight (TOFD) methods to detect internal defects (e.g., inclusions and cold welds).
2. Destructive Testing
Perform tensile and bend peel tests in accordance with CJJ 63-2018. Gas pipelines must also comply with ISO 21751. IV. Manufacturer and After-Sales Evaluation
1. Qualification Verification
Prefer brands that have passed type inspection (such as Yongtong and Huixin) to avoid uncertified products.
Require annual inspection certificates and calibration services.
2. After-Sales Service
Confirm nearby service locations and emergency repair plans to avoid lost work time.
5. Operating Standards Requirements
Construction personnel must be certified and avoid working in wet weather.
Before welding, mill the end faces (gap ≤ 0.3mm) and scrape off the oxide layer to ensure cleanliness.
