1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 13798:2012Ships and marine technology Ships mooring and towingfittings Recessed bitts (Steelplate type)BS ISO 13798:2012 BRITISH STANDARDNational forewordThis British Stan
2、dard is the UK implementation of ISO 13798:2012.The UK participation in its preparation was entrusted to TechnicalCommittee SME/32/-/4, Ships and marine technology - Outfitting anddeck machinery.A list of organizations represented on this committee can beobtained on request to its secretary.This pub
3、lication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsLimited 2012ISBN 978 0 580 69756 2ICS 47.020.50Compliance with a British Standard cannot confer immunity
4、 fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 November 2012.Amendments issued since publicationDate Text affectedBS ISO 13798:2012 ISO 2012Ships and marine technology Ships mooring and towing fittings Recessed bitts
5、 (Steel plate type)Navires et technologie maritime Corps-morts et ferrures de remorquage de navires Bittes damarrage encastres (type plaques dacier)INTERNATIONAL STANDARDISO13798First edition2012-07-01Reference numberISO 13798:2012(E)BS ISO 13798:2012ISO 13798:2012(E)ii ISO 2012 All rights reservedC
6、OPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address bel
7、ow or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 13798:2012ISO 13798:2012(E) ISO 2012 All rights reserved iiiContents PageForewor
8、d ivIntroduction v1 Scope 12 Normative references . 13 Terms and definitions . 14 Classification 14.1 Type . 14.2 Nominal sizes . 15 Dimensions . 16 Materials . 17 Construction . 28 Manufacturing and inspection . 29 Marking . 2Annex A (informative) Basis for strength assessment of recessed bitts (St
9、eel plate type) . 4Bibliography . 6BS ISO 13798:2012ISO 13798:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technica
10、l committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely wit
11、h the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft Interna
12、tional Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be
13、 the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 13798 was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee SC 4, Outfitting and deck machinery.iv ISO 2012 All rights reservedBS ISO 13798:2012ISO 137
14、98:2012(E)IntroductionThe recessed bitt is a type of ships towing fitting installed on the side shell of the ship.The recessed bitts are normally provided to easily attach the towing lines where the height of the mooring deck is too high. ISO 2012 All rights reserved vBS ISO 13798:2012BS ISO 13798:2
15、012Ships and marine technology Ships mooring and towing fittings Recessed bitts (Steel plate type)1 ScopeThis International Standard specifies the design, size and technical requirements for steel plate type recessed bitts to meet normal towing requirements.2 Normative referencesThe following refere
16、nced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.IMO Circular MSC/Circ.1175, Guidance on shipboard towing and mooring e
17、quipment3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1safe working loadSWLmaximum load in kN on the rope that should normally be applied in service conditions.4 Classification4.1 TypeDepending on the manufacturing method, recessed bitts shall
18、be classified as the following two types: Type A manufactured by steel pipes; Type B manufactured by steel plates.4.2 Nominal sizesThe nominal sizes, Dn, of recessed bitts are denoted by reference to the outside diameter of the main post in millimetres, in terms of the nearest number drawn from a ba
19、sic series of preferred numbers. For the recessed bitts having the same post diameter, the alphabetical character is followed by the nominal size for the different SWL.The nominal sizes are: 200, 250, 400A and 400B.5 DimensionsRecessed bitts have dimensions and particulars in accordance with Table 1
20、 and Figure 1.6 MaterialsThe materials of the following components shall be used for manufacturing the recessed bitts: Plates: weldable steel plates having a yield point of not less than 235 N/mm2.INTERNATIONAL STANDARD ISO 13798:2012(E) ISO 2012 All rights reserved 1BS ISO 13798:2012ISO 13798:2012(
21、E) Tubes: weldable steel tubes having a yield point of not less than 215 N/mm2or equivalent.7 Construction7.1 The posts of the recessed bitts shall be constructed from steel tubes or formed from plate.7.2 The recess boxes for the installation of the recessed bitt shall be designed with enough space
22、for easy connection of the towing rope. The recess boxes shall be designed to prevent the chafing and damage of the towing rope as much as possible, and to have enough strength as a part of hull construction.8 Manufacturing and inspection8.1 All surfaces of the recessed bitts, including welding, sha
23、ll be free from any visible flaws or imperfections.8.2 All surfaces in contact with the ropes shall be free from surface roughness or irregularities likely to cause damage to the ropes by abrasion.8.3 The recessed bitts shall be coated externally with an anti-corrosion protective finish.9 Marking9.1
24、 The safe working load (SWL) intended for the use of the recessed bitts shall be noted in the towing and mooring plan available on board for the guidance of the shipmaster, as specified in MSC/Circ.1175.9.2 The actual SWL on board shall be determined by considering the reinforcement around the reces
25、s box, and it shall be marked on the towing and mooring plan. The actual SWL shall not be over the SWL indicated in this International Standard.9.3 The recessed bitts shall be clearly marked with their SWL by weld bead or equivalent. The SWL shall be expressed in tonnes (letter t) and be placed so t
26、hat it is not obscured during operation of the fitting.EXAMPLE SWL XXX t2 ISO 2012 All rights reservedBS ISO 13798:2012ISO 13798:2012(E)Dimensions in millimetresKey1 main post2 top plate3 chill stripP towing forceaSWL marking.bSmooth grinding.Figure 1 Recessed bittsTable 1 Dimensions and SWL of rece
27、ssed bittsDimensions in millimetresNominal sizeDnType D D1R H TSWLbCalculated weightc(kg)(kN) (t)200Type A 216,3250 80 14010,3294 3016,5Type B 210,0 10,0 16,1250Type A 267,4305 100 16012,7491 5026,7Type B 260,0 12,0 25,7400AType A 406,4480 140 30012,7687 7069,7Type B 410,0 12,0 68,0400BType A 406,44
28、80 140 33021,41 177 12099,7Type B 410,0 20,0 96,1aWelding with chamfering is available based on the same welding volume/strength.bThe SWL is the maximum applicable rope tension.The SWLs shown in this table are for reference only. These are based on the loadings as mentioned in Annex A.cThe calculate
29、d weight is for reference only. ISO 2012 All rights reserved 3BS ISO 13798:2012ISO 13798:2012(E)Annex A (informative) Basis for strength assessment of recessed bitts (Steel plate type)A.1 GeneralThe strength of the recessed bitts was evaluated by simple beam theory calculation and determined based o
30、n the following design criteria.A.2 LoadingA.2.1 The recessed bitts are to be designed to withstand the loads imposed by the towing ropes.A.2.2 The recessed bitts are to be designed to withstand the following load case.They are to be designed to withstand the combined load of bending force and shear
31、 force produced by P imposed at the upper position.KeyP towing forced rope diameter (see A.2.3)hp H d/2Figure A.1 Combined loads by towing ropeA.2.3 For the consideration of load point from the towing ropes, the following wire ropes were adopted.4 ISO 2012 All rights reservedBS ISO 13798:2012ISO 137
32、98:2012(E)Table A.1 Diameter of applied ropes for load considerationDimensions in millimetresNominal sizeDnRope diameterd200 30250 35400A 40400B 60A.3 Load and stress criteriaUnder the SWL, the following stress criteria were adopted: The bending stress is limited to 85 % of the yield stress of the m
33、aterial. The shear stress is limited to 60 % of the yield stress of the material. The combined stress is limited to 100 % of the yield stress of the material.A.4 Wear-down allowances and corrosion additionsA.4.1 Wear-down allowancesFor the strength calculation, the wear-down of 2 mm is to be deducte
34、d from the gross thickness, where the rope is rubbing the surface.A.4.2 Corrosion additionsThe corrosion margin was already included in the safety factor and 2 mm wear-down allowance. ISO 2012 All rights reserved 5BS ISO 13798:2012ISO 13798:2012(E)Bibliography1 IACS UR A2, Shipboard fittings and sup
35、porting hull structures associated with towing and mooring on conventional vessels2 OCIMF, Mooring Equipment Guidelines (MEG 3)3 ISO 2408, Steel wire ropes for general purposes Minimum requirements6 ISO 2012 All rights reservedBS ISO 13798:2012BS ISO 13798:2012ISO 13798:2012(E) ISO 2012 All rights r
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