Industrial
Flanges Supplier
India
ASME B16.5 · ASME B16.47 · API 6A certified forged & cast flanges — weld neck, slip-on, blind, socket weld, lap joint, threaded & orifice types. Sizes ½″ to 60″, Class 150 to 2500. Carbon steel, stainless steel, alloy steel & duplex. Full face, raised face & RTJ available. PAN India delivery.
What Are Industrial Flanges?
Flanges are precision-forged or cast circular discs that connect pipes, valves, fittings and equipment into a secure, leak-proof piping system. They allow convenient assembly and disassembly for inspection, maintenance and modification — making them the most critical mechanical joints in oil & gas, refinery and pipeline infrastructure.
At Petropipe Oil & Gas, we supply a comprehensive range of ASME B16.5, ASME B16.47 & API 6A certified flanges in forged carbon steel, stainless steel, alloy steel, duplex & super-duplex materials. Every flange is dimensionally verified per applicable standard, pressure tested and supplied with full Mill Test Certificate (MTC) and chemical & mechanical property reports.
We serve ONGC, IOCL, HPCL, BPCL, GAIL, Reliance, Nayara & major EPC contractors across India. Based in Noida, UP — warehousing in Gujarat & Mumbai for express PAN India delivery within 24–48 hours on in-stock items.
Forged Construction
Higher strength & toughness vs. cast flanges — preferred for high-pressure refinery service.
ASME B16.5 Compliant
Dimensional accuracy, pressure ratings & bolt-hole patterns per ASME & ANSI standards.
All Facing Types
Full Face (FF), Raised Face (RF), Ring Type Joint (RTJ), Tongue & Groove (T&G) available.
Full MTC Documentation
Chemical & mechanical test reports, dimensional inspection records, heat number traceability.
Types of Flanges We Supply
From wellhead connections to pipeline terminals — every certified flange type for every oil & gas application in India.
Weld Neck Flange
Butt Weld · High PressureThe most robust flange type — long tapered hub welded to the pipe end with a butt weld. Distributes stress from the flange to the pipe wall, ideal for high-pressure, high-temperature & cyclic service in refineries, power plants & offshore systems. RTJ facing for Class 900+.
Slip-On Flange
Fillet Weld · General ServiceSlides over the pipe end and is fillet-welded inside and outside. Easier to align and fit than weld neck flanges — popular for non-critical services, utilities, water systems and general process piping below Class 600. Lower material cost vs. weld neck.
Blind Flange
Pipe End Closure · Pressure TestingA solid flange disc used to permanently or temporarily close a pipeline or nozzle end. Essential for pressure testing, pipeline isolation, vessel nozzle blanking & future expansion connections. Available with RTJ groove for high-pressure Class 900–2500 service.
Socket Weld Flange
Small Bore · High PressurePipe is inserted into a socket bore and fillet-welded on the outside only. Used for small-bore piping (½″ to 4″) in high-pressure utility systems, instrumentation leads, chemical injection lines & auxiliary piping in refineries. Stronger joint than threaded.
Threaded Flange
No Weld RequiredInternally threaded (NPT or BSPT) to screw directly onto pipe ends — no welding required. Suitable for low-pressure utility lines, instrumentation connections, air/water service & temporary installations where welding is not practical. Easy field installation.
Lap Joint Flange
With Stub End · Maintenance-FriendlyUsed with a stub end butt-welded to the pipe — the flange slips over and rotates freely, allowing easy bolt-hole alignment. Ideal for systems requiring frequent dismantling for inspection, cleaning & replacement. Economical — flange body can be mild steel even with expensive alloy pipe.
Orifice Flange
Flow MeasurementPaired weld neck or slip-on flanges with tapped pressure-tapping holes for mounting an orifice plate — the most common differential pressure flow measurement device in oil & gas. Supplied with jack screws, equalising valves connections & orifice plate housing as a complete assembly.
Large Diameter Flanges
Series A & B · NPS 26–60For pipeline & vessel nozzle connections above NPS 24 — covered by ASME B16.47 Series A (MSS SP-44) for pipeline flanges and Series B (API 605) for pressure vessel flanges. Available in weld neck & blind types. Commonly used in GAIL, IOCL & ONGC large-bore gas pipelines.
Spectacle Blind & Spacer
Line Blinding / Figure-8Figure-8 shaped blind & spacer (ring) combination — rotated to blind or open a line without full disassembly. Standard for safe isolation of process lines during maintenance in refineries per OSHA process safety management requirements. Also available as individual blinds & spacers.
Flange Facing Types Explained
The facing type determines the gasket seating surface and sealing method — critical for leak-free joints across different pressure classes.
Raised Face (RF)
The most common facing type — a small raised ring on the flange face where the gasket seats. Compatible with all standard sheet & spiral wound gaskets. Used for Class 150 through 2500 in general process service.
Class 150 – 2500Ring Type Joint (RTJ)
A machined groove accepts a solid metallic ring gasket (oval or octagonal). Provides a metal-to-metal seal — ideal for very high pressure (Class 900–2500) and high-temperature refinery, wellhead & subsea service.
Class 900 – 2500 · High PressureFull Face (FF)
The gasket extends across the entire flange face including bolt holes. Required for cast iron and non-metallic flanges to prevent cracking from bolt loads. Common for low-pressure water, air & utility systems.
Class 150 – 300 · Cast IronTongue & Groove / Male-Female
Interlocking facing for superior gasket confinement and alignment. Used in heat exchanger channel cover flanges, pump body flanges & where preventing gasket blowout is critical. Custom machining available.
Special Service · Custom OrderASME B16.5 Pressure–Temperature Ratings
Maximum allowable pressure (bar) for carbon steel (A105) flanges at service temperature — select the correct class for your operating conditions.
| Class | –29°C to 38°C | 100°C | 200°C | 300°C | 400°C |
|---|---|---|---|---|---|
| 150 | 19.6 | 17.7 | 15.8 | 13.8 | 12.1 |
| 300 | 51.1 | 46.6 | 41.4 | 36.0 | 31.6 |
| 600 | 102.1 | 93.2 | 82.7 | 72.0 | 63.2 |
| 900 | 153.2 | 139.8 | 124.1 | 108.0 | 94.8 |
| 1500 | 255.3 | 233.0 | 206.9 | 180.0 | 158.0 |
| 2500 | 425.5 | 388.4 | 344.8 | 300.0 | 263.3 |
Values in bar (barg) for Group 1.1 material (A105 Carbon Steel). Ratings reduce at higher temperatures & for alloy/SS groups. Full P-T tables available — contact our technical team for your specific service conditions.
Get Technical Consultation →Flange Specifications & Standards
Complete specifications for all flange types — material, size range, pressure class, facing options and applicable certifications.
| Flange Type | Joint Method | Material | Size Range | Class | Facing | Standard |
|---|---|---|---|---|---|---|
| Weld Neck | Butt weld to pipe | CS / SS / AS / Duplex | ½″ – 48″ | 150–2500 | RF / RTJ / FF | ASME B16.5 |
| Slip-On | Fillet weld × 2 | CS / SS / Duplex | ½″ – 36″ | 150–600 | RF / FF | ASME B16.5 |
| Socket Weld | Socket + fillet weld | CS / SS / AS | ½″ – 4″ | 150–2500 | RF | ASME B16.5 |
| Blind | Solid end closure | CS / SS / Nickel Alloy | ½″ – 48″ | 150–2500 | RF / RTJ / FF | ASME B16.5API 6A |
| Lap Joint | With stub end | CS / SS | ½″ – 24″ | 150–600 | FF | ASME B16.5 |
| Threaded | NPT / BSPT thread | CS / SS | ½″ – 6″ | 150–2500 | RF / FF | ASME B16.5 |
| Orifice | Butt or fillet weld | CS / SS | 1″ – 24″ | 300–1500 | RF / RTJ | ASME B16.36 |
| Large Dia (B16.47) | Butt weld / Blind | CS / LAS | 26″ – 60″ | 150–900 | RF / RTJ | ASME B16.47 A&B |
| Spectacle Blind | Between flanges | CS / SS / Duplex | ½″ – 36″ | 150–1500 | RF / RTJ | ASME B16.48 |
Flange Manufacturing Processes
Understanding how flanges are manufactured helps procurement managers evaluate quality and select the right type for their pressure and temperature requirements.
Hot Forging
Steel billets are heated and hammer/press-forged into flange shapes — producing a continuous grain flow aligned to the flange geometry. Forged flanges have superior mechanical properties (higher tensile strength, impact toughness & fatigue resistance) vs. castings. Standard method for ASME B16.5 flanges. All Petropipe flanges are forged per ASTM A105/A182 requirements.
Casting (for Large Sizes)
Molten steel poured into moulds for complex shapes and large diameters above NPS 24 where forging becomes cost-prohibitive. Cast flanges per ASTM A216 WCB / A351 CF8M are used for pump bodies, valve bodies & large vessel nozzle flanges. NDT inspection (RT/UT) mandatory to detect casting defects per ASME requirements.
CNC Machining & Facing
Post-forging/casting, flanges are CNC-machined to precise dimensional tolerances — facing (RF, FF, RTJ groove), bore ID, OD, bolt-hole circle diameter (BCD), bolt-hole diameter & quantity, and hub length are all machined to ASME B16.5 tables. RTJ groove geometry (oval vs. octagonal) is particularly critical for high-pressure sealing.
Where Our Flanges Are Used
Petropipe flanges connect pipelines, valves and equipment across every sector of India's oil, gas & petrochemical industry.
Upstream — Wellheads & Manifolds
API 6A ring-groove RTJ flanges for wellhead Christmas tree connections, production manifolds & flowline headers in ONGC & Oil India upstream fields. NACE MR0175 compliance for sour gas environments.
Refineries — Process Units
ASME B16.5 weld neck flanges (Class 300–2500) in ASTM A182 F11/F22/F91 for high-temp refinery units — CDU, VDU, FCCU, Hydrocracker & HDS. RTJ facing for above Class 600 service in IOCL, HPCL & BPCL refineries.
Cross-Country Pipelines
Large diameter ASME B16.47 Series A weld neck flanges for GAIL & IOCL gas transmission pipelines. Slip-on flanges for metering station piping. Orifice flanges for custody transfer flow measurement systems.
Offshore & LNG
Duplex SS (A182 F51) & super-duplex (F53) weld neck flanges for offshore platform piping, topside process systems & LNG terminal pipework at ONGC offshore fields & Petronet LNG Dahej.
Power Plants & Fertilizers
IBR-approved A182 F11/F22 alloy steel flanges for main steam & feed water piping in NTPC thermal power plants. A182 F304L/F316L stainless flanges for RCF & IFFCO fertilizer plant ammonia & urea lines.
Common Flange Combinations
Bolt & Stud Reference
Flange Body Materials & Grades
Material selection determines suitability for your operating pressure, temperature and fluid — we supply all standard and specialty forging grades.
Carbon Steel
ASTM A105 · A350 LF2 · A694Most widely used flange material for standard oil & gas service. A105 for ambient to 425°C. A350 LF2 for sub-zero service (–46°C). A694 for high-yield pipeline service (F52 to F70).
Stainless Steel
A182 F304/F304L · F316/F316L · F321For corrosive, high-purity & cryogenic service. F316L low-carbon grade for welding without sensitisation. F321 titanium-stabilised for high-temp service where post-weld heat treatment is impractical.
Alloy Steel
A182 F5 · F9 · F11 · F22 · F91 · F92Chrome-molybdenum alloy flanges for high-temperature service (450–650°C). F91 (9Cr-1Mo-V) is the standard for main steam piping in ultra-supercritical power plants. IBR approved in India.
Duplex / Super Duplex
A182 F51 (2205) · F53 (2507) · F55High-strength duplex SS flanges for offshore, sour gas & high-chloride environments. F51 (UNS S31803) for general offshore. F53 (UNS S32750) super-duplex for most aggressive corrosive conditions.
Certifications & Standards
Every Petropipe flange is dimensionally verified, pressure tested and shipped with complete traceability documentation.
ASME B16.5
The primary standard for flanges ½″ through NPS 24. Covers pipe flanges and flanged fittings — dimensions, pressure-temperature ratings (14 classes), materials, bolt & gasket information and marking requirements.
ASME B16.47 Series A & B
Large-diameter flanges NPS 26 through 60. Series A (ex MSS SP-44) for pipeline flanges. Series B (ex API 605) for pressure vessel flanges. Weld neck & blind types in Class 75 through 900.
ASME B16.36 — Orifice Flanges
Specification for orifice flanges (weld neck & slip-on types) with pressure-tapping holes for differential pressure flow measurement. Class 300 through 2500, sizes 1″ through 16″.
API 6A — Wellhead Equipment
Ring-groove RTJ flanges for wellhead & Christmas tree equipment. Pressure ratings 2,000 to 20,000 psi. Material Class AA through FF. Mandatory for upstream ONGC, Oil India & private E&P applications.
IBR — Indian Boiler Regulations
IBR Form III-C approved alloy steel (F11/F22/F91) flanges for steam service in Indian boilers, pressure vessels & superheater piping. Mandatory for NTPC, BHEL and thermal power plant projects in India.
NACE MR0175 / ISO 15156
Sour service material requirements for flanges in H₂S environments. Controls hardness & heat treatment of CS flanges (≤22 HRC). Mandatory for ONGC sour gas fields, LNG terminals & offshore platforms.
Why Choose Petropipe for Flanges?
India's procurement engineers trust Petropipe for flange supply because we deliver dimensionally accurate, fully documented flanges — on time, every time.
Dimensional Accuracy Guaranteed
Every flange dimensionally inspected against ASME B16.5 tables — bolt hole circle diameter, bolt hole diameter, face OD, hub OD, back face dimension & RTJ groove geometry. Dimensional reports available.
Full MTC & Forging Traceability
Heat number stamped on every flange. Mill Test Certificate with chemical composition, mechanical properties (yield, tensile, elongation, impact at –29°C or –46°C) and hardness results provided.
Complete Package Supply
We supply flanges with matching gaskets (RTJ, SWG, full-face) and stud bolts (A193 B7 + A194 2H nuts) as a ready-to-install package — reducing procurement complexity for site teams.
PAN India Delivery
In-stock CS flanges dispatched within 24–48 hours. Alloy & duplex grades sourced from certified domestic & international forges with typical 4–6 week lead time. Door-to-site delivery available.
Technical Consultation
Our engineers help select facing type, pressure class, material grade & compatible gasket type for your specific service conditions — P-T ratings, NACE compliance & IBR requirements reviewed free of charge.
Get Flange Quote
Response within 2 business hours.
Flanged Joint Maintenance Best Practices
Properly maintained flanged joints prevent leaks, extend service life & maintain PESO & OISD compliance for Indian oil & gas facilities.
Bolt Torqueing
Follow ASME PCC-1 cross-pattern bolt torqueing procedures. Use calibrated torque wrenches or hydraulic bolt tensioners for Class 900+ flanges. Apply correct lubricant (Molykote or Molyslip) to threads. Verify bolt elongation for critical joints with ultrasonic bolt gauges.
Gasket Replacement
Always replace gaskets on reassembly — never reuse a compressed gasket. For RTJ grooves, inspect groove surface finish (63 Ra max) before fitting a new ring. Use the correct RTJ ring hardness (lower than flange material hardness). Kammprofile gaskets for heat exchangers.
Inspection & Leak Detection
Periodic ultrasonic thickness (UT) checks on flange body for corrosion. Acoustic emission monitoring for high-risk flanged joints. Soap bubble test for gas flanges. Liquid dye penetrant (PT) for crack detection on RTJ grooves during turnarounds.
Corrosion Protection
Apply flange face protectors (plastic caps & plugs) during storage and transport. Paint or coat flange OD and bolt holes with zinc-rich primer in corrosive environments. For buried flanges, use flange isolation kits (GRE washers & sleeves) to prevent galvanic corrosion.
Complete Your Flanged Piping System
Flanges work in combination with pipes, valves, gaskets & fasteners — source everything from Petropipe as a complete package.
Pipes
API 5L, ASTM A106 seamless & welded pipes. ½″ to 72″, all grades & schedules.
Industrial Valves
API 600/6D gate, ball, globe, check & butterfly valves. Class 150–2500.
Gaskets
RTJ, SWG, full-face & kammprofile gaskets for all flange classes & services.
Bolts & Fasteners
ASTM A193 B7 stud bolts & A194 2H heavy hex nuts for all flange classes.
Ready to Source Your Flange Requirements?
Get competitive quotes for ASME B16.5 weld neck, slip-on, blind & socket weld flanges — with full MTC documentation, dimensional reports and PAN India delivery. Gasket & bolt packages available.