ASME B16.5 | Long Weld Neck (LWN) | RF / FF / RTJ | Class 150–2500
Long Weld Neck Flanges (LWN) feature an extended tapered hub that provides a longer transition between the flange and the connecting pipe or equipment. The extended hub can provide additional rigidity and support for applications involving high pressure, elevated temperature, thermal cycling, or demanding mechanical loads.
Long Weld Neck Flanges are commonly used for equipment nozzles, pressure vessels, heat exchangers, high-pressure piping and other specialized applications where a longer hub configuration is required.
Elite supplies Long Weld Neck Flanges in carbon steel, stainless steel, duplex and super duplex stainless steel, alloy steel, low-temperature carbon steel, nickel alloys and copper-nickel alloys. Products are available to applicable ASME, ASTM, MSS, EN, DIN, BS and customer project specifications.
| Category | Specification |
|---|---|
| Flange Type | Long Weld Neck (LWN) Flange |
| Nominal Size | NPS 1/2–24, where covered by the applicable standard and configuration |
| Pressure Classes | 150, 300, 400, 600, 900, 1500, 2500, where applicable |
| Facing | Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), where applicable |
| Primary Dimensional Standard | ASME B16.5, where applicable |
| Large-Diameter Flanges | ASME B16.47, where applicable |
| Pipeline Flanges | MSS SP-44, where applicable |
| Connection | Butt-weld or equipment/nozzle connection, as specified |
| Hub Configuration | Extended / long tapered hub |
| Bore | Standard bore or special bore to suit pipe/equipment requirements |
| Manufacturing | Forged, machined and finished in accordance with applicable specifications |
| Surface Finish | Standard or customer-specified |
| Heat Treatment | As required by applicable material specification |
| Inspection | Visual, dimensional, chemical and mechanical testing as applicable |
| NDE | PMI, UT, MT, PT and other NDE methods as specified |
| Documentation | MTC, EN 10204 3.1/3.2, COC and inspection reports |
| Special Requirements | ITP, third-party inspection, NACE / ISO 15156 and customer specifications |
Long Weld Neck Flanges are supplied to the applicable flange and project standards.
Applicable standards may include:
Note: Long Weld Neck Flanges are often manufactured to custom/project-specific dimensions, particularly for equipment, vessels and specialized piping applications. Therefore, the applicable dimensional standard should always be confirmed with the project specification or drawing.
Carbon Steel
ASTM A105/A105N, ASTM A181, ASTM A350 LF2/LF3 and ASTM A694 F42, F46, F52, F60 and F65.
Stainless Steel
ASTM A182 F304/F304L, F316/F316L, F321/F321H, F347/F347H, F310/F310S, F317 and F904L.
Duplex & Super Duplex
ASTM A182 F51, F53 and F55.
Alloy Steel
ASTM A182 F1, F5, F9, F11, F12, F22, F91 and F92.
Nickel Alloys
Nickel 200/201, Monel 400/K500, Inconel 600/601/625/800/825, Hastelloy C276 and Alloy 20.
Copper-Nickel Alloys
UNS C70600 and C71500, including 90/10 and 70/30 Cu-Ni alloys.
Material selection is based on pressure, temperature, process fluid, corrosion conditions, mechanical loads, thermal cycling and applicable project requirements.
Long Weld Neck Flange Facing Options
Raised Face — RF
The most common configuration for process piping, equipment and industrial applications.
Product designation: LWN RF / Long Weld Neck Raised Face Flange
Flat Face — FF
Used for selected equipment and piping connections where a full-face mating surface is required.
Product designation: LWN FF / Long Weld Neck Flat Face Flange
Ring Type Joint — RTJ
Used for applicable high-pressure and high-temperature applications requiring a metallic ring gasket sealing system.
Product designation: LWN RTJ / Long Weld Neck RTJ Flange
The extended hub provides a longer transition from the flange body to the pipe or equipment connection.
Key characteristics include:
Long Weld Neck Flanges are frequently customized according to equipment nozzle dimensions, vessel design, pipe schedule, bore requirements, pressure class and project drawings.
Elite supplies:
Elite Long Weld Neck Flanges can be supplied with complete quality documentation, including:
Long Weld Neck Flanges are commonly used for:
For quotation, please specify:
NPS + Class + Facing + Material + Bore + Hub Length + Standard / Drawing + Quantity + Inspection Requirements
Example:
6″ Class 600 Long Weld Neck Flange, RF, ASTM A105N, ASME B16.5, Standard Bore, Extended Hub, MTC EN 10204 3.1.
