Heating pipe raw material selection

- Aug 12, 2019-

Heating pipe raw material selection


      Among the elements that cause damage to the quality of electric heating pipes, the quality of raw materials is a critical factor. Effective selection of raw materials for electric heating pipes is a prerequisite for ensuring the quality of electric heating pipes.

The selection of raw materials for electric heating pipes includes:

1. Standard for the use of pipe fittings: high temperature resistance and corrosion resistance

For low temperature pipes, BUNDY, aluminum alloy pipes and T2 copper pipes are usually used. Stainless steel pipes and Ingle pipes are usually used for high temperature pipes. Ingrid 700 electric heating tube can be applied in the case of poor water quality. Ingrid 840 electric heating tube can have very good anti-oxidation energy outside the high temperature working attitude and has good corrosion resistance.


2. Adoption of electric heating wire

Commonly used electric heating wire materials in electric heating pipes are Fe-Cr-Al and Cr20Ni80 electric heating wires. The iron-chromium wire used by KAWAI is 0Cr25Al5 steel grade, which is higher than the usual iron-chromium wire melting point and has a stronger service life. The key difference between the two types of heating wires is that the melting point of 0Cr25Al5 is higher than that of Cr20Ni80, but at higher temperatures, 0Cr25Al5 is more easily oxidized by air, and Cr20Ni80 can maintain its characteristics for a long time at high temperatures. Therefore, the heating wire applied at a high temperature is usually selected from Cr20Ni80.


3. Adoption of magnesium oxide powder

The magnesium oxide powder is located between the heating wire and the wall thickness and is used for the insulation layer between the heating wire and the wall thickness. Together, the magnesium oxide powder has excellent heat transfer properties. However, magnesium oxide powder has strong water absorption, so it must be solved by waterproofing during application (magnesium oxide powder modified material or electric heat pipe sealing solution)

Magnesium oxide powder can be classified into ultra-low temperature powder and high temperature powder according to the temperature range of application. Ultra-low temperature powder is only used at 350 ° C for the following applications, usually magnesium oxide powder solved by modified materials. The magnesia powder is granulated, and the magnesia powder used for the electric heating tube is prepared by arranging the magnesia powder particles of different sizes according to the necessary proportion (mesh ratio).


4. Adoption of sealing raw materials

The effect of sealing raw materials is to prevent the moisture in the air from entering the magnesium oxide powder from the branch pipe, so that the magnesium oxide powder is damp, the dielectric strength can be reduced, and the electric heating tube is powered off and is ineffective. Magnesium oxide powder solved by modified materials can be unsealed.

The key raw materials for sealing (waterproof) of electric heating pipes are laminated glass, epoxy resin, methyl silicone oil and the like. In the electric heating tube sealed with methyl silicone oil, after heating, the methyl silicone oil at the branch pipe position will be evaporated by heat, and the insulating layer of the electric heating tube is lowered. The high temperature resistance of epoxy resin collagen materials is not high, and it can not be applied to high temperature electric heating tubes such as skewers and microwave ovens with high branch temperature. Laminated glass is resistant to high temperatures, but the price is higher, and more is used for sealing high temperature pipes.

In addition, there are silicone hoses, silicone sleeves, porcelain beads, plastic insulators and other components in the branch pipe position. The key is to improve the gap between the electrical equipment and the creepage distance between the rod and the metal wall of the branch pipe. Silicone can have the effect of filling and bonding.