SS 304L FastenersASTM A193 B8 · Manufacturer, stockist & exporter, India
Also sold as AISI 304L · UNS S30403 · W.Nr 1.4307 · Low-carbon 304
SS 304L fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM A193 B8 · A194 8 bar stock to ASME B18 dimensions. It is a low-carbon austenitic chromium-nickel stainless steel, chosen for welded tanks, piping and vessels in general corrosive service. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on every heat
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SS 304L Fasteners?
SS 304L fasteners is a low-carbon austenitic chromium-nickel stainless steel supplied as fasteners to ASTM A193 B8 (UNS S30403). Buyers specify it for welded tanks, piping and vessels in general corrosive service. It is also sold as AISI 304L, UNS S30403, W.Nr 1.4307.
- What it is
- Low-carbon austenitic chromium-nickel stainless steel
- Bar stock
- ASTM A193 B8 · A194 8
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- Welded tanks, piping and vessels in general corrosive service
SS 304L Fasteners Specification & Sizes
| Material | ASTM A193 B8 · A194 8 |
|---|---|
| Dimensional standards | ASME B18.2.1 (bolts) · B18.2.2 (nuts) · B18.31.2 (studs) · DIN 931 / 933 / 934 |
| Types | Stud bolt · Hex bolt · Heavy hex nut · Hex nut · Washer · Threaded rod · U-bolt · Eye bolt · Anchor bolt · Foundation bolt · Socket head cap screw · Machine screw |
| Threads | UNC, UN-8 and metric coarse |
| Coating | Plain · PTFE on request |
| Documents | EN 10204 3.1 |
SS 304L Stud Bolts: Grade & Nut Pairing
Pressure bolting in this material is ASTM A193 B8 studs with ASTM A194 8 heavy hex nuts. A193 B8-series bolting comes in Class 1 (carbide solution treated) and Class 2 (strain hardened, higher strength) — state the class.
Torque (T = K × F × d), stud length and coatings are covered in the fasteners guide.
| Galling | Stainless and nickel-alloy threads gall — always use anti-seize, and avoid high-speed tightening |
|---|---|
| Coatings | Usually supplied plain; PTFE coating on request to ease tightening |
| Marking | Grade symbol and maker's mark on each stud end and nut, as the standard requires |
| Certificates | EN 10204 3.1 for the bar heat; mechanical test reports on the finished bolts on request |
SS 304L Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 17.5 – 19.5 |
| Nickel | 8.0 – 12.0 |
| Carbon | 0.030 max |
| Manganese | 2.00 max |
| Silicon | 0.75 max |
| Nitrogen | 0.10 max |
| Phosphorus | 0.045 max |
| Sulphur | 0.030 max |
| Iron | Balance |
SS 304L Fasteners Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 485 MPa · 70 ksi |
| Yield strength 0.2% | 170 MPa · 25 ksi |
| Elongation | 40% |
| Hardness | 201 HB max |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8 g/cm³ |
| Melting range | 1400 – 1450 °C |
| Magnetic | Non-magnetic annealed |
| PREN (approx.) | ≈ 18 |
SS 304L Equivalent Grades
Values follow ASTM A240 for UNS S30403. Always check against the edition named on your purchase order.
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify SS 304L Fasteners with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. SS 304L is most often mixed up with SS 316 / 316L — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen, so it cannot tell 304 from 304L: the low carbon is confirmed by the mill certificate or optical emission (OES) testing. We PMI-test nickel alloys as standard and any grade on request.
| Element | SS 304L | SS 316 / 316L |
|---|---|---|
| Nickel | 8.0 – 12.0 | 10.0 – 14.0 |
| Chromium | 17.5 – 19.5 | 16.0 – 18.0 |
| Molybdenum | residual | 2.00 – 3.00 |
| Iron | Balance | Balance |
| Manganese | 2.00 max | 2.00 max |
SS 304L fasteners by type
SS 304L Fasteners Applications
SS 304L is specified when the cheaper grade will not survive the service but a higher alloy would be more than the job needs. These are the jobs our buyers use it for.
SS 304L Fasteners vs 304, 316L and 2205
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 304 | ASTM A193 B8 · A194 8 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 304L | ASTM A193 B8 · A194 8 | ≈ 18 | Welded tanks, piping and vessels in general corrosive service |
| SS 316 / 316L | ASTM A193 B8M · A194 8M | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| Duplex 2205 | ASTM A276 / A479 | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
SS 304L Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 304L fits.
About 18% chromium forms the passive film that makes the steel stainless.
Nickel keeps the structure austenitic — tough at low temperature and easy to form and weld.
0.030% carbon max stops carbide forming at grain boundaries during welding, so heavy welds keep their corrosion resistance.
Most mill material today is dual-certified 304/304L, meeting the strength of 304 and the carbon limit of 304L.
How your 304L fasteners order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked and material is PMI-tested before processing.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Welding & Fabricating SS 304L Fasteners
SS 304L welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ER308L (AWS A5.9) |
|---|---|
| Over-alloyed filler | ER309L for dissimilar joints |
| Preheat | Not required; keep interpass temperature low |
| Cutting | Thermal or abrasive cutting; grind off heat-tinted edges before welding |
Follow your approved WPS; this is general guidance. See also 304L fittings and 304L flanges for the matching pipe-system parts.
How to Order SS 304L Fasteners: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Fastener type, size and length
- Thread form
- Material and marking
- Quantity in sets
- Certificate type
- Delivery port and date
SS 304L fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 304L fasteners — questions buyers ask
Is SS 304L the same as AISI 304L?
Yes. AISI 304L, UNS S30403, W.Nr 1.4307 all refer to the same material, and fasteners is ordered to ASTM A193 B8 whichever name is on the enquiry.
Why use SS 304L bolts instead of B7 carbon steel?
On SS 304L flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with SS 304L stud bolts?
ASTM A194 8 heavy hex nuts.
How do I stop SS 304L bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
SS 304L or Duplex 2205 — which should I choose?
SS 304L is chosen for welded tanks, piping and vessels in general corrosive service. Duplex 2205 is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026