Bend Restrictors

two engineers on a ship's deck installing bend restricotrs on a cableDescription & Function

Bend Restrictors are used to prevent the overbending of flexible flowlines, umbilicals and cables during installation and service by locking when the minimum bend radius is reached. They are usually used at the interface between flexible and rigid structures.

The PE Bend Restrictor is designed to bend up to a lock out limit or minimum bend radius above that of the flexible thereby preventing buckling or damage.

The Bend Restrictor is also designed to a maximum stress or bending moment to more than accommodate the highest load to be experienced in the field.

computer generated image of a yellow polyurethane bend restrictor sectionPE Bend Restrictors are designed as interlocking vertebrae each comprising two polyurethane half sections. These sections are fitted together with corrosion resistant metal the last section in the assembly having metal inserts to reinforce the location of maximum stress next to the rigid structure fixing.

This half section design allows for more rapid assembly of the bend restrictor either in the field or at the factory.

When the minimum bend radius is achieved the joints lock out preventing movement past this point. When joined together each element can move small angular distances, which when expanded over the entire Bend restrictor length, matches the required locking radius.

Application

computer generated image of a chain of polyurethane bend restrictorsBend Restrictors are for static applications. Bend restrictors can be used onshore, offshore or subsea and are usually used at the interface between flexible and rigid structures.

Features and Benefits

  • PE Bend Restrictors have near neutral buoyancy and excellent tensile characteristics.
  • Tests have also shown that they have good resistance to the effects of ageing and the marine environment.
  • PE Bend Restrictors retain good load bearing properties across a broad temperature range and have good wear and abrasion performance.
  • PE’s Bend Restrictor is manufactured using PE’s high performance Omnithane® polyurethane allowing different grades of polyurethane are used depending on the application’s requirements.
  • PE Bend Restrictors comply with API 17J Appendix B.
  • PE Bend Restrictors have excellent tensile characteristics.
  • PE Bend Restrictors have excellent load bearing properties across a broad temperature range.

Bend Restrictor Material Performance

Typical Elastomer Performance
  Properties at 23°C Properties at 40 °C Properties at 60 °C
Hardness (DIN 53505) 82 Shore D 75 Shore D 69 Shore D
10% Modulus (DIN 53504) 54.8 MPa 37.9 MPa 14.3 MPa
100% Modulus (DIN 53504) - 29.3 MPa 15.6 MPa
Tensile strength (DIN 53504) 62 MPa 39 MPa 23 MPa
Elongation at break (DIN 53504) 6% 8% 210%
Tear strength : without nick (DIN 53515) 154 kN/m 146 kN/m 105 kN/m
Abrasion loss (DIN 53516) 300 mm³ - -
Compression set (DIN 53517) 91% - -

string of bend restrictors an a construction floor, being measuredPolyurethane Expertise

PE’s expertise in polyurethane technology allows us to cast liquid polyurethane into precision made mouldings to exacting standards, meeting our own very strict dimensional tolerances. Detailed quality checks and testing are carried out on all components.

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