FAQ
Q:What is the size range of corrugated sheets that Zhihe can produce?
A:We can produce sheets to meet the following corrugation specifications:
Corrugation Fin Height:300–1200 mm;Corrugation Depth:100– 370mm;Corrugation Pitch:43 mm and greater.
Q:What are the clear distinguishing features between distribution transformer oil tanks and small main transformer oil tanks?
A:Distribution transformers typically utilize corrugated fins (small radiators), both of which are welded in place. Small main transformers use radiators for cooling (the radiators are detachable PC structures), and most include an oil conservator.
Q:What are the clear distinguishing features between distribution transformer oil tanks and small main transformer oil tanks?
A:Distribution Transformers typically use corrugated finsfor cooling, which are permanently welded to the tank body, forming a compact and sealed unit.
Small Main Transformers (e.g., 10-35MVA range) almost always use detachable radiators for more efficient cooling. Most of them include an oil conservator.
Q:What is the current production capacity of Zhihe?
A:Zhihe's current daily production capacity is as follows:
Distribution Transformer Tanks: 20+ units
Pad-Mounted Transformer Tanks: 10 units
Radiators (Panel-type): 100 units
Main Power Transformer Tanks: 1 unit
Clamps : 35+ sets
Q: What are the default colors for the interior and exterior walls of Zhihe transformer tanks?
A:The conventional color for the interior paint is iron red or apple green.
The conventional exterior paint colors are:
Domestic projects: Sea Gray, 7035 Gray.
International projects: Munsell Green, 70 Gray, 61 Gray.
Q: How to test for leaks in a transformer radiator?
A: To test for leaks, first pressurize the transformer radiator to identify leak points. After repairing all leaks, clean the surface. Then, conduct a pressure test for 30 minutes. If no leakage is observed, the radiator is considered leak-free.
Q: What are the materials used for the fuel tank?
A: Q235 carbon steel, Q355 carbon steel, 304 stainless steel, and low-magnetic steel plate.
Q: How to control welding deformation?
A: Building on historical production experience, Zhihe has employed fixture positioning and anti-deformation techniques. The procedure involves: first positioning the components, then welding in a specified sequence, and adding internal supports to minimize welding stress and distortion.
Q: What is the difference between powder coating and spray painting? In what situations must spray painting be used instead of powder coating?
A:Powder Coating: A process where electrostatically charged powder is applied to a workpiece and then cured under heat to form a finish.
Spray Painting: A process where liquid paint is atomized and applied to a workpiece surface using a spray gun.
Spray painting is required for applications demanding a corrosion resistance level of C5.
Q: How does Zhihe solve the sealing problem of flange faces?
A: Zhihe reprocesses all flange surfaces to ensure that the flatness and roughness of the sealing surface meet the requirements, resulting in uniform sealing after installation without oil leakage or air leakage.
Q: What are the weld appearance standards for Zhihe's products?
A: Zhihe's weld appearance standards require beads to be uniform and flush, free from cracks, porosity, slag inclusions, lack of penetration, and undercut.
Q: What is the surface painting process for Zhihe's transformers?
A: Based on the corrosion protection level required by the customer, we adopt a multi-layer protective coating process. The steel plates are first blasted to remove rust, meeting the Sa2.5 standard, then primed (anti-rust), coated with an intermediate layer, and finally sprayed with an acrylic polyurethane topcoat.
Q: What are the common causes of dielectric loss issues reported by customers?
A: 1. The paint on the inner wall of the tank does not meet the requirements, 2. The inner wall paint is not fully dried, 3. Excessive dust and foreign objects inside the tank, 4. Issues with the oil itself, 5. The transformer body is unclean with assembly impurities, 6. Issues with the paint on the clamps.
Q: When the transformer operates with a high shell temperature, will the paint discolor?
A: In a qualified transformer, the shell temperature may reach 60-80°C during operation. The paint can withstand temperatures up to 130°C without blistering, peeling, or significant discoloration.
Q: What are the standards for Zhihe's qualified products?
A: 1. Appearance: No obvious scratches, uniform coating, no sagging, no missed spraying.
2. Dimensions: Meet the drawing tolerance requirements (generally ±2mm).
3. Color difference: No visible color difference and colorimeter test value < 2.
4. Performance: Corrosion-resistant coating adhesion meets standards (cross-cut test ≥ Grade 1), sealing performance is qualified (air pressure test shows no leakage).
5. Documentation: Includes complete inspection reports and certificates.
Standards reference: GB/T19001 quality management system, transformer industry standards (such as GB/T1094 series).
Q: What are the leak testing procedures for Zhihe's tanks?
A: 1. Penetrant leak test (penetrant + cleaner + developer): First, clean the welds, spray penetrant, let it sit for five minutes; wipe off excess penetrant, then spray developer.
Judgment: Observe the weld surface. Red marks indicate leaks; no red marks mean no leakage.
2. Air tightness test (soapy water or cleaner): Fill the inner cavity with compressed air and seal it. After reaching the specified pressure, maintain pressure and evenly apply soapy water to the welds and joints.
Judgment: Observe if bubbles are produced. Continuous bubbling indicates leaks; no bubbles mean no leakage.
Q: How does Zhihe ensure the paint film thickness of its products?
A: We ensure the paint film thickness meets standards, with no missed spraying or thin coating, through pre-treatment blasting, multi-layer spraying, wet film control, dry film inspection for each unit, pre-coating of corners and hard-to-reach areas, and detailed thickness records for each unit, ensuring traceable quality.
Q: How does Zhihe ensure the adhesion of its products?
A: We ensure the paint film does not peel or flake and meets adhesion standards through pre-treatment blasting, controlling temperature and humidity, standardized paint matching, baking and curing, and cross-cut testing before shipment.
Q: How does Zhihe ensure the correct color of its products?
A: We ensure the correct color and no color difference through incoming material inspection, locked paint mixing formulas, pre-spraying verification, and final inspection before shipment, with checks at every stage from sourcing to delivery.
Q: What tests does Zhihe conduct before shipment?
A: 1. Appearance and dimension inspection, 2. Air pressure leak test, 3. Surface paint film thickness inspection, 4. Color difference inspection, 5. Adhesion inspection, 6. Internal cleanliness, 7. Accessory quantity.
Q: How does Zhihe perform leak testing on corrugated tanks?
A: 1. Place the sealing ring on the tank edge and press it firmly with the cover plate, leaving no air holes. 2. Confirm the pressure gauge is normal and in good condition. 3. Pressurize: first add 50% air, check for leaks and tank deformation. Then add 20% more, continue checking for leaks and tank deformation. Finally, pressurize to the standard requirement and check for leaks and deformation. 4. When repairing welds, release pressure, grind the leak point, and then repair. 5. After repair, grind the repaired area, clean welding slag, and repeat the leak test until no leaks are found.
Q: What is the leak test pressure for corrugated tanks?
A: 315kVA and below: 20kPa, hold for 30 minutes with no leakage.
400kVA and above: 15kPa, hold for 30 minutes with no leakage.
Q: How does Zhihe ensure the internal cleanliness and quality of the tank?
A: The tank interior is treated with blasting and shot blasting. Areas inaccessible to machines are manually processed, including cleaning, blowing, and inspection, to remove welding slag, oxide scale, and steel shot. All internal welds are deslagged, ground, deburred, and cleaned to ensure the inner wall is clean and smooth, without affecting the transformer oil quality or safe.