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Institutionen för ingenjörsvetenskap, fysik och matematik

Safety Turnbuckle

Jonas Olsson

Examensarbete vid Maskiningenjörsprogrammet 02 2006

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Abstract This degree project has been carried out at FMC technology, Kongsberg, Norway. The aim of the project is to design turnbuckles that facilitate length adjustment of a sling during offshore lifting. Additionally, the design has to fulfil FMC technology safety requirements. Further, the project also comprises of studies like material selection, numerical calculations, manufacturing and detailed drawings of all the components of the final design concept. The final design concept presented in this report is based on a modification of an ordinary turnbuckle. Design improvements were carried out in order to fulfil the FMC technology requirements. A material selection has been performed according to DNV 2.7-1, and a suitable surface treatment of the material has been conducted. For the calculations, a safety factor has been taken in to account according to DNV 2.7-1. The drawings of each component of the turnbuckle have been presented and are attached to this report.

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Sammanfattning

Detta examensarbete är en konstruktionsuppgift som är framtagen av FMC technology i Kongsberg, Norge. Syftet med uppgiften är att ta fram en konstruktion för att kunna justera längden på en slinga vid lyftning offshore. Konstruktionen måste uppfylla vissa säkerhetskrav som är framtagna av FMC technology. Uppgiften består också av att välja lämpligt material, utföra beräkningar för dimensionering av konstruktionen, tillverkning, kostnad samt att göra detaljritningar på den färdiga konstruktionen. I rapporten presenteras en konstruktion som i grunden bygger på en vantskruv, konstruktionen har dock ändrats för att uppfylla de gällande säkerhetskraven. Material har valts enligt DNV 2.7-1, samt lämplig ytbehandling för att skydda mot korrosion. Vid beräkningar och dimensionering har säkerhetsfaktor valts enligt DNV 2.7-1. Detaljritningar på varje enskild del på konstruktionen har gjorts och ligger som bilagor i slutet av denna rapport.

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Foreword This degree project has been performed between September 2005 and February 2006 at the Institute of engineering, physics and mathematic, Karlstad University. The project has been carried out at FMC technology in Kongsberg, Norway.

I wish to thank my supervisor Hans Johansson at Karlstad University and my supervisors at FMC technology Bjørn Michaelsen and Brede Thorkildsen.

Karlstad, February 2006

Jonas Olsson

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1 INTRODUCTION......................................................................................................................................... 2 1.1 FMC ........................................................................................................................................................ 2 1.2 BACKGROUND.......................................................................................................................................... 2 1.3 PURPOSE .................................................................................................................................................. 3 1.4 DELIVERABLES ........................................................................................................................................ 4 1.5 HSE......................................................................................................................................................... 5

1.5.1 HSE Policy...................................................................................................................................... 5 1.5.2 HSE Strategy................................................................................................................................... 5 1.5.3 HSE Management System............................................................................................................... 5

2 DESIGN AND MATERIAL......................................................................................................................... 6 2.1 DESIGN REQUIREMENTS ........................................................................................................................... 6 2.2 MATERIAL REQUIREMENTS ...................................................................................................................... 6 2.3 MATERIAL REQUIREMENTS ...................................................................................................................... 7

2.3.1 Alternative designs.......................................................................................................................... 8 2.4 TURNBUCKLE SAFETY ........................................................................................................................... 11 2.5 FINAL DESIGN CONCEPT ......................................................................................................................... 14 2.6 MATERIAL SELECTION ........................................................................................................................... 15

2.6.1 Component properties ................................................................................................................... 15 2.6.2 Stainless steel ................................................................................................................................ 16 2.6.3 High strength steels ....................................................................................................................... 17 2.6.4 Carbon steel................................................................................................................................... 17 2.6.5 Galvanizing ................................................................................................................................... 17 2.6.6 Material and surface treatment of the final concept ...................................................................... 17

2.7 CALCULATIONS...................................................................................................................................... 18 2.7.1 Safety factor .................................................................................................................................. 18 2.7.2 Thread shear and nut thickness ..................................................................................................... 19 2.7.3 Stress area ..................................................................................................................................... 20 2.7.4 Pad eyes......................................................................................................................................... 20 2.7.5 Calculations of screw, body and middle body............................................................................... 21

3 DISCUSSION .............................................................................................................................................. 27

4 CONCLUSIONS ......................................................................................................................................... 28

5 REFERENCES............................................................................................................................................ 29

APPENDIX LIST................................................................................................................................................ 30

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1 Introduction

1.1 FMC FMC Technologies is a manufacturer and supplier of sub-sea production systems, including sub-sea trees, controls and manifold and tie-in systems. In collaboration with their customers, FMC develops technologies that address the demands and needs of customers oilfields. In addition, FMC has a complement of engineering and customer support services such as system engineering, flow assurance, flow measurement, and project management.

1.2 Background Normally, the original turnbuckle is designed with one right threaded “male” part and one left threaded (links) male part that are screwed into a “female” outer body. The length of the “turnbuckle” is adjusted by turning the outer body There are usually no devices or end stops arrangement for preventing the “turnbuckle” from unscrewing. Further, there are usually no indicators showing the engaged thread length In case a “turnbuckle” is screwed to far out during lifting, then failure could be inevitable and might result a major accident or cause a severe failure to the equipment. Because of these major Health, Environmental and Safety issue (HES), turnbuckles are not allowed to be utilized in lifting equipment by FMC When lifting and handling long objects or when the Centre of Gravity of an object lies out of the line, it can be an advantage to use a “turnbuckle” in one or more of the lifting slings. The purpose of the turnbuckle is either to level the object to be lifted or to position it at a skew angle. The latter due to handling difficulties caused by constraints on the drilling rig. When designing and manufacturing a sling, it can sometimes be difficult to achieve an exact length. In this case it can be advantageous to adjust the length with a turnbuckle. Therefore, the aim of this project was to design turnbuckles that facilitate length adjustment of a sling during offshore lifting. As a result in this report a principal discussion which uncovers alternative designs carry out and thoroughly reviewed. Final a design concept (Figure 1) is evaluated and presented. However, at its current state the design dose not withstand the rough environment on a drilling rig.

Figure 1, Illustration of the concept design

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1.3 Purpose The purpose of this project is to come up with a new design for “turnbuckles” which satisfy all HES requirements and which also can be certified by Det Norske Veritas (DNV) for use in lifting equipment

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1.4 Deliverables

• Detail design with drawings of all components • Calculations • Material selection • Design report • Qualification program satisfying DNV 2.7-1 • Cost and schedule for manufacturing • Cost and schedule for qualification • All documentation and drawings in English language

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1.5 HSE Maintaining outstanding Health, Safety and Environment (HSE) performance is a core value of FMC Technologies. Their successful HSE performance has been made possible through the leadership and teamwork of all employees. Their HSE responsibilities are directed by their HSE Vision, Policy, Strategy and Management System, which guide our businesses in the development of their HSE processes. 1.5.1 HSE Policy FMC Technologies accepts a responsibility to protect the environment and the health and safety of their employees and the public. Health, safety and environmental performance are core values of the Company and will be managed as an integral part of their business to benefit employees, customers, neighbours and stockholders. All of FMC Technologies employees are responsible for the Company's achievement of continuous and measurable improvement. 1.5.2 HSE Strategy

• Conducting business in a manner that protects public and occupational health, the environment and employee safety.

• Striving to eliminate all accidents and environmental incidents.

• Making HSE considerations a priority in manufacturing existing products and planning for new products, facilities and processes.

• Complying with all HSE laws and regulations.

• Reducing emissions and waste and using energy and natural resources efficiently and intelligently.

• Working with their employees, suppliers, customers, contractors and partners to promote responsible management of products and processes.

FMC Technologies encourages constructive communication with employees, suppliers, customers, neighbours and stockholders about managing health, safety, and environmental issues.

1.5.3 HSE Management System The FMC Technologies HSE Management System is based on the continual improvement process of the Plan-Do-Check-Act cycle utilized by such global standards as ISO 14001, for environmental management, and OHSAS 18001, for safety management. The management system is the basis for all site HSE process/program development and the Corporate HSE Audit program.

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2 Design and material

2.1 Design requirements The following design requirements shall apply

– It shall disable the “turnbuckle” to unscrew to a position (positive locks) where it separates or the thread shear area is too small to support the safety working load (SWL)

– It shall not allow to modify the turnbuckle in “the field” such that the “positive” locks” are removed or their function disabled

– The length of the “turnbuckle” shall be adjustable in the “field” using conventional tools (e.g. wrench types)

– Once the position is adjusted, a locking device shall “lock” the “turnbuckle” in position. This locking device can be a split ring or equivalent and shall be of a type which shall if removed show that it has been tampered with and in which case a new device shall be inserted.

– Note that for a dedicated sling, it is normally no reason for adjusting the length more than once - if such has taken place it may be dangerous to use the sling without further readjustment and “locking” of the “turnbuckle”

– It is an advantage if the thread engagement length can be clearly seen from the outside – otherwise, rig operators may not trust the design and prohibit its use

– The design shall in general comply with DNV 2.7-1. The code DNV 2-7-1 is used because this a worldwide accepted lifting code with ample safety margins

– The design shall cover the following range of DNV 2.7-1 shackle size: 9.5 ton, 17.0 ton and 25 ton

– The design shall be such that it can cover the full range of DNV 2.7-1 shackles from 2 to 85 ton in case required

2.2 Material requirements

Selection of materials or method of protection shall ensure that internal corrosion does not take place or that it is easy to check if the “turnbuckle” is corroded and shall be in accordance with DNV 2.7-1 The design shall be such that it can withstand the rough environment on an “offshore drilling rig”. No delicate components shall be used.

Steels should comply with the material requirements of the recognized standard, have good ductility at low temperatures, and be able to withstand dynamic loads. Steels in chains, links, rings shackles and couplings should be impact tested by the Charpy impact method. The impact test temperature should be equal to the design temperature, TD. For the finished product, the minimum average impact energy in base material should be 42 J. However, for welded components (chains, links, rings) it is sufficient only to take impact test samples in the weld with the notch centered in the fusion line. The position of the weld should

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be accurately identified by etching with suitable reagent before cutting the notches. The minimum average impact energy should be 27 J. Materials in wire ropes, thimbles and ferrules should be according to relevant standards. Each separate component of the lifting set (e.g. chains, bows and bolts for shackles, links and wire ropes) should be supplied with traceable works material certificates (EN 10 204, inspection certificate, type 3.1B) Other items such as thimbles and ferrules should be supplied with a material certificate to EN 10 204 type 2.2 or to NS 10010 “test report”. (DNV 2.7-1)

2.3 Material requirements The first step in this project is to look at the design of the “turnbuckle”. It is important that the design does not necessary look like an ordinary “turnbuckle”, but all the design requirements must be fulfilled by the final design. The function of the design shall be to adjust the length between the two ends, so that you can adjust the length of an entire sling. Therefore it is not at all necessary to use threaded parts in the design, as in a turnbuckle.

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2.3.1 Alternative designs

Figure 2, A conventional design used for similar purpose Figure 2 shows a design variant that already been used for similar purposes, which in its current state can not be used by FMC. One reason is the lack of safe locking device on the hook. There isn’t any arrangement that locks the chain in the hook on this variant. One alternative can be to use a shackle instead of an ordinary hook, or some special made hook with a suitable locking device. However, an ordinary turnbuckle is easier to adjust and handle.

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Figure 3, An alternative design for adjusting of the length Today, the design in figure 3 is used for some different purposes. One example is a jack stand for cars. To make this design be utilized by FMC some safety requirements must be applied on this design. To prevent the two parts from separating, a bolt with nut is inserted trough the two bodies. Further, to enable adjustment, there is a hole in the male part and a slit in the female part. This bolt can be designed to carry the SWL. So, in case the locking device is removed then the design can anyway carry the SWL. To adjust the length, the locking device must first be removed and then put back to the desired position. This can be difficult to accomplish if the dimensions are significant and therefore heavy. With these models you must make sure that there should not be any load exerted at the pad eyes during adjusting. If the locking device should be removed when it is loaded, then it would be impossible to prevent the two bodies from separating until the bolt reaches the slits ends. The force on the bolt will in that case be very high. For this model, even with a relative small load on the pad eyes, it would be difficult to make adjustment. The weight from the sling etc can be too much and very hard for a single person to handle, and then succeed to insert the locking device in right position while adjusting. The model can be modified and be made easier for adjusting the length of the sling. One idea is to modify the slit on the body. In doing this the design can be locked in position by turning of the body. This variant is easier to lock in a desired position, but can be too heavy to adjust. (see figure4)

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Figure 4. A modified design which allows easy to adjustment The shape of the design of this version can also be made from plates (figure 5) instead of bars.

Figure 5. An alternative design made of plates. The problem with such designs can be experienced during adjusting the length. Since the dimensions are significant the device becomes heavy and cause problem for the operator. Therefore, it is preferable to use an ordinary turnbuckle. A turnbuckle is a suitable design for adjusting of a sling, and one operator can easy adjust the length of the turnbuckle with a conventional tool.

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2.4 Turnbuckle Safety One of the advantages in using an ordinary turnbuckle is its contingency during adjusting the length of the sling. By using a conventional tool the turnbuckle can easily be turned to an exact position by a relative small force, even when there is a small weight in the sling. The turnbuckle is easy to use, handle and adjust for such purpose. But one big problem with an ordinary turnbuckle is that the parts can separate apart during adjusting the length of the turnbuckle. If a “turnbuckle” is screwed to far out, it might cause damage, when lifting and resulting in a major accident and even a loss of life or cause severe equipment damages. Because of this major Health, Environment and Safety issue (HES), FMC does not allow such turnbuckles be used in lifting equipments. In some turnbuckles it also become impossible to observe how far you need to screw the turnbuckle before it is fully separated. In order to prevent parts from separating, some type of stops can be attached to the screws. So, when the turnbuckle reaches the end, these stops could prevent the parts from separating, and also keep the thread engagement in position. If the thread engagement always maintained, then it capable of supporting the safety working load, (SWL). In order to observe how far the turnbuckle is adjusted, a slit can be made in the body, where the screw can be easily be seen from outside. When the turnbuckle is adjusted to a position, a locking device shall be inserted to keep the turnbuckle in position. Because of the tough environment on a rig all robust components design is required. The operator must be able to adjust and handle the turnbuckle with gloves. One common and already used locking device is to use a bolt with a nut and then locking it with a sprint. The locking device is simple, safe and already in use by FMC. It is important not to have any while working offshore to avoid big problems like their disappearance under operation. To prevent problem with loose parts, bolts, nuts and (sprint) can be fastened to a chain or similar arrangements. If the locking device should be removed while the turnbuckle is in use, this will not bring any disaster because this turnbuckle always supports the SWL. If the locking device is removed or tampered with, then it will clearly been seen from outside, and a new locking device can be inserted. This study presents a design concept of a turnbuckle. One of the problems with such design is how to prevent the top of the turnbuckle from unscrewing, and requirement on the locking since the device has to be designed for offshore use. To prevent the top of the turnbuckle from unscrewing, welding or fastening with some type of locking device can be used. This locking device can be a washer with one or two plane sides, on the outside and inside (see figure 6). These plane sides match to the body to the case, and prevent it from unscrewing. To keep this washer in position a locking ring can be mounted in the groove.

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Figure6. Illustration of how the case can be fastened A more inexpensive alternative solution would be to welding the case in place. This result offers a safe and simple solution in locking the case. But if the turnbuckle should be made from a material that is not suitable for welding, or if disassembly of turnbuckle parts is required then alternative welding or connection is needed. The stops on the screws can also be fastened in different ways. The easiest way in this case would be welding the two stops in place. An alternative could be to use some kind stop screws or equivalent. This design will fit if the turnbuckle should be made from stainless steel without any surface treatment. To make the turnbuckle less expensive it is better to use a carbon steel with a surface treatment that can withstand the rough environment on an oil rig. It is advantageous if details of the turnbuckle can be disassembled for surface treatment operation. However, welded details may cause inconveniency to the surface treatment. This design assumes all welding operations to be performed after the surface treatment has been conducted. To make the turnbuckle ready for some kind of surface treatment you must make sure that all parts of the turnbuckle can be assembled after the surface treatment, and welding is not allowed after the treatment.

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Figure 7. An alternative that can be divided up The design in figure 7 can be divided up in two parts, and no threaded cases are needed. The stops that prevent the turnbuckle from unscrewing can be mounted when the two bodies are divided up. The two bodies are then attached to a bar and fastened with bolt, nut and sprint. With this design no welding has to be done, and the turnbuckle is suitable to be galvanized. Each part in this design can be separated and mounted with an ordinary tool. In this design it is necessary to use high strength bolts, otherwise the size of the turnbuckle will be unnecessary big. The highest class of bolts that can be delivered as galvanized is class 8.8. Therefore it is in this case better to connect the parts by using threaded parts, and then prevent these parts from unscrewing by using a small bolt through the parts.

Figure8. The final design concept of the safety turnbuckle

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Figure 9. The three parts the body. Figure 10. The main parts of the safety turnbuckle.

2.5 Final design concept One method used in evaluating and finding the best design concept is to using selection criteria, and then rating and scoring these criteria. For example safety is one of the most important criteria. Table 1 shows a list of 12 different criteria that are important for a “safety turnbuckle”. These criteria are scored one to ten (1-10) and evaluated. Further, to evaluate the criteria, a weighted sum method one to five (1-5) is used. Table1. The concept selection matrix

Criteria Weight Rating (1-10) (1-5) Concept A Concept B Concept C Adjusting 3 8 4 8Locking 3 7 4 7Handling 2 7 4 7Galvanizing 4 7 8 1Manufacture 2 8 6 6Put toghether 2 8 6 3Corrosion 3 7 8 4Safety 5 8 4 7Calculations 1 7 7 7Adjusting possibility 2 9 4 9Dirt etc. 2 6 8 6Clear 3 7 7 7Total Score 238 184 186

Concept A Concept B Concept C

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Concept A is selected as the final design and fulfils all the design requirements that been carried out by FMC technology. All components can be assembled without welding, and thereby allowing surface treatment to be conducted.

2.6 Material selection Things that affect the choice of material in the component are environment, manufacturing, safety requirements etc. Some are requirements that must be fulfilled, and some can affect the shape and size of the component. Tables can be made, one for the component and one for the material. In this table the most important properties are listed for the component and the material, which make material selection easier.

2.6.1 Component properties Table 2. Components properties

Function

Load carrying

Form

Cylindrical

Temp. interval

-20°C - 60°C

Environment

Offshore

Mechanical effects

Strength, Impact energy

Optimize

Material selection

Requirements

DNV 2.7-1

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2.6.2 Stainless steel Many stainless steels have properties that suitable for an oil rig environment. Duplex stainless steels are common stainless steel for offshore application. These steels have a very high strength and excellent corrosion resistance in a marine atmosphere. They also have an impact energy that fulfils the DNV 2.7-1 criteria. SAF 2507 (SS2328) is a conventional stainless steel known for the seawater-resistant properties and has a high strength. SAF 2507 is a registered trademark of Sandvik AB. Mechanical properties at 20°C Rp0.2 = 550N/mm2

Rm = 800N/mm2

Mechanical properties at 100°C Rp0.2 = 480N/mm2

Rm = 600N/mm2 Sandvik SAF 2507 is a high alloy duplex (austenitic-ferritic) stainless steel for service in highly corrosive conditions. It is characterized by:

• excellent resistance to stress corrosion cracking in chloride-bearing environments

• excellent resistance to pitting and crevice corrosion

• high resistance to general corrosion

• very high mechanical strength

• physical properties that offer design advantages

• high resistance to erosion corrosion and corrosion fatigue

• good weldability

Figure 11. Impact energy for SAF 2507

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Using stainless steel in the turnbuckle will increase the manufacturing cost. Therefore, by using a carbon steel with a suitable surface treatment the cost will be lower. Note that for a dedicated sling, there is normally no reason for adjusting the length more than once. So, when the turnbuckle once is installed it is only used as a load carrying component. It is therefore unnecessary to use a stainless steel turnbuckle for this purpose. 2.6.3 High strength steels If a small dimension turnbuckle is required, then it must be made of high strength steels. SS 2541 (34CrNiMo6+QT) can be delivered as bar with yield strength around 800N/mm2. One of the problems with high strength steels is the choice of a suitable surface treatment. Hot dip galvanizing can in some case worsen the properties for the material.

2.6.4 Carbon steel Using a carbon steel with suitable surface treatment will be lower the price compared to using a stainless steel. But it is necessary to have a design that allows some surface treatment. Structural steels are mainly suitable for welding. The most important technical requirements are strength, high impact energy and good conditions for welding. Structural steels are used in both welded and non-welded designs as load carrying elements for bridges, cranes, masts etc. Structural steels can be delivered as plate, bar and tube. One of the structural steel that fulfills the DNV 2.7-1 criteria is S460NL. This steel can be delivered as bars with diameters up to 200mm. The impact energy of S460NL is 47J at -20°C. S460NL can also be galvanized with a good result. 2.6.5 Galvanizing For most applications the cost of galvanizing is lower than other alternative coatings. Furthermore, galvanizing has been gradually getting cheaper compared to painting. According to BSK-99 different environments are divided in to 6 different classes based on the aggressiveness of the environment. According to BSK-99, offshore with high disposition of salt is the most aggressive environment (C5-M). The most suitable treatment for this class is hot dip galvanizing class b or c, dependent on lifetime for the product. Due to the zinc layer, external threads shall have smaller dimensions before hot dip galvanizing. Requirements, dimensions and tolerance can be found in SS 3192 – 3194. Internal threads shall be cleaned to nominal dimensions after galvanizing. External threads of a compound designs must be cleaned after galvanizing. The zinc layer on external threads protects internal threads. 2.6.6 Material and surface treatment of the final concept The safety turnbuckle should be manufactured from S460NL and all details in the turnbuckle shall be hot dip galvanized according to class b or c.

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2.7 Calculations

2.7.1 Safety factor

SFgRBF **min = Where: B is BFmin is Braking force minimum, in Kg R is Rating, maximum gross mass SF is Safety Factor This safety factor consists of a dynamic factor and a design factor against failure Containers with maximum gross up to and including 6 tones, the Safety Factor against breaking, SF, should be taken as:

• Wire rope SF = 10 • Chain Sling SF = 8 • Shackles, links, couplings, hooks SF = 8

For the turnbuckle, the Safety Factor is set to 8, up to 6 tones. For containers with high gross mass, the safety factor may be reduced to the values from the diagram in Appendix F. (see DNV 2.7-1)

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2.7.2 Thread shear and nut thickness The bolt tensile and thread-stripping strengths are balanced when the nut thickness is approximately 0,47d. Since the stress is not uniformly distributed among the threads in contact, the value is a bit low. Therefore the standard nut thickness is set to approximately 7/8d. For a steel nut it is not appropriate to calculate with a higher B to d ratio greater than 1,2, due to the fact that the stress is more distributed on the first threads. In the following calculations: Leff = 1,1d

Figure 12, Shows how the force are divided up thru the threads

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2.7.3 Stress area

According to ISO As is defined as: )2+

(4

= 212 ddAs

π

2.7.4 Pad eyes

Pad eyes should be designed for a total vertical load of: Fp = 3*R*g Where: Fp is RSF, Resulting sling force R is Rating, Maximum gross mass The two following criteria should be fulfilled:

1. Tear-out stress:

tDtHRSF

RH

e ***2*3

≥

Equation 1 is verifying that the stress level at the edge of the bolt hole is acceptable, assuming a stress concentration factor of 3.

2. Contact stress:

tD

RSFR

He *

*19≥

Equation 2 is the formula for compressive stresses at the centre of contact between two parallel cylinders of steel, with a difference in diameter of 4 %

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2.7.5 Calculations of screw, body and middle body

Screw

Pad eye Middle part

Body

Body, top Body, end

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von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

sz A

F=σ

effir Ld

F••

30tan•=

°

πσ

effiyz Ld

F••

=π

τ

9,5 ton = M56 17,0 ton = M68 25,0 ton = M76

σz

τyz

σr

z

x

y

”Screw”

60°

τyz

σy

di

Leff

σ

dy

Leff

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Von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

12 -=

ssz AA

Fσ

effyr Ld

F••30tan•

=°

πσ

effyyz Ld

F••

=π

τ

M68 (d) 9,5 ton = D = 84 M80 (d) 17,0 ton = D = 100 M90 (d) 25,0 ton = D = 115

”Body, end”

z

x

y

σr

τyz

σz

σr Leff

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von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

12 -=

ssz AA

Fσ

effyr Ld

F••30tan•

=°

πσ

effyyz Ld

F••

=π

τ

M56 (d) M68 (d) M76 (d) 9,5 ton = 17,0 ton = 25,0 ton = D = 76 D = 92 D = 106

”Body, top” z

x

y

σz

σr

L

σr Leff

τyz

25

σz

τyz

σr

z

x

y

”Screw, middle part”

60°

τyz

σy

di

Leff

σ

dy

Leff

von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

sz A

F=σ

effir Ld

F••

30tan•=

°

πσ

effiyz Ld

F••

=π

τ

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)-(= 22 rR

Fz πσ

d = 61 d = 73 d = 83 9,5 ton = 17,0 ton = 25,0 ton = D = 84 D = 100 D = 115

”Body and middle part”

z

x

y σz

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3 Discussion By using an ordinary turnbuckle the length of an entire sling can be adjusted by one operator using conventional tool. The modified and final design concept of the turnbuckle fulfils all design requirements that have been carried out by FMC technology. The locking device can be removed without causing any catastrophe. The design supports the SWL which is very important for the safety of the turnbuckle. The design of the safety turnbuckle can be manufacture from carbon steel which can further be galvanized which makes the manufacturing to be cost-effective. By using high strength steel for the turnbuckle, the dimensions and weight will be lower and the turnbuckle will be easier to handle. If stainless steel can be used galvanization can be avoided. However, manufacturing costs will be substantial.

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4 Conclusions The conclusion of this degree exam means that a modified turnbuckle is the best way to adjust the length of an entire sling for offshore lifting. The final design in this degree exam fulfilled all the design requirements that been carried out by FMC technology (see figure 8). The safety turnbuckle can also be adjusted with a conventional tool. The safety turnbuckle can be made from carbon steel and later be hot dip galvanized, that protect the turnbuckle from corrosion. Material selection has been made according to DNV 2.7-1. Safety factors and calculations of the turnbuckle have been made according to DNV 2.7-1.

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5 References MNC handbok nr 4, Rostfria stål, Utgåva 5, oktober 1992 MNC handbok nr 1, del 1, Almänna konstruktionsstål, utgåva 5, november 1988 MNC handbok nr 1, del 2, Almänna konstruktionsstål, utgåva 5, november 1988 MNC handbok nr 14, konstuktörens materialval, utgåva 1, april 1984 Engineering Materials, properties and selection, eighth edition, Kenneth G. Budinski, Michael K. Budinski Bultens handbok, BH 67, Del 1 Artiklar Fundamentals of machine component design, second edition, Robert C. Juvinall, Kurt M. Marshek Handbok och formelsamling i hållfasthetslära, Institutionen för hållfasthetslära, KTH www.zinkinfo.se www.outokumpo.com http://www.fmctechnologies.com/Subsea.aspx http://www.fmctechnologies.com/Subsea/AboutUs/HealthSafetyandEnvironment.aspx http://www.ikp.liu.se/kmt/members/Hakan/f3.pdf

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Appendix list Appendix 1: Detail drawings of all components Appendix 2: Calculations of the Safety Turnbuckle

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Appendix 2: Calculations of the safety turnbuckle Screw von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

sz A

F=σ

effir Ld

F••

30tan•=

°

πσ

effiyz Ld

F••

=π

τ

9,5 ton, M56 F = 9500 * 6,9 * 9,81 = 643045,5N As = 2014mm2 Leff = 56mm di = 50,05 σe = 365N/mm2

17,0 ton, M68 F = 17000 * 5,6 * 9,81 = 933912N As = 3034mm2 Leff = 68mm di = 61,5 σe = 352N/mm2

25,0 ton, M76 F = 25000 * 5,0 * 9,81 = 1226250N As = 3937,36mm2 Leff = 76mm di = 69,505 σe = 358N/mm2

32

Appendix 2: Calculations of the safety turnbuckle Body, middle von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

)( 22 rRF

z −=π

σ

effir Ld

F••

30tan•=

°

πσ

effiyz Ld

F••

=π

τ

9,5 ton, M68 F = 9500 * 6,9 * 9,81 = 643045,5N Leff = 68mm di = 68 D = 84 σe = 359N/mm2

17,0 ton, M80 F = 17000 * 5,6 * 9,81 = 933912N Leff = 80mm di = 80mm D = 100mm σe = 353N/mm2

25,0 ton, M90 F = 25000 * 5,0 * 9,81 = 1226250N Leff = 90mm di = 90 D = 115 σe = 330N/mm2

33

Appendix 2: Calculations of the safety turnbuckle Body, top von Mises equivalent stress:

222222 3+3+3+---++= zxyzxyxzzyyxzyxe τττσσσσσσσσσσ

)( 22 rRF

z −=π

σ

effir Ld

F••

30tan•=

°

πσ

effiyz Ld

F••

=π

τ

9,5 ton, M56 F = 9500 * 6,9 * 9,81 = 643045,5N Leff = 56mm di = 56mm D = 76mm σe = 359N/mm2

17,0 ton, M68 F = 17000 * 5,6 * 9,81 = 933912N Leff = 68mm di = 68mm D = 92mm σe = 353N/mm2

25,0 ton, M76 F = 25000 * 5,0 * 9,81 = 1226250N Leff = 76mm di = 76mm D = 106mm σe = 330N/mm2

34

Appendix 2: Calculations of the safety turnbuckle Pad eyes Pad eyes should be designed for a total vertical load of: Fp = 3*R*g Where: Fp is R is The two following criteria should be fulfilled:

3. Tear-out stress:

tDtHRSF

RH

e ***2*3

≥

4. Contact stress:

tD

RSFR

He *

*19≥

9,5ton Fp = (3*9500*9,81) = 279585N /2 (For each pad eye.) H = 40mm, DH = 34mm, t = 25mm, Gap = 30mm Tear-out stress = 364,7N/mm2 Contact stress = 243,7N/mm2 17ton Fp = (3*17000*9,81) = 500310N /2 (For each pad eye.) H = 52mm, DH = 43mm, t = 35mm, Gap = 40mm Tear-out stress = 351,5N/mm2 Contact stress = 245,0N/mm2

25ton Fp = (3*25000*9,81) = 735750N /2 (For each pad eye.) H = 65mm, DH = 53mm, t = 40mm, Gap = 50mm Tear-out stress = 358,3N/mm2 Contact stress = 250,3N/mm2