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stainless steel air duct

Nanjing Hangyao Ventilation Equipment Co., Ltd

E-mail
772738749@qq.com
Phone
187-5184-8216
Address
No. 12 Xinggu Road, Guli Industrial Park, Guli Street, Jiangning District, Nanjing City

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Production of stainless steel welded air ducts

NegotiableUpdate on 11/24

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Nature of the Manufacturer: Producers

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Overview

1、 Introduction to Stainless Steel Welded Duct Production: Stainless steel ducts, also known as SteelUseStainlessDuct or SUSDuct, can be divided into circular and rectangular types

Product Details

1、 Introduction to the production of stainless steel welded air ducts

Stainless steel duct, also known as Steel Use Stainless Duct or abbreviated as SUS Duct, can be divided into two types: circular and rectangular. We can produce finished air ducts of various shapes, specifications, models, and boards according to the different requirements of the engineering site.

2、 Design Guidelines for Stainless Steel Welded Ducts

1. Compared to water, air has a smaller heat capacity, and as a compressible fluid, its transport efficiency is poorer. Therefore, reducing transportation resistance is also closely related to energy conservation.

2. Due to excessive local resistance being a factor in generating noise and vibration, it is crucial to minimize resistance as much as possible. Therefore, the following points must be noted:

(1) The position of the air conditioner should be as close to the load as possible, and a reasonable air duct route should be planned.

(2) When formulating a typical duct plan, design according to the recommended range of wind speeds.

(3) Try to use a larger curvature radius for curved parts.

(4) Reduce the angle of change when expanding or shrinking the air duct.

(5) The aspect ratio of the air duct section should be as small as possible, especially not greater than 10.

3. When changing the cross-section of stainless steel ducts, sharp changes should be avoided, and the enlarged part should be within 20o and the enlarged part should be within 45o. When it is necessary to exceed this value, guide vanes must be used.

4. When setting branches or nozzles at positions below about 8 times the width of the air duct (about 4 times for guide vanes) from the inner curved surface at the bend to the straight section, the air volume may be insufficient (in extreme cases, no air outlet). To extend the straight-line distance as much as possible, or set up guide vanes appropriately at the bend, or make a static pressure box at the bend. If there is a possibility of insufficient air flow, separate air doors can be connected in parallel.

3、 Processing method of stainless steel welded air duct

1. Hoop type connection: mainly used for connecting steel plate circular air ducts and spiral air ducts. First, roll out bulging ribs at both ends of each pipe section and shrink one end into a small opening. During installation, insert the small opening into the large opening according to the direction of airflow, and use steel clamps to tightly connect the two ends of the drum hoops. Use bolts to secure and tighten them in the middle of the earrings.

2. Plug in connection: mainly used for connecting rectangular or circular stainless steel ducts. First, make the connecting pipe, then insert the air ducts on both sides, and tightly fix them with rivets. Strip connection: mainly used for connecting rectangular ducts. Insert different forms of inserts into both ends of the air duct and compact them.

3. Flexible hose connection: mainly used for connecting air ducts and components (such as radiators, static pressure box side air outlets, etc.). During installation, the two ends of the hose should be placed outside the connected pipe, and then the hose should be tightened with a special soft clamp.

4、 Process flow of stainless steel welded air duct processing

Cutting machine CNC straight bar cutting - coiling - automatic welding - flange sleeve - pipe flanging - acid washing - quality inspection - packaging - shipping inspection. The prefabrication of pipelines must be strictly carried out in accordance with the requirements of SH/T3517-2001. Before prefabricating pipelines, the pipeline layout plan, detailed drawings, and pipe section drawings must be carefully checked to avoid unnecessary rework.

1. Pipe cutting

(1) The cutting should be strictly carried out according to the design single line diagram, and the material size should be carefully checked before cutting. CNC cutting machine for straight cutting (with an error of plus or minus 0.1mm)

(2) When cutting materials, they should be arranged reasonably according to the length of the pipes to reduce waste. For pipelines with small quantities, large diameters, thick pipe walls, and other special materials, the overall discharge should be carried out before cutting, and the amount of pipes should be strictly controlled. Cutting allowance of 100mm or more cannot be treated as waste and should be registered and stored according to the material for future use.

(3) If the identification of the cut pipe is damaged, the original identification should be replicated on the remaining pipe.

(4) Stainless steel pipes must be cut by mechanical or plasma cutting, while other pipes can be cut by flame cutting and prepared with grooves. The cut surface should be smooth, without cracks, heavy skin, burrs, bumps, and shrinkage. Slag, oxides, iron filings, etc. should be removed in a timely manner.

(5) The inclination deviation △ of the incision end face shall not exceed 1% of the outer diameter of the pipe and shall not exceed 2mm.

2. Preparation requirements for groove

The main method of pipeline connection is welding, and the groove is the primary condition for welding, which must be carried out according to the specifications. The groove type of medium and low pressure pipelines is V-shaped, and the YV (double V) groove type is used for high pressure pipelines. The groove processing should be smooth, without cracks, double skin, burrs, iron oxide, etc. The groove and the surrounding 10mm range should be polished with an angle grinder to a metallic luster. The specific groove form shall be executed according to the welding process card.

3. Welding joint assembly

Before pipeline assembly, clean the dirt, oil stains, rust, etc. within 25mm of the inner and outer surfaces of the interface, and use a wire brush or mop to remove debris inside the pipe. Measures should be taken to seal the pipe ends of pipes that are not sealed during prefabrication and installation to prevent debris from entering the pipeline.

4. Allowable deviation for prefabrication

(1) Verticality between flange surface and pipe center: 0.5mm for DN<100, 1.0mm for DN ≤ 300, and 2.0mm for DN>300.

(2) Dimensional deviation: free pipe section ± 10mm, closed pipe section ± 1.5mm.

When aligning pipes, the straightness should be measured at a distance of 200mm from the center of the interface. When DN<100mm, a<1mm。 When DN ≥ 100mm, a<2mm。 But the allowable deviation for the entire length is less than 10mm. When the nominal diameter of the pipe is less than 100mm, the allowable deviation value α is 1mm. When the nominal diameter of the pipe is greater than or equal to 100mm, the allowable deviation value α is 2mm. However, the deviation value for the entire length shall not exceed 10mm.

5. Prefabricated pipeline components should be numbered according to the specified requirements (pipeline number, weld joint number, and welder number) for quality control and easy identification during installation.

6. The prefabricated pipe section should be cleaned internally and the pipe mouth should be promptly closed to ensure cleanliness inside the pipe. It is specifically pointed out that all pipe openings in this project must be completely sealed before installation to ensure 100% sealing of prefabricated pipelines entering the site.

7. The combination of butt welds for pipes of equal thickness should ensure that the inner wall is flush, and the misalignment of the inner wall should not exceed 10% of the wall thickness and should not be greater than 2 millimeters.

8. When assembling components of unequal thickness pipelines, if the misalignment of the inner wall exceeds 1.5mm or the misalignment of the outer wall exceeds 3mm.

9. Requirements for spacing between adjacent welds

(1) The distance between the center surfaces of circumferential welds: DN ≥ 150mm shall not be less than 150mm, and DN<150mm shall not be less than the outer diameter of the pipe.

(2) The distance between the nearest points of the longitudinal weld should be greater than or equal to 5 times the wall thickness of the pipe.

(3) The distance between the opening of the branch pipe and the nearest point of the main pipe circumferential weld or longitudinal weld shall not be less than 3 times the wall thickness of the main pipe.

10. When the ear post or bracket is welded to the pipe, the bracket or ear post weld should not pass through the pipe or fitting weld.

11. The welding of spot welding and fixed fixture welds during welding assembly shall be the same as formal welding.

12. When dismantling fixed fixtures, it is forbidden to directly knock them off with a hammer. Use a grinding machine or gas welding flame to remove them. Flame cutting is limited to the outer layer of the weld seam. The part in contact with the base material should be polished and removed with a grinding machine. If there are defects, they should be repaired after passing the penetration inspection.

13. There shall be no cracks on the surface of the weld seam, no defects such as lack of fusion or incomplete penetration at the root, and the depth of undercutting shall not exceed 0.5mm. In any continuous 300mm long weld seam, the depth shall not exceed 50mm. There shall be no locally dense pores, single pores, or slag inclusions on the surface of the weld seam.

14. After welding is completed, the slag and splashes on the surface of the weld seam should be promptly removed, and the surface quality of the pipeline weld seam should be self inspected.

15. Stainless steel air ducts and fittings should undergo acid pickling and passivation treatment after welding. The surface of the stainless steel joint should be treated with a stainless steel specific acid pickling and passivation solution (paste) to remove oxides generated during welding.

5、 Precautions for installation of stainless steel welded air ducts

1. Before connecting the stainless steel welded air duct to the equipment, it should be prefabricated and installed according to the actual drawings after waiting for the equipment connection to be completed.

2. In terms of components, if the equipment is connected to the air duct, the support and hanger must be separately set and cannot become the suspension point for the air duct.

3. After the double suspension bracket is in place in the air duct, it should ensure that the cross arm is straight, the suspension rod is not twisted, and the double suspension rod is evenly stressed.

4. The distance between the suspension point of the air duct and the air outlet, air valve, and automatic control mechanism should not be less than 200mm.

5. When installing the air duct, it is advisable to open openings for the inlet and outlet during the prefabrication of the air duct. If an air outlet needs to be opened on the installed air duct, the interface should be tight.

6. When installing air ducts, if they need to pass through walls or floors, protective sleeves must be used and non combustible flexible materials must be used for sealing. The thickness of the sleeve cannot be less than 1.6mm, because if the sleeve is too thin, it cannot be effective.