SS 304 vs SS 316 Wire Mesh: Which Grade to Specify
The real difference between SS 304 and SS 316 wire mesh: molybdenum, chloride resistance, cost, L grades, and where each one fits in plant service.
SS 304 and SS 316 look the same, weave the same and are often quoted side by side. The difference sits in the chemistry, and it matters most when chlorides are present: salt, brine, sea air, chlorinated water or some cleaning chemicals. Picking 304 where 316 is needed leads to pitting. Picking 316 where 304 is enough adds cost for no gain.
Composition difference
Both are austenitic stainless steels in the 300 series. The key addition in 316 is molybdenum, at about 2 to 3%. 316 also carries a little less chromium and more nickel than 304. Typical limits are shown below. Exact ranges depend on the standard the wire is made to, so check against the IS or ASTM standard on your drawing and the mill certificate. A fuller table is on the SS chemical composition page.
| Grade | Carbon max (%) | Chromium (%) | Nickel (%) | Molybdenum (%) |
|---|---|---|---|---|
| 304 | 0.08 | 18.0 to 20.0 | 8.0 to 10.5 | none |
| 304L | 0.03 | 18.0 to 20.0 | 8.0 to 12.0 | none |
| 316 | 0.08 | 16.0 to 18.0 | 10.0 to 14.0 | 2.0 to 3.0 |
| 316L | 0.03 | 16.0 to 18.0 | 10.0 to 14.0 | 2.0 to 3.0 |
Chloride resistance
Molybdenum improves resistance to pitting and crevice corrosion, the localised attack that chlorides cause. One common way to compare grades is the pitting resistance equivalent number.
PREN = %Cr + 3.3 × %Mo + 16 × %N
With typical compositions, 304 comes out at roughly 18 to 20 and 316 at roughly 23 to 25. Higher is better. In wire mesh this matters more than in thick plate, because the wires are thin and a pit can cut through a wire quickly. Crevices also exist at every wire crossing, where deposits and liquid can sit.
Neither grade is immune. In warm chloride service, roughly above 50 to 60°C, both 304 and 316 can suffer chloride stress corrosion cracking. Strong chloride duties such as hot brine or seawater immersion may need duplex or higher alloy grades, which is a question for your process or corrosion engineer.
On cost, 316 normally costs more than 304 because molybdenum and the extra nickel are expensive. The gap moves with nickel and molybdenum prices, so compare current quotes rather than using a fixed percentage. On a large screen or a long fencing run, the grade choice can be a significant part of the material cost.
Where each grade fits
- 304: dry sieving, general food handling without salt or strong acids, indoor guards and architectural mesh, insect screens, most water filtration with low chloride, general plant use away from the coast.
- 316: coastal and marine sites, brine and salted food processing, chlorinated or recycled water, fertiliser and chemical plants with chloride exposure, and pharmaceutical equipment where 316L is often the specified grade.
- Food and pharma: both grades are used. The duty, cleaning chemicals and the customer or regulatory specification usually decide it.
What the L grades are for
304L and 316L have lower carbon, 0.03% maximum. During welding, carbon in standard grades can combine with chromium near the weld and leave that zone open to intergranular corrosion, called sensitisation. Low carbon reduces this risk. Woven cloth itself is not welded, but welded mesh, filter elements with welded seams and mesh welded into frames benefit from L grades. Pharma and many process specifications call for 316L by default.
Checking what you received
A magnet test is not reliable. Both grades can become slightly magnetic after cold working, and fine woven wire is heavily cold worked. Ask for a mill test certificate tied to the wire heat, and use PMI (positive material identification) testing if the grade is critical. For comparison with coated carbon steel, see galvanised vs stainless steel.
Gujarat Wire Nettings supplies wire mesh in SS 304, 304L, 316 and 316L. Tell us the duty, chloride exposure and any customer specification, and we will quote the grade and documents you need.
