Forged steel flanges to ASME B16.5 and B16.47
Weld neck, slip-on, blind, socket weld, threaded and lap joint, Class 150 to 2500, RF and RTJ.
Overview
Flanges connect valves, equipment and pipe spools and are specified by type, size, class, facing and material. We stock the full range to ASME B16.5 (½" to 24") and ASME B16.47 Series A and B (26" to 60") so that valve orders can ship with their mating flanges, gaskets and stud bolts in one consignment.
Types include weld neck for high-pressure and cyclic service, slip-on for low-pressure utilities, blind for line ends and future connections, socket weld and threaded for small bore, lap joint with stub ends for stainless and lined systems, and spectacle blinds, spades and spacers for positive isolation.
Flanges are forged, not cast, in A105 normalised carbon steel, A350 LF2 for low temperature, A182 F11 and F22 for high temperature, F304 and F316 stainless, and F51 and F53 duplex, with raised face, flat face or ring-type joint facings and 3.1 certification.
Typical applications
- Valve and equipment connections in all process plants
- Pipeline block valve stations and pig traps
- Steam and boiler piping (alloy flanges)
- Corrosive service (stainless and duplex)
- Positive isolation with spectacle blinds and spades
- Orifice flanges for flow measurement
Specified in refineries, oil & gas fields, fertilizer plants, power & heavy industry.
Specifications
| Types | Weld neck · slip-on · blind · socket weld · threaded · lap joint · long weld neck · orifice · spectacle blind / spade & spacer |
|---|---|
| Sizes | ½" – 24" (ASME B16.5) · 26" – 60" (ASME B16.47 Series A & B) |
| Pressure classes | ASME 150 · 300 · 600 · 900 · 1500 · 2500; PN6 – PN100 (EN 1092-1) |
| Facing | Raised face (RF) · flat face (FF) · ring-type joint (RTJ) · tongue & groove |
| Carbon steel | ASTM A105 (N) · A350 LF2 Cl. 1 / 2 |
| Alloy steel | ASTM A182 F11 · F22 · F5 · F9 · F91 |
| Stainless & duplex | ASTM A182 F304 / F304L · F316 / F316L · F321 · F51 · F53 |
| Certification | EN 10204 3.1 / 3.2 · NACE MR0175 · PMI and hardness test on request |
Sizes, classes and materials listed are typical of our stock and supply programme. Other combinations are quoted against your specification. See what is usually ex-stock.
Specifying the right flange
Flanges are specified by type, size, class, facing and material, and all five must match the mating equipment. Weld-neck flanges are the standard for process and high-pressure lines: the tapered hub transmits stress into the pipe and the butt weld can be radiographed. Slip-on flanges are cheaper and easier to align on low-pressure utility lines; socket-weld flanges serve small-bore high-pressure piping; blind flanges close line ends and nozzles; lap-joint flanges with stub ends suit stainless and lined lines where the flange can be carbon steel. ASME B16.5 covers ½" to 24"; ASME B16.47 Series A (MSS SP-44) and Series B (API 605) cover 26" to 60", and the two series are not interchangeable.
The facing follows the gasket: raised face (RF) with a spiral-wound or sheet gasket is standard to Class 600; ring-type joint (RTJ) with an R, RX or BX ring is specified at Class 900 and above and on wellhead and sour-gas piping. Flat face (FF) mates with cast iron or lined flanges. State the surface finish where it matters (125–250 µin AARH for spiral wound gaskets, smooth for RTJ). Material grades follow the pipe: A105 carbon steel, A350 LF2 low temperature, A182 F11/F22 chrome-moly, F304/F316 stainless, F51/F53 duplex and super duplex. Every flange is stamped with grade, class, size and heat number.
What to send us for a fast quote
- Type: WN, SO, BL, SW, LJ, TH
- Size and class; B16.5 or B16.47 Series A/B
- Facing: RF, RTJ, FF; surface finish
- Material grade; NACE if required
- Bore / schedule for weld neck and socket weld flanges
- Quantity and documents required
Why tenders get rejected, and how we avoid it
Flange bids in Pakistan are rejected for the wrong series (B16.47 A quoted against B), the wrong bore on weld-neck flanges, or stainless flanges offered in F304 against a F316L line. We check each line against the specification, confirm the bore schedule and attach the manufacturer's name and sample MTC with the quotation. More on API licences, authorisation letters and certificates.
Documentation supplied
EN 10204 3.1 material test certificate traceable to heat number, mill test certificate and dimensional report, certificate of origin and manufacturer's certificate of conformity, with NACE, fire-safe, 3.2 and third-party inspection documents where the order requires them. What every document in our package covers.
Frequently asked questions
Weld neck or slip-on?
Weld neck flanges have a tapered hub and a full-penetration butt weld, so they are specified for high pressure, high temperature, cyclic and hazardous service. Slip-on flanges are cheaper and easier to align but are limited to Class 300 and non-critical lines in most specifications.
What is the difference between B16.47 Series A and Series B?
Both cover 26" and larger. Series A (formerly MSS SP-44) flanges are heavier with larger bolts; Series B (formerly API 605) are lighter and more compact. They are not interchangeable, so the series must match the mating equipment.
Do you supply RTJ flanges with matching ring gaskets?
Yes. Ring-type joint flanges are supplied with the correct R, RX or BX ring gasket in soft iron, low-carbon steel, 316 or Inconel.
Weld neck or slip-on?
Weld neck for process, hydrocarbon, steam and any Class 300 and above: stronger, fully inspectable weld, better fatigue life. Slip-on for Class 150 utility and water lines where cost and ease of fit-up matter more.
RF or RTJ?
RF (raised face) with a spiral-wound or sheet gasket is standard to Class 600. RTJ (ring-type joint) is specified at Class 900 to 2500, on wellhead, flowline and sour-gas piping, and wherever the piping class calls for it; the ring gasket seals by metal-to-metal contact and needs a matching groove.
Related products
Order gaskets and stud bolts with the flanges so the joint arrives complete; see the gaskets and stud bolts pages, or send the full material take-off.
Gaskets
Spiral wound, ring joint, kammprofile and non-asbestos sheet gaskets to ASME B16.20 and B16.21.
Sizes, classes and brands
Stud bolts & fasteners
Stud bolts and heavy hex nuts: B7 / 2H, B7M, B8M, L7, plain, galvanized and PTFE coated.
Sizes, classes and brands
Pipe fittings
Butt-weld elbows, tees and reducers to B16.9; forged socket-weld and threaded fittings to B16.11.
Sizes, classes and brands
Gate valves
Full-bore isolation with minimal pressure drop. API 600 cast steel and API 602 forged steel, 2" to 48".
Sizes, classes and brandsRequest a quotation for flanges
Send size, class, material, quantity and required documents on WhatsApp or through the form. We reply within one working day with availability and lead time.