ASTM F2973-21

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Designation: F2973 − 16 F2973 − 21
Standard Specification for
Insulating Lifting Links for Load Lifting Equipment Working
Near Energized Power Lines
This standard is issued under the fixed designation F2973; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers insulating lifting links used for protection of workers positioning a load from accidental contact of
the load lifting equipment with live electrical conductors, apparatus, and circuits.
1.2 This specification includes design, material, and testing requirements for the manufacturer and in-service inspection, testing
and care requirements for the user or the agent of the user.
1.3 Insulating links whose primary application does not pertain to power line electrical safety are not within the scope of this
specification.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
F819 Terminology Relating to Electrical Protective Equipment for Workers
2.2 IEEE Standard:
IEEE 4 Standard Techniques for High-Voltage Testing
2.3 ISO Standard:
ISO 7500–1 Metallic Materials—Verification of Static Uniaxial Testing Machines—Part 1: Tensile Testing Machines—
Corrigendum
This specification is under the jurisdiction of ASTM Committee F18 on Electrical Protective Equipment for Workers and is the direct responsibility of Subcommittee
F18.55 on Inspection and Non-Destructive Test Methods for Aerial Devices.
Current edition approved Oct. 1, 2016May 1, 2021. Published November 2016May 2021. Originally approved in 2014. Last previous edition approved in 20152016 as
F2973 – 15.16. DOI: 10.1520/F2973-1610.1520/F2973-21
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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3. Terminology
3.1 Definitions—Terminology used in this specification is in accordance with Terminology F819.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 design verification test, n—test made on a sample treated as representative of an industrial product.
3.2.2 electrical test, n—a test ensuring that a product meets the minimum electrical requirements of the standard.
3.2.3 flashover, n—a disruptive discharge over the surface of the insulating link.
3.2.4 mechanical test, n—a test confirming that a product meets the minimum mechanical requirements of a standard.
3.2.5 proof load, n—specific mechanical load applied in the performance of the proof load test.
3.2.6 proof test, n—mechanical and electrical tests performed by the manufacturer on all production units.
3.2.7 puncture, n—disruptive discharge through an insulator.
3.2.8 qualified personnel, n—personnel who, by possession of a recognized degree, certificate, professional standing, or skill, and
who, by knowledge, training, and experience, have demonstrated the ability to deal with problems relating to the subject matter,
the work, or the project.
3.2.9 rated load, n—the maximum working load.
3.2.10 visual inspection, n—visual check made to detect defects that impede the performance of a product(s).
4. Materials and Manufacture
4.1 The mechanical design factor shall not be less than 5.0 times its rated load for ratings up to 100 tons and 4.0 times rated load
for ratings 100 tons and up.
4.2 The electrical design factor of the link shall not be less than 2 times it rated use voltage.
4.3 The insulation system shall not absorb water and shall have a water repellent surface.
4.4 Weather shields shall be made of impact resistant nonconductive material.
4.5 UV resistant polymers should be employed by the manufacturer if, without them, electrical performance may be affected.
4.6 Steel used shall meet ASTM or AISI standards.
5. Workmanship and Finish
5.1 The insulating surface of the links shall be free of cracks, nicks, gouges, damage to the insulating surface that would affect
its insulating properties in both dry and wet conditions.
5.2 Markings—Each link should bear permanent, accessible, and readily visible markings that include, at a minimum, the
manufacturer’s mark, ASTM XXX, unit serial number, rated voltage, and rated load.
5.3 Manuals—The manufacturer shall provide a manual with each link. The manual shall contain:
5.3.1 Descriptions, specifications, and ratings of the link.
F2973 − 21
5.3.2 Ambient temperature range for which the link is designed.
5.3.3 Precautions concerning weather.
5.3.4 Instructions regarding routine and frequency of inspections and maintenance.
6. General Test Requirements
6.1 Personnel responsible for the tests outlined in this document shall be qualified individuals in accordance with 3.2.8,
knowledgeable in the use of the test equipment used for tensile loading and high-voltage testing.
6.2 The electrical test equipment shall meet the requirements of IEEE 4-1995. The metering systems including measurement cable
used to measure AC current shall have a system error of 5 % or less.
6.3 The electrical test set up shall provide the operator protection in the performance of his duties and isolate the specimen to guard
against accidental contact by persons in the vicinity.
6.4 The ambient temperature for the test location shall not be lower than 15.5°C.15.5 °C.
6.5 Electrical discharge characteristics and measured current of a test object can be affected by its general arrangement, such as
the clearance from other energized or grounded structures, the height above ground level, or the arrangement of the high-voltage
lead that may affect flashover voltages. For that reason, the general arrangement should be as shown in Fig. 1 for testing links that
are not installed on load lifting equipment.
6.6 Clearance to nearby structures that are equal to or greater than two times the length of the shortest possible electrical discharge
path on the test object should make any proximity effects negligible.
7. Design Verification Tests
7.1 Design verification tests are to be performed on at least one representative unit from each class of insulating link, and this will
qualify that class of link models of variable rated loads for a given rated voltage. A test unit is considered to be representative of
its group if it meets the following requirements:
7.1.1 The same structural and dielectric materials, structural designs, manufacturing, and assembly methods apply to all links in
the group,
7.1.2 The same structural stress and loading analysis can be applied to all the links in the group,
7.1.3 The test unit has the same or smaller electrical creepage and arcing distances per kV of rating.
FIG. 1 Suggested Test Set Up for Insulated Links
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7.2 Mechanical Design Verification Test Procedure:
7.2.1 The insulating link shall withstand a tensile load test of 5.0 times its rated load for rating up to 100 tons and 4.0 times rated
load for ratings 100 tons and up for 60 s without separation. The tensile load test is to be performed on a test bed or hydraulic
pulling machine calibrated to the latest revision of either ASTM E4 or ISO 7500–1.
7.3 Electrical Design Verification Test Procedure:
7.3.1 Three electrical tests to verify design voltage rating shall be peformed.
7.3.2 The insulating link will withstand an applied AC voltage while dry of twice the link-rated AC voltage for 5 min without
dielectric puncture or flashover and leakage of no more than 3 mA.
7.3.3 The link shall be tested to verify that it does not absorb water with time.
7.3.3.1 Install the link in a humidity chamber for 48 h at a temperature between 65 and 100°F 100 °F with a minimum of 93 %
relative humidity.
7.3.3.2 Within a time frame of 5 min after removal from humidity chamber in the vertical use position, apply test voltage in
accordance with Table 1. Increase voltage at approximately 3 kV per second and hold for 3 min.
7.3.3.3 Measure and record the leakage current. A leakage current in excess of the values in Table 1 signifies a failure.
7.3.4 The link shall be tested to verify that it has a water repellent surface.
7.3.4.1 Immerse the entire link completely in a tank under tap water at room temperature for a minimum of 1 min.
7.3.4.2 In the vertical use position allow to set for 2 min to allow water to run off.
7.3.4.3 Apply test voltage in accordance with Table 1 within a time frame of 5 min after wetting
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