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Bend Restrictor Inquiry Form

VBR Inquiry Form


Vertebrae Bend Restrictors

Vertebrae Bend Restrictors provide protection from excessive bending of flexible flowlines, subsea umbilicals, and cables.


Vertebrae Bend Restrictor


The Vertebrae Bend Restrictor (VBR) is designed to prevent damage to the cable it protects. It offsets the action of applied loads which could kink or buckle the internal conduits of an umbilical, cable, flexible riser pipe or MUX line. 
The characteristics of the VBR allow the umbilical to freely flex in any direction,limiting it at the Locking Bend Radius (LBR). At that point the segments of the VBR will lock on each other increasing the effective stiffness of the cable it protects to withstand specified loads applied to the device without violating the specified minimum bend radius (MBR). The VBR will accommodate lines 0.5inch (13 mm) to 16 inches (406 mm) in diameter and is made from either polyurethane or steel depending on the need.
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 Steel VBRs

The Steel Vertebrae Bend Restrictor (SVBR) is designed to prevent damage to the umbilical control line that it supports at higher loads than its polyurethane counterpart. SVBR assemblies share the same characteristics as polyurethane VBR assemblies in that they protect the control-line to a customer specified Minimum Bending Radius (MBR). Due to the material properties of steel in comparison to polyurethane, SVBR assemblies do not exhibit a large difference between the Locking Bend Radius and the MBR under loading.

The SVBR Assemblies are comprised of male and female type segments that fit into each other.  The male segment pair is locked inside the adjacent female segment pairs, thereby reducing the number of fasteners required to complete the assembly. SVBR assemblies are equipped with polyurethane stress wafers that work to evenly distribute the stress during loading.


Hybrid VBRs

ABCO Subsea’s Hybrid Vertebrae Bend Restrictors are made from both steel and polyurethane segments and provide the benefits of both materials in deep water, high load applications. Hybrid VBRs use steel segments near the VBR assembly’s structural support interface, where most loading occurs. Farther from the VBR assembly’s interface, polyurethane segments are used to take advantage of the near neutral buoyancy of the polyurethane.

As opposed to an entirely steel VBR assembly, the Hybrid concept results in cost savings of 5-30% for ABCO Subsea’s customers. Additionally, the polyurethane segments reduce the overall weight of the Hybrid VBR assembly compared to an entirely steel VBR assembly, and the polyurethane segments are easier to handle and assemble, reducing installation vessel schedules.

ABCO Subsea designed and produced its first Hybrid VBR assembly in 2009 after a customer approached the company about a challenging deep water environment.
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Custom VBRs


ABCO custom designs bend restrictors, bend limiters, & bend stiffeners to customers’ specifications. Static and dynamic loads are specified by the customer or calculated by our engineers using catenary tension, angle from the umbilical termination assembly (UTA) at which the tension acts, and the required minimum bending radius. Depending on the required load and product line, the LBR is specified to be anywhere from 10-100% larger than the MBR to account for deflection under load. The urethane used provides excellent elasticity for repeatable loading and catastrophic failure prevention.