1. When the electric heater is subjected to the life test, the heating time is 10-20 min. In the case of intermittent heating, the electric heater has a cumulative total life of not less than 50 h under the condition that the total gap between the center hole of the bolt and the electric heater is 0.8-1.3 mm.
2. The joint between the alloy resistance wire and the lead wire should be firm and reliable, and must not be loose. The enclosure must be well grounded.
3. The cold end seal of the electric heater is required to be tightly sealed to prevent moisture from entering and destroying the insulation.
4. After the electric heater steel casing is cold-shrinked, use the coloring flaw detection or check the surface with a magnifying glass of 5 times or more. There shall be no defects such as cracks, and the tube shall be formed in one direction when the tube is shrunk.
5. After the bolt heater is manufactured, after one and a half months, the insulation resistance (which can be performed at the manufacturer or the user) should be no less than 50M Ω at room temperature with a 500V megger.