Galvanized ventilation pipes are widely used as ducts in industrial and domestic systems. On them, fresh air is supplied to the premises, and the exhaust is removed. Galvanized ducts are classified as rigid and are characterized by high aerodynamic properties. They are easy to transport and install, they are not subject to corrosion. The average service life of galvanized ventilation pipes is 10 years.
Galvanized pipes can form the basis of ventilation systems for residential buildings, offices, public buildings, restaurants and shops, industrial enterprises. They are suitable for central and roof climate systems.
This type of duct is optimal if the system does not plan to allow very hot, humid, or air filled with aggressive vapors.
Types and classes of tightness of a ventilation galvanized pipe
Sectional shape. Galvanized ventilation pipe varies in cross-sectional shape and manufacturing principle:
- straight-seam round;
- spiral-wound round;
- rectangular.
When connecting round straight-line and spiral-welded pipes, nipples are used. Rectangular pipes are made with a flangeless or flange connection.
Properties of galvanized steel ducts:
- light weight;
- low price;
- You can create systems of any configuration;
- ease of installation and service;
- durability.
Galvanized pipes are used to move airflows with humidity up to 60% and temperature up to 80 degrees Celsius.
The zinc layer on the steel sheet is applied by the hot method, creating a zinc film, which is strong and very resistant to aggressive environments. It even withstands contact with aldehyde resins and acid fumes.
For the installation of ventilation systems according to SNiP 2.04.05 - 91, galvanized ventilation pipes of classes P (dense) or H (normal) are used. Dense galvanized ventilation pipes are characterized by increased tightness. Permissible values of air leakage are indicated in SNiP.
Tight galvanized pipes (P) used in ventilation or heating systems with a pressure of 1.4 kPa, in rooms of fire and explosion hazard categories A and B, regardless of the pressure in the system.
Normal galvanized pipes (N) install in any other cases. Small air leaks from the system are allowed.
In the manufacture of galvanized pipes for ventilation of rectangular cross-section of class P, a special sealant is used, applied at the attachment point of the flange and duct. Longitudinal seams are rolled up in tunneling machines providing the highest possible density. On request, some manufacturers also process longitudinal internal joints with sealant.
Spiral ventilation pipe
Spiral ventilation pipes made of galvanized steel are made on machines from a galvanized strip 137 mm wide, twisted in the form of a spiral. The edges of the strip are connected by the type of lock fastening. The seam is outside. Due to the special structure (stiffening ribs), a pipe of this type is very strong, light. The tightness class of spiral-wound pipes is P, it is provided by silicone sealant that processes the joints.
Advantages of spiral-wound ventilation pipes:
- reinforced stiffness;
- simple installation;
- cheaper installation due to savings on fittings;
- the possibility of manufacturing custom-made segments up to 12 meters.
Pieces of pipes are attached to each other with nipples. If it is necessary to connect a pipe section with a shaped element, a nipple is not needed. Flange mounts can also be used.
Passing through such an air duct, the flow receives an additional turbulence and moves faster, producing less noise. The cost of spiral-wound pipes is lower than rectangular pipes, so they are becoming more widespread in construction.
In the manufacture of galvanized pipes for ventilation, steel is used with a thickness depending on the diameter of the pipe:
- 0.55 mm - for a galvanized ventilation pipe 150 - 355 mm;
- 0.7 mm - for a pipe with a diameter of 400 - 800 mm;
- 1 mm - for pipes with a diameter of 900 - 1250 mm.
Usually, sections of a galvanized pipe 200 of 3 or 6 meters are on sale, but for special types of ventilation, the manufacturer can make an air duct of arbitrary length on request.
On request, spiral-welded galvanized steel pipes for ventilation are reinforced with additional stiffeners.
Longitudinal galvanized round pipe for ventilation
Longitudinal galvanized air ducts are made from a sheet of steel, the edges of which are fastened with a nipple connection. Tailored flanged pipes are also available on special order. Steel sheet is cut automatically, on the machine. If a non-standard sized galvanized ventilation pipe 200 is needed, the material is marked and cut on a manual guillotine. Next, the pattern is fed to electric rollers, here it is wrapped in a tube of the required diameter, rolled and sent to a folding mill. The folds are deposited along the entire length of the longitudinal edge of the pipe. Watch the entire manufacturing process on the video.
Such air ducts are used in ventilation systems consisting of small ventilation ducts, as a rule, in private construction.
Standard lengths of longitudinal welded galvanized ventilation pipe - 1.25 m, but not more than 2.5 m. Between themselves, the segments are fastened with fittings. For tightness, joints are treated with sealant or laid with rubber seals.
Advantages of longitudinally galvanized pipes for ventilation:
- relatively inexpensive (compared to rectangular);
- have the best aerodynamic characteristics;
- more "quiet";
- provide the fastest movement of air streams;
- light weight;
- mounted lighter than rectangular.
The wall thickness of longitudinal pipes depends on their diameter. So for a galvanized ventilation pipe 150 mm - 350 mm, steel sheets with a thickness of 0.55 mm are used. A 300 mm galvanized ventilation pipe is sometimes made of 0.7 mm thick steel on request. Air ducts with a diameter of 800 mm or more are 1 mm thick steel.
Rectangular Galvanized Tube
Rectangular galvanized steel ventilation pipes are produced on automatic machines of tunnel assembly from sheet metal with a thickness of 0.55 - 1.0 mm. The larger the diameter of the section, the thicker the material is selected. The minimum diameter of the duct is 10 x 10 cm, the maximum is not limited.
The production of galvanized rectangular pipes for ventilation is carried out in several stages:
- Sheet steel is fed to an automatic line for bending and forming stiffeners. Pipes with a non-rolled longitudinal lock exit the line;
- A longitudinal lock is clamped on the longitudinal assembly apparatus. In one step, a fold is created that closes and rolls;
- A flange from a bus rail is put on and fastened to the edge of the pipe. A corner is put on it. For tightness, it is treated with silicone.
The connection is provided by a flange from a busbar; by customer request, a flangeless connection is possible or by means of a flange from a steel corner.
Additional reinforcement of the ventilation rectangular galvanized pipe is necessary for cross-sectional sides from 400 to 1000 mm and is provided by stiffeners. The metal is bent in the transverse direction or in the form of crosses every 20 to 30 cm.
Rectangular galvanized pipes are suitable for any ventilation, since with a standard length of 1.25 m, you can order pieces from 1 to 2.5 m.
Rectangular galvanized air ducts are made of tightness classes N and P. Class P by order of customers. In contrast to class P, a small air leak is allowed in class H products. High tightness of the air ducts P is achieved by treating the flange with the sealant and the longitudinal joint. By order of customers, the longitudinal seam is also covered inside the pipe. However, the tightly rolled seam and lock provide a sufficient level of tightness even without special treatments.
Rectangular galvanized ventilation pipes of 300 mm and other diameters serve for a long time, reliably resist corrosion. But operating rules imply periodic cleaning and checking the condition of the internal surfaces of the ducts.
Shaped elements for galvanized pipe ducts
For connection, turns and branches of ventilation from galvanized pipes 150, shaped elements are used.
Shaped products include:
- tees;
- transitions;
- bends;
- umbrellas;
- corners;
- tires;
- crosses;
- sidebars.
They are made of rectangular cross section or round, of various diameters for galvanized ventilation pipes 200 and any other sizes. Sometimes, when installing complex ventilation systems, shaped elements are used more than pipes.
Which galvanizing section to choose: rectangular or round?
A rectangular section is more practical, since its cross-sectional area is larger than a round one. If very large boxes are mounted, it is best to make them rectangular or square so that the worker can penetrate inside for cleaning and maintenance. Rectangular pipes are easier to clean.
But, if air filled with dust, sawdust or other impurities passes through the ventilation system, a round section is preferable to avoid accumulation of debris in the ribs and corners of the pipes.
Rectangular ducts are more durable than round ones.
Galvanized pipes for ventilation 300 round cross-section have sound-absorbing qualities, while rectangular pipes on the contrary create a larger hum.
