Stainless Steel Axial Fan Manufacturer: SS 304 and SS 316 for Corrosive, Humid and Coastal Air
NextAir Systems, Faridabad, India. Last reviewed October 2026.
A fan in the wrong metal fails slowly, and the failure is usually noticed as noise or vibration before anyone sees the rust. Impellers lose material unevenly, balance goes, bearings suffer, and the fan that was selected on airflow is replaced on cost. Choosing the material is as much a part of selection as choosing the diameter.
NextAir builds industrial axial fans up to 1,600 mm in mild steel, stainless steel 304 and stainless steel 316. Where the atmosphere is corrosive, humid or coastal, we build in SS 304 or SS 316, with SS 316 the better choice where chlorides are present. This page explains the difference and what to check.
At a glance
- We build in mild steel for general ventilation, SS 304 and SS 316 where the air is corrosive, humid or coastal, with SS 316 better where chlorides are present.
- A pitting resistance equivalent number (PREN = %Cr + 3.3 x %Mo + 16 x %N) gives a rough ranking. Typical figures are about 19 for 304 and about 24 for 316, because of the molybdenum.
- Welded stainless needs its welds cleaned and passivated to keep its corrosion resistance. Ask how this is done.
- Fans up to 1,600 mm, 2,400 Pa, 185,000 m³/h and 100 HP can be built in stainless steel; ATEX and AMCA 99 spark-resistant fans are outside what we build.
Why 316 for chlorides
Stainless steel resists corrosion because of a thin chromium oxide film on its surface. Chlorides, from sea air, salt spray, brine and many chemicals, attack that film locally and cause pitting. Grade 316 contains molybdenum, which makes the film more resistant, and is the usual choice in coastal and chloride-bearing air. Grade 304 is a good general stainless steel for humid, mildly corrosive or washdown conditions without chlorides.
| Grade | Typical Cr (%) | Typical Mo (%) | Approximate PREN (Cr + 3.3 Mo) | Where it suits |
|---|---|---|---|---|
| Mild steel | 0 | 0 | 0 | General, dry ventilation |
| SS 304 | 18 | 0 | 18 to 19 | Humid, mild corrosion, washdown without chlorides |
| SS 316 | 16 to 18 | 2 to 2.5 | about 24 | Coastal, chloride-bearing, more corrosive air |
The compositions are typical ranges, and PREN is a rough comparison and not a guarantee, since pitting also depends on temperature, crevices and surface finish. The ranking is the useful part: SS 316 is meaningfully more resistant to chloride pitting than SS 304, and mild steel has no chloride resistance at all. Our guide to corrosion-resistant axial fans goes further.
What is made of stainless
A fan has an impeller, a casing, a frame, fasteners and often a guard. A stainless impeller in a mild steel casing will still corrode at the casing. Ask which parts are stainless, and ask about fasteners, because a mild steel bolt in a stainless flange corrodes and stains. We fabricate impellers, casings and frames in our own factory, with MIG welding lines and TIG welding lines for mild steel and stainless steel, hydraulic shearing machines for cutting sheet and plate, and a hydraulic press brake for bending, so parts can follow your installation.
Welds and finish
Welding heats stainless steel and leaves a heat-tinted zone with reduced corrosion resistance. Cleaning the weld, by pickling or mechanical finishing and passivation, restores it. A quotation should say how the welds are treated. A fan that looks bright from the factory but has untreated welds can start to stain at the joints within a season in a coastal site. Impellers are dynamically balanced on our own computerised machines before they are fitted, and balance is checked after any welding, since the vibration limits for ventilation fans are in fan vibration and ISO 14694.
Thermal and mechanical differences
Stainless steel expands more with heat than carbon steel: about 17 µm/m·K for 304 against about 12 for carbon steel. For ventilation duty at ordinary temperatures it hardly matters, but for fans running hot the clearances between impeller and casing must allow for it. Stainless is also not harder wearing than mild steel, so abrasive dust needs its own protection, and the range limits stay as they are: up to 1,600 mm, 2,400 Pa, 185,000 m³/h and 100 HP, as separate limits and not one duty point. See our axial fan manufacturer page for the range.
A practical test of any stainless fan quotation is to ask for the material certificates of the sheet and plate used for the impeller and casing, and for the fasteners. A mixed-up grade is a real risk in a busy workshop, a 304 plate where 316 was specified, and a certificate trail is the way to show that the fan in the crate is the fan that was ordered. Ask also how the finished fan is packed and stored on site, since carbon steel dust from nearby work embedded in stainless surfaces can start surface rust.
Cost, delivery and drive
Stainless costs more than mild steel, and the right way to judge it is cost per year of life, as in the comparison in stainless steel centrifugal blowers. We build direct drive and belt drive, and fans ship fully assembled, partially assembled or as CKD kits for assembly on site. Motors and variable frequency drives are bought-out items, selected and matched to each fan.
To compare suppliers use how to choose an axial fan manufacturer.
What to send us for a quotation
- The atmosphere: humidity, salt, chlorides, chemicals, and the temperature
- Airflow and static pressure at the duty point
- Which parts must be stainless
- Drive preference and the delivery format you want
- Voltage and frequency
- Any washdown or hygiene requirement
Send these to us through our contact page and we will confirm the duty is inside our range and propose the grade. If you have a failed fan to show us, photographs of the corrosion and the age of the fan help us see which grade and which parts were the problem. See the axial fan range and our guide to industrial axial fans. Stainless fans are common in chemical and petrochemical plants and coastal power generation, and our notes for Oman and Qatar cover coastal conditions.
Types and variants we build
- Belt-Driven Large-Diameter Axial Fan Supplier: Pulley Ratios, Tip Speed and Trimming Speed on Site
Belt-driven axial fans up to 1,600 mm: how a pulley ratio sets speed, what it does to tip speed, noise and power, and why belts let you trim on site. - Roof Extraction and Wall Axial Fan Manufacturer: Sizing Against Wind and Make-Up Air
Roof and wall axial fans for factory and warehouse ventilation: how wind pressure cuts a wall fan airflow, with a calculated table, and why make-up air matters. - Stainless Steel Axial Fan Manufacturer: SS 304 and SS 316 for Corrosive, Humid and Coastal Air
Stainless steel axial fans in SS 304 and SS 316 up to 1,600 mm: choosing the grade, what pitting resistance numbers mean, and what to check on welds and finish.
Frequently Asked Questions
What stainless grades do you build axial fans in?
SS 304 and SS 316, as well as mild steel. SS 316 is the better choice where chlorides are present.
When do I need SS 316 and not SS 304?
For coastal air, salt spray, brine or chloride-bearing chemicals, where molybdenum in 316 gives much better resistance to pitting.
Are welds a weak point in stainless fans?
Untreated welds can lose corrosion resistance. Ask how they are cleaned and passivated.
Are stainless fans more wear-resistant?
No. Stainless is no more resistant to abrasion than mild steel, so abrasive dust needs its own protection.
What is your largest stainless fan?
The range limits are the same: up to 1,600 mm, 2,400 Pa, 185,000 m³/h and 100 HP, as separate limits and not one duty point.
Talk to Our Engineering Team
Call +91-9311805618 or use our contact form for a facility-specific recommendation.
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