Stainless Steel Bolts Supplier India | SS304 SS316 | Hex Carriage Socket Flange | M3–M20 | DIN ISO ASTM | A2 A4

Name: Kelor Valves
Address: IN
Price range: $$

Stainless Steel Bolts Supplier India — Krishna Industries (KELOR), Ahmedabad

B2B supplier of SS Bolts in all types and grades — SS304 (A2) / SS316 (A4) / Duplex / Nickel Alloy — Hex Head · Carriage · Socket Cap · Socket Thin Head · Socket Low Head · Hex Flange · Hex Lag · T-Bolt — M3 to M20 & 1/8″ to 3/4″ — 6 mm to 200 mm — DIN / ISO / JIS / ASME / ASTM / IS / BSW standards.

MTC on Request · MOQ 10 Nos · GST Invoice (GSTIN: 24AKLPP6499B1ZT) · Pan India Dispatch from Ahmedabad · 2-Hour Quote

A stainless steel bolt (SS bolt) is an externally threaded fastener with a head — used in conjunction with a nut or threaded hole to clamp components together. Unlike a screw, a bolt is designed to pass through clearance holes in both clamped components and be secured by a nut on the opposite side, providing a removable and re-torquable joint. Stainless steel grades — primarily SS304 (A2) and SS316 (A4) — provide corrosion resistance that carbon steel, zinc-plated, or hot-dipped galvanised bolts cannot match in outdoor, marine, chemical, and coastal environments.

Krishna Industries (KELOR), based in Ahmedabad, Gujarat, supplies the complete range of stainless steel bolts — all head types, all standards, all grades — to EPC contractors, structural fabricators, OEM manufacturers, marine fitout contractors, and industrial buyers across India. We also supply SS washers, SS threaded rods & stud bolts, stud bolts, and eye bolts from the same stock. GST invoice. MOQ 10 Nos. Pan India dispatch.

Bolt vs Screw — Understanding the Distinction

The terms “bolt” and “screw” are used interchangeably in India but have a technically important distinction that affects correct specification:

Feature	Bolt	Screw
Installation	Passes through clearance holes in both components — nut provides clamping on the opposite side	Threads directly into a tapped hole, material, or substrate — no nut needed
Thread engagement	Full thread engagement via nut — more predictable preload and clamping force	Thread in substrate — engagement depth depends on material thickness and hardness
Removal	Remove nut to disassemble — bolt reusable indefinitely	Repeated removal may damage threads in substrate
Load bearing	Higher — bolt + nut combination has defined, engineered joint preload per torque table	Lower — thread in substrate can strip; not suitable for high-load structural joints
Standards	DIN 931 (partial thread), DIN 933 (full thread), ASME B18.2.1	DIN 912 (socket cap), DIN 7982 (self-tapping), ASME B18.3
Key Note	All items on this page are bolts — they all require nuts for assembly	See our SS Screws page for self-tapping, socket, and machine screws

DIN 931 vs DIN 933 — Partial Thread vs Full Thread Hex Bolt

The single most commonly confused specification in hex bolt procurement in India. Wrong specification results in bolts that either don’t fit the joint geometry or don’t provide the required grip length.

Feature	DIN 931 (Partially Threaded)	DIN 933 (Fully Threaded)
Thread Coverage	Threaded for approximately 2× diameter from the tip — plain (unthreaded) shank under the head	Threaded full length from tip to head bearing face
Plain Shank	✅ Present — shank diameter equals bolt nominal diameter	❌ No plain shank — fully threaded end to end
Grip Length	Plain shank provides defined grip length — critical for shear load applications where the shank (not thread) carries shear	Thread runs through the full joint — no defined shear plane in plain shank
Structural Joints	✅ Preferred — plain shank in shear plane is the correct structural bolt design per IS 800, AISC	⚠️ Thread in shear plane — weaker in shear; not preferred for structural connections
Adjustability	Limited — nut position constrained by thread length	✅ Nut can be positioned anywhere along the full length — ideal for adjustable connections and varying grip lengths
Availability	Available from M8 onwards — short lengths not possible	Available from M3 — full range of short lengths including M3×6 to M3×30
Specify For	Structural steel connections, machinery bolting, pipe flange assembly (where grip length must be controlled), standard M8 and above general industrial use	All small bolt sizes (M3–M6), adjustable connections, channel-frame assembly, general non-structural use where full-length threading is an advantage

⚠️ For pressure flanges (ASME B16.5): Do not use hex bolts (DIN 931/933) for ASME pressure flange assembly. ASME B16.5 requires stud bolts (threaded both ends, plain shank centre) per ASME B7/B7M, not hex bolts. See our Stud Bolt & Threaded Rod page for ASME pressure flange stud bolts.

Types of Stainless Steel Bolts — When to Specify Each

Hex Head Bolt (Hex Bolt)

Most Common · DIN 931 / DIN 933

Six-sided hexagonal head — tightened with standard open-end spanner, ring spanner, or socket
The universal general-purpose industrial bolt type
DIN 931: partially threaded (grip shank + threaded end)
DIN 933: fully threaded from head to tip
Available M3 to M20 in SS304 (A2) and SS316 (A4)
Specify for: structural connections, pipe flanges (non-ASME), machinery, general industrial assembly

Carriage Bolt (Round Head Square Neck)

Tamper-Resistant Timber · DIN 603

Domed round head — no drive recess; cannot be tightened from bolt head side
Square neck locks into square hole in timber or thin metal — prevents rotation
Provides tamper resistance — nut side only access
SS316 preferred for outdoor and decking applications
Specify for: timber decking to steel frame, outdoor furniture, playground equipment, marine timber structures

Socket Cap Screw / Bolt

High Strength · DIN 912 / ISO 4762

Cylindrical head with internal hexagonal (Allen key) socket drive — high torque, compact profile
Higher tensile strength than standard hex bolts of same nominal size
Standard for machine guards, process equipment, jigs and fixtures
Available M3 to M20 in SS304 (A2-70) and SS316 (A4-80)
Specify for: precision assemblies, machine guards, process equipment panels, pump casings

Socket Thin Head Bolt

Space-Saving · DIN 7984

Reduced head height (~60% of standard DIN 912)
Lower profile for restricted vertical clearance
Specify for: electronics housings, thin panel assemblies, sealed equipment enclosures

Socket Low Head Bolt

Ultra Low Profile · DIN 6912

Head height ~40% of standard DIN 912 with larger diameter drive
Specify for: precision machinery, electronic enclosures, medical equipment

Hex Flange Bolt (Hex Washer Head)

No Separate Washer · DIN 6921

Integral circular flange under head — eliminates need for separate washer
Serrated variant resists loosening under vibration
Specify for: automotive, sheet metal, HVAC, thin-wall sections

Hex Lag Bolt (Lag Screw)

Heavy Timber · DIN 571

Large hex head with coarse wood-screw thread — threads directly into timber, no nut needed
SS316 required for outdoor and treated timber
Specify for: heavy timber connections, decking, marine timber structures

T-Bolt (Hammer Head Bolt)

Channel Frame · DIN 787

T-shaped head inserts into strut channel slot — locks when nut tightened
Infinite adjustment along channel — no precise hole drilling needed
SS316 for outdoor, coastal solar, marine installations
Specify for: Unistrut pipe supports, cable tray, HVAC suspension, solar panel mounting

SS Grade Selection Guide — SS304 vs SS316 vs Duplex

Grade	Designation	Key Property	✅ Specify For	❌ Not For
SS304 (A2)	AISI 304 / DIN 1.4301 / UNS S30400	18% Cr + 8% Ni — general corrosion resistance	Indoor machinery, HVAC, food non-GMP, general engineering — most economical SS grade	Marine, coastal, seawater, ACQ treated timber, chemical with chlorides
SS316 (A4)	AISI 316 / DIN 1.4401 / UNS S31600	18% Cr + 10% Ni + 2–3% Mo — chloride pitting resistance	Marine, coastal, offshore, seawater, chemical plant, ACQ treated timber, food GMP, pharma cleanroom	Budget indoor — 20–30% premium over SS304
SS316L	AISI 316L / DIN 1.4404 / UNS S31603	Low carbon — improved weld zone corrosion resistance	Welded SS assemblies in corrosive service — pharma, food GMP, chemical process	Non-welded standard bolting — specify 316 unless welded
Duplex 2205	UNS S32205 / DIN 1.4462	Dual-phase high strength + chloride pitting resistance	Offshore structural, desalination, seawater infrastructure	Standard industrial — over-specified for typical use
Nickel Alloy	Monel 400 / Alloy 600 / 625	Extreme corrosion — seawater, acids, alkalis	Seawater submerged, chemical acid flanges, offshore splash zone	Standard construction — specify only where SS316 inadequate

Property Class Guide — A2-70, A4-80, A4-100

ISO 3506 property classes define both the material and mechanical strength of the bolt. Always specify both material grade AND property class.

Property Class	Material	Min. Tensile (MPa)	Min. Yield (MPa)	Specify For
A2-70	SS304	700	450	Standard general-purpose SS304 bolting
A2-80	SS304 (work-hardened)	800	600	Higher-load SS304 structural connections
A4-70	SS316	700	450	Standard SS316 in corrosive environments
A4-80	SS316	800	600	High-strength SS316 — marine, chemical, food GMP
A4-100	SS316 (work-hardened)	1000	800	High-load offshore, structural, chemical plant

SS Hex Bolt Dimensions — DIN 933 (Fully Threaded)

Reference dimensions for SS304 and SS316 hex bolts per DIN 933 / ISO 4017.

Thread	Pitch (mm)	Width Flats — s (mm)	Head Height — k (mm)	Standard Lengths (mm)
M3	0.50	5.5	2.0	6, 8, 10, 12, 16, 20, 25, 30
M4	0.70	7.0	2.8	8, 10, 12, 16, 20, 25, 30, 35, 40
M5	0.80	8.0	3.5	10, 12, 16, 20, 25, 30, 35, 40, 50
M6	1.00	10.0	4.0	10, 12, 16, 20, 25, 30, 35, 40, 50, 60
M8	1.25	13.0	5.3	16, 20, 25, 30, 35, 40, 50, 60, 70, 80
M10	1.50	17.0	6.4	20, 25, 30, 35, 40, 50, 60, 70, 80, 100
M12	1.75	19.0	7.5	25, 30, 35, 40, 50, 60, 70, 80, 100, 120
M14	2.00	22.0	8.8	30, 35, 40, 50, 60, 70, 80, 100, 120
M16	2.00	24.0	10.0	30, 35, 40, 50, 60, 70, 80, 100, 120, 150
M18	2.50	27.0	11.5	40, 50, 60, 70, 80, 100, 120, 150
M20	2.50	30.0	12.5	40, 50, 60, 70, 80, 100, 120, 150, 200

SS Bolt Tightening Torque — A2-70 & A4-80 Reference Values

Indicative dry (unlubricated) tightening torque values. Anti-seize lubricant reduces required torque by approximately 25–30% and is strongly recommended to prevent galling in SS-on-SS assemblies.

Thread	A2-70 Torque (Nm) — Dry	A4-80 Torque (Nm) — Dry	With Anti-Seize (approx.)
M4	1.5–2.0	2.0–2.5	1.2–1.7
M5	3.0–4.0	4.0–5.0	2.5–3.5
M6	5.0–7.0	7.0–9.0	4.0–6.0
M8	12–16	16–20	10–14
M10	25–32	32–40	20–28
M12	42–54	55–70	35–48
M14	68–86	88–112	56–76
M16	100–130	132–168	84–115
M20	200–250	260–330	170–220

ℹ️ Critical — SS Bolt Galling Prevention: Stainless steel austenitic grades (SS304, SS316) are highly susceptible to galling (cold welding / thread seizure). Always apply anti-seize lubricant to threads before assembly. Reduce tightening speed — always make final 2–3 turns with a hand ratchet, not a power tool. If galling occurs, do not force — the bolt and nut will need to be cut off. Consider specifying anti-galling coated bolts for assemblies that will be repeatedly assembled and disassembled.

Standards Available

Standard	Bolt Types Covered	Key Application
DIN 933	Hex bolt fully threaded	Most common general-purpose hex bolt in India
DIN 931	Hex bolt partially threaded	Structural and machinery bolting where grip length required
DIN 912 / ISO 4762	Socket cap bolt	Machine guards, process equipment, precision assemblies
DIN 7984	Socket thin head bolt	Space-restricted assemblies
DIN 6912	Socket low head bolt	Ultra-low-clearance assemblies
DIN 6921	Hex flange bolt	Sheet metal, automotive, HVAC without separate washer
DIN 603	Carriage bolt	Timber structures, outdoor furniture, tamper-resistant joints
DIN 571	Hex lag bolt (lag screw)	Heavy timber structural connections
DIN 787	T-bolt (hammer head)	Channel frame / Unistrut assembly
ASME B18.2.1	Hex bolts (US)	US-standard EPC and export projects — inch sizes
IS 1367	General fasteners	Indian standard for government / PSU procurement

Applications — Where SS Bolts Are Specified

Structural & Civil

SS316 hex bolts for outdoor structural steel connections, coastal bridges, jetty structures.

Decking & Timber

SS316 carriage bolts and lag bolts for heavy timber decking, pergola frames.

Marine & Offshore

SS316 hex and socket bolts for marine vessel fittings, offshore platform connections.

Industrial Equipment

SS304/SS316 socket cap and hex bolts for machine guards, process equipment panels.

Solar & Renewables

SS316 T-bolts and hex flange bolts for solar panel mounting channel frames.

Food & Pharma

SS316 socket cap bolts for food processing, dairy plant, pharma cleanroom assemblies.

Chemical Plant

SS316/Duplex hex bolts for piping support, equipment skids, platform grating.

Custom & OEM

Custom lengths, non-standard grades, anti-galling coatings for OEM projects.

How to Order SS Bolts from KELOR

Share on WhatsApp or Email — include all of the following:
1. Bolt type — Hex / Carriage / Socket Cap / Socket Thin / Socket Low / Hex Flange / Lag / T-Bolt
2. Thread standard — DIN 933 (full) / DIN 931 (partial) / ASME B18.2.1
3. Material grade — SS304 / SS316 / SS316L / Duplex
4. Property class — A2-70 / A4-80 / A4-100
5. Diameter — M3 to M20 (or imperial 1/8″–3/4″)
6. Length (mm or inches)
7. Quantity (Nos)
8. Nut & washer required? Yes / No
9. MTC required? Yes / No
10. Delivery location (for freight calculation)

📱 WhatsApp: +91 93135 43530 | 📧 Email: [email protected]

Why Buy SS Bolts from Krishna Industries?

🏭

B2B Industrial Supplier

Dedicated B2B supplier for EPC contractors, structural fabricators, OEMs, and MRO stores. GST invoice on every order.

📄

MTC & Test Certificates

Mill Test Certificate available on request for all SS bolt orders. Grade and standard conformance documented.

⚡

2-Hour Quote

WhatsApp complete specification — price, availability, and delivery confirmed within 2 business hours.

🚚

Pan India Dispatch

Dispatch from Ahmedabad via VRL Logistics, DTDC, and Professional Courier to all major industrial cities.

🔩

Complete Fastener Range

One-stop supplier for bolts, washers, threaded rods, stud bolts, eye bolts, wire nails, and industrial valves.

✅

GSTIN Verified

GSTIN: 24AKLPP6499B1ZT | IEC: AKLPP6499B. All invoices valid for ITC claims. Registered since 2017.

Quick Specification Summary

Parameter	Details
Product	Stainless Steel Bolts — all types
Bolt Types	Hex Head (DIN 933/931) · Carriage · Socket Cap · Socket Thin · Socket Low · Hex Flange · Hex Lag · T-Bolt
Materials	SS304 (A2), SS316 (A4), SS316L, Duplex 2205, Nickel Alloy
Thread Range	M3 to M20 (metric) · 1/8″ to 3/4″ (imperial)
Length Range	6 mm to 200 mm
Property Classes	A2-70, A2-80, A4-70, A4-80, A4-100 per ISO 3506
Standards	DIN 933/931/912/7984/6912/6921/603/571/787, ISO 4017/4014/4762, ASME B18.2.1, IS 1367
MOQ	10 Nos per type per grade per size
HSN Code	73181590
GST Rate	18%
MTC	Available on request
Dispatch	Ahmedabad — Pan India via VRL Logistics, DTDC, Professional Courier
GSTIN	24AKLPP6499B1ZT

Frequently Asked Questions — Stainless Steel Bolts

What is the difference between DIN 931 and DIN 933 hex bolts?

DIN 933 is a fully threaded hex bolt — the thread runs from the tip all the way to the underside of the head, with no plain shank. DIN 931 is a partially threaded hex bolt — the tip is threaded for approximately two times the nominal diameter, but the shank directly under the head is plain (unthreaded). The plain shank in DIN 931 provides a defined grip length and keeps the threaded portion out of the shear plane in structural connections — this is the correct design for load-bearing structural bolting per IS 800.

What is the difference between SS304 and SS316 bolts?

SS304 (A2) bolts contain 18% chromium and 8% nickel — good general corrosion resistance for indoor and non-chloride environments. SS316 (A4) bolts add 2–3% molybdenum which significantly increases resistance to chloride pitting and crevice corrosion. Specify SS316 for marine, coastal, seawater, chemical plant, food GMP, and pharmaceutical environments. The 20–30% cost premium is consistently recovered through extended service life.

What is A2-70 and A4-80 — what do these designations mean?

These are ISO 3506 property class designations that define both the material and mechanical strength. A2 = AISI 304 (SS304); A4 = AISI 316 (SS316). The number represents minimum tensile strength in units of 10 MPa — A2-70 means SS304 bolt with 700 MPa minimum tensile, A4-80 means SS316 bolt with 800 MPa minimum tensile. Always specify both material AND property class.

What is a carriage bolt and when should I use one instead of a hex bolt?

A carriage bolt (DIN 603) has a smooth domed round head with no drive recess — it cannot be turned from the bolt head side. The square neck under the head locks into a matching square hole in timber or thin metal. This provides tamper resistance, aesthetic cleanliness, and simplicity (one person can tighten from nut side). Specify SS316 carriage bolts for outdoor timber decking, playground equipment, marine structures, and street furniture.

How do I prevent SS bolts from seizing (galling) when tightening?

Always apply anti-seize lubricant to bolt threads before assembly — this is the single most effective measure. Reduce tightening speed — use a hand ratchet for final turns, never a power impact driver without speed control. Consider anti-galling coated bolts (PTFE or molybdenum disulphide dry film coating) for assemblies that will be repeatedly assembled and disassembled.

What is the MOQ and lead time for SS bolts?

MOQ is 10 Nos per type per grade per size for standard stock items. For non-standard bolt types, special grades (Duplex, Nickel Alloy), or non-standard lengths, MOQ may be higher with 2–4 weeks lead time. Complete bolt sets (bolt + matching nut + flat washer + spring washer) are available as kits on request. WhatsApp full specification for confirmed price within 2 hours.

What is a T-bolt and where is it used?

A T-bolt (DIN 787) has a T-shaped head that inserts into the slot of a strut channel (Unistrut) and locks when the nut is tightened. It allows infinite adjustment along the channel length. T-bolts are standard for pipe hangers, cable tray support, HVAC suspension, and solar panel racking. Specify SS316 T-bolts for outdoor and coastal applications. The T-head must match the channel slot dimensions (typically 11–12 mm). Supplier India Supplier India — Krishna Industries (KELOR) India Supplier India Supplier Steel Bolts Supplier India — Krishna Supplier India — Krishna Industries (KELOR) Stainless Steel Bolts Supplier India — Stainless Steel Bolts Supplier India — Supplier India