1、Designation: A 640 97 (Reapproved 2002)e1Standard 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 rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTESeveral editorial corrections were made throughout the specification in September 2002.1. Scope1.1 This
3、specification covers two sizes of extra-high-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
4、 regardedas the standard.2. Referenced Documents2.1 ASTM Standards:A 90/A 90M Test Method for Weight of Coating on Zinc-Coated (Galvanized) Iron or Steel Articles2A 902 Terminology Relating to Metallic Coated Steel Prod-ucts2B 6 Specification for Zinc (Slab Zinc)33. Terminology3.1 DefinitionsSee Ter
5、minology 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 integral supportingmessenger strand. The supporting messenger strand has aplastic sheath wit
6、h 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 extruding in oneoperation.4.2 The galvanized steel strand used for the support mes-senger of
7、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 during the stranding operationjust before the wires are laid together. This ensures that allwi
8、res 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 material is only applied to the outsideof the finished strand.NOTE 1The cable manufacturer should a
9、dvise 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 under this specification shall includethe following information:5.1.1 Nominal strand diameter (T
10、able 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 (Note),5.1.5 Package size if different from standard (Section 16),5.1.6 Special package mark
11、ing (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 quality and purity that, when drawn to the size of wirespecified and coated with zinc, the finished
12、 strand and theindividual wires shall be of uniform quality and have theproperties and characteristics as prescribed in this specifica-tion.6.2 The slab zinc, when used for the wire coating, shall beany grade of zinc conforming to Specification B 6.7. Stranding7.1 Six wires shall be stranded with a
13、uniform left-hand layabout a center wire to form the completed strand. All wiresshall be stranded with uniform tension. Stranding shall be1This specification is under the jurisdiction of ASTM Committee A05 onMetallic-Coated Iron and Steel Products and is the direct responsibility ofSubcommittee A05.
14、12 on Wire Specifications.Current edition approved April 10, 1997. Published December 1997. Originallypublished as A 640 71. Last previous edition A 640 91.2Annual Book of ASTM Standards, Vols 01.06 and 02.03.3Annual Book of ASTM Standards, Vols 02.03 and 02.04.1Copyright ASTM International, 100 Bar
15、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.sufficiently close to ensure no appreciable reduction in diam-eter when stressed to 10 % of the specified strength. A left-handlay is defined as a counter-clockwise twist away from theobserver.7.2 The strand shall have a un
16、iform pitch of not less than 14times nor more than 22 times 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 positi
17、on. This shall be accomplished by ameans or process, such as 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 sha
18、ll beacceptable, provided there is not more than one joint 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
19、 the wire and theoverlapping faces shall be smooth, clean, 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 joint
20、s shall be well made and freefrom sharp burrs and sharp projections. 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 sp
21、ecifically permitted by the purchaser.9. 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
22、SteelThe individual wires of the com-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
23、 shall benot less than 0.65 oz/ft2(198 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 beremo
24、ved by rubbing with the bare fingers. 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
25、individual zinc-coated wires shallbe 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 thicknes
26、s.12. Sampling12.1 Sampling for determination 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
27、reels 3Over ten reels 412.2 Each strand 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
28、to determinecompliance with 9.2, 9.3, 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 pur
29、chaser has the option to acceptthe manufacturers certification that tests of the wires madeprior to stranding meet requirements of 9.2, 9.3, 9.4, andSection 10.13. Test Methods13.1 The breaking strength shall be determined on thespecimen tested for elongation in accordance with 13.2. A testin which
30、the breaking strength is below the minimum specifiedpossibly due to slipping of the specimen in the jaws of thetesting machine, by breaking within the jaws or within 1 in.TABLE 1 Mechanical RequirementsNominal Diameter of Strand316 in.(4.76 mm)14 in.(6.35 mm)Nominal diameter of coatedwires, in. (mm)
31、0.062 (1.57) 0.080 (2.03)Minimum breaking strength 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 180W
32、ith flooding compound:lb/1000 ft 75 125kg/km 112 186A 640 97 (2002)e12(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 ja
33、ws of the testing machinefrom the position 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
34、 strength of the strand. The elon-gation 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
35、stripping test in accordance with Test 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 m
36、ade at the place ofmanufacture prior to 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 s
37、hall bemade on samples of wire or strand 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
38、lengths of 5000 ft (1500 m) plus 300 ft (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
39、length and 4 % over the standard length.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
40、ft, plus 300 ft on each piece to allow 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
41、 shall be so specified at the time of 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. U
42、sers of this standard are expressly advised 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 eve
43、ry five years andif not revised, either 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 techn
44、ical committee, which you may attend. 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 Conshohock
45、en, PA 19428-2959,United States. Individual 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 (2002)e13
