1、AN AMERICAN NATIONAL STANDARD ASME B18.2.5M-2013(Revision of ASME B18.2.5M-2009)Metric 12-Point Flange Head ScrewsASME B18.2.5M-2013(Revision of ASME B18.2.5M-2009)Metric 12-PointFlange HeadScrewsAN AMERICAN NATIONAL STANDARDTwo Park Avenue New York, NY 10016 USADate of Issuance: May 22, 2013This St
2、andard will be revised when the Society approves the issuance of a new edition.ASME issues written replies to inquiries concerning interpretations of technical aspects of thisStandard. Periodically certain actions of the ASME B18 Committee may be published as Cases.Cases and interpretations are publ
3、ished on the ASME Web site under the Committee Pages athttp:/cstools.asme.org/ as they are issued.Errata to codes and standards may be posted on the ASME Web site under the Committee Pages toprovide corrections to incorrectly published items, or to correct typographical or grammatical errorsin codes
4、 and standards. Such errata shall be used on the date posted.The Committee Pages can be found at http:/cstools.asme.org/. There is an option available toautomatically receive an e-mail notification when errata are posted to a particular code or standard.This option can be found on the appropriate Co
5、mmittee Page after selecting “Errata” in the “PublicationInformation” section.ASME is the registered trademark of The American Society of Mechanical Engineers.This code or standard was developed under procedures accredited as meeting the criteria for American NationalStandards. The Standards Committ
6、ee that approved the code or standard was balanced to assure that individuals fromcompetent and concerned interests have had an opportunity to participate. The proposed code or standard was madeavailable for public review and comment that provides an opportunity for additional public input from indu
7、stry, academia,regulatory agencies, and the public-at-large.ASME does not “approve,” “rate,” or “endorse” any item, construction, proprietary device, or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with anyitems mentioned in this d
8、ocument, and does not undertake to insure anyone utilizing a standard against liability forinfringement of any applicable letters patent, nor assumes any such liability. Users of a code or standard are expresslyadvised that determination of the validity of any such patent rights, and the risk of inf
9、ringement of such rights, isentirely their own responsibility.Participation by federal agency representative(s) or person(s) affiliated with industry is not to be interpreted asgovernment or industry endorsement of this code or standard.ASME accepts responsibility for only those interpretations of t
10、his document issued in accordance with the establishedASME procedures and policies, which precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publish
11、er.The American Society of Mechanical EngineersTwo Park Avenue, New York, NY 10016-5990Copyright 2013 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword vCommittee Roster . viCorrespondence With the B18 Committee vii1 Scope . 12 Comparisons With ISO St
12、andards . 13 Referenced Standards 14 Terminology . 15 Dimensions 16 Top of Head . 17 Head Height . 18 Wrenching Height 19 Gaging of 12-Point Flange Head 310 Position of Head . 311 Flange 312 Bearing Surface 313 Fillet 414 Body Diameter. 415 Length 416 Points. 617 Straightness. 618 Threads . 719 Leng
13、th Measurements 720 Materials and Mechanical Properties 721 Identification Symbols . 922 Finish . 923 Workmanship 924 Inspection and Quality Assurance . 925 Clearance Holes 926 Designation . 9Tables1 Dimensions 22 Gaging . 33 Tolerance Zones 44 Dimensions of Type F Underhead Fillets 45 Dimensions of
14、 Type U Underhead Fillets 56 Dimensions of Reduced Body Diameter (Type R) 6iii7 Length Tolerances, L, mm . 68 Dimensions of Points . 79 Maximum Grip Lengths, LG, and Minimum Body Lengths, Ls810 Thread Lengths . 9ivFOREWORDThe ASME B18 Standards Committee for the standardization of bolts, screws, nut
15、s, rivets, andsimilar fasteners was organized in March 1922 as Sectional Committee B18 under the aegis ofthe American Engineering Standards Committee (later the American Standards Association, thenthe United States of America Standards Institute and, as of October 6, 1969, the American NationalStand
16、ards Institute, Inc.), with the Society of Automotive Engineers and the American Societyof Mechanical Engineers (ASME) as joint sponsors. In subsequent years, the Committee cameunder the sole sponsorship of ASME.Subcommittee 2 was established and charged with the responsibility for technical content
17、 ofstandards covering wrench head bolts and nuts. In the late 1980s, a draft of B18.2.5M was createdand revised for approval. However, in April of 1995, efforts to finalize a draft of this Standardwere abandoned. At its meeting on November 28, 2006, Subcommittee 2 again took to thedevelopment of thi
18、s Standard, which was the result of those efforts.During 2011, a number of issues that needed correcting were brought to the attention of theB18.2 Subcommittee, resulting in this revision. The changes that were made to this Standardconform with other B18 Standards and improve the quality assurance o
19、f ASME B18.18.4 throughB18.18.Additionally, the material references for steel screws were changed from ASTM F568M (whichhas been withdrawn) to ISO 898-1, and the reference for stainless steel was changed from ASTMF738M to ISO 3506-1. The drawings associated with Tables 1 and 2, and the LGand LSdimen
20、sionsfor M36 in Table 9, were corrected.Suggestions for improvement of this Standard are welcome. They should be sent to The Ameri-can Society of Mechanical Engineers; Attn: Secretary, B18 Standards Committee; Two Park Avenue;New York, NY 10016-5990.This Standard was approved as an American National
21、 Standard on March 13, 2013.vASME B18 COMMITTEEStandardization of Bolts, Nuts, Rivets, Screws, Washers, andSimilar Fasteners(The following is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSJ. Greenslade, ChairD. S. George, Vice ChairW. H. King, Vice
22、 ChairC. J. Gomez, SecretarySTANDARDS COMMITTEE PERSONNELV. Cartina, NylokD. A. Clever, Contributing Member, ConsultantA. P. Cockman, Ford Motor Co.C. D. de la Garza, TSP, Inc.D. S. George, Ramco SpecialtiesC. J. Gomez, The American Society of Mechanical EngineersJ. Greenslade, Industrial Fasteners
23、InstituteJ. J. Grey, Contributing Member, Fastener Consulting Services, Inc.A. Herskovitz, Contributing Member, ConsultantJ. Hubbard, Leland-Powell Fasteners, Inc.J. C. Jennings, Contributing Member, Naval Surface Warfare CenterW. H. King, Porteous Fastener Co.SUBCOMMITTEE 2 EXTERNALLY DRIVEN FASTEN
24、ERSJ. Greenslade, Chair, Industrial Fasteners InstituteC. B. Williamson, Vice Chair, Fastenal Co.V. Cartina, NylokL. Claus, ConsultantD. A. Clever, ConsultantA. P. Cockman, Ford Motor Co.C. D. de la Garza, TSP, Inc.B. A. Dusina, Federal Screw WorksM. A. Elmi, ConsultantJ. S. Foote, Trade Association
25、 Management, Inc.D. S. George, Ramco SpecialtiesA. Herskovitz, ConsultantM. W. Holubecki, Electric Boat Corp.J. Hubbard, Leland-Powell Fasteners, Inc.J. C. Jennings, Contributing Member, Naval Surface Warfare CenterviM. D. Prasad, Contributing Member, GlobalM however, they shouldnot contain propriet
26、ary names or information.Requests that are not in this format may be rewritten in the appropriate format by the Committeeprior to being answered, which may inadvertently change the intent of the original request.ASME procedures provide for reconsideration of any interpretation when or if additionali
27、nformation that might affect an interpretation is available. Further, persons aggrieved by aninterpretation may appeal to the cognizant ASME Committee or Subcommittee. ASME does not“approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.Attending Committee
28、Meetings. The B18 Standards Committee regularly holds meetings thatare open to the public. Persons wishing to attend any meeting should contact the Secretary ofthe B18 Standards Committee.viiINTENTIONALLY LEFT BLANKviiiASME B18.2.5M-2013METRIC 12-POINT FLANGE HEAD SCREWS1 SCOPEThis Standard covers t
29、he complete dimensional andgeneral data for coarse thread metric series 12-pointflange screws recognized as American National Stan-dard. The inclusion of dimensional data in this Standardis not intended to imply that all products described arestock production items.2 COMPARISONS WITH ISO STANDARDSLe
30、tter symbols designating dimensional characteris-tics are in accord with ISO 225, except where capitalletters instead of lowercase letters have been used in theISO standards.3 REFERENCED STANDARDSThe following is a list of publications referenced in thisStandard. Unless otherwise specified, the stan
31、dard(s)referenced shall be the most recently issued at the timeof order placement.ASME B1.3M, Screw Thread Gaging Systems forDimensional Acceptability Inch and MetricThreads (UN, UNR, UNJ, M, and MJ)ASME B1.13M, Metric Screw ThreadsMProfileASME B18.2.8, Clearance Holes for Bolts, Screws, andStudsASM
32、E B18.2.9, Straightness Gage and Gaging for Boltsand ScrewsASME B18.12, Glossary of Terms for MechanicalFastenersASME B18.18, Quality Assurance for FastenersASME B18.24, Part Identifying Number (PIN) CodeSystem Standard for B18 Externally ThreadedFastenersASME Y14.5, Dimensioning and TolerancingPubl
33、isher: The American Society of MechanicalEngineers (ASME), Two Park Avenue, New York, NY10016-5990; Order Department: 22 Law Drive,Box 2900, Fairfield, NJ 07007-2900 (www.asme.org)ASTM F468M Standard Specification for NonferrousBolts, Hex Cap Screws, and Studs for General UseASTM F788/F788M, Standar
34、d Specification for SurfaceDiscontinuities of Bolts, Screws and Studs, Inch andMetric SeriesPublisher: American Society for Testing and Materials(ASTM International), 100 Barr Harbor Drive, P.O. Box1C700, West Conshohocken, PA 19428-2559 (www.as-tm.org)ISO 225, Fasteners Bolts, screws, studs, and nu
35、ts Symbols and descriptions of dimensionsISO 898-1, Mechanical properties of fasteners made ofcarbon steel and alloy steel Part 1: Bolts, screwsand studs with specified property classes Coarsethread and fine pitch threadISO 3506-1, Mechanical properties of corrosion-resistantstainless steel fastener
36、s Part 1: Bolts, screws andstudsPublisher: International Organization forStandardization (ISO), 1 ch. de la Voie-Creuse, Casepostale 56, CH-1211 Geneve 20, Switzerland/Suisse(www.iso.org)4 TERMINOLOGYFor definitions of terms relating to fasteners or fea-tures thereof used in this Standard, refer to
37、ASME B18.12.5 DIMENSIONS(a) All dimensions in this Standard are given in milli-meters (mm), and apply before any coating, unlessstated otherwise.(b) Symbols specifying geometric characteristics arein accordance with ASME Y14.5.6 TOP OF HEADThe top of head shall be chamfered or rounded withdiameter o
38、f chamfer circle or start of rounding beingequal to maximum width across flats within a toleranceof 15% of maximum width across flats.7 HEAD HEIGHTThe head height, K, is the distance, parallel to the axisof the screw, from the plane of the bearing circle to thetop of the head, not including any rais
39、ed markings (seesection 21).8 WRENCHING HEIGHTCorners of the 12 points shall be fully formed andreasonably uniform over the wrenching height, Kw.ASME B18.2.5M-2013Head drive root radius, R4, applies to the entire lengthof the wrenching height, Kw(see Table 1).9 GAGING OF 12-POINT FLANGE HEADThe head
40、 shall be gaged using two ring gages, Aand B, to demonstrate the coincidental acceptability ofwrenching height, corner fill, and width across corners.Gage A shall be placed over the head and shall seat onthe flange. Gage B shall be placed on the top of the headnormal to the screw axis. The two gages
41、 shall not be incontact (see Table 2).10 POSITION OF HEADAt maximum material condition, the axis of the12 points of the head shall be within a positional toler-ance zone whose diameter is equivalent to 2% of themaximum across flats regardless of feature size as speci-fied in Table 3 with respect to
42、the axis of the shank overa distance under the head equal to the nominal screwdiameter, D. The datum shall be as close to the head aspracticable, but within 0.5D from the head, and shall beeither wholly plain body or wholly the thread majordiameter, not including the thread runout or theunderhead fi
43、llet.11 FLANGEThe top surface of the flange shall be conical or slightlyrounded (convex). Radius, R2, applies both at the cornersand at the flats of the 12-point. The contour of edge atflange periphery, between the maximum flange diame-ter, Dcmaximum, and the minimum bearing circle diam-eter, Dwmini
44、mum, shall be optional provided that theminimum flange edge thickness, C minimum, is main-tained at the minimum bearing circle diameter,Dwminimum.12 BEARING SURFACERunout of the bearing surface with respect to the axisof the body shall be within the specified FIM limits inTable 3. Measurement of FIM
45、 shall be made as close tothe periphery of the bearing surface as possible whilethe screw is held in a collet or other gripping device ata distance of one-half of the screw diameter from theunderside of the head and screw is rotated at least360 deg.13 FILLETThe fillet configuration at the junction o
46、f the head andshank shall conform to either Type F, as shown in Table 4,which also specifies limits, or Type U, as shown inTable 5, at the option of the manufacturer unless thefillet type is specified by the purchaser. The fillet shall2be a smooth and continuous curve fairing smoothly intothe bearin
47、g surface and the shank within the limits speci-fied. For Type F, no radius in the fillet contour shall beless than R1minimum specified in Table 4.14 BODY DIAMETERThe diameter of the body, Ds, on screws that are notthreaded full length shall be within the limits specifiedin Table 1, unless the purch
48、aser specifies screws withreduced diameter body. For screws threaded full length,the diameter of the unthreaded shank under the headshall neither exceed the maximum body diameter, Dsmaximum, specified in Table 1, nor be less than theminimum body diameter, Dsminimum, specified inTable 5. Screws of no
49、minal lengths equal to or greaterthan the shortest nominal lengths specified in Table 6may be obtained with reduced diameter body, if so speci-fied. Where reduced diameter body (or “Type R”) isspecified, the body diameter, D2, shall be within thelimits specified in Table 6. The screw shall have a shoul-der under the head. The diameter, Ds, and length, L2,of the shoulder shall be as specified in Table 6.15 LENGTHThe length of the screw is the distance, parallel tothe axis of the screw, from the plane formed by theunderhead bearing circle diameter to the extreme endof the
