1、IINCH-POUNDI MIL-B-24220A(SH) 9 November 1990 SUPERSEDING 28 July 1966 (See 6.8) MIL-B-24220(SHIPS) MILITARY SPECIFICATION BLOCKS, TACKLE, SYNTHETIC ROPE This specification is approved for use by the Naval Sea Systems Command, Department of the Navy, and is available for use by all Departments and A
2、gencies of the Department of Defense, 1. SCOPE 1.1 ScoDe. This specification covers single- and multiple-sheave tackle blocks and snatch blocks. 1.2 Classification. The synthetic rope tackle blocks are of the following types and classes, as specified (see 6.2). Type I - Blocks, steel. Class 1 - Sing
3、le sheave. Class 2 - Double sheave. Class 3 - Triple sheave. Type II - Blocks, snatch, steel, safety-locking. Type III - Blocks, wood, nontoppling. Class 1 - Double, loose, swivel hook. Class 2 - Triple, loose, swivel hook. Class 3 - Double, loose, swivel releasing hook. Type IV - Blocks, steel, non
4、toppling. Class 1 - Double, loose, swivel hook. Class 2 - Triple, loose, swivel hook. Class 3 - Double, loose, swivel releasing hook. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, N
5、aval Sea Systems Command, SEA 5523, Department of the Navy, Washington, DC 20362-5101 by using the self-addredsed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. AMSC N/A FSC 3940 DISTRIBUTION STATEMENT A. Approved for public release;
6、distribution is unlimited. Licensed by Information Handling ServicesProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-2Ll220A 37 W 777770b 0457367 7 E 2, APPLICABLE DOCUMENTS 2.1 Government documents. 2.1.1 SDecifications. standards. and handbook
7、s. The following specifica- tions, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and supplement
8、thereto, cited in the solicitation (see 6.2). SPECIFICATIONS FEDERAL RR-C- 271 - Chains and Attachments, Welded and Weldless, PPP-F-320 - Fiberboard: Corrugated and Solid, Sheet Stock (Container Grade) and Cut Shapes. MI LI TARY MIL-B-3865 - Blocks, Rope, Tackle: Packaging of. MIL-L-19140 - Lumber a
9、nd Plywood, Fire-Retardant Treated STANDARDS FEDERAL FED-STD-H28 - Screw-Thread Standards for Federal Services. MILITARY MIL-STD-130 - Identification Marking of U.S. Military Property. MIL-STD-278 - Welding and Casting Standard. (Unless otherwise indicated, copies of federal and military specificati
10、ons, standards, and handbooks are available from the Standardization Documents Order Desk, Bldg. 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.) 2.2 Non-Government Dubiications. The following docwnent(s) form a part of this document to the extent specified herein. issues of the documents which
11、 are DOD adopted are those listed in the issue of the DODISS cited in the solicitation. Unless otherwise specified, the issues of documents not listed in the DODISS are the issues of the documents cited in the solicitation (see 6.2). Unless otherwise specified, the AMERICAN SOCIETY FOR TESTING AND M
12、ATERIALS (ASTM) General Application. (DoD adopted) A 27 - Standard Specification for Steel Castings Carbon, for A 36 - Standard Specification for Structural Steel. (DoD adopted) A 108 - Standard Specification for Steel Bars, Carbon, Cold A 109 - Standard Specification for Steel, Strip, Carbon, Cold
13、Finished, Standard Quality. (DoD adopted) . Rolled. (DoD adopted) a c JA Y o 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Te MIL-B-24220A 39 m 9999906 0459368 O m - MIL-B-24220A(SH) ASTM (Continued) A 148 - Standard Specification for Steel Casti
14、ng, High Strength, A 153 - Standard Specification for Zinc Coating (Hot Dip) on Iron A 569 - Standard Specification for Steel, Carbon (0.15 Maximum For Structural Purposes. (DoD adopted) and Steel Hardware. (DoD adopted) Percent), Hot Rolled Sheet and Strip Commercial Quality. (DoD adopted) Alloy, f
15、or General Industrial Use. Impregnated). A 668 - Standard Specification for Steel Forgings, Carbon and B 438 - Standard Specification for Sintered Bronze Bearings (Oil (Application for copies should be addressed to the American Society for ting and Materials, 1916 Race Street, Philadelphia, PA 19103
16、.) (Non-Government standards and other publications are normally available from These documents also the organizations that prepare or distribute the documents. may be available in or through libraries or other informational services.) 2.3 Order of Precedence. In the event of a conflict between the
17、text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 First article. When specified (see 6.2), a sample shall
18、be subjected to first article inspection (see 6.4) in accordance with 4.2.1. 3.2 Desien and construction. Block design shall be as shown in tables I and II, and on figures 1 through 5, as applicable as to type, class, style, size and rig specified (see 6.2). adversely affect the performance or maint
19、ainability of individual components. Replacement parts shall be manufactured to standard tolerances to permit replacement without requiring modification. readily accessible for replacement, adjustment, or repair. Each block shall be free from any defects that would All parts subject to wear shall be
20、 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-24220A 37 7997906 04573b9 2 TABLE I. Shell lenpth. working load. and sheave size for tmes I. III. and IV blocks. Safe working load For rope size Sheave size Shell length minimum (inches) 4 6 8
21、10 12 14 Single sheave (pounds ) 2,000 4,000 5,000 6,000 10,000 16,000 Diameter Circum- Outside Double Triple approxi- ference diameter sheave sheave mate nominal minimum (pounds) (pounds) (inches) (inches) (inches) 3,000 5,000 7,000 9,000 15,000 30,000 4,000 6,000 9,000 Il, O00 20,000 36,000 1/2 5/
22、8 7/8 1 - 1/8 1 - 5/16 1 - 5/8 1 - 1/2 2 2-3/4 3 - 1/2 4 5 2 - 1/4 3 - 1/2 4-1/2 6 - 1/4 9 - 1/2 8 I I I hic kne s s at rim, minimum (inches) 5/8 .1- 1/2 1 1-3/8 1 - 5/8 1-7/8 Center pin diameter minimum (inches) 1/2 5/8 3/4 7/8 1 1 - 1/8 TABLE II. Shell length, working: load, and sheave size for tm
23、e II blocks. 7- . Shell I ;:%I; (inches) (pounds) length working minimum 6 8 10 12 14 16 4,000 5,000 6,000 10,000 16,000 20,000 Rope size Diameter Circumference approximate nominal (inches) (inches) 5/8 2 7/8 1 - 5/16 4 1 - 5/8 5 2-3/4 3 - 1/2 1 - 1/8 2 6 Sheave size Outside Thickness Center pin dia
24、meter at rim, diameter minimum I minimum minimum (inches) 3 4 - 1/2 5 - 3/4 6 - 3/4 8 9 (inches) i - i/a 1-3/8 1-7/8 2 - 1/8 2 - 1/4 2 - 5/8 (inches) 5/8 3/4 I 7/8 1 1-1/8 1 - 1/2 3.3 Physical reauirements. 3.3.1 Safe working load. The safe working load (SWL) shall be based on a safety factor of 5 o
25、n the breaking strength of ehe complete block including the rig assembly. and II as applicable for the type block specified, pounds. The SWL, rope size, and sheave size shall be as shown in tables -I The SWL shall be given in 3.3.2 Proof load. The block and assembly shall not show evidence of deform
26、ation, distortion, cracks, or permanent set of any component part (see 4.5.1). I 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.3.3 Breaking load. The block and assembly shall not fail at loads less I than 5 times the SWL specified in tables I a
27、nd II (see 4.5.2). 3.4 Material. Material shall be as specified herein. Material not definitely specified shall be selected by the contractor and shall be subject to all provisions of this specification (see 6.3 and appendix). 3.4.1 Recovered materials. Unless otherwise specified herein, all equipme
28、nt, material, and articles incorporated in the products covered by this specification shall be new and may be fabricated using materials produced from recovered materials to the maximum extent practicable without jeopardizing the intended use. The term “recovered materials“ means materials which hav
29、e been collected or recovered from solid waste and reprocessed to become a source of raw materials, as opposed to virgin raw materials. interpreted to mean that the use of used or rebuilt products is allowed under this specification unless otherwise specifically specified. T t. I _. None of the abov
30、e shall be 3.4.2 Castings. Castings shall be of uniform quality, free of blowholes, porosity, hard spots, shrinkage defects, cracks, or other injurious defects. Strength and other essential physical properties of the castings shall conform to ASTM A 27 for carbon steel and ASTM A 148 for low alloy s
31、teel. 3.4.3 Forginrzs. Forgings shall be of uniform quality, free of flash, scale, cracks, hard spots, cold shuts, and excessive cooling stresses. Strength and other essential physical properties of the forgings shall conform to ASTM A 668. 3.4.4 Welding. Welding (if necessary) shall be performed in
32、 accordance with MIL-STD-278. Welding shall not be used to repair blocks. 3.4.5 Fastening devices. Screws, pins, bolts, and similar parts subject to removal, tightening or adjustment shall not be swaged, peened, staked, or otherwise permanently deformed. 3.4.6 Threads. Threaded parts shall be in acc
33、ordance with FED-STD-H28. 3.4.7 Surface. All castings, forgings, stampings, and welded parts shall be External surfaces shall be free from burrs, sharp edges, and cleaned and free of sand, dirt, fins, sprues, scale, flux, or other harmful or extraneous material. corners. 3.4.8 Coatinvs. 3.4.8.1 Laca
34、uering. Completed wood shells for type III blocks shall, after having been thoroughly and properly sanded, be dipped in high-grade, clear dipping varnish or lacquer, allowed to air dry, and then covered with quick drying varnish or lacquer as a final coat before shipment. 5 Provided by IHSNot for Re
35、saleNo reproduction or networking permitted without license from IHS-,-,-MIL-B-24220A 37 777770b 0457371 O E MIL-B-24220A(CH) 3.4.8.2 Galvanizing. Ferrous metal surfaces of blocks, except bearing surfaces and bushings, shall be hot dip galvanized in accordance with ASTM A 153, class B3. appearance o
36、r protective value of the coating. Galvanizing shall be done prior to assembly of component parts. The basic metal shall be clean and free from defects that will impair 3.5 Rigs. 3.5.1 Assembly. Blocks and fittings of corresponding size and strength shall be assembled into rigs and identified by rig
37、 numbers (see figure 1 and 3.6). Special blocks and rigs not designated on figure 1 shall be assembled as specified in the contract or order (see 6.2). 2 I l additional blocks shall be randomly selected as specified in the original sampling plan and if any defects specified in 4.4 are noted, the ent
38、ire lot shall be rejected. 13 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-B-2LI220A 37 9997906 0959379 5 MIL-B-24220A(SH) Proof test TABLE III. Sampling for examination. Breaking strength test Lot size 2-8 9 - 15 16 - 25 26 - 50 51 - 90 91 -
39、 150 151 - 280 281 - 500 501 - 1200 1201 - 3200 Sample size 2 3 5 8 13 20 32 50 80 125 4.3.2 Samvlinp for Droof test. from each lot in accordance with table IV, for the proof test specified in 4.5.1. If any block fails this test, the entire lot shall be rejected. passing the proof test may be reused
40、 for the breaking load test. Sample blocks shall be randomly selected Sample blocks 4.3.3 SamDling for minimum breaking strength test. Sample blocks shall be selected in accordance with table IV for the minimum breaking strength test specified in 4.5.2. If any,block fails this test, the entire lot s
41、hall be rejected. TABLE IV. SamDline for tests. 2-8 9 - 15 16 - 25 26 - 50 51 - 90 91 - 150 151 - 280 281 - 500 501 - 1200 1201 - 3200 Sample size 2 2 3 5 5 8 13 13 20 32 2 2 2 2 3 3 3 3 5 5 4.4 Examination. Each - be examined to verify conformance to all the requirements of this specification not i
42、nvolving tests, Defects shall be classified in accordance with table V. sample block selected in accordance with 4.3.1 shall 14 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Categories 101 102 103 104 105 106 107 108 109 110 i11 112 113 114 115 116
43、 117 118 119 120 121 122 TABLE V. Classification of defects. Defects Block type and class nonconforming; not for specified size of Material nonconforming; evidence of cracks, blowholes, rope. excessive porosity, hard spots, shrinkage defects, foreign inclusions, cold shuts, sprues, fins, flash, and
44、scale. positioned, fitted or assembled as specified. binding, misalignment of components or excessive looseness. undercut, slag inclusions, porosity, and incomplete or under- size welds. smooth, not free from blisters, lumps, sharp projections or excess coating. Incomplete; component parts missing,
45、not secured, not Rigs and fittings nonconforming; inoperative, evidence of Welding nonconforming; evidence of cracks, nonfusion, deep Galvanizing nonconforming, evidence of uncoated areas, not Evidence of unauthorized welding. Evidence of permanent deformation of fastening devices subject Fastening
46、devices subject to removal not in alignment, Threads nonconforming; size, length and fit not as required; to removal; evidence of swaging, peening or staking. inoperable; excessive looseness. not matching threads with components; stripped, crossed, cracked and incomplete. Shell material not as speci
47、fied; components not fastened securely; not cross bolted as specified. Straps malformed; fail to support center pin as specified. Sheave outside diameter and thickness less than the minimum specified. Sheave fails to turn freely by hand; loose or wobbly on pin, side play exceeds specified tolerance,
48、 Sheave rim and tread section not grooved to fit specified size of rope; surfaces not smooth, evidence of sharp edges, burrs or projections, Sheave rim not concentric with bore. Bushing nonconforming; loose in sheave, length not as Bushing bore nonconforming for center pin. Bushing not grooved for s
49、elf-lubricating as specified, Center pin diameter less than specified, surfaces not smooth; evidence that pin rotates in shell or strap. Lock device nonconforming, inoperative, fails to lock shackle link in position, prevents opening of block for quick entry of rope. specified, wall thickness less than the minimum specified. Hook, eye or shackle fails to swivel as specified. 15 Provided by IHSNot for ResaleNo reproduction or net
