Anchor Flanges / AF-H
Heavy Duty Anchor Flange
Reinforced, large-diameter heavy-duty anchor flange for high pressure and high axial thrust loads.
Technical Specifications
Key Features
- Reinforced heavy body
- High axial load capacity
- Gusset support plates
- Large diameter up to 60"
- High pressure class
- Cryogenic service capable
Applications
- Oil and gas pipelines
- Offshore platforms
- High-pressure steam lines
- LNG / cryogenic lines
- Power plants
- Petrochemical facilities
Design Features
- Reinforced gusset plates
- Thick weld neck
- Full-penetration welds
- Concrete anchor holes
- Hardfacing surface coating
Dimension Table
| Size | Outside Diameter (mm) | Thickness (mm) | Bolt Circle (mm) | No. of Bolts | Anchor Holes | Hole Size (mm) |
|---|---|---|---|---|---|---|
| 4" | 254 | 24 | 200.2 | 8 | 4 | 22 |
| 6" | 318 | 29 | 269.7 | 12 | 6 | 22 |
| 8" | 381 | 32 | 330.2 | 12 | 6 | 26 |
| 12" | 521 | 41 | 463.6 | 16 | 8 | 29 |
| 16" | 648 | 48 | 571.5 | 20 | 8 | 32 |
| 24" | 914 | 62 | 812.8 | 24 | 12 | 39 |
Technical Notes
- 01Sizes above 24" are made to order per ASME B16.47 (Series A/B).
- 02Strength calculation is required for high axial thrust loads.
- 03Charpy impact testing is applied for cryogenic service.
- 04Material certificates provided per EN 10204 3.1/3.2.
What is an anchor flange?
An anchor flange is a heavy forged flange welded into a pipeline and encased in a concrete anchor (thrust) block. It is not a bolted joint: its job is to fix the pipe axially and transfer thrust loads from thermal expansion and internal pressure into the structure. Produced from 2" to 60" to ASME/AWWA practice or fully custom design.
Where and how anchor flanges are used
Anchor flanges are placed wherever the pipeline needs a fixed point: pump and compressor station boundaries, both banks of river and road crossings, steep slopes, aboveground-to-buried transitions and line terminations. The flange is butt-welded into the pipe on both sides and then embedded in a concrete block; expansion forces spread into the concrete through its large outside diameter. Unlike a standard flange it has no gasket face and no bolt holes — it is purely a load-transfer component. Each unit is custom-engineered from the pipe diameter, wall thickness, operating pressure and axial load calculation. Materials: forged carbon steel A105, A694 F42–F70 to match line pipe strength, A350 LF2 for low temperature. Delivered with NDT (UT/MT) and 3.1 certificates.
Frequently Asked Questions
What is the difference between an anchor flange and a standard flange?+
A standard flange is a bolted, demountable joint; an anchor flange has no gasket face or bolt holes — it is a load-transfer component that fixes the pipe into concrete.
What loads does an anchor flange carry?+
Axial thrust loads from thermal expansion/contraction and internal pressure; it takes them from the welded pipe and transfers them into the concrete anchor block.
Where are anchor flanges installed?+
At pump/compressor station boundaries, on both banks of river and road crossings, on steep slopes, at aboveground-to-buried transitions and at line terminations.
Which materials are anchor flanges made from?+
Forged carbon steel A105, A694 F42–F70 to match line-pipe strength, or A350 LF2 for low-temperature service; dimensions are engineered per project and verified with NDT + 3.1 certificates.
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