What matters should be paid attention to in the design, production and production of stainless steel outdoor cabinets?

Matters needing attention in the whole process of design, production and manufacture of stainless steel outdoor cabinets

1. Key points of material selection and design in the early stage (outdoor core, corrosion protection is preferred)

1. Selection and differentiation of stainless steel materials

Ordinary city outdoor (acid-free, mild rain): 304 stainless steel, rain-resistant, atmospheric oxidation, high cost performance; The thickness of the plate is usually 1.2~1.5mm for the cabinet, 1.0~1.2mm for the door frame, and ≥2.0mm or more for the base.

Coastal salt spray, chemical plant and wharf: 316L stainless steel must be used to resist chloride ion corrosion and prevent short-term rust and perforation; It is forbidden to use 201 stainless steel outdoors, which is easy to rust.

Surface of plate: outdoor priority drawing sanding plate, the mirror surface is easy to leave water stains, fingerprints, ultraviolet aging and whitening; Long-term outdoor use of polished mirrors is prohibited.

2. Structural anticorrosion design

Avoid direct contact with dissimilar metals: stainless steel screws are matched with stainless steel nut spring pads, and ordinary galvanized iron screws are prohibited, and electrochemical reaction will accelerate corrosion; The contact surface between the grounding copper bar and the cabinet is isolated by insulating gasket.

Reduce the dead angle of stagnant water: the top cover of the cabinet should have a one-way drainage slope (≥ 5), and waterproof eaves should be raised around the top cover to prevent rainwater from infiltrating along the cracks in the door and the roof; The roof is forbidden to be designed without edges.

Put an end to water storage grooves: there is no concave water storage groove at bending and splicing, and all bending corners are arc transition to reduce sediment and rainwater accumulation.

Anti-condensation due to temperature difference between cold and hot: outdoor temperature difference between day and night is large, so anti-condensation structure must be made inside the cabinet, and it cannot be completely sealed.

Second, waterproof and dustproof structure design (IP protection core)

Door panel seal

EPDM foam sealing strip is selected, which is resistant to high and low temperature and ultraviolet rays, and ordinary rubber is aged and cracked for half a year; The whole circle of continuous sealing strips has no breakpoints, and double waterproof grooves (labyrinth waterproof) are added to the door frame, and the first rainwater retaining groove is intercepted to avoid direct spraying of sealing strips.

The door lock is made of stainless steel outdoor waterproof lock, with waterproof lock cover and dust-proof waterproof glue plug in the lock hole; The hinge is 304 stainless steel exposed hinge, and the built-in hidden hinge is easy to rust and get stuck in water.

Ventilation and heat dissipation+waterproof balance (key, condensation will occur when sealed)

Waterproof vent valves/rainproof louvers+dustproof cotton filter are arranged up and down, and the louvers are inclined downward to prevent rainwater from pouring in; The cotton filter can be disassembled and replaced to stop dust mosquitoes.

High-power equipment is equipped with stainless steel rain-proof fan, with rain-proof hood on the outside and dust-proof net on the inside; It is forbidden to directly open holes without rain-proof structures.

Waterproofing of incoming and outgoing lines

Wiring at the bottom, and it is forbidden to open holes at the upper side to enter the wire; Waterproof glen head and stainless steel cable waterproof joints are adopted, rubber sealing rings are added at the openings, and weather-resistant silicone weather-resistant glue is applied at the gaps.

Drain holes are reserved at the bottom of the cabinet, and rubber dust-proof plugs are provided, so that the internal condensed water can be automatically discharged, and it is usually blocked to prevent mosquitoes.

Protection grade standard: IP54 is required for routine outdoor, IP55 is required for high humidity and rainy coastal areas, and IP56 is required for completely open-air rainy scenes.

Three, condensation prevention, temperature control design

Temperature difference solution: A constant temperature dehumidifier and a temperature and humidity controller are installed inside the cabinet, which can automatically start at low temperature and high humidity, so as to eliminate the corrosion of components caused by condensation and dripping on the inner wall.

Inner wall treatment: epoxy anticorrosive primer can be sprayed inside the cabinet, and the bare stainless steel plate is prone to condensation due to large temperature difference, and the primer reduces water vapor adsorption.

Space reservation: a heat dissipation gap of ≥20mm is reserved around the equipment and the cabinet to prevent the equipment from heating and aggravating the internal water vapor accumulation.

Four, sheet metal processing and production process matters needing attention

1. Cutting and bending process

Laser cutting: the incision is smooth and burr-free, and burrs will accumulate rainwater impurities to induce pitting corrosion; After cutting, grind all sharp corners, and at the same time remove rust and scale on the surface of the plate.

Bend the R angle uniformly to avoid water and pollution in the right-angle cracks; The bending edge of the door panel is thickened, which improves the anti-deformation ability, and the door panel is prone to warping in the outdoor wind and sun.

2. Welding process (high incidence of outdoor cabinet rust)

Welding method: full welding is adopted, and spot welding and intermittent welding are prohibited; The gap in spot welding will leak water and hide rainwater, and the short-term weld will rust.

Welding seam treatment: argon arc welding of stainless steel to reduce welding slag oxidation; After welding, pickling and passivation must be carried out to remove the oxidized black layer of the weld and restore the rust-proof ability of stainless steel; Welds that are not passivated are prone to rust.

Splicing gap: the splicing gap of the side plate, top plate and base of the cabinet is controlled to be ≤0.5mm, and the outdoor weather-resistant neutral silicone sealants is used outside the gap, with double sealing inside and outside.

3. Surface treatment process

Basic treatment: after the processing is completed, the whole oil is removed, the welding spots are removed, and the passivation and corrosion protection film is formed, which greatly improves the outdoor service life.

Coloring requirements: If outdoor paint needs to be sprayed, epoxy primer must be sprayed first, and then outdoor polyurethane topcoat; Ordinary paint peels off after half a year; Direct painting on stainless steel surface is prohibited.

Fingerprint processing: fingerprint-free wire drawing can be done to reduce the adhesion of rainwater scale and make daily maintenance easier.

Five, base, installation load-bearing and outdoor wind-resistant design

Stainless steel base of floor cabinet: thick stainless steel square pipe welded, height ≥150mm, isolated from ground rain, water and sediment; The base is fully welded and passivated, and drainage space is reserved at the bottom.

Wall-mounted cabinet: it is equipped with 304 stainless steel wall-mounted bracket, thickened load-bearing steel plate, and the bracket is bent with reinforcing ribs to prevent strong wind and equipment weight from deforming and falling off; Stainless steel expansion bolts are selected for the wall fixing bolts.

Wind-resistant reinforcement: For high-rise buildings and open-air scenes, the back of the cabinet is provided with reinforcing ribs, the top cover is thickened, and the door panel is provided with reinforcing square tubes to avoid deformation and sealing failure of the door panel caused by strong wind.

Six, accessories, hardware selection all stainless steel.

Standard parts: all screws, hinges, locking rods, buckles and grounding bolts are made of 304/316 stainless steel, and no iron fittings are allowed.

Seals: only EPDM, PVC and ordinary rubber are aged, cracked and leaked for one year outdoors.

Vent valves, fans and glen head are all made of outdoor waterproof industrial grade, and ordinary indoor fittings are not applicable.

Seven, grounding, electrical safety design

Stainless steel grounding braid is installed between the cabinet, door panel and base to ensure the whole equipotential grounding and prevent the equipment from being damaged by lightning static electricity.

The grounding bolt is thick and matched with stainless steel elastic pad to avoid long-term outdoor loose contact; Grounding terminals are reserved outside the cabinet to facilitate outdoor lightning protection and grounding construction.

Internal wiring partition, strong and weak electricity separation, wiring bracket is made of stainless steel, and plastic bracket is not used for long-term high-temperature aging.

Eight, late assembly, inspection and factory protection

Assembly: the sealing strip is flat without stretching and breaking, and the whole circle of rubber strips is evenly attached without gap after the door panel is closed; The door lock opens and closes smoothly without jamming.

Factory inspection:

Waterproof rain test: simulate outdoor rain, and check that there is no water seepage in the door crack, opening and weld;

Salt spray sampling inspection (required for coastal 316L cabinets);

Inspection of opening and closing durability and sealing integrity.

Packaging protection: the finished product is attached with protective film, and corner protectors are installed to avoid scratching the passivation layer during transportation; The protective film is outdoor tearable, and there is no glue stain left after long-term storage.

Nine, outdoor use environment targeted supplementary matters needing attention

High temperature exposure area: the cabinet can be added with a sunshade top cover to reduce the aging of the sealing strip accelerated by high temperature inside; Avoid direct sunlight to accelerate the aging of paint surface and adhesive tape.

Cold area: increase the power of heater, and choose low-temperature resistant sealing tape to prevent the sealing effect from becoming hard at low temperature.

Dust mining area and farmland: increase the area of dust-proof cotton filter, and reserve a quick replacement cotton filter access.

Chemical corrosion plant area: upgrade the 316L material, thicken the anti-corrosion coating on the inner wall, and reduce the exposed welding gaps.

Ten, common production mistakes to avoid pit summary

Replace 304/316 with 201 stainless steel, which will rust and be scrapped in a short time;

Spot welding replaces full welding, the weld is not passivated, and the weld is corroded and leaked;

Using ordinary rubber sealing strip, it cracks and leaks within 1 year;

Completely sealed without vent valve, and a large amount of condensation inside corrodes the equipment;

Iron screws and hardware produce electrochemical reaction to corrode the cabinet;

The roof has no drainage eaves and flat top cover, and rainwater directly penetrates into the crack of the door;

There is no raised base at the bottom, and the bottom of the cabinet is rusted by ground rain.