Section 1 Anchors

1.1.1 This Section makes provision for the manufacture and testing of anchors constructed from cast, forged and fabricated components.

1.1.2 This Section is applicable to the following types of anchor:

1. Ordinary.

2. High holding power (HHP).

3. Super high holding power (SHHP).

1.1.3 In the context of this Section, the reference to swivels and swivel shackles refers to those directly attached to the anchor shank in lieu of the conventional 'D' shackle. For other mooring equipment swivels, see Ch 10, 2.13 Fittings for chain cables.

1.2.1 All anchors including their accessories are to be of an approved design. For any separate accessories not part of the approved design, see Ch 10, 2.13 Fittings for chain cables. In addition, HHP and SHHP anchor designs including their accessories are required to be tested in accordance with Ch 10, 1.3 Anchor holding power tests for HHP and SHHP anchors so as to confirm the holding power.

1.3.1 Anchor designs for which approval is sought as HHP anchors are to be tested at sea to show that they have holding powers of at least twice those of approved standard stockless anchors of the same mass. In the case of SHHP anchors, a holding power of at least four times that of an ordinary stockless anchor of same mass is to be demonstrated.

1.3.2 Full scale tests are to be carried out at sea on various types of bottom, normally, soft mud or silt, sand or gravel and hard clay or similar compounded material. The tests are to be applied to anchors of mass which are as far as possible representative of the full range of sizes proposed.

1.3.3 HHP and SHHP anchors are to be tested along with an ordinary stockless anchor to establish the holding power. They are to be of approximately the same mass and tested in association with the size of chain required for that anchor mass.

1.3.4 Where an ordinary stockless anchor is not available for testing a HHP anchor, the use of a previously approved HHP anchor may be considered. For testing SHHP anchors, a previously approved HHP or SHHP anchor may be considered.

1.3.5 The length of the cable attached to each anchor is to be such that the pull on the shank remains horizontal during the test. For this purpose a scope of 10 is considered normal but a scope of not less than 6 may be accepted. Scope is defined as the ratio of length of cable to depth of water.

1.3.6 Three tests are to be taken for each anchor and each type of bottom. The stability of the anchor and ease of breaking out are to be noted where possible. Tests are to be carried out from a tug but, alternatively, shore based tests will be specially considered The pull is to be measured by dynamometer. Measurements of pull, based on the RPM/bollard pull curve of the tug will be considered as an alternative to a dynamometer.

1.3.7 For approval and/or acceptance for a range of HHP anchor sizes, tests are to be carried out for at least two anchor sizes. The mass of the maximum size approved is not to be more than 10 times the mass of the largest size tested.

1.3.8 For approval and/or acceptance for a range of SHHP anchor sizes, at least three anchor sizes are to be tested, indicative of the bottom, middle and top of the mass range.

1.3.9 The holding power test load is not to exceed the proof load of the anchor.

1.4.1 Cast steel anchor heads, shanks, shackles, swivels and swivel shackles are to be manufactured and tested in accordance with the requirements of Ch 4, 1 General requirements and Ch 4, 2 Castings for ship and other structural applications. The Special grade quality is to be used for anchor heads, shanks and shackles.

1.4.2 Swivel and swivel shackles shall be manufactured to at least Grade U2. Special consideration will be given to the use of other grades of steel.

1.4.3 To confirm the quality of cast anchor components, the Surveyor is to witness drop and hammering tests.

1.4.4 When drop and hammering tests are required, they are to be carried out as follows:

1. Each anchor, or the components of an anchor made from more than one piece, is to be dropped from a clear height of 4 m onto a steel slab laid on a solid foundation.

2. Separately cast shanks and shackles are to be suspended horizontally from a clear height of 4 m before being dropped. Cast anchor flukes are to be suspended vertically, from a clear height of 4 m before being dropped. Alternatively, a horizontal drop test for the anchor fluke can be carried out as agreed by the manufacturer and Surveyor.

3. Anchors cast in one piece are to be drop tested twice from a clear height of 4 m. For the first test, the shank and flukes are to be horizontal. For the second test, two steel blocks are to be placed on the slab, arranged so that the middle of each fluke makes contact with the blocks without the crown making contact with the slab, and the orientation of the anchor is to be vertical with the crown nearest the slab.

4. If the slab is broken by the impact, the test is to be repeated on a new slab.

1.4.5 When hammering tests are required, they are to be carried out after the drop test on each anchor head and shank, which is slung clear of the ground, using a nonmetallic sling, and hammered to check the soundness of the component. A hammer of at least 3 kg mass is to be used.

1.4.6 As part of the manufacturer’s works approval, consideration may be given to carrying out drop tests in alternative locations to the manufacturer’s when the facilities and location are not suitable.

1.4.7 Repair of fractures or unsoundness detected during the drop or hammering tests are not permitted and the component is to be rejected.

1.5.1 Forged steel anchor pins, swivels, shanks, shackles and swivel shackles are to be manufactured and tested in accordance with the requirements of Ch 5, 1 General requirements and Ch 5, 2 Forgings for ship and other structural applications carbon and carbon-manganese steel for welded construction. Rolled steel bar may be used provided that the requirements of Ch 5, 1.2 Manufacture 1.2.9 are met.

1.5.2 Swivel and swivel shackles shall be manufactured to at least Grade U2. Special consideration will be given to other grades of steel.

1.6.1 Where it is proposed to use plate material for fabricated steel anchors, it is to comply with the requirements of Ch 3, 2 Normal strength steels for ship and other structural applications or Ch 3, 3 Higher strength steels for ship and other structural applications, and the proposed manufacturing procedure is to be submitted for approval.

1.6.2 Fabricated anchors are to be manufactured in accordance with Ch 13 Requirements for Welded Construction.

1.6.3 Stress relief is to be carried out as required in the approved welding procedure.

1.7.1 All rectification is to be agreed with the Surveyor.

1.7.2 Rectification of defective castings is to be carried out in accordance with Ch 4, 1.11 Rectification and dressing of castings.

1.7.3 Rectification of defective forgings is to be carried out in accordance with Ch 5, 1.9 Rectification of defects.

1.7.4 Rectification of defective fabricated anchors is to be carried out by suitably qualified welders within the parameters of the approved welding procedure used in construction.

1.7.5 Rectification of defective castings, forgings or fabricated anchors by welding is to be carried out using qualified weld procedures in accordance with Ch 12, 1 General qualification requirements and Ch 12, 2 Welding procedure qualification tests for steels, and in accordance with Ch 13, 1 General welding requirements and Ch 13, 2 Specific requirements for ship hull structure and machinery.

1.8.1 The impact test requirements for SHHP anchor shackles are to be in accordance with the requirements for Grade U3 in Table 10.2.1 Mechanical properties of finished chain cable and fittings.

1.9.1 Assembly and fitting, including any accessories, is to be carried out in accordance with the approved design.

1.9.2 Securing of anchor pins, shackle pins, swivels or swivel shackles by welding is to be carried out by suitably qualified welders in accordance with an approved welding procedure.

1.10.1 Anchors are to be tested in the presence of the Surveyor at a proving establishment recognised by LR. A list of recognised proving establishments is published separately by LR. In addition to the requirements stated in this Chapter, attention must be given to any relevant statutory requirements of the National Authority of the country in which the ship or mobile offshore unit is to be registered.

1.10.2 The anchor is to be visually examined before application of the proof test load to ensure that it is free from cracks, notches, inclusions and other surface defects that would impair the performance of the product.

1.10.3 As required by Ch 10, 1.10 Proof test of anchors, each anchor is to be subjected to a proof loading test in an approved testing machine and is to withstand the load given in Table 10.1.1 Proof load tests for anchors (see Notes 1 and 2) for the appropriate mass of the anchor. The proof load is to be applied on the arm or on the palm at a spot which, measured from the extremity of the bill, is one-third of the distance between it and the centre of the crown. For stocked anchors, each arm is to be tested individually. For stockless anchors, both arms are to be tested at the same time, first on one side of the shank, then reversed and tested on the other.

1.10.4 The general arrangements for the test are to be such that the complete anchor, including the shackle, shackle pins, swivel or swivel shackle and any welded or bolted connections are included in the test. If a replacement shackle, swivel or swivel shackle is needed which requires welding or heating for fitting, the combined anchor and accessories are to be proof load tested. If welding or heating is not involved in fitting, the accessories may be proof load tested separately from the anchor.

1.10.5 The mass to be used in Table 10.1.1 Proof load tests for anchors (see Notes 1 and 2) is:

1. For stockless anchors, the total mass of the anchor.

2. For stocked anchors, the mass of the anchor excluding the stock.

3. For high holding power anchors, a nominal mass equal to 1,33 times the actual total mass of the anchor.

4. For mooring anchors, including positional mooring anchors, a nominal mass equal to 1,33 times the actual total mass of the anchor, unless specifically agreed otherwise.

5. For super high holding power anchors, a nominal mass equal to twice the actual total mass of the anchor.

1.10.6 For positional mooring anchors, the proof test loading is to be that required by Ch 10, 1.10 Proof test of anchors 1.10.3 or 50 per cent of the minimum break strength of the intended anchor line, whichever is the greater.

1.10.7 The gauge length is to be measured with 10 per cent of the required load applied, before and after proof test. The two measurements shall differ by no more than 1 per cent. The gauge length is the distance between the tip of each fluke and a point on the shank adjacent to the shackle pin, see Figure 10.1.1 Location of gauge length measurement during proof load.

Figure 10.1.1 Location of gauge length measurement during proof load

1.10.8 After proof testing, all accessible surfaces are to be visually inspected by the Surveyor.

1.10.9 Following proof testing, NDE is to be conducted as described in Table 10.1.2 NDE requirements following proof testing for Ordinary and HHP anchors for ordinary and HHP anchors and Table 10.1.3 NDE requirements following proof testing for SHHP anchors for SHHP anchors.

1.10.10 Each casting is to be subjected to ultrasonic inspection in the region of runners and risers, or where excess material has been removed by thermal methods. This examination is to extend around the whole periphery of the casting and for a distance of t/3 beyond the area affected, where t is the maximum thickness. In addition, random areas are to be selected by the Surveyor and examined.

1.10.11 Acceptance criteria for castings are to be in accordance with Ch 4 Steel Castings.

1.10.12 Acceptance criteria for forgings are to be in accordance with Ch 5 Steel Forgings.

1.10.13 Paint or anti-corrosive coatings are not to be applied until these inspections are completed to the satisfaction of the Surveyor.

1.10.14 On completion of the proof testing, anchors made in more than one piece are to be examined for free movement of their heads over the complete range of rotation.

1.11.1 Where no fitting tolerances are specified on the approved plans the following assembly and fitting tolerance are to be applied.

1.11.2 The clearance either side of the shank within the shackle jaws and the shackle pin in the shank end hole is to be no more than 3 mm for small anchors up to 3 tonnes, 4 mm for anchors up to 5 tonnes, 6 mm for anchors up to 7 tonnes and is not to exceed 12 mm for larger anchors.

1.11.3 The shackle pin to hole tolerance is to be no more than 0,5 mm for pins up to 57 mm and 1,0 mm for pins of larger diameter and the eyes of the shackle are to be chamfered on the outside to ensure a good tightness when the pin is fitted. The shackle pin is to mate with the shackle such that it can be inserted with moderate hand pressure, allowing disassembly if required.

1.11.4 The trunnion pin is to fit within the chamber such that it will achieve the closest fit which can be carried out by hand. The pin is to be long enough to prevent horizontal movement. The gap is to be no more than 1 per cent of the chamber length.

1.11.5 The lateral movement of the shank is not to exceed 3 degrees from the centreline datum, see Figure 10.1.2 Allowable lateral movement of shank.

Figure 10.1.2 Allowable lateral movement of shank

1.11.6 Unless otherwise agreed, the verification of mass and dimensions is the responsibility of the manufacturer. The Surveyor is only required to monitor this inspection. The mass of the anchor is to exclude the mass of the swivel or swivel shackle, unless the swivel or swivel shackle is in lieu of the conventional ‘D’ shackle.

1.12.1 The manufacturer is to adopt a system of identification, as per the requirements of Ch 1, 4.8 Identification of materials, which will enable all anchor components to be traced to the original cast and the Surveyor is to be given full facilities for tracing the castings when required.

1.12.2 Identification marks on the shank are to be approximately level with the fluke tips. On the fluke, these markings are to be approximately at a distance of two thirds from the tip of the bill to the centre line of the crown on the right hand fluke, looking from the crown towards the shank.

1.12.3 The following details are to be shown on all anchors:

1. LR or Clasifications Register and abbreviated name of LR's local office issuing the certificate.

2. Number of the certificate.

3. Month and year of test.

4. Mass (also the letters `HHP' when approved as high holding power anchors or ‘SHHP’ when approved as super high holding power anchors).

5. Mass of stock (in the case of stocked anchors).

6. National Authority requirements, as applicable.

7. Manufacturer's mark.

1.12.4 In addition to Ch 10, 1.12 Identification 1.12.3, each important part of an anchor is to be plainly marked by the maker with the words `forged steel' or `cast steel' as appropriate. Fabricated steel anchor heads do not require special marking.

1.13.1 The manufacturer is to provide the Surveyor with a written statement that the anchor has been manufactured and tested in accordance with LR Rules together with the following particulars:

1. Purchaser`s name and order number.

2. Type of anchor and principal dimensions.

3. Mass of anchor.

4. Identification mark which will enable the full history of manufacture to be traced.

5. Chemical composition.

6. Details of heat treatment.

7. Mechanical test results.

8. Proof load.

9. Results of the non-destrucive examination.

10. Weld location maps (cast steel anchors only).

1.13.2 Shanks, heads, pins, shackles and swivels are to be certified by LR in accordance with the relevant sections of Chapters Ch 3 Rolled Steel Plates, Strip, Sections and Bars, Ch 4 Steel Castings and Ch 5 Steel Forgings.

1.13.3 An LR Anchor Certificate is to be issued for the completed anchor which will include the following particulars:

1. Manufacturer's name.

2. Type of anchor.

3. Mass of anchor.

4. Grade of materials.

5. Proof test load.

6. Heat treatment.

7. Marking applied to anchor.

8. Dimensions.

9. General Approval of an Anchor Design Certificate Number.

10. Fluke and shank identification numbers.