Guide to Purchasing High Modulus Synthetic Fibre Mooring
Contents
1. Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines High Modulus Polyethylene HMPE High Modulus Synthetic Fibre HMSF Inspection Tactile Inspection visual Laid ropes Lay length Linear density Liquid Crystal Polymer LCP Minimum Breaking Load MBL Plaited Rope Pre tension Size number Splice Strand Stranding Tail pennant Tension tension fatigue Twist Twisting Wire lay rope Yarn A polyethylene fibre produced by gel spinning of an Ultra High Molecular Weight PolyEthylene UHMWPE feedstock Also called extended chain PE ECPE or high performance PE HPPE The generic term given to a range of fibre materials that include Aramid LCP and HMPE fibres anipulation of the rope by hand or other means to determine hardness and flexibility Examination of the exterior or interior of a rope by visual methods which may include magnification Ropes made by twisting of three or more strands together with the twist direction opposite that of the strands Length along a rope for a complete revolution of a single strand in laid twisted or plaited rope or cordage The mass per unit length of a fibre yarn or rope A class of aromatic polyester polymers The minimum breaking load of a new dry mooring line as declared by the manufacturer For the purposes of this document the MBL refers to that of a spliced rope A rope structure consis2. HMPE mooring lines elevated temperature and load accelerate the creep rate This should be considered as being of relevance when the ambient temperature is 40 C or greater Figure 1 1 illustrates the impact of heat and load on creep for HMPE Manufacturers or suppliers should be consulted as the effect of creep can be mitigated by rope design fibre or increased size Ultra violet degradation Aramid and LCP fibres may be susceptible to the effects of ultra violet UV degradation t is important that the exposure of the fibres is minimised and that ropes are properly stowed and covered when not in use A jacket constructed from polyester or other suitable synthetic fibre while primarily providing chafe protection will also serve to protect the HMSF from UV exposure Axial compression Some Aramids are susceptible to repetitive axial compression causing local fatigue which can occur when a rope is at a low tension and fibres are actually pushed into compression Three primary causes of axial compression are rope non uniformity induced twist and bending Rope non uniformity if the rope s components are not the same length when tension is relieved the longer components will be in compression and the shorter ones will be in tension This is especially important in spliced terminations Induced twist when the rope is twisted in service the outer fibres in the longer path are under tension and the inner fibres will be forced into comp
3. abrasion between the two components While unjacketed ropes are more vulnerable to external damage and particle ingress the absence of a jacket facilitates inspection repair and splicing The jacketed rope may have a larger diameter than a non jacketed rope having the same MBL and this may be an issue if storage space on winch reels is limited Coating Suppliers may offer the option of coated ropes or ropes constructed from coated yarns The specialist coatings may serve to enhance the rope s performance and potential service life in a number of areas Purchasers should request information from suppliers regarding the coatings used and their potential benefits Independent chafe protection Rope manufacturers may be able to supply independent chafe protection such as that fitted to the rope during construction fixed or sliding or retro fitted to the rope in service When determining the need for chafe protection and its specification purchasers should discuss their requirements with suppliers Considerations should include material type construction length s and placement End terminations The purchaser should specify the requirements for spliced eyes at one or both ends of the mooring line The length of eye should be specified by the purchaser Typical eye lengths will be from 1 8 to 2 5 metres 22 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 2 7 2 8 2 8
4. by a working group comprised of representatives from OCIMF and SIGTTO member companies In addition rope manufacturers and suppliers represented by the industry associations Cordage Institute and the European Federation of Rope Twine and Netting Industries EUROCORD have provided valuable technical contributions 8 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 1 1 Properties of High Modulus Synthetic Fibre mooring lines General When considering the procurement of High Modulus Synthetic Fibre HMSF mooring lines it is useful for the purchaser to have an understanding of the basic properties of the different materials used in construction These properties are briefly described in the following section and are summarised in table 1 1 igh Modulus Polyethylene fibres igh Modulus Polyethylene HMPE is a fibre that has a high strength to weight ratio and ow stretch characteristics but limited resistance to high temperatures The fibres have good abrasion resistance and tension tension fatigue life HMPE is resistant to axial compression and has a low coefficient of friction It is susceptible to creep that under certain conditions can lead to creep rupture However this can be mitigated through design and or choice of HMPE fibre For further information on creep see section 1 2 5 Mooring lines constructed from 100 HMPE fibres float If jacketed HMPE ropes
5. supplier should also be consulted on the proper installation of their rope for the type of winch it will be used on Bedding in of mooring lines When a new mooring line is first placed into service the construction elements will compact as the fibre components of the line adjust under load It may take several operations for the line to stabilise The associated elongation and reduced restraint capability may adversely impact load sharing when a new line is deployed in conjunction with existing lines Care needs to be taken during this new line bedding in period to ensure that the integrity of the overall mooring pattern is not compromised Load sharing When two or more lines are performing the same function for example as breast lines they should be of the same material and construction have the same MBL and be of similar length It is important that the lines are properly tended to ensure that the load is shared equally between them Incorrect tending could result in more stress being put on the higher loaded line Use of tails Tails may be used on mooring lines to improve the overall elasticity in the mooring system and therefore lower peak loads Tails may be constructed from various materials including polyester polyester polyolefin or nylon polyamide Tails should be properly matched to the mooring line to which they are attached Experience indicates that tails of different lengths should be used depending on the location of
6. the berth For further information reference should be made to Mooring Equipment Guidelines reference 1 The rope manufacturer s recommendations regarding the proper method of connecting tails to the mooring lines such as by use of a cow hitch or shackle should be followed to improve the service life of both the mooring lines and tails Some HMSF line types can be damaged should tails not be connected using the recommended method Records of mooring line service A record should be maintained on board of the use of HMSF mooring lines detailing the 16 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 1 3 6 number of mooring hours Any significant events for example brake rendering and the effect of surge such as from passing ships should also be recorded Individual lines should be clearly identified and the record should state when the lines were placed on board and the date when placed in service Any use of lines in non traditional service such as to secure a tug being turned up on bitts or to warp the vessel along the berth should be recorded The log of mooring hours should only record the time when the vessel is moored and lines are deployed namely from all fast to all let go Ship s fairleads HMSF mooring lines may suffer from abrasion if fairleads chocks and other contact surfaces are not maintained clean smooth and rust free Consideration should be given to fi
7. the shipment and terminalling of crude oil and oil products including marine pollution and safety Society of International Gas Tanker and Terminal Operators SIGTTO is anon profit making organisation dedicated to protect and promote the mutual interests of its members in matters related to the safe and reliable operation of gas tankers and terminals within a sound environment The Society was founded in 1979 and was granted consultative status at IMO in November 1983 Terms of Use The advice and information given in the Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines the Guide is intended to be used at the user s own risk Acceptance or otherwise of recommendations and or guidance in this Guide is entirely voluntary The use of the terms will shall must and other similar such words is for convenience only and nothing in this Guide is intended or should be construed as establishing standards or requirements No warranties or representations are given nor is any duty of care or responsibility accepted by the Oil Companies International Marine Forum OCIMF the Society of International Gas Tanker and Terminal Operators SIGTTO the membership or employees of OCIMF SIGTTO or by any person firm corporation or organisation who or which has been in any way concerned with the furnishing of information or data the compilation or any translation publishing supply or sale of the Guide for the accuracy of any informatio
8. 1 2 8 2 The purchaser should indicate whether chafe protection for the eye such as a protective sleeve is required The provision of eyes on both ends of the rope will facilitate end for end rotation potentially increasing the rope s service life EYE PROTECTION TYP 1 8m TO 2 5m Figure 2 2 End terminations Material specification and certification The purchaser should indicate the fibres from which the rope is to be made and should request a certificate from the manufacturer Marking and certification Marking The purchaser should specify the requirements for the rope to be uniquely identified by product labels firmly attached to each end of the rope The label should include information to link back to the rope s certificate such as the following e Rope manufacturer e Serial number e Product name e Minimum breaking load Certification Certification may be in the form of the following Rope certificate The manufacturer should provide a certificate to accompany each supplied rope demonstrating compliance with the requirements of the purchase order Certificates may be issued by the manufacturer and or a third party such as a classification society 23 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 2 9 2 10 2 11 1 The certificates should identify either a specific line or a batch or run of line that is made into multiple moori
9. 1500 references 2 and 3 Purchaser s requisition form The purchaser s requisition form should contain as much detail as possible particularly with regard to the intended rope application see section 2 2 A detailed requisition form will enable the supplier to provide the best match possible to the purchaser s requirements Quality control HMSF mooring lines should be manufactured and supplied under quality assurance processes that are independently verified such as those required under ISO 9001 reference 4 or equivalent Effective control of raw materials and finished products is of critical importance and the manufacturer s quality assurance and control procedures should address material certification traceability and testing requirements The design of individual rope types should be based on fully documented and independently verified prototype tests Ropes should be constructed in accordance with the agreed design specification The manufacturer should have documented procedures that address the frequency of batch break tests to confirm that stated MBL criteria is being met in accordance with ISO 2307 or Cl 1500 references 2 and 3 The manufacturer should have an inspection and test plan that includes the following as a minimum e Manufacturing and test plan e identification and control of materials parts and components 25 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Moorin
10. OCIMF Oil Companies International Marine Forum Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines First edition February 2014 The purpose of the Society of International Gas Tanker The OCIMF mission is to be the foremost and Terminal Operators is to promote shipping and authority on the safe and environmentally terminal operations for liquetied gases which are safe responsible operation of oil tankers terminals environmentally responsible and reliable and offshore support vessels promoting continuous improvement in standards of design and operation Copyright OCIMF and SIGTTO 2014 Issued by the Oil Companies International Marine Forum 29 Queen Anne s Gate London SW1H 9BU United Kingdom The Society of International Gas Tanker and Terminal Operators 17 St Helen s Place London EC3A 6DG United Kingdom First published 2014 Oil Companies International Marine Forum Bermuda Society of International Gas Tanker and Terminal Operators British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library The Oil Companies International Marine Forum OCIMF is a voluntary association of oil companies having an interest in the shipment and terminalling of crude oil and oil products OCIMF is organised to represent its membership before and to consult with the International Maritime Organization and other governmental bodies on matters relating to
11. able for intertwining to form a textile structure via any one of a number of textile processes 4 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Yarn on yarn abrasion Wear that occurs when two or more yarns move against each other 5 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Abbreviations ECPE Extended chain PolyEthylene EUROCORD European Federation of Rope Twine and Netting Industries HMSF High Modulus Synthetic Fibre HPPE High performance PolyEthylene ISO International Organization for Standardization LCP Liquid Crystal Polymer MBL Minimum Breaking Load OCIMF Oil Companies International Marine Forum SIGTTO Society of International Gas Tanker and Terminal Operators UHMWPE Ultra High Molecular Weight PolyEthylene 6 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Bibliography The following publications and documents are referenced within the text Reference 1 Reference 2 Reference 3 Reference 4 Mooring Equipment Guidelines 3 Edition OCIMF ISO 2307 2010 Fibre ropes Determination of certain physical and mechanical properties Cl 1500 Current version Test Methods for Fiber Rope ISO 9001 2008 Quality Management Systems In addition to the above referenced documents the following publications are useful sources of
12. additional information ISO 1968 ISO 9554 ISO 10325 Cl 1202 1903 1904 1907 2001 2003 O O OC OY Fibre Ropes and Cordage Vocabulary Fibre Ropes General Specifications Fibre Ropes High Modulus Polyethylene Terminology for Fiber Rope Aramid Fiber Rope MPE Fiber Rope MPE Fiber Rope Extra High Strength Fiber Rope Inspection and Retirement Criteria Fibers for Cable Cordage Rope and Twine 7 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Introduction The purpose of this document is to provide guidance to those involved in the procurement of High Modulus Synthetic Fibre HMSF mooring lines HMSF lines include those manufactured from Aramid Liquid Crystal Polymer LCP and High Modulus Polyethylene HMPE fibres The guidance is provided with the aim of increasing the understanding of the particular properties of the HMSF mooring lines and to encourage the adoption of improved specifications and quality assurance processes It should be noted that international standards exist for the construction of HMPE but the standards for Aramid and LCP fibres are very limited The guidance contained in this document should assist when considering procurement options HMSF mooring lines may be considered as an alternative to traditional steel wire ropes owing to their higher strength to weight properties and advantages associated with their rel
13. ative ease of handling Over the years the marine industry has gained considerable experience using moorings constructed from HMPE but the use of Aramid and LCP fibres for large ship moorings has not been extensive With regard to HMPE mooring lines after many years of relatively incident free use the industry has experienced a number of failures recently particularly on large liquefied gas carriers Although analysis of the failures has not identified any specific cause a number of contributory factors have been highlighted as being of potential importance including rope design manufacturing quality ambiguity in the specification of minimum breaking load MBL impact and frequency of dynamic loads consideration of creep and high ambient temperatures As a result the lack of a clear detailed industry specification for use in the procurement of HMPE mooring lines was considered significant It was found that purchasers often specified an MBL based for example on a shipyard specification but did not appreciate how to define this number and did not always specify other requirements such as line construction minimum HMPE content grade of HMPE and requirements for testing the finished product This Guide contains recommendations relating to the scope of procurement specifications and provides brief information on the relevance of the various specified requirements to the mooring line s in service performance The guidance has been developed
14. can have a higher density and may sink However this will depend on the rope s diameter and the material that the jacket is made from Aramid fibres Aramid fibre typically has high strength and low stretch It does not creep significantly and does not melt but chars at high temperatures Aramid is susceptible to axial compression fatigue that occurs when tightly constrained fibres are forced into axial compression Aramid is resistant to tension tension fatigue Aramid ropes do not float They are typically jacketed with some other synthetic fibre such as polyester to increase abrasion resistance and protect against UV degradation Liquid Crystal Polymer fibres Liquid Crystal Polymer LCP fibres have high strength and low stretch and good resistance to creep and tension tension fatigue The fibre has a temperature resistance between that of HMPE and Aramid LCP fibres are known for their long term durability to fatigue cutting and abrasion Table 1 1 provides details of some of the typical properties of HMSF ropes when compared with steel wire ropes 9 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Material Specific Specific Specific Dynamic Melt Point Other Characteristics Gravity Modulus Strength Coefficient of Deg C N tex N tex Friction against Metal Low melt point Lighter than water Potential creep and HMPE 0 97 110 3 5 0 07 147 creep rupture problem
15. d the supplier should discuss and mutually agree on the requirements for packing and delivery of the mooring line s After sales service User manual The purchaser should identify the documentation they require from the supplier This may include guidance on issues such as e Pre installation preparation of contact surfaces e Mooring line installation e Safe handling 24 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines A AF 2 12 2 13 e Chafe protection and repair procedures e Connection of tails e Stopper materials and use e End for ending e Storing e Cropping and splicing e Mooring log recommended practices e In service inspection procedures and recommended intervals Training The purchaser should identify any instructional resources required from the rope supplier to support crew training Training may be in the form of documentation computer based resource or hands on with a representative from the supplier In service testing The purchaser may wish to consider having a sample of the supplied mooring lines tested to determine residual strength following a period of time in service The supplier s procedures for such testing should be requested as part of the procurement process When tests are intended allowance for them should be made when specifying the length of the line Tests should be undertaken in accordance with ISO 2307 or Cl
16. e of tails of the correct material and length attached to the mooring line see section 1 3 4 Creep and heat exposure Creep is the tendency of a solid material to slowly move or deform permanently under the influence of load Creep always increases with temperature and is more severe in materials that are subjected to heat for long periods The rate of deformation is a function of the material properties exposure time exposure temperature and the applied load Depending on the magnitude of the applied load and its duration the deformation may become so large that a component can no longer perform its function resulting in failure There are two key properties of creep namely creep strain and creep rupture Creep strain is the non recoverable increase in length and creep rupture is the failure that occurs after a period of time with an applied load Rope creep is of particular concern when evaluating ropes that operate under high loads and or high temperatures 13 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines c 2 o o Time to Failure Figure 1 1 The impact of heat and load on creep for high modulus polyethylene fibre 1 2 6 1 2 7 The creep rate depends on the type of fibre used For Aramid and LCP ropes creep rate and creep life are negligible in most likely operating conditions For HMPE mooring lines elevated temperature and load accelerate the creep rate For
17. g Lines e Inspection process for verification of materials and manufacturing process e Designated inspection and test points A copy of the plan should be made available to the purchaser on request 2 14 Summary of considerations Table 2 1 below provides a summary of items that purchasers should consider when procuring HMSF mooring lines Mooring Information Mooring analysis results Vessel type size Winch rating design and arrangements including drum storage capacity ooring arrangement nformation on fairleads type and condition Berth arrangements exposed sheltered Trading area pattern Environmental conditions Rope Characteristics BL Spliced Construction aterial Diameter Length Termination type and required protection Rope protection jacket coatings chafe protection Colour Quantity required including spares Additional requirements Tails if required type quantity length diameter and termination Marking and certification Packaging and shipping After sales support Delivery terms and timing Training requirements Quality control procedures Table 2 1 Summary of considerations 26 Copyright OCIMF and SIGTTO 2014
18. iers e Vessel s likely trading area pattern e Potential berth arrangements exposed sheltered e Environmental conditions e g temperature wind swell current etc When replacing a line or lines from an existing mooring outfit it is recommended that the replacement lines are compatible with the existing lines For example they should have similar strength and elasticity characteristics Minimum breaking load The minimum breaking load MBL is a critical performance criteria when procuring rope The required MBL of individual lines will be established at the vessel s design stage following mooring force calculations and an analysis of mooring restraint requirements against standard environmental criteria as described in Mooring Equipment Guidelines reference 1 Where necessary site specific studies may be 19 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 2 4 2 5 2 6 2 6 1 undertaken to assess factors that may include the impact of dynamic loads on the mooring arrangement The specified MBL should be for spliced ropes based on break tests undertaken in accordance with ISO 2307 or Cl 1500 References 2 and 3 The manufacturer should have type approval for the rope being supplied issued by an approved third party such as an ACS member Diameter For naming and reference purposes ropes are specified by Nominal Diameter The rope s actual diameter
19. king strength Creep Creep rupture Critical temperature Cyclic loading Design factor Density Diameter nominal Dynamic load Elastic elongation Elasticity Elongation End for end Extension Fibre Filament continuous The ability of a fibre or rope to withstand wear and rupture due to motion against other fibres or rope components internal abrasion or a contact surface which can be a portion of the rope itself external abrasion A manufactured high modulus fibre made from a long chain synthetic aromatic polyamide in which at least 85 of the amide linkages join two aromatic rings The tendency of a fibre to fail when it is subjected to cyclic loading which exerts compression along its axis Rope formed by braiding intertwining or plaiting the strands together as opposed to twisting them For cordage the nominal force or load that would be expected to break or rupture a single specimen in a tensile test conducted under a specified procedure On a group of like specimens it may be expressed as an average or as a minimum based on statistical analysis A time dependant increase in length while under a continuing load which is non recoverable following the removal of the load Creep rupture is failure of a material due to a sustained load that it less than the break strength of the material The temperature at which the properties of a fibre begin to deteriorate Repeated loading of a rope or other s
20. may vary Some standards and specifications require that for a specific rope size the measured diameter or circumference be within a stated tolerance In some cases the variance of the actual diameter can be up to 10 from the nominal diameter depending on the rope s material and construction and whether it has been bedded in or not The nominal diameter of a jacketed rope includes the additional thickness of the jacket For storage purposes the actual diameter should be used Should there be any physical constraints where the rope dimensions are critical the purchaser should specify the maximum physical diameter of the rope including jacket if applicable Length The purchaser should specify the length of mooring line required for the rope application taking into account end termination arrangements as necessary and any additional length required to cater for residual strength testing Rope construction Construction options HMSF mooring lines are commonly available having the following constructions e 3 4 60r7 strand wire lay e 8or 12 strand braided e Double braided e Parallel lay These constructions may or not be jacketed and may or may not use multiple cores Depending on the rope s construction consideration should be given to having a means to easily determine the presence of induced twist in the rope 20 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 4 S
21. n or advice given in the Guide or any omission from the Guide or for any consequence whatsoever resulting directly or indirectly from compliance with adoption of or reliance on guidance contained in the Guide even if caused by a failure to exercise reasonable care on the part of any of the aforementioned parties Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines NN NN SN Contents Glossary 3 Abbreviations 6 Bibliography 7 Introduction 8 Properties of high modulus synthetic fibre mooring lines 9 General 9 Factors that may impact the service life of high modulus synthetic fibre mooring lines 10 Considerations associated with the use of high modulus synthetic fibre mooring lines 15 Guidance for specifying high modulus synthetic fibre mooring lines 19 General 19 Rope application 19 Minimum breaking load 19 Diameter 20 Length 20 Rope construction 20 Material specification and certification 23 Marking and certification 23 Purchaser s test requirements 24 Packing and delivery 24 After sales service 24 Purchaser s requisition form 25 Quality control 25 Summary of considerations 26 2 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Glossary Within this guide the terms below have the following meanings Abrasion resistance Aramid fibre also para aramid Axial compression fatigue Braided rope Brea
22. ng lines Details on the certificates should include e Product name e Product type e Detailed description size length diameter e Detailed description of yarn including yarn producer and yarn grade or type e Details of coatings jackets and eyes as appropriate e Weight per unit measure e MBL and test method e Identification number Type certificate A type certificate is a certificate confirming that the rope is manufactured in accordance with the particular design The certificate may be issued following third party inspection The Type Certificate will not typically be provided to the purchaser unless specifically requested Additional test results such as those from cyclic bend or abrasive tests may also be available for specific rope applications Purchaser s test requirements The manufacturer will typically undertake a break load test on a prototype and batch basis for a rope of similar size and construction in accordance with ISO 2307 or CI 1500 references 2 and 3 The purchaser should ask for and understand the test methods employed by the manufacturer The purchaser may require a full scale break load test of a sample rope taken from the ordered batch The purchaser may also specify requirements for independent observation and verification of the test Depending on the rope s application the purchaser may specify their own additional test requirements Packing and delivery The purchaser an
23. oduce an advertised range of ropes designed to meet the requirements of a diverse customer base Unlike some specialist applications such as single point mooring SPM hawsers High Modulus Synthetic Fibre HMSF mooring lines will be batch manufactured against standard designs and be offered in a range of constructions sizes and strengths The onus is therefore on the purchaser in discussion with potential suppliers to ensure that the specified rope will meet the required performance criteria This section provides guidance on the various factors that should be considered when procuring HMSF mooring lines Particular attention should be given to the specifications of the initial outfit of mooring lines procured for new buildings Rope characteristics should be measured using an international standard such as ISO 2307 Reference 2 or Cordage Institute Cl 1500 Reference 3 A mooring analysis should be conducted to determine the performance parameters of the mooring lines necessary for maintaining mooring system integrity refer Mooring Equipment Guidelines Reference 1 Rope application General information should be provided by the purchaser to the supplier regarding the proposed application and intended service of the rope such as e Vessel type size e Winch design and arrangements e Information on fairleads type and condition Purchasers should also consider the following and exchange relevant information with suppl
24. r of mooring hours and any significant events see section1 3 5 10 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines On board handling and care procedures should include instructions for in service repair and if required end for ending In addition retirement criteria should be established taking into account manufacturer s recommendations In a dynamic environment th peak loads in the mooring an e use of tails of a suitable material and length could reduce d mitigate wear Factor Description Occurrence Preventive Measures Abrasion Rope contacting rough Normal Usage Maintain smooth surfaces External surfaces Use of jacketed rope External chafe protection Proper use of tails to mitigate wear Abrasion Yarn on yarn abrasion Normal Usage Use of coatings Internal Construction of the rope Ingress of foreign Storage arrangements material Use of jacketed rope Handling procedures Cut Exposure to sharp Normal Usage Inspect mooring fittings and deck for object under tension sharp objects grind smooth where needed Avoid contact from crossing of mooring lines External chafe protection Twist Introduction of twist in Normal Usage Proper installation on the drum line which decreases Proper line handling strength Conduct periodic visual rope inspections Avoid combining dissimilar rope constructions braided versus twisted in series nclude a tracing marke
25. r on the exterior of the rope Tension Cyclic loading of rope Applicable to open aintain balanced tension on all lines Tension water berths and 5 roper type and length of tails Fatigue STS operations ieee g Creep and rreversible elongation Applicable to high Keep ropes within manufacturer s Heat Exposure caused by loading over extended periods of time Impacted by temperature loads and or temperatures HMPE only stated operating range Adequate rope design and or HMPE fibre for creep performance UV Degradation Prolonged exposure to UV radiation Aramid and LCP fibres more susceptible Adequate rope design Proper storage when not in use 1 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Axial Compression in line Aramid fibres only Compression induced Applicable to e Adequate rope design e Proper tail connection The factors listed above may combine resulting in heightened effect Table 1 2 Factors that may Impact the service life of HMSF ropes 1 2 1 121 1 1 2 1 2 1 2 2 The factors identified in table 1 2 are further described in the following sections Abrasion Different synthetic fibres have different coefficients of friction as well as general strength against abrasion Abrasion can come from external influences such as a chock but may also occur inside the rope between strands and fibre
26. ression Bending when a rope is bent and cycled the strands and yarns on the inside of the bend 14 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 1 3 1 3 1 can be forced into compression Yarn coatings and specific rope constructions may impact axial compression and guidance should be sought from manufacturers Aramid ropes should not be attached to tails by a cow hitch as this leads to axial compression Figure 1 2 High modulus synthetic fibre mooring line on split drum winch Considerations associated with the use of high modulus synthetic fibre mooring lines Although this document is primarily intended to address issues relating to the procurement of HMSF mooring lines it may be beneficial for purchasers to be aware of some of the operational aspects that impact on line performance and service life These are briefly described in the following sections Considerations when using high modulus synthetic fibre mooring lines The vessel s expected trading route and the environmental conditions it will likely be subjected to in the ports of call need to be taken into account when selecting the type of HMSF mooring lines that are to be installed on a vessel Factors to consider when determining the type of HMSF to be installed on a vessel should include the primary strength material and the amount used rope construction and if necessary chafe protection such as a jacke
27. s Long tension tension fatigue life Potential axial compression fatigue problems but these Chars can be overcome Aramid 1 44 49 2 03 0 15 500 Long tension tension fatigue life High strength and low stretch Bel 1 40 60 24 0 13 300 Long tension tension fatigue life Corrodes Steel wire 7 85 26 0 18 0 23 1 600 Heavy Moderate tension tension fatigue life Notes Table indicates approximate values actual properties may vary The unit tex is the weight in grammes of 1 000 metres of material Newtons tex MN kg m where kg m is rope linear density Multiply Newtons tex by 102 3 x SG to obtain kg mm Multiply Newtons tex by 145 400 x SG to obtain lb in Steel wire is 0 23 but when lubricant finishing is used the coefficient may vary Table 1 1 Typical properties of High Modulus Synthetic fibres and steel wire ropes 1 2 Factors that may impact the service life of high modulus synthetic fibre mooring lines Table 1 2 summarises factors that may affect the service life of HMSF mooring lines The purchaser and supplier should discuss individual requirements in order to develop the optimal purchasing specification taking into account intended use and operating environment All mooring lines will be exposed to wear and tear in service and it is important that they are subjected to routine inspection A record should be maintained on board documenting the numbe
28. s There are a number of ways to protect against abrasion and these are discussed in the following sections External abrasion All HMSF mooring lines are susceptible to chafing damage from contact surfaces It is important that deck fittings are regularly inspected and are kept smooth and free from chafe points Ideally steel fairleads should be clean smooth and rust free but this may be difficult to achieve in practice As an alternative consideration may be given to fitting sleeves or liners in way of contact surfaces Roller fairleads should be well maintained and kept free to rotate The ability of a rope to resist external abrasion damage may be improved by the addition of an abrasion resistant overall jacket or individual strand jackets Alternatively additional external chafe protection may be considered see Section 1 3 6 Relative to other HMSFs Aramid fibres have lower abrasion resistance However like all HMSFs certain coatings used on Aramids can increase the lifetime of the fibre Internal abrasion Internal abrasion such as yarn on yarn abrasion occurs when a rope is subjected to cyclic loading or cyclic bending The impact may be mitigated by the use of tails of the correct material and length attached to the mooring line see section 1 3 4 Internal abrasion can be alleviated with particular rope constructions and or the application of coatings Internal abrasion will increase should the rope be exposed to contaminant
29. s such as grit or sand and it is therefore important that ropes are protected by covers when stowed Cut Deck arrangements including outboard fittings such as fairlead foundations should be assessed to determine whether there is a risk of deployed moorings contacting sharp edges which could cut the rope and rapidly result in mooring failure Where necessary localised chafe protection should be used to prevent damage 12 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 1 2 3 1 24 1 2 5 Ropes under tension may be damaged by contact with other mooring lines Mooring arrangements should be carefully planned to minimise the risk of such contact Twist Induced twist may reduce a mooring line s strength and where possible measures should be taken to minimise the introduction of twist into a deployed rope Such measures include the proper stowage of ropes on their drums and the avoidance of connecting ropes with tails of dissimilar constructions in series Ropes should be inspected under tension to assess the degree of twist that may be present Depending on the rope s construction the use of an external tracing marker may assist in determining the extent of induced twist Tension tension fatigue Tension tension fatigue occurs under conditions of cyclic loading such as those experienced in open water or exposed berths The impact of cyclic loading may be reduced by the us
30. t or specialised coating The location of the berths exposed or sheltered will indicate the potential for the lines to be exposed to dynamic loads Mooring arrangements at exposed berths can be subject to first order wave motions that will induce tension tension loads Wave forces are of two types the first order forces at wave period and the second order wave drift forces which vary much more slowly The periods of first order ship motions are normally much shorter than the periods of natural 15 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 1 3 2 1 3 3 1 34 1 35 response of the ship mooring system so the wave induced motion analysis can be decoupled from the properties of the mooring system First order wave motion will not have much effect on vessel movement although this is very dependent on wave period and direction Long period waves quartering or beam on will create large vessel motions Larger ships experience proportionally higher tension loads from the wave induced motions as compared to smaller ships In addition the tension induced by wave motion can be more pronounced in aft breast lines than forward breast lines due to the considerable increase in weight aft versus forward on ships with accommodation blocks aft The expected environmental conditions will indicate if the lines will be subjected to extreme temperatures or exposure to abrasive particles The rope
31. ting of two pairs of strands twisted to the right and two pairs of strands to the left and braided together such that pairs of strands of opposite twist alternately overlay one on another Additional load applied to a mooring line by a powered winch over and above that required to remove sag from the main run of the line A nominal designation of rope size determined from the approximate circumference measured in inches calculated as three times the approximate rope diameter The joining of two ends of yarn strand or cordage by intertwining or inserting these ends into the body of the product The largest individual element used in the final rope making process and obtained by joining and twisting or braiding together several yarns or groups of yarns The process of combining a number of roping yarns by twisting to form a strand A short length of synthetic rope attached to the end of a mooring line to provide increased elasticity and also ease of handling Fatigue caused by cyclic axial loading at given mean load load amplitude and frequency A rotation induced in the rope during service The process of making rope in which two or more strength members yarns or strands are rotated together around a central axis Rope made by stranding three or more strength members together in a helical pattern Also called stranded rope A generic term for a continuous strand of textile fibres filaments or material in a form suit
32. trand Rope 6 Strand Rope with core 7 Strand Rope 8 Strand Rope 12 Strand Braided Rope Construction and arrangement of strands vary Double Braid Rope Parallel Strand Rope Number and construction of strands vary Jacketed Strands Strands Strand Jacket Strand or Rope Jacket Strands Strands i CEEELECEE SG Cora 11919919311 NS NNN SAAR LL dis dds ds ddd db bh dp nana Rope Jacket Figure 2 1 High modulus synthetic fibre mooring rope constructions 21 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 2 6 2 2 6 3 2 6 3 1 2 6 3 2 26 3 3 2 6 4 Linear density Linear density is the weight of the rope per unit length typically expressed in kg 100 m and tested in accordance with ISO 2307 or Cl 1500 references 2 and 3 The manufacturer should supply this information It should be noted that some rope manufacturers allow up to 10 tolerance in the linear density of supplied ropes from the prototype design Rope protection Jacket Purchasers should specify whether or not the rope should be jacketed to provide additional chafe protection Ropes can be provided with overall jackets and or individual strand jackets The jacket while serving to protect the load bearing core will make it difficult to monitor the condition of the core should that be necessary With some constructions the jacket and core may move separately risking possible
33. tructure in service or on a test machine A factor that is used to calculate the recommended working load by dividing the minimum breaking strength of the rope by the design factor The design factor should be selected only after a professional assessment of risk The mass per unit volume See Linear Density Approximate diameter of cordage used for naming or reference purposes Any rapidly applied force that increases the load on a rope significantly above the normal static load The temporary change in length of a fibre or yarn under tension which is reversed when the tension is removed The elastic non permanent elongation of a unit length of an element caused by a unit load May refer to a material or a composite structure such as a mooring line The ratio of the extension of a rope under an applied load to the length of the rope prior to the application of the load expressed as a percentage The process of rotating a rope or wire on its stowage drum so that the working section is changed This involves removing the rope or wire from the drum and re stowing it with the previous outboard end next to the drum The deformation change in length of a rope when a load is applied A long fine very flexible structure that may be woven braided stranded or twisted into a variety of fabrics twine cordage or rope Manufactured fibres of an indefinite length which may be converted into filament yarn staple or tow 3
34. tting chafe protection to the section of rope passing through the fairlead see figure 1 3 An example of a low friction low abrasion fairlead insert At exposed terminals chafe protection may assist in reducing the effect but may not completely prevent the rope being abraded Care should be taken to maintain the effectiveness of the chafe protection during the port stay For Panama leads chafe protection in the form of retrofitted low friction inserts may be considered The insert reduces the coefficient of friction between the line and the fitting Inserts should not be fitted in a manner that adversely affects the strength of the Panama lead Figure 1 3 An example of a low friction low abrasion fairlead insert HMPE lines may also experience damage from frictional heat generated by high loads at leads Chafe protection or jacketing may reduce this effect HMPE lines may also suffer heat damage from prolonged exposure to hot mooring surfaces such as chocks and fairleads which could occur during daylight hours in high ambient temperature ports 17 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines Figure 1 4 Examples of Chafe protection 18 Copyright OCIMF and SIGTTO 2014 Guide to Purchasing High Modulus Synthetic Fibre Mooring Lines 2 1 2 2 2 3 Guidance for specifying high modulus synthetic fibre mooring lines General Mooring rope manufacturers will pr
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