In industrial procurement, incoming material inspection and foreign trade product delivery inspection, it is necessary to quickly and accurately judge the quality of tubular electric heating tubes. Professional visual detection methods can directly identify the quality advantages and defects of electric heating tubes without professional precision instruments, which is efficient and convenient, and is widely used in factory inspection, customer acceptance and on-site quality screening, providing a simple and effective quality judgment standard for purchasers and users.
The first step of visual quality inspection is surface cleaning and pretreatment. Before detection, the surface of the electric heating tube must be thoroughly wiped clean with a clean rag to remove surface dust, oil stains, protective wax and other impurities. Ensure that the metal tube wall is smooth and clean without attachments, so as to avoid the interference of surface impurities on the detection results and ensure the accuracy of subsequent quality judgment. Clean surface is the basic premise for effective detection.
The second step is air dry heating test with standard power supply. Connect the cleaned electric heating tube to the AC 220V standard power supply for dry burning in the air. Observe the heating state of the tube wall in real time. Qualified high-quality electric heating tubes have uniform heating speed and consistent surface temperature, without local overheating, sudden redness and abnormal noise. After the tube surface is completely red, cut off the power supply immediately and let the electric heating tube cool down naturally to room temperature completely, which is a key step in the detection process.
The third step is residue inspection to judge product quality. After the electric heating tube is completely cooled, wipe the surface of the tube wall repeatedly with clean napkin paper. For high-quality qualified electric heating tubes, there will be no black oxide powder on the white napkin paper after wiping. This indicates that the internal heating alloy wire of the electric heating tube has stable performance, no oxidative combustion reaction occurs during electrified heating, the internal sealing is good, and no air and moisture penetrate to cause component oxidation failure.
If black oxide powder appears on the napkin paper after wiping, it proves that the quality of the electric heating tube is unqualified. Unqualified products have poor internal sealing performance, incomplete drying of internal materials or inferior alloy heating wires. Oxidation reaction will occur during dry burning, producing oxide residues attached to the tube wall. Such products have unstable heating performance, easy power attenuation, short service life and potential electric leakage hazards, and are not suitable for industrial formal use and foreign trade export delivery. This intuitive detection method is simple, efficient and accurate, and is an essential quality inspection skill for electric heating tube procurement and acceptance.
