What are the installation points of stainless steel welded air duct in environmental protection ventilation engineering of underground garage?

Here's a list of installation points of stainless steel welded air duct in underground garage environmental protection ventilation project, which is concise and practical, can be used directly on site, with prominent focus and no verbosity.

Installation points of stainless steel welded air duct (special for underground garage)

First, the preliminary preparation

Air duct inspection: material (304/316L), thickness, flatness, no corrosion, no deformation, and no defects in welds.

Pay-off positioning: mark the direction, elevation and position of supports and hangers of the air duct according to the drawings, and pay attention to avoid spraying, bridges and pipelines in the underground garage.

Precast supports and hangers: The supports are made of galvanized steel. It is forbidden for carbon steel to contact stainless steel directly, and rubber/nylon pads must be added for isolation to prevent electrochemical corrosion.

Second, the steam-water installation

Horizontal duct spacing:

Long side/diameter ≤400mm: spacing ≤ 3 m.

> ＞400mm: spacing ≤ 2.5m.

Vertical air duct: bracket spacing ≤3m, and each floor shall have at least one fixed point.

Brackets and hangers must be added at elbows, tees, reducers and valves to avoid stress and deformation.

All bracket expansion bolts are firmly fixed, and stainless steel expansion bolts are preferred in wet environment of underground garage.

Third, air duct splicing and hoisting

Butt welding is adopted for air duct butt joint, and the weld seam is continuous and full, without air holes, slag inclusion and incomplete penetration.

After the welding is completed, the welding slag and splash shall be cleaned, and pickling passivation shall be done when necessary to improve the corrosion resistance.

Lifting by sections to avoid deformation caused by excessive stress at a single point; Soft slings are used for hoisting, and steel wire ropes are prohibited from directly pulling the stainless steel surface.

Installation sequence: main pipe → branch pipe → fittings → valve, ensuring straight and smooth transition.

Fourth, the installation accuracy control

The levelness deviation is ≤3‰, and the total length is not more than 20mm.

The verticality deviation is ≤2‰, and the total length is not more than 10mm.

Flange/weld shall be aligned, and the offset shall be ≤ 1/5 of the plate thickness.

Diagonal error of rectangular air duct ≤3mm.

Five, through the wall, floor, fire partition

When crossing the firewall and floor, a steel protective sleeve is set, and the thickness of the sleeve is ≥ 1.6 mm..

The air duct and the casing are sealed and compacted with incombustible flexible materials.

When crossing the fire zone, a 70℃ fire damper must be installed, close to the wall, with a separate hanger.

Interface shall not be located in the wall, wear plate section.

Six, valves, parts installation

The direction of fire damper, smoke exhaust valve and check valve must be correct, and the fusible piece should face the airflow direction.

The flexible short pipe is made of fireproof and anticorrosive materials, with a length of 150 ~ 250 mm, and shall not be twisted.

Air volume control valve, muffler and other components are provided with supports and hangers separately, so as not to make the air duct bear the load.

Seven, sealing and tightness

Underground garage ventilation is generally a medium-pressure system, so light leakage detection or air leakage test must be done.

There is no obvious air leakage at welds, flanges and joints.

The sealant adopts weather-resistant and corrosion-resistant neutral silicone adhesive, and acid adhesive is not allowed.

Eight, anti-static and anti-corrosion grounding

Stainless steel air duct system shall be connected by anti-static jumper, and the flange joint shall be connected by copper braided belt.

The whole system is reliably grounded to prevent electrostatic accumulation.

All carbon steel supports and bolts shall be protected against corrosion, so as to prevent rust from polluting stainless steel.

Nine, system debugging and finished product protection

After the installation is completed, carry out single machine commissioning and system linkage debugging.

Check whether the wind speed, air volume, noise and valve opening and closing are normal.

Avoid trampling and hitting the air duct during construction, and keep the inner wall clean.

The underground garage is damp, and it is forbidden to soak the bottom of the air duct with accumulated water.