Lap Joint Flanges
Lap Joint Flanges
ASME B16.5 | Lap Joint (LJ) | FF / RF / RTJ | Class 150–300
Lap Joint Flanges are designed for use with a compatible stub end and provide a loose, rotating flange connection around the pipe. The flange itself is not welded directly to the pipe; instead, the stub end is welded to the pipe and the Lap Joint Flange is positioned over the stub end.
This configuration allows the flange to rotate for easier bolt-hole alignment and is particularly useful where frequent dismantling, inspection, maintenance, or alignment is required.
Elite supplies Lap Joint Flanges in carbon steel, stainless steel, duplex and super duplex stainless steel, alloy steel, low-temperature carbon steel, nickel alloys, and copper-nickel alloys. Flanges are available to ASME B16.5, applicable ASTM material specifications, international standards, and customer project requirements.
Technical Specifications
| Category | Specification |
|---|---|
| Flange Type | Lap Joint (LJ) Flange |
| Connection | Used with compatible Stub End |
| Nominal Size | NPS 1/2–24 per ASME B16.5; larger sizes available to applicable standards |
| Pressure Classes | 150, 300, 400, 600, 900, 1500, 2500, where applicable |
| Facing | Flat Face (FF), Raised Face (RF), RTJ where applicable to the configuration |
| Primary Dimensional Standard | ASME B16.5 |
| Large-Diameter Flanges | ASME B16.47, where applicable |
| Pipeline Flanges | MSS SP-44, where applicable |
| Manufacturing | Forged or manufactured in accordance with applicable specifications |
| Bore | Compatible with specified stub-end configuration |
| Flange Rotation | Loose/rotatable around the stub end |
| 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 |
Applicable Standards
For process and industrial applications, Elite Lap Joint Flanges are primarily supplied in accordance with ASME B16.5.
Applicable standards may include:
- ASME B16.5 — Pipe Flanges and Flanged Fittings
- ASME B16.47 — Large Diameter Steel Flanges, where applicable
- MSS SP-44 — Steel Pipeline Flanges, where applicable
- ASTM material specifications
- ASME Section II material requirements, where specified
- NACE MR0175 / ISO 15156 — Sour-service applications, where specified
- EN 1092-1 — European flange systems
- DIN standards, where specified
- BS standards, where specified
- Customer drawings and project specifications
For ASME applications, ASME B16.5 provides the primary dimensional and pressure-rating requirements for applicable Lap Joint Flanges.
Materials
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 operating pressure, temperature, process fluid, corrosion conditions, mechanical requirements and applicable project specifications.
Lap Joint Flange Facing Options
Flat Face — FF
Commonly used with Lap Joint Flange assemblies where a full-face gasket arrangement is required.
Raised Face — RF
Available for applicable Lap Joint flange configurations and mating arrangements.
Ring Type Joint — RTJ
Available for applicable high-pressure configurations where a metallic ring gasket sealing arrangement is specified.
Lap Joint Flange & Stub End Connection
A Lap Joint Flange assembly consists of two primary components:
- Stub End
The stub end is butt-welded to the pipe and provides the sealing face and flange-bearing surface. - Lap Joint Flange
The loose flange is installed over the stub end and can rotate independently before bolting.
This configuration provides several practical advantages:
- Easy bolt-hole alignment
- Rotatable flange
- Simplified installation
- Easier dismantling
- Convenient maintenance and inspection
- Reduced flange replacement cost in selected applications
- Suitable for corrosive services when properly engineered
- Useful for systems requiring frequent disassembly
The flange material and stub-end material can be selected independently where permitted by the applicable design and project requirements.
Quality & Inspection
Elite Lap Joint Flanges can be supplied with complete quality documentation, including:
- Material Test Certificates (MTC)
- EN 10204 3.1 / 3.2 certification
- Dimensional inspection reports
- Chemical analysis
- Mechanical test results
- Heat-treatment records
- Positive Material Identification (PMI)
- Ultrasonic Testing (UT)
- Magnetic Particle Testing (MT)
- Liquid Penetrant Testing (PT)
- Visual inspection reports
- Certificate of Conformance (COC)
- Third-party inspection reports
- ITP and quality documentation
- Packing and marking records
Product Types
Elite supplies:
- ASME B16.5 Lap Joint Flanges
- Lap Joint Raised Face Flanges
- Lap Joint Flat Face Flanges
- Lap Joint RTJ Flanges, where applicable
- Stainless Steel Lap Joint Flanges
- Carbon Steel Lap Joint Flanges
- Alloy Steel Lap Joint Flanges
- Duplex Lap Joint Flanges
- Super Duplex Lap Joint Flanges
- Nickel Alloy Lap Joint Flanges
- Copper-Nickel Lap Joint Flanges
- Forged Lap Joint Flanges
- High-Pressure Lap Joint Flanges
- Large-Diameter Lap Joint Flanges
- Custom Lap Joint Flanges
- Lap Joint Flange & Stub End Assemblies
Applications
Lap Joint Flanges are commonly used in:
- Oil & Gas
- Refining
- Petrochemical
- Chemical Processing
- LNG & Natural Gas
- Offshore & Marine
- Water & Wastewater
- Power Generation
- Process Skids
- Package Equipment
- Pipeline Systems
- Food Processing
- Pharmaceutical Processing
- Pulp & Paper
- Mining & Minerals
- General Process Piping
Ordering Information
For quotation, please specify:
NPS + Class + Facing + Flange Material + Stub End Type/Material + Pipe Schedule + Standard + Quantity + Inspection Requirements
Example:
6″ Class 150 Lap Joint Flange, RF, ASME B16.5, ASTM A105N, for MSS SP-43 Type A Stub End, MTC EN 10204 3.1.
