Swivel Flanges - The Ultimate Solution for Quick & Precise Bolt Alignment
Are you struggling with bolt-hole misalignment during critical pipeline installations? We know that in offshore and subsea environments, every minute of diver time costs a fortune.
At Sunhy, we engineer Swivel Flanges (also known as Swivel Ring Flanges) to solve this exact problem. Unlike standard weld neck flanges, our unique two-piece design allows the outer ring to rotate 360° around the inner hub. This means you can align bolt holes instantly without rotating the entire pipe—saving you massive amounts of installation time and reducing residual stress on your piping system.
Types of Swivel Flanges We Supply
Stainless Steel Flanges
By Design Type
By Standard & Class
Advanced Materials
Swivel Flanges
Why Choose Sunhy Swivel Flanges?
Rapid Installation: Eliminates the frustration of “two-holing.” Perfect for subsea tie-ins where manipulating heavy pipe is impossible.
Engineered for Reliability: Manufactured strictly to ASME B16.5, API 6A, and MSS SP-44 standards. We don’t cut corners on wall thickness or material grade.
Versatile Pressure Ratings: Available from Class 150 to Class 2500. Whether it’s standard stainless steel or high-yield carbon steel, we forge durability into every piece.
Custom Solutions: Need a special facing or a non-standard dimension? Our engineering team has 15+ years of experience in custom flange fabrication.
What is Swivel Flanges ？
A Swivel Flange (SRF) is a two-piece pipe connection assembly consisting of a heavy forged welding hub and a rotating outer ring. The hub is welded directly to the pipeline, while the outer ring is fitted over the hub and held in place by a mechanical retainer (typically a snap ring or spring steel), allowing it to rotate 360 degrees around the hub.
| Feature | Specification Details |
| Design Structure | Two-piece: Heavy forged welding hub + Rotating outer ring |
| Size Range | 1/2″ to 60″ (Custom sizes available) |
| Pressure Ratings | ASME Class 150, 300, 600, 900, 1500, 2500 |
| Materials | Stainless Steel (304/304L, 316/316L), Duplex, Carbon Steel (A105), Alloy Steel |
| Face Types | Raised Face (RF), Ring Type Joint (RTJ), Flat Face (FF) |
| Key Standards | ASME B16.5, ASME B16.47, API 17D, MSS SP-44 |
Related blog
FAQ
What is the difference between a swivel flange and a lap joint flange?
The primary difference lies in their pressure-retaining capacity and structural integrity.
- Swivel Flange (SRF): Designed for high-pressure critical applications (up to Class 2500 or API 10,000 psi). It utilizes a heavy forged hub and a locking retainer mechanism that allows the flange to withstand significant bending moments and end loads typical in deepwater risers.
- Lap Joint Flange (LJF): Designed for low-pressure (typically Class 150–300), non-critical utility systems. It relies on the face contact between the stub end and the backing flange and lacks the shear strength required for high-pressure dynamic environments. Engineering Note: A Lap Joint Flange must never be used as a substitute for a Swivel Flange in high-pressure subsea applications due to its inability to handle the required axial and bending loads.
Are swivel flanges compatible with standard flanges?
Yes, Swivel Flanges are geometrically compatible with standard flanges. The mating dimensions—specifically the bolt circle diameter, number of bolts, and bolt hole size—are manufactured to strictly adhere to industry standards such as ASME B16.5, MSS SP-44, or API 6A. This ensures that a Swivel Flange can be bolted directly to any standard Weld Neck (WN) flange or valve of the same pressure class and size. However, while the connection interface is standard, the internal geometry (specifically the hub wall thickness) is non-standard and is typically thicker to compensate for stress concentrations at the retainer groove.
What Design Codes and Pressure Ratings Apply to Swivel Flanges?
Swivel Flanges are available in pressure ratings ranging from Class 150 to Class 2500 and can be engineered for API 10,000 psi service. Unlike standard flanges which follow dimensional look-up tables (ASME B16.5), the structural design of a Swivel Flange hub must be calculated according to ASME Boiler and Pressure Vessel Code (BPVC) Section VIII, Division 2. This rigorous analytical design method ensures the flange hub and retainer ring can withstand the longitudinal and shear stresses that exceed the scope of standard flange design rules.