1、INCH-POUNDMIL-DTL-24749A(SH)21 August 1997 SUPERSEDINGMIL-S-24749(SH)13 August 1990DETAIL SPECIFICATIONGROUNDING STRAPS AND BOSSES, ELECTROMAGNETICGENERAL SPECIFICATION FORThis specification is approved for use by the Naval Sea Systems Command,Department of the Navy, and is available for use by all
2、Departments andAgencies of the Department of Defense.1. SCOPE1.1 Scope. This specification covers the general requirements andtests for electrical grounding straps, hereafter identified as bond straps andbosses.1.2 Classification. The bond straps contained in this specificationare classified into fo
3、ur types meeting general characteristics as follows:(see 6.1 and 6.2)Type I - Corrosion-resisting bond straps of CRES 316 wire ropewith mounting bosses attached to each end.Type II - Flat CRES 316 bond strap with mounting holes in eachend.Type III - Flat copper bond strap with mounting holes in each
4、 end.Type IV - Flat copper braid bond strap with mounting holes ineach end.Beneficial comments (recommendations, additions, deletions) and any pertinentdata which may be of use in improving this document should be addressed to:Commander, Naval Sea Systems Command, SEA 03Q, 2531 Jefferson Davis Highw
5、ay,Arlington, VA 22242-5160 by using the self-addressed Standardization DocumentImprovement Proposal (DD Form 1426) appearing at the end of this document orby letter.AMSC N/A FSC 5975DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.Provided by IHSNot for ResaleNo repr
6、oduction or networking permitted without license from IHS-,-,-MIL-DTL-24749A(SH)22. APPLICABLE DOCUMENTS2.1 General. The documents listed in this section are specified insections 3 and 4 of this specification. This section does not includedocuments cited in other sections of this specification or re
7、commended foradditional information or as examples. While every effort has been made toensure the completeness of this list, document users are cautioned that theymust meet all specified requirements cited in sections 3 and 4 of thisspecification, whether or not they are listed.2.2 Government docume
8、nts.2.2.1 Specifications, standards, and handbooks. The followingspecifications, standards, and handbooks form a part of this document to theextent specified herein. Unless otherwise specified, the issues of thesedocuments are those listed in the issue of the Department of Defense Index ofSpecificat
9、ions and Standards (DODISS) and supplement thereto, cited in thesolicitation (see 6.2).SPECIFICATIONSFEDERALFF-W-92 - Washer, Flat (Plain).QQ-A-200/4 - Aluminum 5083 Hll Bar.QQ-A-250/7 - Aluminum Alloy 5086, Plate and Sheet.QQ-B-575 - Braid, Wire, (Copper, Tin-Coated, or SilverCoated, Tubular, or Fl
10、at).QQ-N-281 - Nickel-Copper Alloy Bar, Rod, Plate, Sheet,Strip, Wire, Forgings, and Sructural andSpecial Shaped Section.QQ-P-35 - Passivation Treatments for Corrosion- QQ-S-763 - Steel Bars, Wire, Shapes, and Forgings,Corrosion Resisting.DEPARTMENT OF DEFENSEMIL-S-1222 - Studs, Bolts, Hex Cap Screw
11、s, Socket HeadCap Screws and Nuts.MIL-J-24445 - Joint, Bimetallic Bonded, Aluminum to Steel.MIL-A-45225 - Aluminum Alloy Armor, Forged.MIL-F-18240 - Fastener Element Self-Locking, ThreadedFastener, 250F Maximum.MIL-W-83420/2 - Wire Rope, Flexible, Type I, Composition B.STANDARDSDEPARTMENT OF DEFENSE
12、MIL-STD-167-1 - Mechanical Vibrations of Shipboard Equipment(Type I - Environmental and Type II -Internally Excited).MIL-STD-248 - Welding and Brazing Procedure andPerformance Qualification.MIL-STD-1252 - Inertia Friction Welding Process, Procedureand Performance Qualification.Provided by IHSNot for
13、 ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-24749A(SH)3(Unless otherwise indicated, copies of the above specifications,standards, and handbooks are available from the Defense Automated PrintingService, 700 Robbins Avenue, BLDG. 4D, Philadelphia, PA 19111-5094.
14、)2.3 Non-Government publications. The following document(s) form a partof this document to the extent specified herein. Unless otherwise specified,the issues of the documents which are DoD adopted are those listed in theissue of the DoDISS cited in the solicitation. Unless otherwise specified,the is
15、sues of documents not listed in the DoDISS are the issues of thedocuments cited in the solicitation (see 6.2).AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)ASTM A 312 - Standard Specification for Seamless and WeldedAustenitic Stainless Steel Pipes.ASTM A 580 - Standard Specification for Stainless
16、 SteelWire.ASTM A 666 - Standard Specification for Austenitic StainlessSteel, Sheet, Strip, Plate and Flat Bar.ASTM B 36 - Standard Specification for Brass Plate, Sheet,and Rolled Bar. (DoD adopted)ASTM B 152 - Standard Specification for Copper Sheet, Strip,Plate, and Rolled Bar. (DoD adopted)(Appli
17、cation for copies should be addressed to the American Societyfor Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA19428-2859.)(Non-Government standards and other publications are normally availablefrom the organizations that prepare or distribute the documents. Thesedocuments also
18、may be available in or through libraries or other informationalservices.)2.4 Order of precedence. In the event of a conflict between the textof this document and the references cited herein, the text of this documenttakes precedence. Nothing in this document, however, supersedes applicablelaws and r
19、egulations unless a specific exemption has been obtained.3. REQUIREMENTS3.1 First article. When specified (see 6.2), a sample shall besubjected to first article inspection (see 6.3) in accordance with 4.3.3.2 Bond stray components.3.2.1 Type I bond strap assembly. Type I bond strap assembly shallcon
20、sist of three components: (a) one bond strap, (b) two self locking boltsand washers and (c) two (aluminum/CRES bimetallic or CRES) bosses (seefigure 1).3.2.1.1 Bond strap. A bond strap consists of two components; (a) oneannealed and pickled CRES 316, 1/4“ diameter stranded wire cable, and (b) twolug
21、s fabricated from CRES 316L Schedule 80S pipe (see figure 2).3.2.1.1.1 Stranded wire cable. Stranded wire cable shall be 1/4 inchdiameter CRES 316 in accordance with MIL-W-83420/2. Wire will be annealed andpickled in accordance with ASTM A 580 condition A.3.2.1.1.2 Lug. Lugs shall be fabricated from
22、 CRES 316L SCHED 80S pipein accordance with ASTM A 312. The lugs shall be formed from the blank pipeas follows: prepare pipe by cutting 1 inch length; insert stranded wirethrough entire 1.5“ length of pipe; compress end 3/4 inch to .24 inchthickness and ensure that both mounting surfaces of the lug
23、are smooth andflat; burnish the end to remove sharp edges; drill 25/64 inch hole in the lugto facilitate 3/8“ self locking bolt.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-24749A(SH)43.2.1.2 Boss. Bosses shall be either of four different
24、types: CRES316L conforming to QQ-S-763; bimetallic (CRES 316L/Aluminum) in accordancewith MIL-STD-1252 and MIL-J-24445; bimetallic (CRES/Brass); or bimetallic(Brass/Aluminum); (see figure 3). Bosses used with Type I bond straps shallbe the CRES 316L or CRES 316L/Aluminum bimetallic.3.2.1.2.1 Aluminu
25、m bimetallic bosses. The foot of the aluminum bossesshall be manufactured from aluminum alloy 5083 or 5456 in accordance withMIL-A-45225, aluminum alloy 5083-Hll in accordance with QQ-A-200/4, oraluminum alloy 5086 in accordance with QQ-A-25O/7. The foot shall be bondedto QQ-S-763 to form the Alumin
26、um/CRES boss or ASTM B 36 to form the Aluminum/Brass boss. An interstitial layer of an appropriate metal may be used toenhance strength and weldability. Acceptable interstitial metals includechromium, tantalum, molybdenum and titanium (see figure 3).3.2.1.2.2 CRES/Brass bimetallic boss. The foot of
27、the CRES/Brassbimetallic bosses shall be manufactured from CRES 316L in accordance withQQ-S-763. The foot shall be bonded to brass in accordance with ASTM B 36(see figure 3).3.2.1.3 Bolts and washers. Bolts and washers used in conjunction withbosses shall be fabricated from the same material as the
28、threaded portion ofthe boss, for example: QQ-S-763 for CRES and ASTM B 36 for brass.3.2.1.3.1 Bolt. The bolt shall be a 3/8 inch -16 v 3/4 inch self-locking bolt in accordance with MIL-F-18240 and MIL-S-1222. Bolts shall bemade of corrosion resistant steel CRES 316, in accordance with QQ-S-763 orbra
29、ss in accordance with ASTM B 36.3.2.1.3.2 Washer, flat. The washer shall be a 3/8 inch flat washer inaccordance with FF-W-92 and AN960-C616L. Washers shall be corrosion resistantsteel CRES 316 in accordance with QQ-S-763 or brass in accordance withASTM B 36.3.2.2 Type II bond strap. Type II bond str
30、aps shall be manufactured ofcorrosion resistant steel (CRES 316) meeting ASTM A 666, annealed andpassivated in accordance with QQ-P-35 (see figure 4).3.2.3 Type III bond strap. Type III bond straps shall be manufacturedof flat copper meeting ASTM B 152 (see figure 4).3.2.4 Type IV bond strap. Type I
31、V bond straps shall consist of twocomponents; (a) one strap braid, and (b) two end terminals (see figure 5).3.2.4.1 Braid. Bond strap braid material shall be flat copper braid inaccordance with QQ-B-575.3.2.4.2 End terminal. End terminals shall be flat copper in accordancewith ASTM B 152.3.3 Physica
32、l requirements. Bond strap dimensions shall be as specifiedherein. Dimensions are in inches. Strap length shall be of standard sizes asdetailed on figure 8; or as specified by the contracting activity (see 6.2).3.3.1 Type I bond strap.3.3.1.1 Stranded wire cable. Stranded wire cable shall meet thedi
33、mensions as detailed in paragraph 3.2.1.1.1 and figure 8.3.3.1.2 Lug. Lugs shall meet the dimensions as detailed on figure 2.3.3.2 Type II, III, and IV bond straps. Bond straps shall be furnishedin the dimensions detailed on figure 8. Bond strap dimensions shall beapplicable after manufacturing. Typ
34、e II and III bond strap length to widthdimensions shall not be greater than a 5 to 1 ratio.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-24749A(SH)53.3.3 Fabrication. Bond straps shall conform to the fabricationdetails on figure 2, and as s
35、pecified herein for Type I bond straps; andfigures 4 and 5 for Types II, III and IV bond straps. Standard sizes for allbond straps are shown on figure 8. Fabrication techniques shall be used whichlend themselves to automation, allowing ease of manufacturing at minimum cost.3.4 Performance requiremen
36、ts.3.4.1 Visual inspection. When tested as specified in 4.5.1, bondstraps shall be visually inspected to ensure conformance with the requirementsspecified herein (see 3.2, 3.3 and 3.5).3.4.2 Bosses. Bosses shall be tested as specified in 4.5.2 and meetthe requirements contained therein.3.4.3 Pull te
37、st. When tested as specified in 4.5.3, Type I bond strapsshall withstand a load of 1000 lbs and be maintained within plus or minus 50lbs for 3 minutes. No visually observable wire breakage shall occur.3.4.4 Vibration. Type I bond straps shall be tested as specified in4.5.4. Any current interruption
38、equal to or greater than one microsecondshall be reason for rejection of the sample.3.4.5 Conformability and flexibility. Type I bond straps shall betested as specified in 4.5.5. The strap shall exhibit no visual evidence ofwire breakage.3.4.6 Electrical resistance. Bond straps shall be tested as sp
39、ecifiedin 4.6.6. The strap direct current (dc) resistance shall not be greater than1.15 milliohm per 1 inch of strap length.3.5 Identification. Bond straps shall be marked with an identifyinglegend consisting of the part number (see 6.2 and 6.4), and the manufacturersCommercial and Government Entity
40、 (CAGE) code. Type I bond strap bosses shallbe marked with the metal type of the boss foot, “AL“ for aluminum and “CR“ forCRES. Brass/Aluminum and Brass/CRES bosses shall be marked “BA“ and “BC“respectively. Marking shall be by metal stamp with a minimum character heightof not less than 0.08 inches.
41、3.6 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally preferable materials should be used tothe maximum extent possible provided that the material meets or exceeds theoperational and maintenance requirements, and promotes economicallyadvantageous l
42、ife cycle costs.3.7 Workmanship. Every detail of manufacture shall be in accordancewith the best practices for manufacture of bond straps and the following:(a) The materials used shall be free from all defects that couldadversely affect installation, appearance, or long term use.(b) Lug terminals, f
43、lat copper straps, and soldered terminals offlat braid straps shall be free from blistering, burrs,cracks, laps, peeling, pitting, sharp edges, slag, or otherforeign material which could affect welding or bond strapinstallation.3.8 JAN and J marking. The United States Government has adopted, andis e
44、xercising legitimate control over the certification marks “JAN“ and “J“,respectively, to indicate that items so marked or identified to, and meetingall of the criteria specified herein and in applicable specifications shallbear the certification mark “JAN“ except that items too small to bear thecert
45、ification mark “JAN“ shall bear the letter “J“. The “JAN or “J“ shall beplaced immediately before the part number except that if such location wouldProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-24749A(SH)6place a hardship on the manufacture
46、r in connection with such marking, the“JAN“ of “J“ may be located on the first line above or below the part number.Items furnished under contracts or orders which either permit or requiredeviation from the conditions or requirements specified herein or inapplicable specifications shall not bear “JAN
47、“ or “J“. In the event an itemfails to meet the requirements of these specification and the applicablespecification sheet or associated specifications, the manufacturer shallremove completely the military part number and the “JAN“ or “J“ certificationmark shall not be used on products acquired to co
48、ntractor drawings orspecifications. The United States Government has obtained Certificate ofRegistration Number 504,860 for the certification mark “JAN“ and RegistrationNumber 1,586,261 for the certification mark “J“.4. VERIFICATION4.1 Classification of inspections. The inspection requirementsspecif
49、ied herein are classified as follows:(a) First article inspection (see 4.3).(b) Quality conformance inspection (see 4.4).4.2 Inspection conditions. Unless otherwise specified, all inspectionsshall be performed in accordance with the test conditions specified in 4.3.4.3 First article inspection. A first article preliminary inspectionshall determine that all samples are acceptable products for testing and thatobvious defects are detected prior to the tests. Sample bon
