WNRF, WNFF & WNRTJ flanges in carbon steel, stainless steel, duplex, alloy steel, Monel, Inconel, Hastelloy, Titanium & Copper Nickel. ASME B16.5 Class 150–2500, ASME B16.47, EN 1092-1, DIN, BS, AS 2129, API 605/6A. Size ½" to 56" NB. EN 10204 3.1/3.2 MTC. Exporting to 65+ countries for 30+ years.
A weld neck flange is a forged pipe flange with a long tapered hub that is butt-welded directly to the pipe. The bore is precision-machined to match the pipe's inside diameter exactly, creating a smooth, unobstructed flow path with no crevice or step at the weld joint. This design makes weld neck flanges — also designated WNRF (Weld Neck Raised Face) — the strongest, most fatigue-resistant, and most code-compliant flange type in existence.
Tesco Steel & Engineering manufactures weld neck flanges in the complete range of industrial materials and international standards — from everyday ASTM A105 carbon steel to exotic nickel alloys — with full traceability to EN 10204 3.1 material test certificates. Our weld neck flanges are dimensioned per ASME B16.5, ASME B16.47, EN 1092-1, DIN 2631–2638, BS 4504, AS 2129, API 605, and API 6A. Ready stock is available for the most common sizes and materials; custom and large-diameter flanges are manufactured to order.
The bore is machined to match the pipe ID precisely. No step, no crevice, no restriction — fluid flows through without turbulence, cavitation, or erosion at the joint. Critical for high-velocity, abrasive, and erosive service such as slurry, steam, and produced water.
The butt weld joint can be fully inspected by radiography (RT), ultrasonic testing (UT), and magnetic particle inspection (MPI) — unlike slip-on flange fillet welds. Mandatory in ASME B31.3 severe cyclic service, nuclear piping, and high-consequence gas pipelines.
The long tapered hub distributes stress from the flange face gradually into the pipe wall, avoiding the abrupt stress concentration at the weld toes that causes fatigue cracking. Weld neck flanges have approximately 50% higher fatigue life than slip-on flanges under cyclic loading.
Available in Class 150 through 2500 per ASME B16.5. At ambient temperature, Class 2500 carbon steel weld neck flanges are rated at 6,170 PSI (425 bar). Suitable for cryogenic service (down to −196°C with LTCS or stainless grades) and elevated temperatures up to 700°C+ with alloy steel or nickel alloy grades.
Weld neck flanges are available with Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue & Groove (T&G), and Male & Female (M&F) facings. This versatility makes them compatible with virtually every gasket type and every process piping application across all industries.
Weld neck flanges are accepted by every major piping code worldwide: ASME B31.1, B31.3, B31.4, B31.8; API 6A/6D; EN 13480; ISO 15590-3; Norsok L-001; Shell DEP; ExxonMobil GP. No other flange type is as universally specified in international process piping standards.
| Size Range | ½" NB to 56" NB (DN 15 to DN 1400) |
| Pressure Classes (ASME B16.5) | Class 150, 300, 400, 600, 900, 1500, 2500 |
| Large Diameter (ASME B16.47) | Series A: Class 150, 300, 400, 600, 900 | Series B: Class 75, 150, 300, 400, 600, 900 |
| Schedule / Wall Thickness | STD, XS, XXS, Sch 20, 40, 60, 80, 100, 120, 140, 160 |
| PN Ratings (EN / DIN / BS) | PN 2.5, 6, 10, 16, 25, 40, 63, 100, 160, 250, 320, 400 |
| Facing Types | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue & Groove (T&G), Male & Female (M&F) |
| Carbon Steel | ASTM A105 |
| Low Temp. Carbon Steel (LTCS) | ASTM A350 LF2 / LF3 |
| Alloy / Chrome-Moly Steel | ASTM A182 — F5, F9, F11, F12, F21, F22, F91 |
| Stainless Steel | ASTM A182 — F304, F304L, F304H, F316, F316L, F316H, F316Ti, F309, F310, F317L, F321, F347, F904L |
| Duplex & Super Duplex Steel | ASTM A182 — F51 (2205), F53 (2507), F55 (Zeron 100) |
| Copper Nickel | ASTM B564 — UNS C70600 (90/10), C71500 (70/30), C71640 |
| Monel | ASTM B564 — UNS N04400 (Monel 400), N05500 (Monel K-500) |
| Nickel | ASTM B564 — UNS N02200, N02201 |
| Inconel / Incoloy | ASTM B564 — UNS N06600, N06601, N06625, N08800, N08810, N08825 |
| Hastelloy | ASTM B564 — UNS N10276 (C276), N06022 (C22), N10665 (B2), N06455 (C4) |
| Titanium | ASTM B381 — Grade 1, Grade 2, Grade 3 |
| Special Coatings | Hot Dip Galvanized (HDG / GI), Epoxy Coated, FBE Coated, Sand Blasted, Shot Peened |
| Certification | EN 10204 Type 3.1 (standard) / Type 3.2 (third-party witnessed — BV, Lloyds, TUV, SGS, Intertek) |
| Feature | Weld Neck (WNRF) | Slip-On (SORF) | Socket Weld (SWRF) |
|---|---|---|---|
| Weld Type | Single butt weld (full penetration) | Two fillet welds (inside + outside) | Single fillet weld (outside only) |
| Weld Inspectability | Full RT / UT / MPI / DPI | Limited (fillet weld) | Limited (fillet weld) |
| Bore Match to Pipe | Exact — no step | Approximate | None (socket bore) |
| Pressure Rating | Highest — all classes | Lower (≈ 67% of WN) | Moderate (2" NB max) |
| Fatigue Resistance | Excellent | Good | Good |
| Max Size Available | 56" NB and above | 56" NB and above | 2" NB (ASME B16.5) |
| Installation Ease | Requires precise pipe end prep | Easy — slides over pipe | Easy — socket guides pipe |
| Relative Cost | Higher | Lower | Moderate |
| Ideal Application | Critical, high-pressure, cyclic, hazardous service | General process, utilities, low-medium pressure | Small-bore instrument lines, ≤ 2" |
| Industry | Typical Weld Neck Flange Applications |
|---|---|
| Oil & Gas — Upstream | Wellhead connections, flowlines, choke manifolds, test separators, high-pressure process headers, pig launchers |
| Oil & Gas — Downstream | Refinery process piping, crude distillation units, hydrotreater connections, FCC feed and product lines, compressor nozzles |
| Petrochemical & Chemical | Reactor nozzle connections, high-pressure heat exchanger shell connections, column feed/draw nozzles, hazardous chemical headers |
| Power Generation | Main steam piping, feedwater lines, turbine casing connections, boiler drum nozzles, superheater headers (alloy steel F11/F22/F91) |
| LNG & Cryogenic | LNG transfer lines (LTCS A350 LF2), liquefaction process piping, cold-box connections, cryogenic pump discharge (stainless steel 316L) |
| Offshore & Marine | Subsea pipeline connectors, riser flanges, turret swivel joints, seawater lift headers (copper nickel), topside process headers |
| Pulp, Paper & Desalination | High-pressure process steam, brine and acid service, hot caustic piping, seawater intake headers |
Click any standard below to access the full dimension table for that pressure class or PN rating.
| ANSI B16.1 Class 125 Weld Neck Flange |
| ANSI B16.1 Class 250 Weld Neck Flange |
| DIN 2631 PN 6 Weld Neck Flange |
| DIN 2632 PN 10 Weld Neck Flange |
| DIN 2633 PN 16 Weld Neck Flange |
| DIN 2634 PN 25 Weld Neck Flange |
| DIN 2635 PN 40 Weld Neck Flange |
| BS 4504 PN 2.5 Weld Neck Flange |
| BS 4504 PN 6 Weld Neck Flange |
| BS 4504 PN 10 Weld Neck Flange |
| BS 4504 PN 16 Weld Neck Flange |
| BS 4504 PN 25 Weld Neck Flange |
| BS 4504 PN 40 Weld Neck Flange |
| BS 3293 Class 150 Weld Neck Flange |
| BS 3293 Class 300 Weld Neck Flange |
| BS 3293 Class 400 Weld Neck Flange |
| BS 3293 Class 600 Weld Neck Flange |
| VSM 18703 PN 6 Weld Neck Flange |
| VSM 18703 PN 16 Weld Neck Flange |
| SABS 1123 Class 600 Weld Neck Flange |
| SABS 1123 Class 1000 Weld Neck Flange |
| SABS 1123 Class 1600 Weld Neck Flange |
| SABS 1123 Class 2500 Weld Neck Flange |
| SABS 1123 Class 4000 Weld Neck Flange |
| MSS SP-44 Class 150 Weld Neck Flange |
| MSS SP-44 Class 300 Weld Neck Flange |
| MSS SP-44 Class 400 Weld Neck Flange |
| MSS SP-44 Class 600 Weld Neck Flange |
| MSS SP-44 Class 900 Weld Neck Flange |
| NFE 29203 Type 11 PN 10 Weld Neck Flange |
| NFE 29203 Type 11 PN 16 Weld Neck Flange |
| NFE 29203 Type 11 PN 25 Weld Neck Flange |
| NFE 29203 Type 11 PN 40 Weld Neck Flange |
| JIS 30K Weld Neck Flange |
| JIS 40K Weld Neck Flange |
| JIS 63K Weld Neck Flange |
Countries We Export To: UAE, Saudi Arabia, Kuwait, Qatar, Bahrain, Oman, Iraq, Germany, Netherlands, UK, Italy, France, Russia, Turkey, Kazakhstan, USA, Canada, Mexico, Venezuela, Colombia, Peru, Brazil, Nigeria, Kenya, South Africa, Tanzania, Angola, Algeria, Sudan, Libya, Egypt, Israel, Jordan, Iran, Pakistan, Malaysia, Indonesia, Philippines, Thailand, Vietnam, Singapore, Australia, China, South Korea, Japan, Bangladesh.
India (Domestic): Mumbai, Delhi, Bengaluru, Hyderabad, Ahmedabad, Chennai, Kolkata, Surat, Pune, Jaipur, Nagpur, Vadodara, Ludhiana, Coimbatore, Visakhapatnam, Bhopal, Indore, Thane, Pimpri-Chinchwad, all states.
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All materials, all standards, all schedules — ASME B16.5 Class 150 to 2500, B16.47, EN 1092-1, API 6A. Ready stock in CS, SS, and duplex. Custom and large-diameter flanges manufactured to order.