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Stud Bolt Supplier India — A193 B7 / 2H Nut Set — Krishna Industries, Ahmedabad
B2B supplier of ASTM A193 B7 Stud Bolts with A194 2H Heavy Hex Nut sets — alloy steel AISI 4140 quenched and tempered — ASME B18.2 dimensions — UNC (imperial ½”–4″) and Metric (M12–M48) — plain / yellow zinc / hot dip galvanised (HDG) / PTFE / Xylan coated — all standard stud bolt grades: B7 / B7M / B8 / B8M / B16 / A320 L7.
MOQ 100 Nos · GST Invoice · Pan India Dispatch from Ahmedabad
An ASTM A193 B7 Stud Bolt is a fully threaded alloy steel rod — AISI 4140 chromium-molybdenum steel, quenched and tempered — used with two ASTM A194 2H heavy hex nuts to bolt flanged joints on valves, flanges, heat exchangers, and pressure vessels in process plant piping. The B7 / 2H nut set is the default bolting specification on every Indian process plant piping class document for carbon steel service — chemical plants, oil refineries, power plants, CGD networks, and pressure vessels per ASME VIII.
Krishna Industries (KELOR), Ahmedabad, is a B2B stud bolt supplier in India — ASTM A193 B7 and all standard grades — ASME B18.2 heavy hex dimensions — UNC imperial and metric — plain / HDG / zinc / PTFE / Xylan coated — MTC EN 10204 3.1 standard — MOQ 100 Nos — Pan India dispatch. Enquire for ASTM A193 B7 studs price via WhatsApp — project BOM pricing within 4 hours.
⚠️ Most common Indian site bolting mistake: Pairing A193 B7 stud with IS Grade 5 or IS Grade 8 nut instead of A194 2H. ASME PCC-1 requires nut proof load to exceed stud yield — A194 2H (175 ksi) vs A193 B7 (105 ksi yield) — correct. IS Grade 5 (85 ksi proof load) is WEAKER than B7 yield — nut strips before adequate preload — flanged joint leaks. Always use matched ASTM A194 nut grade with each A193 stud grade. Never substitute IS nuts on ASTM stud bolts.
Complete Stud Bolt Grade Range — B7 2H Nut Set and All Grades
MOST COMMON
A193 B7 + A194 2H — Alloy Steel
- AISI 4140 Cr-Mo alloy steel — Q&T
- Tensile: 125 ksi / 862 MPa (≤2½” / M64)
- Yield: 105 ksi / 724 MPa (≤2½”)
- Hardness: max HRC 35
- Temp: −45°C to +450°C
- Finish: Plain / Zinc / HDG / PTFE / Xylan
- Use: Standard process plant Class 150–2500
- → Full B7/2H product page
SOUR SERVICE / NACE
A193 B7M + A194 2HM
- Same AISI 4140 as B7 — hardness restricted
- Max hardness: HRC 26 (NACE MR0175 / ISO 15156)
- For H₂S sour gas environments
- Upstream oil and gas — offshore platforms
- NACE compliance report available
- Paired with A194 2HM nut (same hardness limit)
SS304
A193 B8 (Class 1/2) + A194 8
- AISI 304 austenitic stainless steel
- Class 1: solution annealed (lower strength)
- Class 2: strain hardened (higher strength)
- For SS304 flanged connections — no galvanic risk
- Do NOT use B7/2H on SS304 flanges — galvanic corrosion
SS316
A193 B8M (Class 1/2) + A194 8M
- AISI 316 stainless steel — 2–3% Mo
- For SS316 flanged connections
- Chemical plant, chloride, pharma, food GMP, offshore
- Do NOT pair with A194 2H — galvanic corrosion on SS flange
LOW TEMP / CRYOGENIC
A320 L7 + A194 4
- Cr-Mo alloy steel — Charpy impact tested
- Down to −101°C
- LNG terminals, liquid nitrogen, cryogenic piping
- ASME B31.3 low temperature service
- Impact test certificates mandatory
HIGH TEMP / STEAM
A193 B16 + A194 7
- Cr-Mo-V alloy steel
- Up to 540°C continuous — above B7’s creep limit
- Power plant high pressure steam headers
- ASME Boiler & Pressure Vessel Code bolting
- Where B7 creep relaxation is a concern above 450°C
ASTM A193 B7 Chemical Composition — Alloy Steel AISI 4140
ASTM A193 B7 stud bolts are manufactured from AISI 4140 / 4142 chromium-molybdenum alloy steel — quenched in a liquid medium and tempered at minimum 620°C (1150°F). The alloy elements chromium (0.75–1.20%) and molybdenum (0.15–0.25%) provide the high tensile strength, hardness, and elevated temperature resistance that make B7 the default alloy steel stud bolt for Indian process plant flanged joints.
| Element | ASTM A193 B7 (AISI 4140/4142) — % by weight | Role |
|---|---|---|
| Carbon (C) | 0.37 – 0.49% | Base strength — quench hardenability |
| Manganese (Mn) | 0.65 – 1.10% | Hardenability — toughness |
| Chromium (Cr) | 0.75 – 1.20% | Corrosion resistance — hardenability — high temp strength |
| Molybdenum (Mo) | 0.15 – 0.25% | High temperature strength — creep resistance — hardenability |
| Silicon (Si) | 0.15 – 0.35% | Deoxidation — strength |
| Phosphorus (P) | Max 0.035% | Impurity limit — embrittlement control |
| Sulphur (S) | Max 0.040% | Impurity limit — machinability vs toughness trade-off |
ASTM A193 B7 Mechanical Properties by Diameter
| Diameter Range (UNC) | Metric Equiv. | Min Tensile (ksi / MPa) | Min Yield (ksi / MPa) | Min Elongation (%) | Max Hardness |
|---|---|---|---|---|---|
| ≤ 2½” (2.5″) | ≤ M64 | 125 ksi / 862 MPa | 105 ksi / 724 MPa | 16% | HRC 35 / HBW 321 |
| 2½” – 4″ (incl.) | M64 – M100 | 115 ksi / 793 MPa | 95 ksi / 655 MPa | 15% | HRC 35 / HBW 321 |
| 4″ – 7″ (incl.) | M100 – M175 | 100 ksi / 690 MPa | 75 ksi / 517 MPa | 13% | HRC 35 / HBW 321 |
💡 B7M note (NACE service): B7M has the same chemical composition and strength requirements as B7 — the only difference is a restricted maximum hardness of HRC 26 (HBW 237) per NACE MR0175 / ISO 15156. Specify B7M for any H₂S sour gas service. Both grades supplied from Ahmedabad with MTC.
ASME B16.5 Stud Bolt Length — UNC Imperial — Class 150 and Class 300
Standard reference for flanged joint stud bolt length — raised face (RF) flanges — 3mm spiral wound gasket. Length shown is total stud bolt length including both threaded ends. Quantity = stud bolt + nut sets per flanged joint.
| Pipe Size | DN | Class 150 — Length (mm) | Class 150 — Qty | Class 150 — Thread | Class 300 — Length (mm) | Class 300 — Qty | Class 300 — Thread |
|---|---|---|---|---|---|---|---|
| ½” | DN15 | 95 | 4 | ½” UNC | 108 | 4 | ½” UNC |
| ¾” | DN20 | 95 | 4 | ½” UNC | 108 | 4 | ½” UNC |
| 1″ | DN25 | 108 | 4 | ½” UNC | 121 | 4 | ⅝” UNC |
| 1½” | DN40 | 121 | 4 | ½” UNC | 133 | 4 | ¾” UNC |
| 2″ | DN50 | 121 | 4 | ⅝” UNC | 152 | 8 | ¾” UNC |
| 3″ | DN80 | 152 | 4 | ⅝” UNC | 184 | 8 | ¾” UNC |
| 4″ | DN100 | 152 | 8 | ⅝” UNC | 190 | 8 | ¾” UNC |
| 6″ | DN150 | 165 | 8 | ¾” UNC | 210 | 12 | ⅞” UNC |
| 8″ | DN200 | 184 | 8 | ¾” UNC | 235 | 12 | 1″ UNC |
| 10″ | DN250 | 190 | 12 | ⅞” UNC | 267 | 16 | 1⅛” UNC |
| 12″ | DN300 | 210 | 12 | ⅞” UNC | 286 | 16 | 1⅛” UNC |
| 16″ | DN400 | 241 | 16 | 1″ UNC | 337 | 20 | 1¼” UNC |
| 20″ | DN500 | 279 | 20 | 1⅛” UNC | 381 | 24 | 1¼” UNC |
| 24″ | DN600 | 305 | 20 | 1¼” UNC | 425 | 24 | 1½” UNC |
ASTM A193 B7 Stud Bolt — Metric Sizes M12 to M48 (DIN/IS Flange Bolting)
For Indian projects using IS or DIN flanges with metric bolting. Metric B7 stud bolts are increasingly specified on IS 1538 / DIN PN10 / PN16 flanges in water treatment, HVAC, and general industry projects where the piping system uses metric flange drilling rather than ANSI B16.5.
| Metric Size | Approx UNC Equiv. | Thread Pitch (coarse) | Across Flats — 2H Nut (mm) | Nut Height (mm) | Min Tensile (MPa) | Min Yield (MPa) |
|---|---|---|---|---|---|---|
| M12 | ~½” | 1.75mm | 19 | 10.8 | 862 | 724 |
| M16 | ~⅝” | 2.00mm | 24 | 14.8 | 862 | 724 |
| M20 | ~¾” | 2.50mm | 30 | 18.0 | 862 | 724 |
| M24 | ~1″ | 3.00mm | 36 | 21.5 | 862 | 724 |
| M27 | ~1⅛” | 3.00mm | 41 | 23.8 | 862 | 724 |
| M30 | ~1¼” | 3.50mm | 46 | 25.6 | 862 | 724 |
| M33 | ~1⅜” | 3.50mm | 50 | 28.7 | 862 | 724 |
| M36 | ~1½” | 4.00mm | 55 | 31.0 | 862 | 724 |
| M39 | ~1⅝” | 4.00mm | 60 | 33.4 | 793 | 655 |
| M42 | ~1¾” | 4.50mm | 65 | 34.0 | 793 | 655 |
| M45 | ~1⅞” | 4.50mm | 70 | 36.0 | 793 | 655 |
| M48 | ~2″ | 5.00mm | 75 | 38.0 | 793 | 655 |
Metric B7 stud bolt nut dimensions per ISO 4032 heavy hex. Mechanical properties per ASTM A193 B7 — equivalent values for metric diameters. WhatsApp thread size, grade, finish, length, and quantity for pricing.
Full Thread vs Double-End Stud Bolt — Which to Specify
| Type | Description | ✅ Specify For |
|---|---|---|
| Full Thread (Continuous Thread) | Threads run entire length — no unthreaded body — same thread pitch end to end | ✅ Standard for all ASME B16.5 flange bolting — allows any cut length — default type on Indian process plant |
| Double-End (Equal Length Stud) | Threaded at both ends — plain (unthreaded) body in middle — specified thread engagement length each end | Pressure vessel nozzle bolting, heat exchanger bolting — where stud is screwed into a tapped hole one end and takes a nut the other end — ASME VIII applications |
| Tap-End Stud | Short thread one end (for tapped hole) — long thread other end (for nut) — different thread lengths each end | Cylinder head bolting, pump casing bolting — one end screwed permanently into casting, nut at other end for assembly/disassembly |
A193 B7 Stud Bolt Tightening Torque Reference — Lubricated (Zinc/PTFE Coated)
Reference torque values for ASTM A193 B7 stud bolts with A194 2H nuts — lubricated assembly (zinc plated or PTFE coated) — targeting 70% of bolt proof load. These are reference values only — actual torque must be verified from the gasket manufacturer’s joint assembly procedure and ASME PCC-1 guidelines for the specific gasket, flange, and service condition.
| Stud Size (UNC) | Metric Equiv. | Torque — Lubricated (Nm) | Torque — Dry/Plain (Nm) | Target Bolt Load (kN) |
|---|---|---|---|---|
| ½” | M12 | 45 – 55 | 65 – 80 | ~32 |
| ⅝” | M16 | 90 – 110 | 130 – 155 | ~55 |
| ¾” | M20 | 160 – 190 | 230 – 270 | ~90 |
| ⅞” | M22 | 250 – 300 | 360 – 430 | ~128 |
| 1″ | M24–M27 | 380 – 450 | 550 – 650 | ~178 |
| 1⅛” | M27–M30 | 550 – 650 | 790 – 940 | ~235 |
| 1¼” | M30–M33 | 760 – 900 | 1,090 – 1,290 | ~310 |
| 1½” | M36–M39 | 1,300 – 1,550 | 1,870 – 2,230 | ~500 |
⚠️ Never torque B7 stud bolts dry (plain/black oxide) without lubrication. Dry torque coefficient (K factor) is approximately 0.20–0.22 vs 0.13–0.15 for lubricated. Dry bolting on same torque setting achieves only 60–70% of lubricated bolt load — flanged joint may leak at operating pressure. Always lubricate threads and nut face before assembly — use molybdenum disulfide paste, zinc-rich paste, or PTFE-coated studs which are self-lubricating.
Coating and Finish Selection Guide
| Finish | Standard | ✅ Specify For | Cost |
|---|---|---|---|
| Plain (Black Oxide) | — | Indoor dry process plant — coated with moly paste before assembly — standard for Indian refinery, chemical plant, power plant indoor bolting | ✅ Lowest |
| Yellow Zinc Plated | ASTM B633 | Mild corrosion protection — general industrial indoor with occasional moisture — 5–8 micron zinc | Low |
| Hot Dip Galvanised (HDG) | ASTM A153 | ✅ Outdoor pipe racks, water treatment plants, cooling water flanges, coastal industrial — 45–85 micron zinc — 10–25 year protection — prevents nut seizure at maintenance | Moderate |
| PTFE Coated | — | Anti-galling on SS flanges, clean room, pharma — self-lubricating — controlled torque — white/grey colour | Higher |
| Xylan / Fluoropolymer | — | Offshore, subsea, severe marine — maximum salt water corrosion protection — where HDG insufficient | Premium |
Industries & Applications
🏭 Process Plant Flanges
A193 B7/2H plain or zinc — default on every Indian piping class document — Class 150–2500 ASME B16.5 flanges at chemical plants, refineries, CGD networks.
⚡ Power Plants
B7/2H and B16/7 for high pressure steam — pressure vessel and heat exchanger bolting — MTC and 3.1 certificate mandatory for ASME VIII bolting.
⛽ Oil & Gas
B7M/2HM NACE MR0175 for sour gas — L7/4 for LNG cryogenic — B8M/8M SS316 with Xylan for offshore SS flanged joints.
💧 Water Treatment
B7/2H HDG for outdoor WTP flanged connections — prevents bolt seizure in damp outdoor conditions — ETP, STP, municipal water plants.
⚗️ Chemical Plants
B7/2H for CS piping — B8M/8M for SS316 flanged connections at Gujarat chemical belt (Ankleshwar, Vapi, Dahej, Surat).
💊 Pharma & Food
B8M/8M SS316 with PTFE coating for pharma GMP piping — FDA-safe — no zinc contamination — anti-galling on SS flange face.
🏗️ EPC Projects
Full project BOM supply — mixed grades, sizes, finishes — single GST invoice — MTC package for project QA — 100–100,000+ Nos per project.
🔧 MRO & Maintenance
Standard B7/2H plain in all sizes for plant maintenance stores — fast dispatch from Ahmedabad for urgent shutdown requirements.
Why EPC Contractors and Procurement Teams Choose Krishna Industries
📍
Ahmedabad — Central Supply Hub
Fastest supply to Gujarat chemical cluster (Ankleshwar, Vapi, Dahej), Mumbai, and all India via VRL — shorter transit than Mumbai suppliers for Gujarat buyers.
📄
MTC EN 10204 3.1
Mill test certificate with heat number traceability — ASTM A193 chemical composition and mechanical properties. 3.2 third-party witnessed (TUV / BV / Lloyd’s) available on request.
🔩
Matched B7 / 2H Sets
Stud and nut supplied as matched grade set per ASME PCC-1. B7 with 2H, B8M with 8M — no mismatched pairing risk — every set compliant.
🧾
GST Invoice
100% GST compliant. GSTIN: 24AKLPP6499B1ZT. E-Way bill for interstate. HSN 73181590 (studs) / 73182900 (nuts).
📦
Project BOM Supply
Mixed grades (B7, B8M, L7), sizes, finishes — 100 Nos to 100,000+ Nos — single consignment, single GST invoice, single MTC package.
⏱️
4-Hour Project Quote
WhatsApp grade, thread size (UNC or metric), finish, length, and quantity. Single-item pricing within 2 hours. Project BOM pricing within 4 hours.
Need A193 B7 Stud Bolt Price or Project BOM Quote?
Share grade (B7 / B7M / B8M / L7) · thread size (UNC ½”–4″ or metric M12–M48) · finish (plain / HDG / zinc / PTFE) · stud length (or flange size + class) · quantity. Pricing within 2–4 hours.
📲 WhatsApp for Stud Bolt PriceSupply Coverage — PAN India from Ahmedabad
Krishna Industries dispatches A193 B7 stud bolts from Ahmedabad to: Mumbai, Pune, Nashik, Nagpur (Maharashtra) · Chennai, Coimbatore, Bengaluru, Hyderabad, Vizag (South India) · Delhi, Noida, Gurugram, Jaipur (North India) · Surat, Vadodara, Rajkot, Ankleshwar, Vapi, Dahej (Gujarat) and all states via VRL / Professional Courier.
Frequently Asked Questions — A193 B7 Stud Bolt and 2H Nut
What nut must be paired with A193 B7 stud bolt — and why not IS nuts?
The correct nut is ASTM A194 Grade 2H heavy hex nut. ASME PCC-1 (Guidelines for Pressure Boundary Bolted Flange Joint Assembly) requires that nut proof load must exceed bolt minimum yield strength — ensuring the bolt yields before the nut strips, maintaining preload through the bolting cycle. A194 2H has a 175 ksi proof load against A193 B7’s 105 ksi yield — a 67% safety margin. An IS Grade 8 nut has approximately 116 ksi proof load — marginal. An IS Grade 5 nut has approximately 85 ksi — lower than B7 yield — the nut strips before adequate preload is reached — the joint leaks at operating pressure or at the first thermal cycle. This is the most common cause of flanged joint leakage on Indian process plant sites — IS nuts substituted for A194 2H to reduce cost. Never substitute IS Grade nuts for A194 2H on A193 B7 stud bolt flanged connections.
What is the price of ASTM A193 B7 stud bolts in India?
ASTM A193 B7 stud bolt price in India depends on thread size (½” to 4″ UNC or M12 to M48 metric), stud length, surface finish (plain / HDG / zinc / PTFE), and order quantity. Plain B7/2H sets are the most economical — HDG adds approximately 15–25% premium over plain. Metric B7 studs are priced similarly to UNC equivalents at the same weight. Krishna Industries provides competitive Ahmedabad pricing — WhatsApp grade, size, finish, length, and quantity for current pricing within 2 hours. Project BOM pricing with formal quotation within 4 hours.
What is the difference between A193 B7 and B7M?
Both B7 and B7M are AISI 4140/4142 chromium-molybdenum alloy steel — same chemical composition, same minimum tensile and yield strength. The only difference is maximum hardness. B7 has a maximum hardness of HRC 35. B7M has a restricted maximum hardness of HRC 26 (HBW 237) per NACE MR0175 / ISO 15156 — the standard for materials in H₂S sour gas service — to prevent hydrogen-induced stress cracking (HISC) and sulphide stress cracking (SSC). Specify B7M with A194 2HM nuts for sour gas service, upstream oil and gas H₂S environments, and offshore installations where H₂S is present. Specify standard B7 for all non-sour service.
Can A193 B7 stud bolts be used on stainless steel flanges?
Not recommended for outdoor or wet service. Carbon steel B7 in contact with a stainless steel flange face in the presence of moisture creates a galvanic couple — carbon steel corrodes preferentially, the stud corrodes, and the nut seizes in the SS flange face making removal impossible without drilling. For SS304 flanged connections specify A193 B8 / A194 Grade 8 set. For SS316 connections specify A193 B8M / A194 Grade 8M set. B7/2H is correct for carbon steel flange to carbon steel flange joints only. For dry indoor installations some Indian engineers use PTFE-coated B7 on SS flanges as a cost measure — this reduces but does not eliminate galvanic risk.
How many stud bolts does a 6 inch Class 150 flange require?
A 6 inch DN150 ASME B16.5 Class 150 flange requires 8 stud bolts with 2 nuts each — 16 nuts total per flanged joint. The standard stud bolt length per ASME B16.5 for raised face flanges with 3mm spiral wound gasket is 165mm. Thread size is ¾” UNC. For the Class 300 equivalent — 12 studs per joint, 210mm length, ⅞” UNC thread. WhatsApp the flange size, class, and gasket type for stud bolt length and quantity confirmation on any non-standard configuration.
What does EN 10204 3.1 MTC mean and when is 3.2 required?
EN 10204 3.1 MTC is a manufacturer’s test certificate — signed by the manufacturer’s own authorised quality representative — confirming chemical composition and mechanical properties with heat number traceability. Provided standard with every KELOR stud bolt order. EN 10204 3.2 MTC is a third-party witnessed certificate — an independent inspector (TUV, BV, Lloyd’s, or similar) witnesses the testing and countersigns the certificate. 3.1 satisfies the documentation requirement for the majority of Indian EPC project QA plans and ASME VIII pressure vessel bolting (UG-10). 3.2 is required for European PED-compliant export, certain offshore project specifications, and government PSU projects that explicitly require third-party witness. Specify 3.1 or 3.2 at order stage — 3.2 incurs additional cost for the inspector visit.
When should HDG finish be specified instead of plain for stud bolts?
Specify HDG (hot dip galvanised ASTM A153) for outdoor pipe racks, cooling water flanges, water treatment plant bolting, and any installation exposed to rain, humidity, or salt air. Plain black oxide B7 corrodes rapidly outdoors — within 2–3 years nuts seize on corroded stud threads, making removal for maintenance extremely difficult or impossible without cutting. HDG provides 10–25 years corrosion protection and prevents nut seizure. The HDG cost premium over plain is small relative to the cost of cutting seized bolts and refacing flange faces at a maintenance shutdown. For coastal and offshore service where HDG is still insufficient, specify Xylan or fluoropolymer coating.