ASME B107.300-2010 Torque Instruments

A N A M E R I C A N N A T I O N A L S T A N D A R D

ASME B107.300-2010(Incorporation of ASME B107.14, B107.28, and B107.29)

Torque Instruments

Copyright ASME International Provided by IHS under license with ASME

Not for ResaleNo reproduction or networking permitted without license from IHS

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ASME B107.300-2010(Incorporation of ASME B107.14, B107.28, and B107.29)

TorqueInstruments

A N A M E R I C A N N A T I O N A L S T A N D A R D



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Date of Issuance: April 19, 2010

This Standard will be revised when the Society approves the issuance of a new edition. There willbe no addenda issued to this edition.

ASME issues written replies to inquiries concerning interpretations of technical aspects of thisStandard. Periodically certain actions of the ASME B107 Committee may be published as Cases.Cases and interpretations are published on the ASME Web site under the Committee Pages athttp://cstools.asme.org as they are issued.

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 Committee 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 industry, 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 any

items mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability forinfringement of any applicable letters patent, nor assume 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 infringement 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 this 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 publisher.

The American Society of Mechanical EngineersThree Park Avenue, New York, NY 10016-5990

Copyright © 2010 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERS

All rights reservedPrinted in U.S.A.



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CONTENTS

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ivCommittee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vCorrespondence With the B107 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

ASME B107.14 Hand Torque Tools (Mechanical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

ASME B107.28 Electronic Torque Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

ASME B107.29 Electronic Tester, Hand Torque Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Nonmandatory AppendixA Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

iii



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FOREWORD

The American National Standards Committee B107 on Socket Wrenches and Drives was origi-nally under the sponsorship of The American Society of Mechanical Engineers (ASME). It wassubsequently reorganized as an ASME Standards Committee and its title was changed to HandTools and Accessories. In 1996, the Committee’s scope was expanded to include safetyconsiderations.

The purpose of B107.300 is to define essential performance and safety requirements for thefollowing three types of torque instruments:

(a) manually operated torque instruments, commonly used for mechanical measurement oftorque for control of the tightness of threaded fasteners

(b) electronic torque testers used for checking manually operated hand-held torque wrenchesand screwdrivers

(c) manually operated electronic torque instruments with integral or interchangeable headsIt includes requirements for endurance, torque value ranges, and accuracy for these torque

instruments. It specifies test methods to evaluate performance related to the defined requirementsand safety, and indicates limitations of safe use.

This Standard may also be used as a guide by state authorities or other regulatory bodies inthe formulation of laws or regulations. It is also intended for voluntary use by establishmentsthat use or manufacture the instruments covered.

This Standard includes(a) B107.14, Hand Torque Tools (Mechanical), approved by the American National Standards

Institute on December 16, 2004(b) B107.28, Electronic Torque Instruments, approved by the American National Standards

Institute on March 14, 2005(c) B107.29, Electronic Tester, Hand Torque Tools, approved by the American National Standards

Institute on March 16, 2005Prior editions of these individual standards are obsolete and no longer available.In addition to the consolidation of these individual torque standards into this Standard, principal

changes are the uniform inclusion of performance requirements and test methods that evaluateboth performance and safety as well as uniform format for sections on definitions, references,performance requirements, tests, and safety requirements and limitations of use.

Members of the Hand Tools Institute Torque Instruments Standards Committee through theirknowledge and hard work have been major contributors to the development of the B107 standards.Their active efforts in the promotion of these standards is acknowledged and appreciated.

The format of this Standard is in accordance with The ASME Codes & Standards Writing Guide2000. Requests for interpretations of the technical requirements of this Standard should beexpressed in writing to the Secretary, B107 Committee, at the address below.

Suggestions for the improvement of this Standard are welcome. They should be addressed tothe Secretary, ASME B107 Standards Committee, Three Park Avenue, New York, NY 10016-5990.

The requirements of this Standard become effective at the time of publication.ASME B107.300-2010 was approved by the B107 Standards Committee on September 8, 2009 andby the Board on Standards and Testing on October 12, 2009. It was approved as an AmericanNational Standard on February 18, 2010.

iv



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ASME B107 COMMITTEEHand Tools and Accessories

(The following is the roster of the Committee at the time of approval of this Standard.)

STANDARDS COMMITTEE OFFICERS

W. T. Pagac, ChairD. S. McKittrick, Vice Chair

J. H. Karian, Secretary

STANDARDS COMMITTEE PERSONNEL

N. C. Cantlon, Jore Corp.J. D. Davidson, Sears Holdings Corp.J. Apida, Alternate, Sears Holdings Corp.P. A. Desmarais, Danaher Tool GroupD. M. Eggert, Snap-On, Inc.J. S. Foote, Trade Association Management, Inc.J. H. Karian, The American Society of Mechanical EngineersD. S. McKittrick, McKittrickG. E. Olson, Gene Olson Engineering Consultant, Ltd.W. T. Pagac, Forever AssociatesW. C. Snyder, Wright Tool Co.J. M. Ster, General Services Administration, Heartland Global SupplyJ. F. Chaney, Alternate, General Services Administration, Heartland Global Supply

SUBCOMMITTEE 3 — TORQUE INSTRUMENTS

J. S. Foote, Chair, Trade Association Management, Inc.J. F. Chaney, General Services Administration, Heartland Global SupplyJ. R. Reynertson, Sturtevant Richmont Division, Ryerson Corp.

v



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CORRESPONDENCE WITH THE B107 COMMITTEE

General. ASME Standards are developed and maintained with the intent to represent theconsensus of concerned interests. As such, users of this Standard may interact with the Committeeby requesting interpretations, proposing revisions, and attending committee meetings.Correspondence should be addressed to:

Secretary, B107 Standards CommitteeThe American Society of Mechanical EngineersThree Park AvenueNew York, NY 10016-5990http://go.asme.org/Inquiry

Proposing Revisions. Revisions are made periodically to the Standard to incorporate changesthat appear necessary or desirable, as demonstrated by the experience gained from the applicationof the Standard. Approved revisions will be published periodically.

The Committee welcomes proposals for revisions to this Standard. Such proposals should beas specific as possible, citing the paragraph number(s), the proposed wording, and a detaileddescription of the reasons for the proposal, including any pertinent documentation.

Proposing a Case. Cases may be issued for the purpose of providing alternative rules whenjustified, to permit early implementation of an approved revision when the need is urgent, or toprovide rules not covered by existing provisions. Cases are effective immediately upon ASMEapproval and shall be posted on the ASME Committee Web page.

Requests for Cases shall provide a Statement of Need and Background Information. The requestshould identify the standard, the paragraph, figure or table number(s), and be written as aQuestion and Reply in the same format as existing Cases. Requests for Cases should also indicatethe applicable edition(s) of the standard to which the proposed Case applies.

Interpretations. Upon request, the B107 Committee will render an interpretation of any require-ment of the Standard. Interpretations can only be rendered in response to a written request sentto the Secretary of the B107 Standards Committee.

The request for interpretation should be clear and unambiguous. It is further recommendedthat the inquirer submit his/her request in the following format:

Subject: Cite the applicable paragraph number(s) and the topic of the inquiry.Edition: Cite the applicable edition of the Standard for which the interpretation is

being requested.Question: Phrase the question as a request for an interpretation of a specific requirement

suitable for general understanding and use, not as a request for an approvalof a proprietary design or situation. The inquirer may also include any plansor drawings that are necessary to explain the question; however, they shouldnot contain proprietary names or information.

Requests that are not in this format will be rewritten in this format by the Committee priorto being answered, which may inadvertently change the intent of the original request.

ASME procedures provide for reconsideration of any interpretation when or if additionalinformation 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 Meetings. The B107 Committee regularly holds meetings, which are opento the public. Persons wishing to attend any meeting should contact the Secretary of the B107 Stan-dards Committee.

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ASME B107.300-2010 (B107.14)

ASME B107.14

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

5 Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

6 Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7 Safety Requirements and Limitations of Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figures1 Type I, Class A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Type I, Class B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Type I, Class C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Type I, Class D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Type I, Class E, Style 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Type I, Class E, Style 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Type II, Class A, Style 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Type II, Class A, Style 3 (Shown Without Interchangeable Head) . . . . . . . . . . . . . . . . . . 59 Type II, Class B, Style 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510 Type II, Class B, Style 3 (Shown Without Interchangeable Head) . . . . . . . . . . . . . . . . . . 511 Type II, Classes A and B, Style 3 (Shown With Interchangeable Head) . . . . . . . . . . . . . 512 Flexible Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613 Type III, Class A, Style 1, Design A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 614 Type III, Class A, Style 1, Design B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 615 Type III, Class A, Style 2, Design A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616 Type III, Class A, Style 2, Design B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 617 Type III, Class B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718 Gravity-Independent Test Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 819 Graduated Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 920 Gravity-Dependent Test Positions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1021 Accuracy Test Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Tables1 Torque Instrument Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Torque Instrument Increments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Torque Instrument Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Torque Instrument Operating Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1



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ASME B107.300-2010 (B107.14)

HAND TORQUE TOOLS (MECHANICAL)

1 SCOPE

This Standard provides performance and safetyrequirements for manually operated torque instruments,commonly used for mechanical measurement of torquefor control of the tightness of threaded fasteners. It isnot intended to describe products infrequently utilizedor those designed for special purposes.

This Standard may be used as a guide by state authori-ties or other regulatory bodies in the formulation of lawsor regulations. It is also intended for voluntary use byestablishments that use or manufacture the instrumentscovered.

2 CLASSIFICATION

2.1 Type I: Indicating

Class A: deflecting beamStyle 1: plain scaleStyle 2: scale with signal mechanismStyle 3: scale with memory indicator

Class B: deflecting beam with interchangeable headconnection

Style 1: plain scaleStyle 2: scale with signal mechanismStyle 3: scale with memory indicator

Class C: rigid housingStyle 1: plain scaleStyle 2: scale with signal mechanismStyle 3: scale with memory indicator

Class D: rigid housing with interchangeable head con-nection

Style 1: plain scaleStyle 2: scale with signal mechanismStyle 3: scale with memory indicator

Class E: screwdriver gripStyle 1: enclosed dialStyle 2: exposed dial

2.2 Type II: Setting

Class A: graduatedStyle 1: nonratcheting

Design A: clockwise (right-hand) and counter-clockwise (left-hand) torquing

Design B: clockwise torquingDesign C: counterclockwise torquing

Style 2: ratchetingDesign A: clockwise (right-hand) and counter-

clockwise (left-hand) torquing

2


Style 3: interchangeable head connectionDesign A: clockwise (right-hand) and counter-

clockwise (left-hand) torquingDesign B: clockwise torquingDesign C: counterclockwise torquing

Style 4: flexible ratchet headDesign A: clockwise (right-hand) and counter-


Class B: nongraduatedStyle 1: nonratcheting

Design A: clockwise (right-hand) and counter-clockwise (left-hand) torquing


Style 2: standard ratcheting headDesign A: clockwise (right-hand) and counter-


Style 3: interchangeable head connectionDesign A: clockwise (right-hand) and counter-


Style 4: flexible ratchet headDesign A: clockwise (right-hand) and counter-


2.3 Type III: Limiting

Class A: screwdriver gripStyle 1: graduated

Design A: external square driveDesign B: internal hex drive

Style 2: nongraduatedDesign A: external square driveDesign B: internal hex dive

Class B: “T” handle gripStyle 1: nonratchetingStyle 2: ratcheting



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ASME B107.300-2010 (B107.14)

3 REFERENCES

The following documents form a part of this Standardto the extent specified herein. The latest edition shallbe used.

ASME B107.4, Driving and Spindle Ends for PortableHand, Impact, Air, and Electric Tools (Percussion ToolsExcluded)

ASME B107.10, Handles and Attachments for HandSocket Wrenches

ASME B107.29, Electronic Tester, Hand Torque ToolsPublisher: The American Society of Mechanical

Engineers (ASME), Three Park Avenue, New York,NY 10016-5990; Order Department: 22 Law Drive, Box2300, Fairfield, NJ 07007-2300 (www.asme.org)

Guide to Hand Tools — Selection, Safety Tips, ProperUse and Care

Publisher: Hand Tools Institute (HTI), 25 NorthBroadway, Tarrytown, NY 10591 (www.hti.org)

4 DEFINITIONS

accuracy: the permissible deviation, tolerance, or errorband. A higher value means a lower certainty ofcorrectness.

full scale: see rated capacity.

graduation: a mark on the instrument indicating a torquevalue.

hand torque instrument: tool combining hand wrenchingand torque measurement functions, formerly referred toas “hand torque wrench.”

increment: the value of the difference between adjacentgraduations.

indicated value: for Type I, the value the instrument dis-plays when torque is applied; for Types II and III, thevalue to which the instrument is set or preset.

measured value: the actual torque determined by a torquetester.

operating load: the operating load shall be calculated bydividing the rated capacity by the distance between theaxis of the torque moment and the center of the grip ordesignated load point.

rated capacity: for graduated instruments, the maximumgraduated torque value, also known as full scale; fornongraduated instruments, the maximum manufac-turer-specified torque.

scale: the representation of the range of the instrument,divided into increments marked by numbered andunnumbered graduations.

setting: the amount of torque the instrument is expectedto apply.

3

Fig. 1 Type I, Class A

Handle

Scale

Pointer

Drive

Fig. 2 Type I, Class B

10

FOO

T PO

UN

DS

100

30

30

20

20

40

40

5 REQUIREMENTS

Figures 1 through 20 are descriptive and not restric-tive. They are not intended to preclude the manufactureor purchase of other forms of torque instruments con-forming to this Standard.

Torque Instruments shall pass all applicable tests insection 6.

5.1 Design

5.1.1 Type I, Classes A, B, C, and D — Indicating(a) Operation. Instruments shall indicate torque

applied through a deflecting member. They shall operatein both clockwise and counterclockwise directions.

(1) Type I, Classes A and B — Deflecting Beam. Flexingof a cantilever beam connecting the square drive andthe hand grip shall provide the basis of operation. Type I,Class A deflecting beam torque instruments may be sim-ilar to that shown in Fig. 1. Type I, Class B deflectingbeam torque instruments may be similar to that shownin Fig. 2.

(2) Type I, Classes C and D — Rigid Housing. Thedeflecting member and dial mechanism shall beenclosed within the rigid housing. The pointer and dialface shall be protected by a transparent cover whichshall be so located and constructed as to be reasonablyfree from accidental damage resulting from being struckor abraded. Type I, Class C rigid housing torque instru-ments may be similar to that shown in Fig. 3. Type I,Class D rigid housing torque instruments may be similarto that shown in Fig. 4.

(3) Type I, Classes B and D — Interchangeable HeadConnection. The torque instrument shall be equippedwith a connection, suitable for accepting a variety ofmating wrenching heads. The connection and standard



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ASME B107.300-2010 (B107.14)

Fig. 3 Type I, Class C

Drive Housing

Dial

Hand grip

Fig. 4 Type I, Class D

wrenching heads shall be designed so that the require-ments of para. 5.8 are met throughout the specified accu-racy range. The wrenching heads shall comply with therequirements of para. 5.5. Indicating torque instrumentswith an interchangeable head may be similar to Fig. 2(Class B) or Fig. 4 (Class D).

(b) Indicator. A dial or scale shall be located to permitconvenient and accurate reading. The graduation marksshall be colored and shaped to be distinct and easilyread. The width of the graduation mark shall not begreater than one-half the adjacent space width. Thewidth of the pointer tip or indicator line shall not begreater than the widest graduation mark, nor shall thepointer completely cover any graduation mark on theouter scale. The pointer shall be located close to thescale face so as to meet the parallax error requirementsof para 6.2.

(c) Hand Position. If, in order to achieve the requiredaccuracy, it is necessary to apply the load at a specificpoint on the hand grip, the hand grip shall be pivotedat that point.

(d) Auxiliary Functions. Additional features may beincorporated on the torque instrument to improve accu-racy or usefulness. The inclusion of such features shallnot be cause for rejection of the torque instrument pro-viding it conforms to the performance requirements ofthis Standard.

(e) Type I, Classes A, B, C, and D, Style 1 — PlainScale. No auxiliary operational features are required.

(f) Type I, Classes A, B, C, and D, Style 2 — Scale WithSignal Mechanism. A signal mechanism capable of beingadjusted without the use of tools to any graduated valueof the instrument shall be provided. The signal shalloperate automatically within the accuracy requirementsof this Standard.

(g) Type I, Classes A, B, C, and D, Style 3 — Scale WithMemory Indicator. An auxiliary pointer or other devicecapable of retaining an indication of the maximum

4

Fig. 5 Type I, Class E, Style 1

1020

30

405060

70

80

torque transmitted through the instrument shall be pro-vided. The auxiliary pointer shall function at any gradu-ated torque value within the accuracy requirements ofthis Standard. Means shall be provided for resetting theauxiliary pointer. Normal handling of the instrumentshall not cause the auxiliary pointer to be displaced.

(h) Type I, Classes A, B, C, and D TorqueInstruments. These shall be calibrated in the direction(s)of intended use.

5.1.2 Type I, Class E — Indicating, Screwdriver Grip.The grip and the drive shall lie on the same axis ofrotation to allow the instrument to be used like a screw-driver. Instruments shall be limited to a capacity of100 lbf-in. (11.3 N·m) and those with capacities over40 lbf-in. (4.5 N·m) shall be equipped with a 1⁄4-in.(6.3 mm) female square drive on the top of the handle,or with other auxiliary driving means.

(a) Type I, Class E, Style 1 — Enclosed Dial. The pointerand face shall be protected by a suitable transparentcover. The instrument may be similar to that shown inFig. 5.

(b) Type I, Class E, Style 2 — Exposed Dial. The pointerand face shall be left unprotected. The instrument maybe similar to that shown in Fig. 6.

Type I, Class E torque instruments shall be calibratedin the direction(s) of intended use.

5.1.3 Type II — Setting(a) Operation. Instruments shall sense torque transmit-

ted by comparing the torque applied with aself-contained standard. The transmission of the pre-selected value shall be indicated by a physical impulse,



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ASME B107.300-2010 (B107.14)

Fig. 6 Type I, Class E, Style 2

2 244

68

1012

14

68

1012

14

224 4

68

1012

14

68

1012

14

Fig. 7 Type II, Class A, Style 2

Graduated scale

BarrelLockDrive

Hand grip

Fig. 8 Type II, Class A, Style 3(Shown Without Interchangeable Head)

with or without audible signal, which shall cause a tem-porary reduction in the torque applied. Operation shallbe such as to minimize abrupt overtravel. Reset shall beautomatic upon release of load application.

(b) Hand Position. If, in order to achieve the requiredaccuracy, it is necessary to apply the load at a specificlocation on the handgrip other than the center, the hand-grip shall be so designed or marked.

(c) Auxiliary Functions. Additional features may beincorporated in the torque instrument to improve accu-racy or usefulness. The inclusion of such features shallnot be cause for rejection of the torque instrument, pro-viding it otherwise conforms to the requirements of thisStandard.

(d) Type II, Class A — Graduated. A graduated scalewith increments appropriately numbered shall belocated on the instrument and positioned as to permitconvenient reading. Selection of the desired torque valueshall be made by manual means, using a handgrip, andshall not require a separate tool or implement. Provisionshall be made to indicate accurately the selected torquevalue on the graduated scale. A suitable portion of thetorque instrument grip shall be designed to facilitateturning of the adjustable portion of the grip. Means shallbe provided to protect the torque setting from accidentalchanges and shall not require a separate tool or imple-ment. Graduated setting type torque instruments maybe similar to those shown in Figs. 7 and 8.

5

Fig. 9 Type II, Class B, Style 2

Drive Barrel

Hand grip

Fig. 10 Type II, Class B, Style 3(Shown Without Interchangeable Head)

Fig. 11 Type II, Classes A and B, Style 3(Shown With Interchangeable Head)

(e) Type II, Class B — Nongraduated. The torque instru-ment shall not be graduated or equipped with a meansfor graduated adjustment. A separate tool or implementshall be required to engage the adjustment provision ofthe instrument in order to select the controlling torquevalue. Means shall be provided to protect the torquesetting from accidental changes. Nongraduated settingtype torque instruments may be similar to those shownin Figs. 9 and 10.

(f) Type II, Classes A and B, Style 1 — Nonratcheting. Asquare drive tang without auxiliary operational featuresshall be provided. The drive shall comply with therequirements of para. 5.5.1.

(g) Type II, Classes A and B, Style 2 — Ratcheting. Thesquare drive tang provided shall be equipped with aratcheting mechanism. The ratchet shall comply withthe requirements of para. 5.5.2.

(h) Type II, Classes A and B, Style 3 — InterchangeableHead Connection. The torque instrument shall beequipped with a connection, suitable for accepting avariety of mating wrenching heads. The connection andstandard wrenching heads shall be designed so thatthe requirements of para. 5.8 are met throughout thespecified accuracy range. The wrenching heads shallcomply with the requirements of para. 5.5.4. Settingtorque instruments with an interchangeable head maybe similar to that shown in Fig. 11.

(i) Type II, Classes A and B, Style 4 — Flexible RatchetHead. A flexible joint shall be provided to allow thebody to flex about an axis that is in a plane perpendicularto the axis of the drive tang and perpendicular to the



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ASME B107.300-2010 (B107.14)

Fig. 12 Flexible Head

Fig. 13 Type III, Class A, Style 1, Design A

2 6

14 18 22

axis of the body (see Fig. 12). Flex angle shall be limitedto an amount that will contain the induced torque accu-racy error including the instrument tolerance error towithin the accuracy specified in para. 5.8. A mechanismshall be provided to maintain the ratchet head under itsown weight in one or more positions including one thatplaces the drive axis perpendicular to the longitudinalaxis of the instrument. The ratchet shall comply withthe requirements of para. 5.5.2.

(j) Type II Torque Instruments. These shall be calibratedin the direction(s) of intended use.

5.1.4 Type III — Limiting(a) Operation. Limiting torque instruments shall oper-

ate by releasing the drive tang at the preselected torquevalue followed by automatic reset. The release and resetsequence shall occur a minimum of two times in onefull revolution of the drive. The reset action should notcause a reverse torque (backlash), which might tend toloosen the fastener being tightened.

(b) Type III, Class A — Screwdriver Grip. The instru-ment shall be in a screwdriver configuration. The fullscale setting of Type III, Class A instruments shall notexceed 40 lbf-in. (4.5 N·m).1

(1) Type III, Class A, Style 1 — Graduated. A gradua-ted scale with increments appropriately numbered shallbe located on the instrument and positioned so as topermit convenient reading. Selection of the torque valueshall be made by manual means not requiring a separatetool or implement. Provision shall be made to indicateaccurately the selected torque value on the graduatedscale. The adjustment means shall be adequately pro-tected against accidental change by an appropriatedevice or lock not requiring a separate tool or imple-ment. The instrument may be similar to that shown inFigs. 13 and 14.

(2) Type III, Class A, Style 2 — Nongraduated. Thetorque instrument shall not be graduated or equipped

1 This limitation is for safety reasons.

6

Fig. 14 Type III, Class A, Style 1, Design B

Fig. 15 Type III, Class A, Style 2, Design A

Fig. 16 Type III, Class A, Style 2, Design B

with a means for graduated adjustment. A separate toolor implement shall be required to engage the adjustmentprovision of the instrument in order to select the torquevalue. Means shall be provided to protect the torquesetting from accidental changes. The instrument may besimilar to that shown in Figs. 15 and 16.

(c) Type III, Class A, Styles 1 and 2, Design A — ExternalSquare Drive. A 1⁄4-in. (6.3 mm) square drive tang with-out auxiliary operational features shall be provided. Thedrive shall comply with the requirements of para. 5.5.1.

(d) Type III, Class A, Styles 1 and 2, Design B — InternalHex Drive. A 1⁄4-in. (6.3 mm) hexagon socket drive inte-gral with the torque instrument shall be provided. Thedrive shall comply with the requirements of para. 5.5.3.

(e) Type III, Class B — “T” Handle Grip. The instrumentshall be in a “T” handle configuration and may be similarto that shown in Fig. 17. The instrument shall not begraduated nor equipped with a means for graduatedadjustment. A separate tool or implement shall berequired to engage the adjustment provision of theinstrument in order to select the controlling torque value.Means shall be provided to protect the torque settingfrom accidental changes. The full scale setting shall notexceed 150 lbf-in. (16.9 N·m). The drive shall complywith the requirements of para. 5.5.1.

(1) Type III, Class B, Style 1 — Nonratcheting. Asquare drive tang without auxiliary operational featuresshall be provided.

(2) Type III, Class B, Style 2 — Ratcheting. A squaredrive tang with an integral ratcheting mechanism shallbe provided. The ratchet shall be nonreversible and pro-vide driving engagement in the clockwise direction. Theratchet shall index a minimum of eight times in one fullrevolution of the drive.



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ASME B107.300-2010 (B107.14)

Fig. 17 Type III, Class B

Type III instruments shall be calibrated in a clockwisedirection.

5.2 Materials

The materials used in the manufacture of torqueinstruments shall be such as to ensure compliance withthe requirements of this Standard.

5.3 Marking

Torque instruments shall be marked in a legible andpermanent manner with the following information:

(a) the manufacturer’s name or a trademark of suchknown character that the source of manufacture andcountry of origin shall be readily determined

(b) model number(c) units of torque

NOTE: While torque may commonly be expressed as in.-oz, in.-lb,or ft-lb, etc., it is proper to indicate that these measures use force,not mass. The preferred expressions are ozf-in., lbf-in., and lbf-ft.

(d) arrow or arrows with the word “TORQUES” or“TORQUE” indicating the direction of torque for instru-ments that are calibrated in one direction.

Optional markings such as serial number, conversiontable, secondary torque scale, date code, or month andand year of manufacture (e.g., 12/02 for December 2002),etc., may also be included.

5.4 Finish

5.4.1 Surfaces. All exterior surfaces shall be thor-oughly cleaned, free from cracks, and essentially freefrom burrs, pits, nodules, and other detrimentalconditions.

5.4.2 Coating. Coatings shall be tightly adherent,uniform in appearance, and free from conditions thatwould prevent full compliance with the requirementsof this Standard. They shall protect the base metal fromcorrosion under use and storage conditions normally

7

Table 1 Torque Instrument Capacity

Drive Size Maximum Torque

in. mm lbf-in. lbf-ft N·m

1⁄4 6.3 250 . . . 303⁄8 10.0 1,200 100 1351⁄2 12.5 3,000 250 3403⁄4 20.0 8,400 700 1 0001 25.0 . . . 2,000 2 700

11⁄2 40.0 . . . 6,000 9 000

associated with hand tools, and they shall not peel,crack, or blister in such use or storage. Minor blemishesshall be permitted provided they do not detract substan-tially from the appearance or operation of the torqueinstrument. Cadmium plating shall not be used as acoating.

5.5 Drives

5.5.1 Plain Square Drives. Drive tangs shall con-form to the requirements of ASME B107.4. The squaredrive shall be oriented so two of the opposite flats areparallel within 5 deg of the longitudinal axis of thetorque instrument. The drive ball or similar retainingmechanism shall be located as shown in Fig. 1.

5.5.2 Ratchet Drives. The operational characteris-tics of ratchet drives incorporated in all ratchet drivetorque instruments shall conform to the requirementsof ASME B107.10M.

5.5.3 Internal Hex Drives. Internal hex drives usedin Type III, Class A, Styles 1 and 2, Design B instrumentsshall accommodate screwdriver bits meeting therequirements of ASME B107.4. Insertion and removal ofbits shall be accomplished without the use of tools, andmeans shall be provided to hold the bits securely inplace.

5.5.4 Interchangeable Heads. Heads other thanplain square drives or ratchet drives shall meet theappropriate dimensional and testing requirements of theASME specification covering the head type.

5.6 Capacity

The rated capacity of the torque instrument shall notexceed the limit specified in Table 1.

5.7 Increments

The range between the lowest and highest graduatedvalues shall be divided into equal increments. The valueof each increment shall be equal to or less than thatspecified by Table 2. For Type I instruments, graduationsshall be identified by appropriate numbers at intervalsnot greater than each tenth increment. The lowest gradu-ated value shall be no greater than 20% of the highestgraduated value on Types I and II torque instruments.



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ASME B107.300-2010 (B107.14)

Table 2 Torque Instrument Increments

Maximum Increment Value asInstrument Type Percent of Rated Capacity

I 5II 2III 6

Table 3 Torque Instrument Accuracy

20% to 100% of Rated Capacity Below 20% of Rated CapacityType Class/Style/Design (times Indicated Value) (times Rated Capacity)

I All ±4% ±0.8%II Classes A and B, Styles 1,2, and 3, ±4% CW, ±6% CCW ±0.8% CW, ±1.2% CCW

Design AII Classes A and B, Style 4, Design A ±4% unflexed, +4%−10% flexed CW; ±0.8% unflexed, +0.8%−2% flexed CW;

±6% unflexed, +6%−12% flexed CCW ±1.2% unflexed, +1.2%−2.4% flexed CCWII Classes A and B, Style 4, ±4% unflexed, +4%−10% flexed ±0.8% unflexed, +0.8%−2% flexed

Designs B and CII All others ±4% ±0.8%III All ±6% CW only ±1.2% CW only

Fig. 18 Gravity-Independent Test Position

Torque tester

Support

This requirement shall not apply to nongraduatedinstruments.

5.8 Accuracy

The difference between the indicated value and mea-sured value of a torque instrument shall not exceed val-ues shown in Table 3 when tested in the horizontal (withthe drive in the vertical) orientation (see Fig. 18).

5.9 Operating Load

Loads applied to the center of the handgrip or desig-nated load point shall not exceed those shown in Table 4when an amount of torque equal to the rated capacityhas been transmitted through it. Appropriate extensionhandles shall be used as provided by the manufacturer.This requirement shall not apply to Type I, Class E norType III instruments.

6 TESTS

Many tests required herein are inherently hazardousand adequate safeguards for personnel and propertyshall be employed in conducting such tests. These testsare designed to evaluate the tools and materials and donot condone the use of the tools in an environment, orin a manner, inconsistent with safe use of the tools.

8

Table 4 Torque Instrument Operating Load

Drive Size Maximum Load

in. mm lbf N

1⁄4 6.3 50 2203⁄8 10 125 5551⁄2 12.5 175 7803⁄4 20 250 1 110

1 and larger 25 and larger 300 1 335

Instruments with an interchangeable head connectionshall be tested with a properly rated head so that thehead will not fail during testing.

Testing shall be performed at a temperature not fluctu-ating by more than 2°F (1°C). This temperature shall bein the range of 64°F (17°C) to 82°F (27°C) (maximumrelative humidity 90%) and shall be documented.

6.1 Visual Examination

Conformance with requirements not verified by testshall be established by visual examination. Coating com-position and characteristics shall be determined eitherby appropriate tests or reference to manufacturer’s spec-ifications, drawings, or procurement documents. Forgraduated torque instruments, if the graduated scale issuch that major graduations are on the barrel and minorgraduations are on the handgrip and one full rotationof the handgrip advances one graduation on the barrel,then the zero graduation on the handgrip must alignwith the corresponding graduation on the barrel within



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ASME B107.300-2010 (B107.14)

Fig. 19 Graduated Range

Graduation

Increments

IN LBS

4 2 0 18 16

180140100

60

20016012080

40

plus/minus one increment throughout its entire gradua-ted range (see Fig. 19).

6.2 Parallax Error Type I

The torque instrument scale shall be located so thatit is in a horizontal plane. The pointer shall be adjustedto indicate zero when viewed from directly above thescale. The viewing plane shall be rotated 45 deg clock-wise about an axis through the pointer and the apparentchange in the relationship between the pointer and scaleobserved. The change shall not exceed 4% of the maxi-mum graduated value.

6.3 Accuracy

(a) Test Equipment. Accuracy testing shall be per-formed on equipment capable of indicating torqueapplied with an accuracy of 25% or less of the accuracyrequirement of the instrument under test. Interpolatedreadings of measuring equipment shall be made no moreprecisely than one-half of the smallest increment. Accu-racy of the test equipment shall be independently veri-fied by a route traceable to the National Institute ofStandards and Technology (NIST).

(b) Test Points. All torque instruments except nongrad-uated types shall be subjected to an accuracy test atthe graduated value nearest to 20%, 60%, and 100% ofmaximum graduated value. Nongraduated instrumentsshall be tested at the value at which they are set, or ifsupplied not set, at the full scale setting of the instrumentmaximum rated torque value and at a value equal to20% of the rated capacity. Refer to flowchart in Fig. 21.

(c) Load Position. All accuracy test loads shall beapplied at the midpoint of the handgrip or designatedload point in a plane perpendicular to the axis of theinstrument drive tang. Flexible head instruments shallbe tested in the unflexed position.

(d) Test Sequence. Accuracy test readings shall be takenin progression from lower torque values to higher. Allinstruments shall be operated three times at 100% ofmaximum graduated value in the direction of test before

9

any test sequence is begun. After the unrecorded opera-tions and before any test operation is begun, Type Iinstruments shall be adjusted to indicate zero torqueapplied in the plane of operation before instrument isput onto tester. Types II and III instruments shall beadjusted to lowest graduation prior to setting the firsttest point. Type I, Style 2 instruments shall have thesignal device adjusted between each test operation.

If, during a torque setting adjustment with a Type IIor Type III graduated instrument, the target test valueis exceeded on the scale, the instrument shall be firstadjusted back to below the target value, and then backto the target test value. All torque instruments shallalso be operated three times at each test point beforerecording readings at that point.

(e) Test Operation. Torque shall be applied at theappropriate place within the designated hand positionuntil the instrument indicates and/or signals the targettorque value. The value shown by the tester shall beread and recorded. Immediately following the taking ofthe tester reading, torque shall be removed from theinstrument. On Type II instruments, three readings shallbe taken at each of the three target torque settings begin-ning with the lowest. On Type III instruments, six read-ings shall be taken at each of the three target settingsbeginning with the lowest. Each reading taken at eachtest point shall be within the allowed tolerance of theinstrument.

(1) Type I, Classes A, B, C, and D. The pointer orneedle of the torque instrument shall be adjusted toindicate zero torque applied in the plane of operationbefore being mounted in the tester for any test sequence.Classes A, B, C, and D, Style 2 torque instruments shallhave the signal device appropriately adjusted betweeneach test operation.

(2) Type II. The torque shall be applied at a ratesufficiently slow and steady so that after the release, theinstrument will not over-travel causing the test equip-ment to indicate torque in excess of the release setting.

(3) Type III. The torque shall be applied at a ratesufficiently slow and steady so that the torque at thepoint of release can be accurately read.

6.4 Gravity Error

6.4.1 Type I. The torque instrument shall be locatedso it is in a horizontal plane and the drive in a verticalplane. The pointer shall be adjusted to indicate zerowhen viewed from directly above the scale. The torqueinstrument shall then be rotated and supported at eachend so the scale is in a vertical plane and the pointeraxis is horizontal. In this position, and when viewed at90 deg to the scale, the pointer shall not be off the zeroposition more than ±2% of the maximum graduatedvalue.

6.4.2 Types II and III. The gravity-induced error testshall be conducted immediately after the accuracy test



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ASME B107.300-2010 (B107.14)

Fig. 20 Gravity-Dependent Test Positions

Gravity and force inthe same direction

(a)

Gravity and force in opposing directions

(b)

Up

Load

Load

Up

Load

Load

at the lowest test point specified in para. 6.3(b). Theinstrument shall meet the accuracy requirements speci-fied below with the instrument oriented in each positionshown in Fig. 20.

Instruments shall operate within the accuracy limitsin para. 5.8 in any orientation with respect to gravityexcept that the allowable increase in accuracy percentagedue to orientation influenced by gravity shall be limitedto 2% of set torque when the rated capacity of the instru-ment is under 251 lbf-in. (32.6 N·m) or over 250 lbf-ft(339 N·m).

Flexible head instruments shall be tested in theunflexed position.

6.5 Calibration Life and Overload

The calibration life tests shall be performed after theaccuracy test has been satisfactorily completed.

The torque instrument shall be loaded to rated capac-ity and completely relieved 5,000 times in each cali-brated direction of operation at the rate of 60 cycles perminute or less. Types I and II instruments shall then beloaded once to 125% of rated capacity in each calibrateddirection of operation. Type II, Style 4 instruments shallbe loaded in the maximum flexed position.

The instrument shall be examined for physical failureand shall be rejected if evidence of physical failure isfound. The instrument shall then be subjected to therequirements of para. 5.8 and the test procedure of

10

para. 6.3, and shall be rejected if the tests are not satisfac-torily completed.

If the instrument passes the above tests, it shall then beloaded to 50% of rated capacity and completely relieved20,000 times in each calibrated direction of operation.Accurate performance shall not be required at the con-clusion of this test, but deformation or physical failureshall be cause for rejection.

6.6 Flexible Head Error Test

This test shall be conducted on Type II, Class A, Style 4instruments after the gravity error test. The instrumentshall be tested in accordance with para. 6.3, but withthe body of the instrument at the maximum flexedangles. The accuracy of the instrument shall be withinthe limits in Table 3.

7 SAFETY REQUIREMENTS AND LIMITATIONS OFUSE

(a) Instructors and employers shall stress proper useand safety in the use of torque instruments, informationabout which can be found in the HTI publication, Guideto Hand Tools—Selection, Safety Tips, Proper Use and Care.

(b) Torque instruments shall be supplied with instruc-tions indicating their accuracy limits, direction of opera-tion, application, use, care, and guidance on the properuse of adapters and extensions. The instructions shall



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ASME B107.300-2010 (B107.14)

Fig.

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11



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ASME B107.300-2010 (B107.14)

indicate the extent to which design features of the instru-ment, such as flexible or interchangeable heads, affectthe accuracy of the instrument.

(c) Torque instruments perform correctly only whenproperly used, cared for, and calibrated.

(d) A fastener improperly torqued with a torqueinstrument may be very dangerous even if the torquewrench is in proper working order, or appears to be inproper working order but is out of calibration.

12

(e) The failure to follow manufacturer instructions[see para. 7(b)] for the use of these instruments is farmore serious than with most hand tools. For most handtools, improper use will harm only the user, butimproper use of a torque instrument could lead to sys-temic failure.



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ASME B107.300-2010 (B107.28)

ASME B107.28

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

5 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

7 Safety Requirements and Limitations of Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure1 Drive Ball Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Tables1 Torque Instrument Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 Torque Instrument Operating Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

13



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ASME B107.300-2010 (B107.28)

ELECTRONIC TORQUE INSTRUMENTS

1 SCOPE

This Standard provides performance and safetyrequirements for manually operated electronic torqueinstruments with integral or interchangeable heads. Itincludes requirements for endurance, torque valueranges, and accuracy for these torque instruments. It isnot intended to describe products infrequently utilizedor those designed for special purposes.

2 CLASSIFICATION

2.1 Type I: Electronic Torque Instruments

One percent accuracy.

2.2 Type II: Electronic Torque Instruments

Four percent accuracy.

3 REFERENCES

The following documents are referenced in thisStandard. The latest edition shall be used.


ASME B107.10, Handles and Attachments for HandSocket Wrenches — Inch and Metric Series

Publisher: The American Society of MechanicalEngineers (ASME), Three Park Avenue, New York,NY 10016-5990; Order Department: 22 Law Drive, Box2300, Fairfield, NJ 07007-2300 (www.asme.org)



4 DEFINITIONS

accuracy: the permissible deviation, tolerance, or errorband. A higher value means a lower certainty ofcorrectness.

rated capacity: the maximum intended torque the usershall measure or apply.

5 REQUIREMENTS

The illustration shown herein is descriptive and notrestrictive, and is not intended to preclude the manufac-ture of an electronic torque instrument that is otherwise

14

in accordance with this Standard. Conformance withrequirements not verified by test shall be established byvisual examination. Coatings composition and charac-teristics shall be determined either by appropriate testsor reference to manufacturer’s specifications, drawings,or procurement documents.

5.1 Design

The torque instrument shall be capable of electroni-cally indicating the torque applied through the use of atransducer and digital display. The torque value readoutshall be visible at a viewing angle up to 45 deg fromnormal. It shall have an integral power supply capable ofmeeting the requirements specified in para. 5.11. Whentested in accordance with para. 6.1, the maximum allow-able digital conversion time shall not exceed 100 msec(minimum of 10 times per second).

5.2 Finish

Exterior surfaces of the torque instrument shall besmoothly finished. Sharp edges and corners capable ofcausing injury shall be removed and parts subject tocorrosion shall be appropriately protected. Minor blem-ishes shall be permitted provided they do not detractsubstantially from the appearance or operation of thetorque instrument. Protection from environmental dam-age shall be provided by suitable coating or transparentcover.

5.3 Coatings

Coatings shall be tightly adherent, uniform in appear-ance, and free from conditions that would prevent fullcompliance with the requirements of this Standard. Theyshall protect the base metal from corrosion under useand storage conditions normally associated with handtools, and they shall not peel, crack, or blister in such useor storage. Minor blemishes shall be permitted providedthey do not detract substantially from the appearanceor operation of the torque instrument. Cadmium platingshall not be used as a coating.

5.4 Drives

Drives shall conform to the requirements of ASMEB107.4.

5.4.1 Plain Square Drive. The square drive shall beoriented so two of the opposite flats are parallel within5 deg of the longitudinal axis of the instrument. Thedrive ball shall be located as shown in Fig. 1.



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ASME B107.300-2010 (B107.28)

Fig. 1 Drive Ball Location

Ball location

Table 1 Torque Instrument Capacity


in. mm lbf-in. lbf-ft N·m

1⁄4 6.3 250 . . . 303⁄8 10.0 1,200 100 1351⁄2 12.5 3,000 250 3403⁄4 20.0 . . . 700 1 000

Table 2 Torque Instrument Operating Load


in. mm lb N

1⁄4 6.3 50 2203⁄8 10.0 125 5551⁄2 12.5 150 6703⁄4 20.0 250 1 110

5.4.2 Ratchet Drive. The operational characteristicsof the ratchet when incorporated shall conform to therequirements of ASME B107.10.

5.5 Operating Range

The rated capacity of the torque instrument shall notexceed the limit specified in Table 1. The lowest indicatedvalue shall be no greater than 20% of the rated capacity.

5.6 Resolution

The range between the lowest and highest values shallbe divided into equal increments. The size of each incre-ment shall be equal to or less than 0.1% of the ratedcapacity value for Type I and 0.4% for Type II.

5.7 Operating Loads

The load required to achieve the rated capacity of theinstrument shall not exceed those shown in Table 2. Theload must be applied to the center of the designatedhandgrip or marked load position and perpendicular tothe instrument axis (centerline). Extension handles shallbe used when provided by the manufacturer.

5.8 Accuracy

The torque instrument shall operate within the accu-racy limits specified herein throughout its calibratedrange. The calibrated range shall be from 20% or less to100% of the rated capacity value. Within the calibratedrange, the value indicated by the torque instrument shall

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not deviate more than 1% of the applied torque in aclockwise and 1.5% of the applied torque in a counter-clockwise hand direction for Type I and 4% in a clock-wise and 6% in a counterclockwise hand direction forType II.

5.9 Calibration and Cycle Life

The torque instrument shall pass the test in para. 6.2.

5.10 Overload

The instrument shall have a warning device to indicatewhen the applied torque has exceeded its rated capacityand shall pass the test in para. 6.3.

5.11 Battery Life

The torque instrument shall pass the test specified inpara. 6.4 and shall have an indicator to warn of a lowbattery condition. On a torque instrument having thecapability of storing torque readings, the indicator shallstore values internally or give sufficient notice to allowfor downloading of the stored values to a data loggeror similar device.

5.12 Marking

The torque instrument shall be marked in a legiblemanner with the following information:

(a) the manufacturer’s name or a trademark of suchknown character that enables positive identification ofthe manufacturer

(b) model number and serial number(c) rated capacity with units of measure(d) load position (on instruments for which accuracy

is dependent upon load position)

5.13 Operating Modes

At least one of the following shall be provided:(a) Track Mode. The torque instrument shall allow

direct measurement of the torque applied and shall dis-play the value.

(b) Peak Mode. The torque instrument shall allowdirect measurement of the torque applied and shall dis-play the highest value since last reset for a minimum of5 sec.

6 TEST PROCEDURES

Many tests required herein are inherently hazardousand adequate safeguards for personnel and propertyshall be employed in conducting such tests. These testsare designed to evaluate the tools and materials and donot condone the use of the tools in an environment, orin a manner inconsistent with safe use of the tools.

Testing shall be performed at a temperature not fluctu-ating by more than 2°F (1°C). This temperature shall bein the range of 64°F (17°C) to 82°F (27°C) (maximumrelative humidity 90%) and shall be documented.



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ASME B107.300-2010 (B107.28)

6.1 Accuracy TestsThe instrument shall be loaded three times to maxi-

mum capacity and the instrument reset to zero beforeaccuracy tests are conducted. Accuracy tests on thetorque instrument shall be conducted at 20%, 60%, and100% of rated capacity. Three readings shall be takenat each test point starting with the lowest value andprogressing to the rated capacity. Each reading taken ateach test point shall be within the allowed tolerance ofthe instrument being measured. When the sequence hasbeen completed with the readings at the highest targetvalue, the test load shall be relieved and the torqueinstrument removed from the tester. All test loads shallbe applied at the midpoint of the handgrip or at themarked load position.

The test shall be performed on equipment capable ofindicating torque applied within an accuracy of ±0.25%for Type I and ±1% for Type II at any point within thecalibrated range of the torque instrument. Interpolatedreadings of the measuring equipment shall be made nomore precisely than one-half of the smallest increment.Accuracy of test equipment shall be independently veri-fied by a route traceable to the National Institute ofStandards and Technology (NIST).

6.2 Calibration and Cycle Life TestThe torque instrument shall meet, without recalibra-

tion (adjustment of electronic circuitry) or adjustmentsto the instrument, the accuracy requirements after beingstressed from no load to rated capacity, 5,000 times ina clockwise direction and then in a counterclockwisedirection at a rate not to exceed 20 operations perminute. Subsequently, the instrument shall be stressedfrom no load to 50% of rated capacity, 20,000 times ina clockwise direction and then 20,000 times in a counter-clockwise direction at a rate not to exceed 20 times perminute. The instrument, after recalibration and minoradjustment if necessary, shall meet the accuracy require-ments. Instrument display shall be active. Batteries maybe replaced as required.

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6.3 Overload Test

The torque instrument shall be loaded once to 125%of its rated capacity in each a clockwise and a counter-clockwise direction using a known torque reference. Thetorque instrument shall show no signs of permanentdeformation or physical failure. Accurate performanceshall not be required at the conclusion of this test.

6.4 Battery Life Test

When the torque instrument is continually cycled atits maximum power consumption, battery life shall be10 hr minimum. The instrument shall not be cycled inexcess of four cycles per minute.


(a) Instructors and employers shall stress proper useand safety in the use of electronic torque instruments,information about which can be found in the HTI publi-cation, Guide to Hand Tools—Selection, Safety Tips, ProperUse and Care.

(b) Each electronic torque instrument shall be sup-plied with instructions covering its accuracy, applica-tion, calibration, installation, setup, and safe use.

(c) Torque instruments perform correctly only whenproperly used, cared for, and calibrated.

(d) A fastener improperly torqued with a torqueinstrument may be very dangerous even if the torquewrench is in proper working order, or appears to be inproper working order but is out of calibration.

(e) The failure to follow manufacturer instructions[see para. 7(b)] for the use of these instruments is farmore serious than with most hand tools. For most handtools, improper use will harm only the user, butimproper use of a torque instrument could lead to sys-temic failure.



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ASME B107.300-2010 (B107.29)

ASME B107.29

1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

6 Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

7 Safety Requirements and Limitations of Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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ASME B107.300-2010 (B107.29)

ELECTRONIC TESTER, HAND TORQUE TOOLS

1 SCOPE

This Standard provides performance and safetyrequirements for electronic torque testers used for check-ing manually operated hand-held torque wrenches andtorque screwdrivers.

2 CLASSIFICATION

2.1 Type I: Torque Tester With Torque-GeneratingUnit

Class A: accuracy ±0.25% of indicated valueClass B: accuracy ±0.50% of indicated valueClass C: accuracy ±1% of indicated value

2.2 Type II: Torque Tester With Hand Actuation

Class A: accuracy ±0.25% of indicated valueClass B: accuracy ±0.50% of indicated valueClass C: accuracy ±1% of indicated value

3 REFERENCES

The following documents are referenced in thisStandard. The latest edition shall be used.


ASME B107.14, Hand Torque Tools (Mechanical)ASME B107.28, Electronic Torque InstrumentsPublisher: The American Society of Mechanical

Engineers (ASME), Three Park Avenue, New York,NY 10016-5990; Order Department: 22 Law Drive, P.O.Box 2300, Fairfield, NJ 07007-2300 (www.asme.org)



4 DEFINITIONS

accuracy: the difference between a known applied torqueand the torque displayed on the electronic indicator mea-sured in percentage of the displayed torque.

first peak: the maximum torque value just prior to thetorque drop-off, which on Type II torque wrenchesoccurs as the wrench begins its momentary reductionin torque.

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peak: the maximum torque value reached during theprocess of applying the load to the wrench.

rated capacity: the maximum intended torque the usershall measure or apply.

resolution: the smallest distinguishable change in dis-played value.

track: continuous readout of torque applied at anymoment.

usable range of the transducer: the range to which theaccuracy requirements of para. 5.2 are applied.

5 REQUIREMENTS

The tester shall pass all tests in section 6. Conformancewith requirements not verified by test shall be estab-lished by visual examination. The composition and char-acteristics of coatings and finishes shall be determinedeither by appropriate tests or by reference to the manu-facturer ’s specifications, drawing, or procurementdocuments.

5.1 Design

The tester shall be designed for checking clockwiseand counterclockwise hand torque tools conforming toASME B107.14 and ASME B107.28.

The tester shall consist of the following components:(a) Electronic Torque Indicator. The tester shall have an

electronic digital indicator. The digital indicator must beeasily viewed and accessed by the operator. Indicationsshall be provided on the panel of the digital indicatorto indicate, at a minimum, the following conditions:

(1) power on(2) torque units of measure(3) operating modes

(a) first peak(b) peak(c) track

(4) clockwise or counterclockwise operation(b) Controls. All controls shall be readily accessible

and clearly identified.(c) Overload Indication. A visual, audible, or both,

overload indication shall be provided.(d) Calibration Adjustment. A means shall be provided

to calibrate the equipment or change any calibrationfactor or other correction data stored in the memory ofthe equipment.



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ASME B107.300-2010 (B107.29)

(e) Torque Transducers. Multiple torque transducersmay be used to cover the range of the torque tester.Transducers shall be interchangeable. The usable rangeof the transducer shall be clearly indicated on the trans-ducer’s label. The drives on the transducer, adapter, orboth, shall conform to ASME B107.4.

(f) Torque-Generating Unit. The Type I tester shall havea torque-generating unit. The torque-generating unit’ssensitivity must be commensurate with the resolutionof the indicator. During testing, the application of theload on the handle shall be applied in accordance withthe test procedure specified in ASME B107.28 andASME B107.14.

5.2 Accuracy and Resolution

Accuracy of the measured torque and resolution shallnot exceed the values shown below.

ResolutionClass (Percent of Rated Capacity) Accuracy

A 0.01 ±0.25B 0.02 ±0.50C 0.05 ±1.00

The accuracy test shall be conducted at a minimumof three values, including both ends of the usable range.

5.3 Materials

The materials used in the manufacture of torque test-ers shall be such as to ensure compliance with therequirements of this Standard.

5.4 Operating Conditions

The tester shall meet the requirements of the Standardwithin a temperature of 64°F (17°C) to 82°F (27°C) withrelative humidity up to 90% (noncondensing).

5.5 Overload

The tester shall be capable of transmitting an amountof torque equal to 125% of the rated capacity in bothdirections without physical failure.

5.6 Calibration

The tester shall be capable of being calibrated to thespecified accuracy by a method traceable to the NationalInstitute of Standards and Technology (NIST).

6 TESTS

Many tests required herein are inherently hazardous,and adequate safeguards for personnel and propertyshall be employed in conducting such tests. These testsare designed to evaluate the tools and materials and donot condone the use of the tools in an environment orin a manner inconsistent with safe use of the tools.

Testing shall be performed at a temperature not fluctu-ating by more than 2°F (1°C). This temperature shall be

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in the range of 64°F (17°C) to 82°F (27°C) (maximumrelative humidity 90%) and shall be documented.

6.1 Accuracy Tests

6.1.1 Measuring Equipment. Accuracy testing shallbe performed by the use of a deadweight standard. Theaccuracy of the deadweight standard (weights and cali-bration arms combined) shall be at least four times betterthan the accuracy of the tested electronic torque tester.

6.1.2 Test Sequence. Accuracy test readings shallbe taken in progression from lower torque values tohigher ones.

(a) The torque tester shall be loaded to rated capacitythree times in the direction of test.

(b) The load shall be removed and the tester shall bezeroed.

(c) Accuracy test readings shall be taken from lowto high.

(d) Repeat from step (a) using next direction of testas applicable.

6.2 Overload Test

The torque tester shall be loaded once to 125% of fullcapacity in each direction. The torque tester shall becapable of withstanding an amount of torque equal to125% of maximum capacity in each direction withoutphysical failure.

6.3 Endurance Test

The torque tester shall perform satisfactorily for 5,000cycles in each direction of operation at maximum capac-ity without physical failure while maintaining therequired level of accuracy. Subsequently, the torque tes-ter shall perform for 50,000 cycles in each direction ofoperation at 50% of capacity without physical failure.Subsequent to the 50,000 cycles in each direction, thetorque tester and generating unit shall be capable ofbeing calibrated within the specified accuracy.


(a) Instructors and employers shall stress proper useand safety in the use of this special-purpose tool andshall emphasize the necessity to wear and ensure theuse of appropriate eye protection. The publication,Guide to Hand Tools — Selection, Safety Tips, Proper Useand Care, provides guidelines for safe use of these tools.

(b) The torque tester shall be conveniently and easilyoperated and not constitute a hazard to the operatorunder normal operating conditions.

(c) The tester shall be supplied with instructions cov-ering its accuracy, application, calibration, installation,setup, and safe use.



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ASME B107.300-2010

NONMANDATORY APPENDIX ATABLES

Table A-1 Examples of Accuracy Percent Calculation for ASME B107.14

Torque Wrench Measured Value Calculation of Difference Between Calculation ofIndicated Value on Tester Measured and Indicated Value Error Indication Calculation of Percent

100 ft. lb 103 103 − 100 p 3 3⁄100 p +0.03 0.03 � 100 p 3%100 ft. lb 102 102 − 100 p 2 2⁄100 p +0.02 0.02 � 100 p 2%100 ft. lb 98 98 − 100 p −2 −2⁄100 p −0.02 −0.02 � 100 p −2%

60 ft. lb 62 62 − 60 p 2 2⁄60 p +0.0333 0.0333 � 100 p 3.33%60 ft. lb 61 61 − 60 p 1 1⁄60 p +0.0167 0.0167 � 100 p 1.67%60 ft. lb 57 57 − 60 p −3 −3⁄60 p −0.05 −0.05 � 100 p −5%

20 ft. lb 19.5 19.5 − 20 p −0.5 −0.5⁄20 p −0.025 −0.025 � 100 p −2.5%20 ft. lb 21 21 − 20 p 1 1⁄20 p +0.05 0.05 � 100 p 5.0%20 ft. lb 23 23 − 20 p 3 3⁄20 p +0.15 0.15 � 100 p 15.0%

Table A-2 Examples of Test Point Calculation forASME B107.14 [Reference 6.3(b)]

Torque Wrench Scale Graduations

Maximum graduation: 200 in. lbMinimum graduation: 20 in. lbIncrements: 2 in. lb

Test Point Calculations

20% test toint: 0.2 � 200 in. lb p 40 in. lb (or nearest to 40 in. lb)60% test point: 0.6 � 200 in. lb p 120 in. lb (or nearest to 120 in. lb)100% test point: 1 � 200 in. lb p 200 in. lb (or nearest to 200 in. lb)

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N10910

ASME B107.300-2010



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Documents

ASME B107.300-2010 Torque Instruments