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Bend Restrictors Are present at the interface between flexible service lines (flexible flow-lines, umbilicals or cables) and rigid structures to prevent the over-bending of the service line during installation and service. They are designed to be flexible but lock at a bend radius (MBR) greater than that of the service line, providing protection to the line from buckling or over bending. Near neutrally buoyant half vertebra (shore 82D) are joined with corrosion resistant fasteners (UNS S32760). Using extensive experience DGDG-EU have designed standard parts that comply with API 17J.
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DGDG-EU bend restrictorstandardisation
October MMXIII
Bend Restrictor Standardisation 3
AgendaSlide1. Oct - MMXIII2. Introduction3. Agenda4. Polyurethane bend restrictors5. Vertebra material selection6. Standard internal Ø7. Service line MBR & Ø8. Variables9. Vertebra moment resistance (M )10. 2nd Moment of area (I )11. Line tension (F )12. Factors of safety
13. Vertebra moment resistance14. Line tension15. Other material selection-------------------------------------------16- 20. Examples21. Bolt calculations22. Standard products23. Different vertebra & materials24. Bespoke designs25. AOB26. Thank you27. Contact
DGDG-EU
Bend Restrictor Standardisation 4
Polyurethane bend restrictors• Are present at the interface between flexible service lines (flexible flow-
lines, umbilicals or cables) and rigid structures to prevent the over-bending of the service line during installation and service.
• They are designed to be flexible but lock at a bend radius (MBR) greater than that of the service line, providing protection to the line from buckling or over bending.
• Near neutrally buoyant half vertebra (shore 82D) are joined with corrosion resistant fasteners (UNS S32760).
• Using extensive experience DGDG-EU have designed standard parts that comply with API 17J.
DGDG-EU
Bend Restrictor Standardisation 5
Vertebra material selection
• Polyurethane - Generic = 82 Shore D• Specific gravity = 1.14• Tensile strength (σ ) 41-64MPa =
41MPa• Operating temperature = -10° + 60° C• Standard colour = Yellow
• Sub supplied 3.1B CertifiedDGDG-EU
Bend Restrictor Standardisation 6
Vertebra internal Ø
DGDG-EU
ElementType Min Max bore Ø T012 0.09 0.12 0.13T015 0.12 0.15 0.16T019 0.15 0.19 0.20T025 0.19 0.25 0.26T033 0.25 0.33 0.34T044 0.33 0.43 0.44T057 0.43 0.57 0.58T070 0.57 0.7 0.72
Service Line Ø
Bend Restrictor Standardisation 7
Service line minimum bend radius & service line Ø
Service line MBR (l ) = 10 x service line Ø
DGDG-EU
Bend Restrictor Standardisation 8
Vertebra moment resistance & line tension calculation definitions
DGDG-EU
M = Moment resistanceσ = Tensile strength I = 2nd moment of areaD = External Ød = Internal ØF = Line tensionl = MLR restrictor (≥ MBR umbilical)
Bend Restrictor Standardisation 9
Moment resistance calculation (M ) hollow cylinder
DGDG-EU
• Bending theory - peak bending moment - cylinder
(Ref:- Mechanics of Engineering Matl's -Benham & Crawford)
𝑀= 2𝜎𝐼𝐷
Bend Restrictor Standardisation 10
2nd moment of area (I ) hollow cylinder
DGDG-EU
𝐼= 𝜋64× ሺ𝐷4 − 𝑑4ሻ
11
Line tension (F ) at 90°
DGDG-EU Bend Restrictor Standardisation
𝐹= 𝑀𝑙
Bend Restrictor Standardisation 12
Safety factors
DGDG-EU
• Line tension MBR 20%• Fail - Material – supplier 0-33%• Low 25% of Fail• Max 50% of Fail
Bend Restrictor Standardisation 13
Standard moment resistance
DGDG-EU
Type (Fail) (low) (Max)T012 22 5 11T015 45 10 20T019 65 15 35T025 137 35 70T033 221 55 110T044 437 110 220T057 870 215 435T070 1407 350 705
Moment resistance kNm
Bend Restrictor Standardisation 14
Line Tension at 90°
DGDG-EU
Type MLR (Fail) (low) (Max)T012 1.3 17 5 8T015 1.6 28 5 15T019 2 33 10 15T025 2.6 53 15 25T033 3.4 65 15 30T044 4.4 99 25 50T057 5.8 150 35 75T070 7.2 195 50 100
Line Tension kN
Bend Restrictor Standardisation 15
Other material selection
• Fasteners UNS S32760• End termination CS S355• Anodes Norsok std• Paint Norsok std
• Sub supplied 3.1B Certified
DGDG-EU
Bend Restrictor Standardisation 16
Example T033 Vertebra internal Ø (d )
& minimum lock radius (r ) • Element internal Ø (d ) = 0.34m• MBR (l ) = 0.34m x 10 = 3.4m • r = MBR + 20% • r = 4.1m
Note: r is the centre of the unloaded restrictor geometry.
DGDG-EU
Bend Restrictor Standardisation 17
Example T033 Moment resistance (M ) calculation
DGDG-EU
• Service line Ø = 0.25-0.33m• Minimum clearance (c ) = 0.01m• Internal Ø (d ) = 0.33 + c = 0.34m• Element wall (t ) = 0.05m• External Ø (D ) = d + 2t = 0.44m
Bend Restrictor Standardisation 18
Example T033 2nd moment of area (I )
DGDG-EU
𝐼= 𝜋64× ሺ0.444 − 0.344ሻ ∴ 𝐼= 1.18 × 10 ³̄𝑚4
Bend Restrictor Standardisation 19
Example T033 Moment resistance(M )
DGDG-EU
𝑀= 2× 41𝑀𝑃𝑎× 1.18 × 10 ³̄𝑚40.44𝑚 ∴ 𝑀= 221 kNm
Bend Restrictor Standardisation 20
Example T033 line tension (F ) at 90°
DGDG-EU
𝐹= 221𝑘𝑁𝑚3.4𝑚 ∴ 𝐹= 65 kN
Bend Restrictor Standardisation 21
Bolt calculations
Are not covered in this presentation, to determine the bolt size extensive calculation is required for each restrictor involving the compressive strength of the polyurethane and the tensile strength of the bolt material. The sizes on the following chart are based upon established historic values.
DGDG-EU
Bend Restrictor Standardisation 22
DGDG-EU bend restrictors
DGDG-EU
TypeMin Max bore Ø MLR Bolt (Fail) (low) (Max) (Fail) (low) (Max)
T012 0.09 0.12 0.13 1.3 M8 22 5 11 17 5 8T015 0.12 0.15 0.16 1.6 M10 45 10 20 28 5 15T019 0.15 0.19 0.20 2 M10 65 15 35 33 10 15T025 0.19 0.25 0.26 2.6 M12 137 35 70 53 15 25T033 0.25 0.33 0.34 3.4 M12 221 55 110 65 15 30T044 0.33 0.43 0.44 4.4 M16 437 110 220 99 25 50T057 0.43 0.57 0.58 5.8 M20 870 215 435 150 35 75T070 0.57 0.7 0.72 7.2 M24 1407 350 705 195 50 100
Service Line Ø Line Tension kNMoment resistance kNmElement
Bend Restrictor Standardisation 24
Different shapes of vertebra
DGDG-EU
Bend Restrictor Standardisation 25
Bespoke design
• What are the possibilities to go outside the standard manufacturing program?
• DGDG-EU has experience and knowledge to design all types of bend restrictors, from polyurethane to steel and hybrids.
DGDG-EU
Bend Restrictor Standardisation 26
AOB
DGDG-EU
Bend Restrictor Standardisation 28
Thank you for your time.
DGDG-EU
Bend Restrictor Standardisation 29
For further information contact
DGDG-EU