The following aspects should be paid attention to when installing stainless steel welded air ducts in the hotel ventilation project:

1. Preparation before construction

1. Drawing review:

- Carefully review the design drawings of the ventilation project to ensure that the layout, size and connection of the air ducts meet the ventilation requirements and building structural characteristics of the hotel. For example, it is necessary to check whether the air pipe can smoothly pass through the structure of the building beam, column, etc., to avoid the situation of on-site cutting and modification due to the size discrepancy during installation. At the same time, check whether the marking of the slope of the air duct (if required) in the drawing is accurate. Generally, the air duct should ensure a certain slope in order to drain or discharge condensate, and the slope is usually between 1%-3%.

- Confirm that the position of connection points with other equipment (such as air conditioning units, fans, etc.) in the drawing is accurate to ensure the continuity of the entire ventilation system.

2. Material inspection:

- Strict inspection of stainless steel sheets and welding materials. The thickness of the stainless steel sheet should meet the design requirements, and the thickness of the commonly used stainless steel duct sheet is between 0.5-2.0 mm, and the specific thickness is determined according to the size and pressure level of the duct. Check the surface of the plate for scratches, rust and other defects, if there are defects should be replaced in time.

- The welding material should be matched with the stainless steel material to ensure the welding quality. For example, for 304 stainless steel sheet, the appropriate stainless steel welding wire should be selected, and its composition should ensure good welding performance and corrosion resistance of the weld.

3. Site cleaning:

- Before installing the air duct, clean the construction site to ensure that the site is clean, tidy and free of debris. In particular, the obstacles around the installation position of the air duct should be removed to provide enough space for the handling and installation of the air duct. For the renovated area inside the hotel, protective measures should be taken to avoid damage to the decorative surface of the hotel during the construction process.

2. Welding process

1. Welding process selection:

- Select the appropriate welding process according to the thickness, size and specific requirements of the stainless steel air duct. Common welding methods are argon arc welding, manual arc welding and so on. For thin-walled stainless steel air pipes (generally less than 1.5 mm thick), argon arc welding is a more suitable welding method, because it can provide a stable arc and good weld quality, and the heat input during the welding process is relatively small, which can reduce welding deformation.

- For thicker stainless steel sheets, the combination welding process of argon arc welding primer and manual arc welding cover can be used to ensure the strength and tightness of the weld.

2. Welding environment control:

- Welding work should be carried out in a dry, no wind or breeze environment. The humid environment will affect the welding quality, which may lead to defects such as pores and cracks in the weld. Excessive wind speed will also interfere with the stability of the welding arc, and the wind speed at the welding site is generally required to be no more than 2 m/s.

- Protective barriers should be set up around the welding area to avoid the impact of other construction activities on the welding process, such as welding spark splash may cause fire and other safety accidents, and to prevent dust and debris from entering the welding area.

3. Welding quality control:

- Before welding, the welding parts of the stainless steel plate should be cleaned to remove impurities such as oil and rust, and special cleaning agents or mechanical grinding can be used. When welding, it is necessary to ensure that the width and height of the weld are uniform, and the surface of the weld should be smooth and flat, without porosity, slag inclusion, cracks and other defects.

- For the welds of important parts, such as the joint welds of air pipes and the welds at the interface with equipment, non-destructive testing should be carried out, such as X-ray inspection, ultrasonic inspection, etc., to ensure that the quality of welds meets the relevant standards and design requirements. It is generally required that the flaw detection proportion of the weld is not less than 20%, and the key parts should be 100% tested.

Third, the installation process

1. Air duct positioning and support:

- Accurately determine the installation position of the air duct according to the design drawings, and use measuring tools (such as level, theodolite, etc.) to ensure that the levelness and verticality deviation of the air duct are within the allowable range. Generally, the levelness deviation does not exceed 3 mm/m, and the perpendicularity deviation does not exceed 2 mm/m.

- Reasonably set the support and hanger of the air duct, and the spacing should be determined according to the size and weight of the air duct. For large diameter or long length of stainless steel air duct, the spacing of support and hanger should be appropriately reduced, generally horizontal air duct hanger spacing does not exceed 3 meters, vertical air duct bracket spacing does not exceed 4 meters. The support and hanger should be firm and reliable, and the appropriate connecting parts should be fixed with the building structure to prevent the air duct from shaking or sinking during operation.

2. Air duct connection and sealing:

- The connection of stainless steel welded air duct should be continuously welded to ensure the tightness of the air duct. After the welding is completed, the weld is polished to make it flush with the surface of the air duct to avoid the increase of wind resistance or dust accumulation caused by the weld bulge.

- At the interface of the air duct, through the wall, through the floor and other parts, sealing materials should be used for sealing treatment. Commonly used sealing materials are fireproof sealant, sealing gasket and so on. The selection of sealing materials should meet the fire protection requirements of the hotel and the operating conditions of the ventilation system to ensure a good sealing effect and prevent air leakage. For example, when the air duct passes through the firewall, a sealing material with fireproof performance should be used, and the sealing thickness is not less than 50 mm.

3. Connection with other devices:

- When stainless steel welded air ducts are connected with fans, air conditioning units and other equipment, flexible connection methods should be used, such as the use of canvas soft joints or rubber soft joints. The flexible connection can reduce the vibration generated during the operation of the equipment to the air pipe and avoid the damage of the air pipe due to vibration. The installation of the soft joint should ensure that the connection is tight, without distortion, deformation, etc., and its length is generally 150-300 mm.

- The bolts of the connection parts should be tightened evenly and moderately to prevent too tight or too loose. For example, the tightening torque of the bolt should be controlled according to the specifications of the bolt and the requirements of the connection part. Generally, the tightening torque of the M8 bolt is between 15-20 nm.

4. Check and debug after installation

1. Appearance inspection:

- After the installation is complete, the appearance of the stainless steel welded air duct is thoroughly inspected. Check whether there are scratches, deformation, welding burns and other defects on the surface of the air duct. If there are problems, repair or replace them in time. At the same time, check whether the identification of the air duct is clear and accurate, including the purpose and direction of the air duct, so as to facilitate future maintenance and management.

2. Air leakage check:

- Use light leakage method or air leakage test method to check the tightness of the air duct. Light leakage method is in a dark environment, in the duct with a strong flashlight, observe whether there is light leakage on the outside surface of the duct, if there is obvious light leakage, it indicates that there is air leakage point. For the hotel ventilation system with more stringent requirements, the air leakage test should also be carried out, according to the relevant standards and design requirements, the air leakage of the air duct should be controlled within a certain range, generally not more than 5% of the system air volume.

3. System debugging:

- Start the ventilation system for debugging, and check whether the wind speed and pressure of the air duct meet the design requirements. By adjusting the speed of the fan, the opening of the damper and other parameters, the wind speed and wind pressure in the air duct can reach the best state. For example, the wind speed of the air supply pipe in the hotel room area is generally controlled between 2-4 m/s, and the wind speed of the return air pipe is generally between 3-5 m/s. At the same time, observe whether there is abnormal noise, vibration and other conditions during the operation of the air duct. If there is a problem, it is necessary to find the cause and deal with it in time. It may be caused by the installation of the air duct, improper connection with the equipment or internal debris.

In short, when installing stainless steel welded air ducts in the hotel ventilation project, it is necessary to strictly control all aspects of the pre-construction preparation, welding process, installation process and post-installation inspection and debugging to ensure the installation quality of the air ducts and the normal operation of the ventilation system, and provide a good ventilation environment for the hotel.