1、Designation: A 640 97 (Reapproved 2009)1Standard Specification forZinc-Coated Steel Strand for Messenger Support of Figure 8Cable1This standard is issued under the fixed designation A 640; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEReapproved with editorial changes in May 2009.1. Scope1.1 This specification covers two sizes of extra-high
3、-strength grade of concentric-lay steel wire strand, composed ofseven, zinc-coated steel wires, specifically intended for use asthe supporting messenger in Figure 8-type communication andelectrical cables.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in pa
4、rentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.2. Referenced Documents2.1 ASTM Standards:2A 90/A 90M Test Method for Weight Mass of Coating onIron and Steel Articles with Zinc or Zinc-Alloy CoatingsA 902 Terminology Relating to
5、 Metallic Coated Steel Prod-uctsB6 Specification for Zinc3. Terminology3.1 DefinitionsSee Terminology A 902 for definitions ofgeneral terminology relating to metallic coated steel products.4. Description4.1 Figure 8 cable consists of a plastic-sheathed communi-cation or electrical cable made with an
6、 integral supportingmessenger strand. The supporting messenger strand has aplastic sheath with a narrow, longitudinal web connecting tothe plastic sheath of the cable. Generally the plastic sheath overthe supporting strand, the connecting web, and the plasticsheath over the cable are all applied by
7、extruding in oneoperation.4.2 The galvanized steel strand used for the support mes-senger of Figure 8-type cable is generally coated by floodingwith a sealing compound before the plastic sheath is applied(Note). It is generally preferred that this sealing compound beapplied to the individual wires d
8、uring the stranding operationjust before the wires are laid together. This ensures that allwires are completely covered and the interstices between thewires are sealed with a thermoplastic flooding compound toprevent intrusion of moisture under the plastic sheath. Some-times the thermoplastic materi
9、al is only applied to the outsideof the finished strand.NOTE 1The cable manufacturer should advise the strand manufac-turer of the plastic to be used for the sheath so that a sealing compound canbe selected to avoid any adverse effects on the sheath.5. Ordering Information5.1 Orders for material und
10、er this specification shall includethe following information:5.1.1 Nominal strand diameter (Table 1),5.1.2 Quantity of each size of strand, length in feet (metres),5.1.3 Unit length (see 16.1),5.1.4 Sealing compound, if required, and the method ofapplication. Special requirements of sealing compound
11、 (Note),5.1.5 Package size if different from standard (Section 16),5.1.6 Special package marking (see 16.4), and5.1.7 Inspection (Section 14).6. Materials and Manufacture6.1 The base metal of the wires shall be steel made by theopen-hearth, basic-oxygen, or electric-furnace process and ofsuch qualit
12、y and purity that, when drawn to the size of wirespecified and coated with zinc, the finished strand and theindividual wires shall be of uniform quality and have theproperties and characteristics as prescribed in this specifica-tion.1This specification is under the jurisdiction of ASTM Committee A05
13、 onMetallic-Coated Iron and Steel Products and is the direct responsibility ofSubcommittee A05.12 on Wire Specifications.Current edition approved May 1, 2009. Published August 2009. Originallyapproved in 1971. Last previous edition approved in 2002 as A 640 - 97(2002).2For referenced ASTM standards,
14、 visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 194
15、28-2959, United States.6.2 The slab zinc, when used for the wire coating, shall beany grade of zinc conforming to Specification B6.7. Stranding7.1 Six wires shall be stranded with a uniform left-hand layabout a center wire to form the completed strand. All wiresshall be stranded with uniform tension
16、. Stranding shall besufficiently close to ensure no appreciable reduction in diam-eter when stressed to 10 % of the specified strength.Aleft-handlay is defined as a counter-clockwise twist away from theobserver.7.2 The strand shall have a uniform pitch of not less than 14times nor more than 22 times
17、 the nominal strand diameter.7.3 All wires in the strand shall lie naturally in their truepositions in the completed strand and, when the strand is cut,the ends shall remain in position or be readily replaced by handand then remain in position. This shall be accomplished by ameans or process, such a
18、s preforming, post forming, or formsetting at the manufacturers option.8. Joints and Splices8.1 Electric-welded butt joints made prior to the start of colddrawing of the wire are permitted.8.2 Joints made in the individual finished wires shall beacceptable, provided there is not more than one joint
19、in any150-ft (45.7-m) section of the completed strand. Such jointsshall either be the brazed-lap type or electric-butt-welded type.When the brazed type of joint is used, the length of the lap shallbe not less than three times the diameter of the wire and theoverlapping faces shall be smooth, clean,
20、properly fluxed, andcompletely covered by the brazing metal. When the electric-butt-welded type of joint is used, care shall be taken to preventinjury to the wire during the electric-butt-welding. The wiresshall be in alignment and the joints shall be well made and freefrom sharp burrs and sharp pro
21、jections. The joints shall becoated with zinc after completion so that the joints shall haveprotection from corrosion equivalent to that of the zinc-coatedwire itself.8.3 The finished strand shall not be joined or spliced as aunit, unless specifically permitted by the purchaser.9. Physical Requireme
22、nts Physical Requirements9.1 The minimum breaking strength and minimum elonga-tion in 24 in. (610 mm) of the strand and the nominal diameterof individual wires are given in Table 1. The approximateweights per 1000 ft (305 m) are given in Table 2.9.2 Ductility of SteelThe individual wires of the com-
23、pleted strand shall not fracture when wrapped at a rate of notexceeding 15 turns/min in a close helix of at least two turnsaround a cylindrical mandrel equal to three times the nominaldiameter of the wire under test.9.3 Weight of CoatingThe weight of zinc coating shall benot less than 0.65 oz/ft2(19
24、8 g/m2) of uncoated wire surface onthe316-in. (4.8-mm) and14-in. (6.4-mm) strand.9.4 Adherence of CoatingWhen the wire is wrapped onthe cylindrical mandrel in accordance with 9.2, the zinc coatingshall not crack or flake to such an extent that any zinc can beremoved by rubbing with the bare fingers.
25、 Loosening ordetachment during the adhesion test of superficial, smallparticles of zinc formed by mechanical polishing of the surfaceof the zinc-coated wire shall not be considered cause forrejection.10. Permissible Variations in Diameter10.1 The diameter of the individual zinc-coated wires shallbe
26、the nominal size as given in Table 1 within a tolerance of60.003 in. (0.08 mm).11. Finish11.1 The zinc-coated wire shall be free from imperfectionsnot consistent with good commercial practice. The zinc coatingshall be continuous and of reasonably uniform thickness.12. Sampling12.1 Sampling for deter
27、mination of compliance to thisspecification shall be performed on each lot of material. A lotshall consist of all strands of one size in each shipment. Thenumber of samples to be taken shall be as follows:Number of SamplesOne reel 1Two to four reels 2Five to ten reels 3Over ten reels 412.2 Each stra
28、nd sample taken shall be tested for conform-ance to the requirements of 7.2 and Table 1.12.3 In addition to the strand testing in 12.2 the individualwires from the strand samples shall be tested. Four wires are tobe selected from the seven-wire strand and tested to determinecompliance with 9.2, 9.3,
29、 9.4, and Section 10. Individual wiresamples selected for compliance to Section 10 shall be dis-carded if any distortion of the wire occurred during thestranding operation.12.4 Instead of testing the wires from the completed strandin accordance with 12.3, the purchaser has the option to acceptthe ma
30、nufacturers certification that tests of the wires madeprior to stranding meet requirements of 9.2, 9.3, 9.4, andSection 10.TABLE 1 Mechanical RequirementsNominal Diameter of Strand316 in.(4.76 mm)14 in.(6.35 mm)Nominal diameter of coatedwires, in. (mm)0.062 (1.57) 0.080 (2.03)Minimum breaking streng
31、th ofthe strand, lbf (kN)3990 (17.748) 6650 (29.581)Minimum elongation of thestrand in 24 in. (610 mm), %4.0 4.0TABLE 2 Approximate Weight of StrandNominal Diameter of Strand316 in.(4.76 mm)14 in.(6.35 mm)Before flooding:lb/1000 ft 73 121kg/km 109 180With flooding compound:lb/1000 ft 75 125kg/km 112
32、 186A 640 97 (2009)1213. Test Methods13.1 The breaking strength shall be determined on thespecimen tested for elongation in accordance with 13.2. A testin which the breaking strength is below the minimum specifiedpossibly due to slipping of the specimen in the jaws of thetesting machine, by breaking
33、 within the jaws or within 1 in.(25.4 mm) of the jaws, or by the improper socketing of aspecimen shall be disregarded and another sample from thesame reel shall be tested.13.2 The elongation shall be determined as the percentincrease in separation between the jaws of the testing machinefrom the posi
34、tion after application of the initial load to theposition at the initial failure of the test specimen. The separa-tion of the jaws of the testing machine shall be approximately2 ft (610 mm) when under an initial load equal to 10 % of therequired minimum breaking strength of the strand. The elon-gati
35、on values shall be recorded only for specimens which breakover 1 in. from the jaws of the testing machine. Additionalsamples shall be taken from the same length when previoustests are to be disregarded.13.3 The weight of the zinc coating shall be determined bya stripping test in accordance with Test
36、 Method A 90/A 90M.14. Inspection14.1 The manufacturer shall afford the inspector represent-ing the purchaser all reasonable facilities to satisfy him that thematerial is being furnished in accordance with this specifica-tion. All tests and inspection shall be made at the place ofmanufacture prior t
37、o shipment, unless otherwise specified, andshall be so conducted as not to interfere unnecessarily with theoperation of the works.15. Rejection15.1 If the wire or strand fails in the first test to meet anyrequirement of this specification, two additional tests shall bemade on samples of wire or stra
38、nd from the same reel. If failureoccurs in either of these tests, the lot of strand shall be rejected.16. Packaging and Marking16.1 The strand shall be furnished on reels in standardlengths in accordance with Table 3. These standard lengths aremultiples of unit lengths of 5000 ft (1500 m) plus 300 f
39、t (91 m)to allow for threading into an extruder. If a length different thanthese standard lengths or unit lengths of 5000 ft is required, thepurchase order shall include this requirement.16.2 The permissible length of strand is permitted to varybetween standard length and 4 % over the standard lengt
40、h.16.3 Ten percent of any lot of strand is permitted to besupplied in lengths shorter than the standard length, providedthe shipped length is one or more of the unit lengths asspecified on the purchase order, or if no unit length is specified,a multiple of 5000 ft, plus 300 ft on each piece to allow
41、 forthreading an extruder.16.4 Each reel shall have a strong weather-resistant tagsecurely fastened to it showing the nominal diameter, length,ASTM Specification A 640, and the name and mark of themanufacturer. If additional information is required on the tag,it shall be so specified at the time of
42、purchase.17. Keywords17.1 Figure 8 cable support strand; messenger strand; steelwire strand; steel wire-zinc coatedASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly ad
43、vised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, eithe
44、r reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend.
45、If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Indiv
46、idual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 3 Standard LengthsNominal Diameter ofStrand, in. (mm)Standard Length,ft (m)316 (4.76) 20 300 (6187)14 (6.35) 15 300 (4663)A 640 97 (2009)13
