The standard process specification of heater element's production line (Part 2)

The standard process specification of heater element's production line (Part 2)

10. Annealing

1. Whether the heater element is annealed, the annealing method and temperature are in accordance with the requirements of the production order;

a. The copper tube is annealed with oxygen welding flame, the temperature is about 400℃, and the annealing color is dark red;

b. Use a local annealing machine for carbon steel pipe and stainless steel pipe. The temperature of the carbon steel pipe is about 500℃, and the annealing color is medium red. The temperature of the stainless steel tube is about 700℃, and the annealing color is slightly white.

2. When annealing in an electric furnace, put the heater element into the furnace evenly in layers, and not cause uneven annealing due to crowding

　　 Work clamp measuring tools and equipment: annealing furnace, partial annealing furnace, oxygen welding equipment

11. Elbow

1. Cut the exposed length of the lead rod according to the production order, chamfer the cut off the damaged thread, and chamfer 0.5×45° to ensure that the matching thread can be smoothly screwed in;

2. According to the drawing or sample bending shape, the appearance of the electric heating tube must not have obvious mechanical scars or local expansion, and there must be no wrinkles, bumps, etc. at the bend;

3. In the case that the bending radius is less than 3 times the pipe diameter and is not annealed, the direction of the pipe weld seam should be inward R (not easy to break);

4. Self-inspection is the main task, and the inspector conducts the first inspection and random inspection.

Tooling and measuring tools and equipment: pipe bending fixture, pipe bending machine, hydraulic press, punch, grinder, caliper, universal angle ruler, tape measure.

12. Welding

1. When brazing flanges or quick-connecting plate parts are required, the brazing parts must be firm and reliable;

2. Used for heating liquids or airtight electric heating tubes, which should be able to withstand a pressure of 0.3 to 1.2 MPa. There was no leakage during the 5mm hydrostatic pressure test.

Work clamp measuring tools and equipment: oxygen welding equipment, various welding rods.

13. Sealing

1. Time sealing is carried out according to the production order;

2. Dig out the MgO powder at both ends to a depth of 3 to 4 mm and clean it up. Pay special attention to the inner wall of the tube and the threaded part without magnesium powder;

3. Before sealing, check one by one to make the components withstand voltage 2000V/1s, no flashover, and infinite insulation;

4. Put in the sealing glue, turn the magnetic plug and press it on, then install the nut and washer;

5. The heater element of the two ports should be implemented in accordance with the operating procedures.

14. Surface treatment

1. Decide whether to surface treatment and the type of surface treatment according to the production order;

2. The coating layer is required to be uniform, smooth, and free of blistering, peeling, and local accumulation;

3. The lead rod shall not be damaged (corroded) during pickling;

4. Pre-treat the surface to be treated. Especially glue, oxidation spots, etc.

15. Final inspection

1. Insulation: Infinity, which lasts 10s;

2. Withstand voltage: 3000V/10s within φ16 and within 4 meters; φ10～φ8 2000V/10s within 4 meters; φ6. 1800V/10s within 2 meters;

No breakdown flashover

3. Cold resistance: meet the requirements of the production order;

4. Appearance inspection, geometric shape and size should meet product requirements; the above is a piece-by-piece inspection.

5. The leakage current shall be randomly inspected at 5% per batch; the leakage current shall be less than 0.5mA;

6. Thermal insulation is sampled at 5% per batch; at the same time, the uniformity of heating is observed.

Check the thermal insulation ≥2MΩ within 1 minute after the power is cut off, and monitor the insulation to be restored to more than 100 MΩ after cooling for 1 hour under natural conditions.

Tools and measuring tools and equipment: automatic breakdown device, resistance digital meter, leakage meter, caliper, tape measure, steel ruler, flat plate.

16. Marking

   According to the requirements of the production order.

17. Packaging:

   According to the requirements of the production order.

18. Storage