The mold temperature machine uses a flat flange type electric heating tube. The mold temperature machine mainly has an oil temperature machine and a water temperature machine, that is, the heating medium is oil and water. Now the main heating tube has problems that are all heating water, and the heating environment It is like this: the pressure is 5-10KG, the working temperature is 130-180℃.
Problem: 304 pipe with diameter 12, magnesium powder is SHGZ-8A# medium and high temperature powder, electric heating wire is 0.65 iron chromium wire, heating tube length is 800mm, cold end at both ends is 65mm, power is 10w/cm2, customer use It burst in the corner after 10 days, and the customer’s original supplier also experienced this situation. 40-60 of 100 sticks were broken one after another.
Analysis opinion: Because the heating environment is similar to the heating in the boiler, water vapor will be formed, which will cause the electric heating tube to be damaged when it is dry at a very high temperature. The working temperature is 180℃, the maximum pressure is 10kg.f/cm2, and the water is in In this environment, a lot of bubbles will be generated, especially near the bending part. The higher the temperature, the more bubbles. The part with bubbles is equivalent to local dry burning. The surface temperature is about 475℃. The phenomenon of “brittleness” cannot withstand the high pressure inside and outside the tube, resulting in the phenomenon of tube bursting due to brittleness. Of course, this is also related to the quality of the pipe itself, the structure of the customer's equipment, the water quality and the correct use method.
Suggest:
(1) The pipe material is changed to 316L, 321, 840 or 800, and the pipe wall thickness is greater than 1mm
(2) Replace magnesium powder with high temperature powder
(3) The density of magnesium powder should be greater than 3.2g/cm3
(4) Heat treatment at 1000℃ at the bend
(5) Flatten at the bend
(6) AB resin glue for sealing material
(7) The insulation resistance is greater than 10,000 megohms when leaving the factory
(8) Strengthen the quality control in the production process.