As a targeted detection device, the electric spark detector has become a core tool for quality control in anti-corrosion engineering due to its precise and efficient leak point identification ability. In anti-corrosion engineering, the integrity of the coating directly determines the service life of the equipment or pipeline. Even if the coating thickness meets the standard, tiny pinholes, cracks, and other leakage points can become channels for corrosive media to invade, causing substrate corrosion.
1、 Working principle: Using "breakdown discharge" to locate leakage points
The electric spark detector works based on the principle of "gas ionization breakdown". During testing, the instrument applies a specific voltage (usually 500V-30kV, adjusted according to the coating thickness) to the coating surface through a probe or brush, and the substrate forms a circuit with the instrument through a grounding wire. When there is a leakage point in the coating, the air between the electrode and the substrate will be ionized by high voltage, generating obvious electric sparks and accompanied by sound and light alarms, thus accurately locating the location of the leakage point. This principle determines its high sensitivity to small leaks (with a diameter recognizable up to 0.01mm), far exceeding visual observation or conventional detection methods.
2、 Leak detection operation: Four steps to achieve precise detection
（1） Preparation before testing
Firstly, it is necessary to ensure that the surface of the substrate is dry and clean, and to remove impurities such as dust and oil stains to avoid affecting the accuracy of the detection; Secondly, set the voltage according to the coating thickness, following the principle of "low voltage for thin coatings and high voltage for thick coatings" (such as 3kV voltage for 80 μ m coatings), and check whether the grounding wire is firmly connected to the substrate to prevent circuit interruption and misjudgment.
（2） Formal testing process
The handheld probe scans the coating surface at a constant speed of 5-10cm/s, maintaining a distance of 1-3mm between the probe and the coating to avoid direct contact and scratching of the coating. For areas such as welds and corners that are prone to leakage, slow down the movement speed and scan repeatedly 2-3 times. If electric sparks and alarm sounds occur during the detection process, immediately mark the location of the leakage point, record the size and distribution density of the leakage point.
（3） Leakage review and confirmation
For the preliminarily marked leakage points, reduce the voltage and scan again to confirm whether the leakage points are truly present (excluding false alarms caused by impurity interference). At the same time, use tape or marker pen to clearly mark the range of the missing points, providing clear guidance for subsequent repairs.
（4） Post detection processing
After the testing is completed, promptly turn off the instrument power, organize the testing data, and issue a testing report. For the discovered leaks, the same type of coating should be used for repair, and after repair, the detector should be used again for verification to ensure that the leaks are sealed.
3、 Key considerations: Ensure the effectiveness of testing
When operating, two core points should be noted: first, the voltage selection should be precise. If the voltage is too high, it may penetrate the intact coating, and if it is too low, the leakage point cannot be identified, and reference should be made to the voltage parameters provided by the coating manufacturer; Secondly, the testing environment needs to be controlled to avoid testing in damp and high dust concentration environments. If the substrate surface is damp, it needs to be dried before testing to prevent moisture conduction from causing false alarms.
In anti-corrosion engineering, the electric spark detector converts "invisible" leakage points into "visible" signals through scientific principles and standardized operations, building the last line of defense for coating quality. Mastering its application methods can not only improve the reliability of anti-corrosion engineering, but also extend the service life of equipment and reduce maintenance costs in the later stage.