Insulation resistance and insulation withstand voltage strength required for the performance of electric heating tubes

Insulation resistance and insulation withstand voltage strength required for the performance of electric heating tubes

5.3.4 Insulation resistance:

The cold insulation resistance during factory inspection should not be less than 50M Ω

The insulation resistance after sealing test, long-term storage or use shall not be less than 1M Ω

The thermal insulation resistance at working temperature should not be lower than the calculated value in equation (2), but the minimum should not be less than 1M Ω

In the formula: R - thermal insulation resistance, unit: megaohms (M Ω)

T -- Heating length, in millimeters (mm)

T -- Working temperature, in degrees Celsius (℃)

5.3.5 Insulation withstand voltage strength:

The component should be maintained for 1 minute under the specified test conditions and test voltage, without any flashover or breakdown phenomenon

Performance requirements for metal heating tubes - Power on/off capability and overload capability

5.3.6 Ability to withstand power on and off:

The component has undergone 2000 power on/off tests under the specified test conditions without any damage.

5.3.7 Overload capacity:

The component should be able to withstand 30 cycles without damage under the specified test conditions and input power.

Heat resistance and service life of electric heating tubes

5.3.8 Heat resistance:

The component should be able to withstand 1000 cycles of heat resistance testing under the specified test conditions and test voltage without damage.

5.3.9 Service life:

The component shall operate at rated voltage and rated power, and its service life shall not be less than 3000h.

5.1.6 Construction:

5.1.6.1 When designing components, factors such as thermal expansion, erosion, oxidation, and creep should be taken into consideration to avoid malfunctions caused by deformation during normal operation.

5.1.6.2 The design of the internal structure of components should ensure that the materials selected for manufacturing the components are not damaged at the highest temperature or the highest temperature conditions that may be encountered during processing, and can still work reliably

The welding structure design of components should comply with relevant standards. The welding seams of pressure components, especially the parts inside the container, should be minimized and the position of the welding seams should be easy to inspect.

5.1.6.4 The design of the shell and accessories of pressure bearing components must comply with relevant standards

5.1.6.5 For components with spiral fins at both ends, the spiral fins should fully cover the heating length of the component along the axis. The inner diameter of the spiral fins should be matched with the outer diameter of the metal tube of the component, and the two ends should be spot welded to the metal tube wall

5.1.6.6 Components (including ends) must be sealed

Note: If there is an agreement, temporary sealing measures or no sealing can be used at the end, and the sealing performance of the end will not be evaluated.

5.1.6.7 Components used for heating corrosive media must be made of corrosion-resistant metal tubes or have protective sleeves to ensure the service life of the components.

When the shell is made of ordinary steel or other alloy materials with better performance than ordinary steel, the wall thickness should not be less than 0.35mm. When the shell is made of materials such as copper or alloy, it must have corresponding mechanical strength to adapt to harsh working environments.

The bending radius of the component should not be less than 2.5 times the pipe diameter.

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