Which one has a longer service life, galvanized air duct or stainless steel welded air duct?

The service life of galvanized air duct and stainless steel welded air duct is influenced by many factors, such as material characteristics, use environment, maintenance and so on. The following comparative analysis from different dimensions helps to judge which one is more suitable for specific scenes:

A, material characteristics comparison

Dimension galvanized air duct stainless steel welded air duct

Basic material galvanized steel plate (carbon steel substrate+surface galvanized layer) stainless steel plate (steel containing alloy elements such as chromium and nickel)

Anti-corrosion zinc coating (the thickness of zinc coating is usually 10-100μm) can prevent rust,

However, long-term exposure to humidity and acid-base environment is easy to break and rust. Stainless steel itself contains chromium (≥12%), forming a passive film.

Corrosion resistance is significantly better than that of galvanized layer, especially acid, alkali and salt resistance.

The base material of strength and toughness is carbon steel, which has high strength, but general toughness and is easy to crack after long-term vibration. Stainless steel (such as 304/316) has high strength, good toughness and stronger impact and vibration resistance.

The high-temperature resistant galvanized layer is easy to melt and peel off at high temperature (> 300℃).

Suitable for normal temperature or medium-low temperature environment (≤250℃). Stainless steel (such as 304) can withstand 800℃ high temperature, 316L can withstand 1200℃,

Suitable for high temperature smoke, drying and other scenes.

Second, the key influencing factors of service life

1. Use environment

Wet/corrosive environment (such as basement, chemical workshop, coastal area):

Galvanized air duct: The zinc layer is easy to be corroded by chloride ions (such as seawater and sweat), resulting in "white rust" or "red rust", and its service life may be 5-10 years.

Stainless steel air duct: the passivation film has strong corrosion resistance. If the material is 316L (containing molybdenum), the service life can reach more than 20 years.

Dry/normal temperature environment (such as ordinary factory buildings, air conditioning and ventilation systems):

Galvanized air duct: low corrosion risk and 10-15 years service life under normal use.

Stainless steel air duct: almost non-corrosive, with a service life of more than 30 years, far exceeding that of galvanized air duct.

High temperature environment (such as kitchen smoke exhaust and industrial waste gas emission):

Galvanized air duct: the zinc layer falls off at high temperature, and the substrate is easy to oxidize, with a service life of 5-8 years.

Stainless steel air duct: high temperature oxidation resistance, life of 15-20 years.

2. Processing technology and maintenance

Processing technology:

Galvanized air duct: Bite connection or flange connection is mostly used, and the joints are easy to rust due to poor sealing. If the machining accuracy is low, the service life may be shortened by 20%-30%.

Stainless steel air duct: the welding process (such as argon arc welding) has good sealing performance, which reduces the risk of crevice corrosion, and the standard construction can prolong the service life by 10%-15%.

Maintenance:

Galvanized air duct: it is necessary to regularly check the damage of zinc layer and apply antirust paint, which is costly to maintain. If it is not properly maintained, its service life may be shortened to less than 5 years.

Stainless steel air duct: no special maintenance is needed in daily life, only the surface needs to be cleaned. The maintenance cost is low, and the correct maintenance can approach the theoretical life.

3. Installation scenario and load

High vibration scene (such as fan outlet, compressor pipeline):

Galvanized air duct: carbon steel has poor toughness, and long-term vibration can easily lead to cracks in welds or bites, causing corrosion, with a service life of 8-10 years.

Stainless steel air duct: good toughness, strong anti-vibration ability and life span of 15-20 years.

High-pressure air supply scenario (such as pneumatic conveying and dust removal system):

Galvanized air duct: Limited bearing capacity (usually ≤1500Pa), easy to deform and leak air under high pressure, accelerated corrosion, and life span of 6-10 years.

Stainless steel air duct: It has stronger bearing capacity (up to over 3000Pa), stable structure and service life of over 15 years.

Third, comprehensive comparison and selection suggestions

1. Life conclusion

Stainless steel welded air duct > galvanized air duct (in the same environment, the service life is usually 2-3 times that of galvanized air duct).

2. Cost and cost performance ratio

Initial cost: The price of stainless steel air duct is about 2-3 times that of galvanized air duct (for example, galvanized 40 yuan/m2, 304 stainless steel 100-150 yuan/m2).

Long-term cost: galvanized air ducts need regular maintenance and replacement, and the comprehensive cost may be higher than that of stainless steel air ducts (especially in corrosive or demanding scenarios).

3. Selection suggestions

Preferential selection of galvanized air duct:

Limited budget and short-term use (< 10 years).

Dry, non-corrosive, normal temperature ventilation scene (such as ordinary office air conditioning, temporary works).

Stainless steel welded air duct is preferred:

Long-term use (> 15 years) and high reliability requirements.

Humid/corrosive environment (such as basement, food processing and chemical industry) and high temperature scene (such as kitchen and industrial smoke exhaust).

High vibration and high pressure load scenes (such as mechanical ventilation and pneumatic conveying system).

Fourth, practical measures to prolong life

Galvanized air duct:

Choose hot galvanizing (zinc layer thickness ≥85μm) instead of cold galvanizing.

Seal the joints (such as applying sealant) and regularly check the touch-up paint.

Avoid contact with corrosive substances such as acid, alkali and salt.

Stainless steel air duct:

Made of 304/316 material and passivated after welding.

Choose high temperature resistant stainless steel (such as 310S) in high temperature scene.

Avoid contact with carbon steel (prevent electrochemical corrosion).

Summary: if long-term durability is pursued, stainless steel welded air duct is a better solution; If the budget is limited and the environmental requirements are low, galvanized air duct can be used as an economic choice. The actual selection should be combined with specific working conditions, service life expectation and comprehensive cost decision.