SS 316 Fasteners Supplier in Ahmedabad

JMIKS Fasteners supplies SS 316 fasteners for places where SS 304 is not enough: near the sea, in chemical and pharma plants, and wherever chlorides are present. SS 316 is often called marine grade stainless steel. We are a fastener wholesaler and supplier in Nava Odhav, Ahmedabad, since 2014.

What Molybdenum Adds

SS 316 is an austenitic stainless steel with 16 to 18 % chromium, 10 to 14 % nickel and 2 to 3 % molybdenum. Molybdenum strengthens the oxide film where chlorides attack it, so SS 316 resists pitting and crevice corrosion far better than SS 304.

The pitting resistance number, PREN = % Cr + 3.3 × % Mo + 16 × % N, is typically about 24 for SS 316 against about 19 for SS 304. 316L, with 0.03 % carbon at most, is the low-carbon version for welded parts.

A4 Marking and Strength

Under ISO 3506-1, SS 316 fasteners are marked A4: “A” for austenitic, “4” for the molybdenum group.

• A4-70: cold worked, 700 MPa minimum tensile and 450 MPa yield strength; the usual class for bolts.
• A4-80: strongly cold worked, 800 MPa tensile and 600 MPa yield.

These equal A2-70 and A2-80: SS 316 buys corrosion resistance, not strength. Low-carbon fasteners may be marked A4L, and the ASTM A193 stud grade for SS 316 is B8M.

Where SS 316 Is Worth It

• Marine and coastal: jetties, boats, salt works, desalination plants and anything within reach of salt spray.
• Coastal solar and electrical: module clamps, junction boxes and outdoor panels.
• Chemical and fertiliser plants: pipe supports, flanges, tanks and walkways.
• Pharma and food plants: equipment washed with chlorinated or acidic cleaners.
• Water and effluent treatment: chlorine dosing areas and pump houses.
• Swimming pools: ladders, rails and fittings that are cleaned often.

Where Even SS 316 Struggles

SS 316 is more resistant, not immune.

• Warm chloride solutions above about 60 °C can crack stressed parts (stress corrosion cracking).
• Stagnant sea water in tight gaps, such as under washers, can cause crevice corrosion.
• Hydrochloric acid and other strong reducing acids attack it.
• Hidden load-bearing fixings above indoor pools need higher-alloy grades under EN 1993-1-4.

In these cases, follow your designer’s choice of material.

SS 316 or SS 304: Worth the Extra Cost?

SS 316 costs noticeably more than SS 304, because molybdenum and the extra nickel are costly. On a dry inland site it adds little. Near the sea or chemicals it lasts much longer, which usually repays the higher first cost.

Use SS 316 for the whole set: an SS 304 nut or SS 202 washer on an SS 316 bolt becomes the weak point. Our grade comparison guide covers all three.

Telling SS 316 from SS 304

SS 316 stays almost non-magnetic after cold forming, as its higher nickel keeps the steel stable, while SS 304 often turns slightly magnetic. Even so, a magnet cannot prove the grade, because some SS 304 parts are non-magnetic too. The A4 marking and a chemical test can.

SS 316 threads can also gall (seize) when tightened fast and dry: use anti-seize and tighten steadily, as our SS 304 fasteners page explains.

SS 316 Fasteners from JMIKS

These are listed in SS 316, grouped by use:

• Marine and coastal: hex bolts, hex nuts, nylock nuts, plain washers, spring washers and U bolts for pipes.
• Chemical, pharma and process plants: Allen cap screws, dome nuts, SS stud bolts, half threaded studs, B8M studs for pipeline flanges, and DIN 975 full threaded studs (see studs and threaded rods).
• Coastal solar and public fittings: anti-theft bolts, security shear nuts, flange bolts, flange nuts and wedge lock washers.
• Everything else: every other screw, nut, washer and special bolt in our bolts, nuts, washers and special type bolts ranges is listed in SS 316 too, except grub screws.

Sizes: M3 to M36 and 1/4″ to 1-1/4″ BSW; each product page gives its exact range.

SS 316 Fastener FAQs

Is SS 316 stronger than SS 304?

No. A4-70 and A2-70 share the same minimums: 700 MPa tensile and 450 MPa yield strength. You pay for corrosion resistance. For more strength, use coated high tensile bolts.

Can SS 316 fasteners rust in sea water?

Far less than SS 304, but it is not immune: stagnant sea water in tight gaps and warm chlorides can still attack it. Joints that drain and fresh water rinsing help.

What is the difference between SS 316 and SS 316L?

SS 316L has a lower carbon limit, 0.03 % against 0.08 %, which protects welded zones. Bolts and nuts are not welded, so standard SS 316 is usual. Low-carbon fasteners may be marked A4L.

Are B8M studs SS 316?

Yes. ASTM A193 B8M is the SS 316 stud grade, for flanges and valves exposed to chlorides or chemicals; B8 is the SS 304 version. See our B7 and B8 stud bolt page.

How do I check that bolts are really SS 316?

Look for the A4 head marking. A magnet cannot tell SS 316 from SS 304. For critical work, a chemical test such as a portable XRF analyser confirms the 2 to 3 % molybdenum.

Get a Quote for SS 316 Fasteners

Send the product, size, grade and quantity on WhatsApp +91 90333 11425, use our enquiry form, or download the catalogue (PDF). We reply within one working day, Monday to Saturday, 10 am to 8 pm.