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1、BRITISH STANDARD MARINE SERIES CONFIRMED JULY 1999 BS MA 62:1974 Specification for Weed grids for sea inlets UDC 629.12.011.7:621.646.97.057.2 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 This
2、British Standard, having been approved by the Shipbuilding and Marine Industry Standards Committee, was published under the authority of the Executive Board on 29 July 1974 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference SME/3 Draft for comment 73/37
3、437 DC ISBN 0 580 08026 9 Foreword This British Standard has been prepared under the authority of the Shipbuilding and Marine Industry Standards Committee and is based on a proposal of the British Ship Research Association. Underwater openings are provided in ships for the purpose of admitting sea w
4、ater under controlled conditions for ballasting and other essential services. This standard specifies details of protective weed grids for such openings in order to provide coarse straining of large water-borne debris. This standard makes reference to the following British Standards: BS 499, Welding
5、 terms and symbols Part 2: Symbols for welding. BS 729, Hot dip galvanized coatings on iron and steel articles. BS 1400, Copper alloy ingots and copper and copper alloy castings. BS 1574, Split cotter pins metric and inch series. BS 1936, Undercuts and runouts for screw threads Part 2: ISO metric sc
6、rew threads. BS 2045, Preferred numbers. BS 2870, Rolled copper and copper alloys. Sheet, strip and foil. BS 2873, Copper and copper alloys. Wire. BS 2874, Copper and copper alloys. Rods and sections (other than forging stock). BS 3692, ISO metric precision hexagon bolts, screws and nuts. BS 4320, M
7、etal washers for general engineering purposes. BS 4360, Weldable structural steels. CP 3003, Lining of vessels and equipment for chemical processes. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct
8、 application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 11 and a back cover. This standard has been updated (see copyright date) and may have
9、had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS
10、MA 62:1974 BSI 03-2000i Contents Page ForewordInside front cover 1Scope1 2Types1 3Nominal sizes and designation1 4Construction and dimensions1 5Materials1 6Quality of manufacture1 7Inspection1 Appendix A Installation of weed grids3 Figure 1 Weed grid: Type A4 Figure 2 Weed grid: Type A5 Figure 3 Wee
11、d grid: Type B6 Figure 4 Man access grate: Type B7 Figure 5 Weed grid: Type C8 Figure 6 Grid construction9 Figure 7 Typical cast grid10 Figure 8 Typical weed grid attachment11 Table 1 Nominal sizes of weed grids1 Table 2 Materials2 Licensed Copy: London South Bank University, London South Bank Unive
12、rsity, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 BSI 03-20001 NOTEUsers of this British Standard: Marine Series should
13、 note that while observing the requirements of the standard they should at the same time ensure compliance with such statutory requirements, rules and regulations as may be applicable to the individual ship concerned. 1 Scope 1.1 This British Standard specifies a range of weed grids to act as coarse
14、 strainers for sea water inlets on ships. The standard specifies types and sizes of grids, materials, dimensions, quality of manufacture and fixing details. 1.2 Appendix A relates to the application and shipboard installation of weed grids. 2 Types Weed grids manufactured in accordance with this sta
15、ndard shall comprise three types, as follows: 3 Nominal sizes and designation Weed grids shall be designated by reference to their type and nominal size as given in Table 1 (e.g. Type A25, Type B63 etc.). NOTEThe nominal sizes of the weed grids are related to the clear areas (m2) which are graduated
16、 in accordance with a preferred series of numbers (see R5 series of BS 2045). Table 1 Nominal sizes of weed grids 4 Construction and dimensions 4.1 The construction of the weed grids and their dimensions shall be in accordance with Figure 1 to Figure 7. Typical details of fixing brackets and screws
17、are shown in Figure 8. 4.2 The dimensions and finish of fasteners shall comply with the requirements of BS 1574, BS 3692 and BS 4320. Grid fixing screws to BS 3692 shall have the thread under the screw head undercut in accordance with the requirements of BS 1936-2 (plunge-cut f1). 5 Materials The ma
18、terials used for the manufacture of weed grids shall be in accordance with the requirements of Table 2. Other materials may be used provided they are at least as suitable for the intended duty. 6 Quality of manufacture 6.1 Weed grids shall be either fabricated by welding or of cast form as shown by
19、the appropriate figures. NOTEThe welding symbols used in Figure 6 are in accordance with the requirements of BS 499-2, but the associated dimensions are expressed in terms of the weld throat thickness and not leg length. 6.2 All welding shall be of good quality without undue porosity or undercut. Af
20、ter welding, and prior to any protective coating, sharp edges and surface roughness shall be removed or smoothed. 6.3 Fabricated and cast weed grids shall have the bars evenly spaced with a gap between bars of 25 mm. 6.4 Fabricated steel grids, after the completion of all welding, shall be galvanize
21、d in accordance with the requirements of BS 729. When grids are to be coated other than by galvanizing, special preparation of the surfaces may be required and reference should be made to CP 3003. See Appendix A for influence of thickness of coatings on clear area. 6.5 Cast weed grids shall be clean
22、ed to remove any casting fins, attached scale or foundry sand. 6.6 Holes for fixing screws shall be accurately positioned and drilled in accordance with dimensions specified. For cast grids the holes shall be spot faced on the nut/washer surface. 7 Inspection 7.1 Fabricated and cast weed grids shall
23、 be checked to ensure there is no excessive distortion. 7.2 Cast weed grids shall be visually inspected for any detrimental defects such as porosity, blow holes or cracks. 7.3 Coated weed grids shall be visually inspected to ensure that the coating is sufficiently adherent and presents a uniform pro
24、tection to the surfaces of the grid. Type A:Circular(See Figure 1 and Figure 2) Type B:Elliptical(See Figure 3 and Figure 4) Type C:Rectangular(See Figure 5) Nominal size Type AType BType C Clear areaClear areaClear area 25 m2 0.025 m2 0.25 m2 0.25 400.0400.40 630.0630.63 1000.1001.00 1600.160 Licen
25、sed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 2 BSI 03-2000 Table 2 Materials ItemComponentMaterial British Standard number Designation 1Weed gridCarbon steel (See note) BS 4360Grade 43A Copper alloy
26、BS 1400LG2, LG4 2Fixing screwsCopper alloyBS 2874CA103 3Nuts 4WashersCopper alloyBS 2870PB102 5Split pinsBS 2873PB102 NOTEShip quality steel plate may be used. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS
27、 MA 62:1974 BSI 03-20003 Appendix A Installation of weed grids The clear area through the grid or grids is not to be less than twice that of the valve or valves connected to the sea inlet box. In this context the area of the space between the rim of the grid and the shell of the ship may be included
28、. When steel grids are specified to have a protective coating, other than galvanizing, attention is drawn to the need to check that the clear area is not reduced below the ratio of 2 : 1 required by the regulatory bodies. Weed grids are to be fitted in position with the length of the bars in the for
29、ward and aft direction. Weed grids are to be securely attached to the shell of the ship and the nuts prevented from slackening. No part of a grid or its fasteners is to protrude beyond the external surface of the shell plating. Reference should be made to the rules of the regulatory bodies regarding
30、 any requirements for shell strength compensation in the areas of water inlet box openings. For large inlet boxes combinations of standard grids may be used. Water boxes should be provided with drain holes where it is intended that access should be made through the shell opening or through man-gates
31、 in the weed grids. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 4 BSI 03-2000 Nom. size Clear area through grid (m2) ABCDEFG 250.0252301605650280600 400.0402802105650330600 630.063340270565039
32、0600 Figure 1 Weed grid: Type A Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 BSI 03-20005 Nom. size Clear area through grid (m2) ABCDEFG 1000.1004253001855680475600 1600.1605403503105680590685
33、Figure 2 Weed grid: Type A Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 6 BSI 03-2000 Nom. size Clear area through grid (m2) ABCDEFGHJKLMNP 250.2501 00050090517358739304305003601 050550600 400.
34、4001 2006001 08420758571 1305306004401 250650685 630.6301 5007501 35526058665001 4306807505701 550800900 1001.0001 8009001 62631058755001 7308309007001 8509501 000 Figure 3 Weed grid: Type B Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006
35、, Uncontrolled Copy, (c) BSI BS MA 62:1974 BSI 03-20007 Figure 4 Man access grate: Type B Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 8 BSI 03-2000 Nom. size Clear area through grid (m2) ABCDE
36、FR 250.2506005955302805650125 Figure 5 Weed grid: Type C Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 BSI 03-20009 Figure 6 Grid construction Licensed Copy: London South Bank University, London
37、 South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 10 BSI 03-2000 Figure 7 Typical cast grid Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 BSI 0
38、3-200011 Grid nominal sizeL 25 Type A 7540 63 100 80 160 25 Type B100 40 63 100 25Type C80 Figure 8 Typical weed grid attachment Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:20:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS MA 62:1974 BSI 389 Chiswick Hi
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