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.

1. DGDG-EU bend restrictor
standardisation
October MMXIII

2. Introducing
DGDG-EU
Bend Restrictor Standardisation
2

3. Agenda
Slide
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Oct - MMXIII
Introduction
Agenda
Polyurethane bend restrictors
Vertebra material selection
Standard internal Ø
Service line MBR & Ø
Variables
Vertebra moment resistance (M )
2nd Moment of area (I )
Line tension (F )
Factors of safety
DGDG-EU
13. Vertebra moment resistance
14. Line tension
15. Other material selection
------------------------------------------16- 20. Examples
21. Bolt calculations
22. Standard products
23. Different vertebra & materials
24. Bespoke designs
25. AOB
26. Thank you
27. Contact
Bend Restrictor Standardisation
3

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
4

5. Vertebra material selection
•
•
•
•
•
Polyurethane - Generic
Specific gravity
Tensile strength (σ ) 41-64MPa
Operating temperature
Standard colour
• Sub supplied
DGDG-EU
= 82 Shore D
= 1.14
= 41MPa
= -10° + 60° C
= Yellow
3.1B Certified
Bend Restrictor Standardisation
5

6. Vertebra internal Ø
Type
T012
T015
T019
T025
T033
T044
T057
T070
DGDG-EU
Service Line Ø Element
Max bore Ø
Min
0.13
0.12
0.09
0.16
0.15
0.12
0.20
0.19
0.15
0.26
0.25
0.19
0.34
0.33
0.25
0.44
0.43
0.33
0.58
0.57
0.43
0.72
0.7
0.57
Bend Restrictor Standardisation
6

7. Service line minimum bend radius
& service line Ø
Service line MBR (l ) = 10 x service line Ø
DGDG-EU
Bend Restrictor Standardisation
7

8. Vertebra moment resistance & line
tension calculation definitions
M
σ
I
D
d
F
l
DGDG-EU
=
=
=
=
=
=
=
Moment resistance
Tensile strength
2nd moment of area
External Ø
Internal Ø
Line tension
MLR restrictor (≥ MBR umbilical)
Bend Restrictor Standardisation
8

9. Moment resistance calculation (M )
hollow cylinder
• Bending theory - peak bending moment - cylinder
2𝜎𝐼
𝑀=
𝐷
(Ref:- Mechanics of Engineering Matl's -Benham & Crawford)
DGDG-EU
Bend Restrictor Standardisation
9

10. 2nd moment of area (I )
hollow cylinder
𝜋
𝐼=
× 𝐷4 − 𝑑4
64
DGDG-EU
Bend Restrictor Standardisation
10

11. Line tension (F ) at 90°
𝑀
𝐹=
𝑙
DGDG-EU
Bend Restrictor Standardisation
11

12. Safety factors
•
•
•
•
Line tension MBR
Fail - Material – supplier
Low
Max
DGDG-EU
Bend Restrictor Standardisation
20%
0-33%
25% of Fail
50% of Fail
12

13. Standard moment resistance
Moment resistance kNm
Type (Fail)
(low)
(Max)
T012
22
5
11
T015
45
10
20
T019
65
15
35
T025
137
35
70
T033
221
55
110
T044
437
110
220
T057
870
215
435
T070
1407
350
705
DGDG-EU
Bend Restrictor Standardisation
13

14. Line Tension at 90°
Type
T012
T015
T019
T025
T033
T044
T057
T070
DGDG-EU
Line Tension kN
MLR (Fail) (low) (Max)
1.3
17
5
8
1.6
28
5
15
2
33
10
15
2.6
53
15
25
3.4
65
15
30
4.4
99
25
50
5.8
150
35
75
7.2
195
50 100
Bend Restrictor Standardisation
14

15. Other material selection
•
•
•
•
Fasteners
End termination
Anodes
Paint
UNS S32760
CS S355
Norsok std
Norsok std
• Sub supplied
DGDG-EU
3.1B Certified
Bend Restrictor Standardisation
15

16. Example T033
Vertebra internal Ø (d )
& minimum lock radius (r )
•
•
•
•
Element internal Ø (d )
MBR (l ) = 0.34m x 10
r
r
= 0.34m
= 3.4m
= MBR + 20%
= 4.1m
Note: r is the centre of the unloaded restrictor geometry.
DGDG-EU
Bend Restrictor Standardisation
16

17. Example T033
Moment resistance (M ) calculation
•
•
•
•
•
Service line Ø
Minimum clearance (c )
Internal Ø (d ) = 0.33 + c
Element wall (t )
External Ø (D ) = d + 2t
DGDG-EU
Bend Restrictor Standardisation
= 0.25-0.33m
= 0.01m
= 0.34m
= 0.05m
= 0.44m
17

18. Example T033
nd
2
moment of area (I )
𝜋
4
4
𝐼=
× 0.44 − 0.34
64
∴
DGDG-EU
𝐼 = 1.18 × 10ˉ³𝑚4
Bend Restrictor Standardisation
18

19. Example T033
Moment resistance(M )
2 × 41𝑀𝑃𝑎 × 1.18 × 10ˉ³𝑚
𝑀=
0.44𝑚
∴
DGDG-EU
4
𝑀 = 221 kNm
Bend Restrictor Standardisation
19

20. Example T033
line tension (F ) at 90°
221𝑘𝑁𝑚
𝐹=
3.4𝑚
∴ 𝐹 = 65 kN
DGDG-EU
Bend Restrictor Standardisation
20

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
21

22. DGDG-EU bend restrictors
Type
T012
T015
T019
T025
T033
T044
T057
T070
Service Line Ø
Element
Min
Max bore Ø MLR
0.09
0.12
0.13 1.3
0.12
0.15
0.16 1.6
0.15
0.19
0.20
2
0.19
0.25
0.26 2.6
0.25
0.33
0.34 3.4
0.33
0.43
0.44 4.4
0.43
0.57
0.58 5.8
0.57
0.7
0.72 7.2
DGDG-EU
Bolt
M8
M10
M10
M12
M12
M16
M20
M24
Moment resistance kNm
Line Tension kN
(Fail)
(low)
(Max)
(Fail)
(low) (Max)
22
5
11
17
5
8
45
10
20
28
5
15
65
15
35
33
10
15
137
35
70
53
15
25
221
55
110
65
15
30
437
110
220
99
25
50
870
215
435
150
35
75
1407
350
705
195
50
100
Bend Restrictor Standardisation
22

23. DGDG-EU bend restrictors
DGDG-EU
Bend Restrictor Standardisation
23

24. Different shapes of vertebra
DGDG-EU
Bend Restrictor Standardisation
24

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
25

26. AOB
DGDG-EU
Bend Restrictor Standardisation
26

27. Thank you for your time.
DGDG-EU
Bend Restrictor Standardisation
27

28. Thank you for your time.
DGDG-EU
Bend Restrictor Standardisation
28

29. For further information contact
info@dgdg.eu
DGDG-EU
Bend Restrictor Standardisation
29