SS Weld Neck Flange Supplier India | ASTM A182 F304 F316 F316L | Class 150 to 1500 | DN15–DN900 | RF FF RTJ | ASME B16.5 | KELOR

Description

SS Weld Neck Flange Supplier India | ASTM A182 F304 / F316 / F316L | Class 150–1500 | DN15–DN900 | Raised Face / Flat Face / RTJ | ASME B16.5 / B16.47 | KELOR

Supplier: Krishna Industries (KELOR) – Ahmedabad, Gujarat, India
Established: 2017 | GSTIN: 24AKLPP6499B1ZT | IEC: AKLPP6499B
MOQ: 10 Nos | Material: ASTM A182 F304 / F316 / F316L / F304L
Standard: ASME B16.5 / B16.47 | Sizes: DN15–DN900 | Pressure: Class 150–1500

SS Weld Neck Flange Supplier in India

Krishna Industries (KELOR), based in Ahmedabad, Gujarat, is a B2B supplier of Stainless Steel Weld Neck Flanges — ASTM A182 F304 (SS304) / F316 (SS316) / F316L (SS316L) / F304L forged — weld neck with tapered hub — butt weld end — raised face (RF) / flat face (FF) / ring type joint (RTJ) — Class 150 / 300 / 600 / 900 / 1500 — DN15 (½”) to DN900 (36″) — ASME B16.5 (DN15–DN600) / ASME B16.47 Series A/B (DN650–DN900) — schedule-matched bore — MTC ASTM A182 heat certificate — GST invoice — MOQ 10 Nos — Pan India dispatch from Ahmedabad.

The weld neck flange is the premium flange type for high pressure, high temperature, cyclic, and critical service SS piping — the tapered hub distributes pipeline stress gradually into the flange body, the single full-penetration butt weld is RT/UT inspectable, and there is no annular crevice between pipe and hub bore. These properties make weld neck flanges mandatory in most Indian refinery, petrochemical, pharma, and chemical plant piping class specifications at Class 300 and above, and in all lethal service and hydrogen service piping regardless of pressure class.

Weld Neck vs Other SS Flange Types — Selection Guide

ASTM A182 Grade Selection — F304 vs F316 vs F316L

Flange Facing Selection

Schedule-Matched Bore — Why It Must Be Specified

The bore of a weld neck flange hub must match the pipe bore (inside diameter) exactly. The hub outside diameter at the weld end matches the pipe outside diameter — the hub inside diameter (bore) must match the pipe inside diameter for the specific pipe schedule ordered. A mismatch — even 1–2mm — creates a step in the internal flow path at the weld joint, which causes turbulence and localised erosion, makes radiographic interpretation of the weld difficult (the step creates a shadow), and is a violation of ASME B31.3 piping code which requires bore matching at all butt weld joints.

Standard SS pipe schedules and corresponding flange bore specifications: Schedule 10S (thin wall — pharma, food, low pressure) / Schedule 40S (standard — most industrial SS piping) / Schedule 80S (heavy wall — higher pressure chemical service) / Schedule 160 / XXS (very high pressure on request). Specify the pipe schedule at order stage — Krishna Industries supplies weld neck flanges with bore machined to match the specified schedule.

Technical Specifications

Applications in Indian Industries

• Pharmaceutical API plants — GMP utility piping — ASTM A182 F316L weld neck RF Class 150 Sch 40S DN15–DN150 — purified water (PW), water for injection (WFI), clean steam, nitrogen piping flanged connections — F316L mandatory for GMP piping per USFDA and WHO GMP utility piping specifications — weld neck for crevice-free internal surface at flanged joints — MTC with heat number traceability for GMP documentation file — pharma clusters: Ahmedabad, Hyderabad, Baddi, Ankleshwar
• Chemical plants — Ankleshwar, Vapi, Dahej GIDC — ASTM A182 F316L weld neck RF Class 150/300 Sch 40S/80S DN25–DN300 — corrosive chemical process piping flanged connections — acid and alkali transfer lines, solvent piping, chlorinated compound service — F316L for sensitisation-free welded joints in aggressive chemical environment — RT of butt welds specified in chemical plant piping class B and above — weld neck mandatory for RT testability
• Oil and gas and refinery — process SS piping — ASTM A182 F316 or F316L weld neck RTJ Class 600/900/1500 DN25–DN200 — high pressure SS process piping in Indian refineries — instrument and utility SS lines at high pressure — RTJ facing for Class 600+ joints — MTC and RT of butt weld per piping class quality plan — NACE MR0175 compliance for sour service on request (F316L inherently low hardness)
• Food and beverage processing — ASTM A182 F304 or F316L weld neck RF Class 150 Sch 10S/40S DN25–DN150 — process and utility piping flanged connections — Schedule 10S for food and beverage standard thin-wall SS piping — F316L for GMP food contact service — F304 for non-chloride food utility — smooth bore from schedule-matched weld neck flange bore important for CIP cleanability at flanged joints
• Power plants — SS auxiliary piping — ASTM A182 F316 weld neck RF Class 150/300 DN25–DN200 — DM water piping, condensate polishing, chemical dosing lines — cryogenic service (liquid nitrogen, liquid CO2) — F304 and F316 both rated to -196°C — weld neck for cyclic thermal service in power plant temperature cycling conditions — tapered hub resists fatigue cracking at flanged joints under steam cycle thermal cycling

Related Products — Krishna Industries (KELOR)

• Threaded / Slip-On Flanges — CS and SS slip-on, threaded, socket weld, blind flanges — for lower pressure utility service where weld neck is not required
• Stud Bolts — ASTM A193 B8M (SS316) — SS316 stud bolts with SS316 nuts for SS flange bolting — A193 B8M / A194 8M is the correct fastener grade for SS flanges — supplying SS flanges with CS A193 B7 studs creates galvanic corrosion at the joint
• SS316L Ball Valve — flanged Class 150/300 SS316L ball valve — pairs with F316L weld neck flanges in same SS piping system
• SS Needle Valve — instrument root valves on the same SS process piping where weld neck flanges are used at equipment connections
• SS304 3-Piece Ball Valve — screwed BSP SS304 ball valve — in the same food and pharma utility piping systems where F304 weld neck flanges connect equipment

Frequently Asked Questions

1. Why must the weld neck flange bore match the pipe schedule exactly?

ASME B31.3 Process Piping Code (the governing code for most Indian process plant piping) requires that butt weld joints have matching bore diameters at the weld — a bore mismatch is called “hi-lo” and creates a step in the internal flow path. This step causes turbulence and localised erosion at the weld zone, creates a shadow on radiographic film that makes weld defect interpretation difficult or impossible, and is a code violation that will be flagged by the piping inspection team during construction inspection. When ordering weld neck flanges for a piping system, always specify the pipe schedule — Schedule 10S, 40S, 80S, or custom — so the flange bore is machined to match the pipe bore exactly.

2. When is ASTM A193 B8M stud bolt required instead of A193 B7 for SS flange joints?

ASTM A193 B7 is a chrome-moly alloy steel stud — excellent mechanical strength but dissimilar to SS flanges in electrochemical potential. When B7 CS studs are used with SS316 flanges in a corrosive environment (chemical plant, coastal, process with corrosive vapour), galvanic corrosion occurs at the stud-to-flange interface — the dissimilar metals form a galvanic couple and the CS stud corrodes preferentially. For SS flanges in corrosive service, specify ASTM A193 B8M (SS316 studs) with A194 Grade 8M (SS316 nuts) — same electrochemical potential as the SS flange, no galvanic corrosion. For SS flanges in clean non-corrosive service (DM water, inert gas), B7 studs are acceptable. The project piping specification or material selection document will typically specify the correct stud grade for each service.

3. What is the difference between ASME B16.5 and ASME B16.47 and when does B16.47 apply?

ASME B16.5 covers flanges from DN15 (½”) to DN600 (24″) in all standard pressure classes. ASME B16.47 covers large diameter flanges from DN650 (26″) to DN1500 (60″) in two series: Series A (equivalent to MSS SP-44 — larger, heavier flanges) and Series B (equivalent to API 605 — more compact). For DN15 to DN600 SS weld neck flanges, ASME B16.5 is the applicable standard in India. For DN650 and above — large bore process vessels, storage tank nozzles, large bore pump flanges — ASME B16.47 applies. When ordering, specify B16.5 for all standard sizes up to DN600 and B16.47 Series A or B for larger bore requirements.

4. Can raised face SS weld neck flanges be connected to flat face cast iron flanges?

Not directly — connecting a raised face (RF) SS weld neck flange to a flat face (FF) cast iron flange creates a bending stress on the cast iron flange face as the bolts are tightened, which can crack the CI flange. The standard solution is to use a flat face SS weld neck flange (specify FF at order) with a full face gasket that covers the entire flange face including bolt holes. Alternatively, a raised face SS flange can be connected to a FF CI flange using a full face gasket and an isolation kit, but the simplest solution is to order FF facing on the SS flange when the mating equipment (pump, valve, strainer) has CI flanged connections.

5. What is the MOQ and what documents are supplied?

MOQ is 10 Nos per line item. Full project BOM supply — multiple sizes, grades, and pressure classes in one consolidated order. Documents supplied: MTC (ASTM A182 heat certificate — chemical composition and mechanical properties with heat number), dimensional inspection report confirming ASME B16.5 face dimensions and bolt circle, GST invoice with HSN code 73072100. Third party inspection (TPI) by Lloyds, BV, or DNV on request for EPC project quality requirements. WhatsApp grade (F304/F316/F316L), pressure class, size list, pipe schedule, facing (RF/FF/RTJ), and quantity for project pricing within 2 hours.

Conclusion

Krishna Industries (KELOR) supplies SS Weld Neck Flanges for chemical plant, pharma GMP piping, oil and gas, food processing, power plant, and cryogenic service — ASTM A182 F304 (SS304) / F316 (SS316) / F316L (SS316L) / F304L forged — weld neck tapered hub — butt weld end — raised face (RF) / flat face (FF) / ring type joint (RTJ) — Class 150 / 300 / 600 / 900 / 1500 — DN15 (½”) to DN900 (36″) — ASME B16.5 / B16.47 — schedule-matched bore (Sch 10S / 40S / 80S) — MTC ASTM A182 heat certificate — GST invoice — Pan India dispatch from Ahmedabad. WhatsApp grade, pressure class, size list, pipe schedule, facing, and quantity for project pricing within 2 hours.