A Riser Hang-Off Collar is a high-strength, metallic ring-shaped device installed on the exterior of a riser joint, typically near the connector. It acts as a load-bearing shoulder, safely transferring millions of pounds of string load to the rig’s rotary table or hang-off brackets during operational pauses or equipment maintenance.
Core Materials
Within this system, different materials have clear divisions of labor to withstand extreme deep-sea environments:
High-Strength Steel: Sustaining Extreme Loads
Application: The main body of the Hang-Off Collar.
Rationale: It must support static loads ranging from hundreds to over a thousand tons. It is typically forged from heat-treated alloy steel to ensure zero deformation under massive tensile and compressive stresses.
High-Performance Polyurethane (PU): Providing System Protection
While the collar body itself is not made of polymer, polyurethane elastomers play a vital role in the riser system's peripheral accessories:
1. Internal Liners: High-performance polyurethane liners are often embedded on the inner diameter of the collar or at the interface with the pipe body. These liners effectively prevent direct metal-to-metal friction from damaging the riser’s anti-corrosion coatings and base material.
2. Vibration Damping & Guidance: Polyurethane possesses excellent impact resistance and damping properties. During hang-off, PU components absorb vibrations caused by ocean swells, thereby reducing metal fatigue.
3. Auxiliary Line Clamps: Risers are typically equipped with external hydraulic lines and cables. The clamps for these lines are often manufactured from hydrolysis-resistant, high-hardness polyurethane, leveraging its wear resistance and sea-water corrosion resistance without damaging the auxiliary lines.
Primary Application Scenarios
Emergency Suspension in Severe Weather: When typhoons or heavy swells necessitate disconnection, the hang-off collar is used to "lock" the string temporarily to the platform.
Load Transfer: Shifting the load from the active tensioner system to the fixed platform structure, allowing for tensioner maintenance.
Offline Preparation: Used for the pre-assembly and storage of riser sections within the moonpool area.
Technical Advantages Summary
Component | Core Material | Primary Function |
Collar Body | High-Strength Alloy Steel | Ultimate load-bearing and structural support |
Protective Liners | High-Performance PU | Cushioning, damping, and coating protection |
Sealing/Dust Caps | Polyurethane Elastomer | Seawater isolation and protection of precision mating surfaces |
Looking for High-Performance Riser Solutions?
Ensure the safety and longevity of your offshore operations with our precision-engineered Hang-Off Collars. Contact our technical team today.
