How to check the sealing of the insulation layer of the straight-tube stainless steel electric heating ring after installation?

After the straight stainless steel electric heating coil insulation layer is installed, the following methods can be used to check the sealing:
Appearance inspection method: Observe the surface of the insulation layer directly with the naked eye, focusing on the interfaces, ends and joints of the insulation material, where gaps are prone to appear. Check whether there are obvious cracks, holes or unsealed gaps in these places. If gaps are found, even if they are very small, they may affect the insulation effect and require further treatment.
Touch inspection method: When the electric heating coil is not powered on, gently touch the surface of the insulation layer with your hand to feel whether there is air flow. Especially in key areas such as interfaces and ends, if you can feel a slight airflow, it means that there may be a problem with the sealing. You can also press the insulation layer with your hand to observe whether there is air squeezed out of the gap. If so, the corresponding parts need to be sealed.
Smoke test method: Place some smoke sources around the insulation layer, such as aromatherapy sticks or special smoke generating devices, and then observe the flow of smoke. If the insulation layer is well sealed, the smoke should be evenly around the insulation layer, and there will be no obvious smoke leakage. If smoke is found to be leaking out quickly from a certain part, it means that the part has a problem of poor sealing and needs to be repaired.
Temperature test method: After the electric heating coil is powered on and works for a period of time, use an infrared thermometer to measure the temperature distribution on the surface of the insulation layer. If the insulation layer is well sealed, the surface temperature distribution should be relatively uniform, and there will be no situation where the local temperature is significantly lower or higher. If it is found that the temperature in a certain area is significantly lower than that in other parts, there may be gaps in the insulation layer in this area, resulting in faster heat loss, and the seal needs to be checked and repaired.
Pressure test method: For some occasions with high requirements for sealing, the pressure test method can be used. Place the electric heating coil wrapped with the insulation layer in a sealed container, and then fill the container with a certain pressure of gas, such as air or nitrogen. The sealing of the insulation layer is judged by observing the changes in the pressure gauge readings. If the pressure drops significantly within a certain period of time, it means that there is a leak in the insulation layer, and the leak point needs to be found and repaired.