ASTM D4731-13(2020)

Standard Specification for Hot-Application Filling Compounds for Telecommunications Wire and Cable

ABSTRACT
This specification covers a variety of petroleum-based and other compounds used for filling the air spaces in telecommunications wires and cables (both electrical and fiber optic) for the purpose of preventing water and other undesirable fluids from entering or migrating through the cable structure. The two basic types of filling compounds are specified: Type I which are general-purpose filling compounds that include all materials to be used for filling cables that are not required to function under electrical stress and Type II which are electrical-type filling compounds that include materials having prescribed electrical properties and used for filling wires and cables that are required to function fully or partially under electrical stress. Filling compound furnished shall inhibit the corrosion of any metallic wire and cable elements with which it comes in contact, while serving as a radial and longitudinal barrier to moisture transmission. Contact of the filling compound with any cable component shall not cause degradation of performance of the cable component. The filling compound shall display adhesive properties to provide adhesion between metallic sheath elements and the outer jacket materials of wire and cable. The following properties of filling compounds manufactured shall be determined: homogeneity, color and opacity, color stability, foreign materials, and other properties that includes volatility, thermal oxidative stability, and corrosion prevention.
SCOPE
1.1 This specification covers a variety of petroleum-based and other compounds used for filling the air spaces in telecommunications wires and cables (both electrical and fiber optic) for the purpose of preventing water and other undesirable fluids from entering or migrating through the cable structure. (For related standards see Specifications D4730 and D4732).  
1.2 A hot-application compound is a material that requires melting in order to be applied as a liquid and its melting point affects its performance in the finished cable product.  
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.4 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.

General Information

• Status: Published
• Publication Date: 31-Jul-2020
• ICS: 33.120.10 - Coaxial cables. Waveguides
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.07 - Electrical Insulating Materials

Relations

• Refers: ASTM D445-24 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Apr-2024
• Refers: ASTM D1500-24 - Standard Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
• Effective Date: 01-Mar-2024
• Refers: ASTM D445-23 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Nov-2023
• Refers: ASTM D4568-13(2020) - Standard Test Methods for Evaluating Compatibility Between Cable Filling and Flooding Compounds and Polyolefin Wire and Cable Materials
• Effective Date: 01-Aug-2020
• Refers: ASTM D4730-13(2020) - Standard Specification for Flooding Compounds for Telecommunications Wire and Cable
• Effective Date: 01-Aug-2020
• Refers: ASTM D445-16 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Dec-2016
• Refers: ASTM D2161-10(2016) - Standard Practice for Conversion of Kinematic Viscosity to Saybolt Universal Viscosity or to Saybolt Furol Viscosity
• Effective Date: 01-Jul-2016
• Refers: ASTM D127-08(2015) - Standard Test Method for Drop Melting Point of Petroleum Wax, Including Petrolatum
• Effective Date: 01-Jan-2015
• Refers: ASTM D445-14 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D445-14e1 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D4568-13 - Standard Test Methods for Evaluating Compatibility Between Cable Filling and Flooding Compounds And Polyolefin Wire and Cable Materials
• Effective Date: 01-Nov-2013
• Refers: ASTM D4730-13 - Standard Specification for Flooding Compounds for Telecommunications Wire and Cable
• Effective Date: 01-May-2013
• Refers: ASTM D97-12 - Standard Test Method for Pour Point of Petroleum Products
• Effective Date: 01-Dec-2012
• Refers: ASTM D1500-12 - Standard Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
• Effective Date: 01-Dec-2012
• Refers: ASTM D92-12a - Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester
• Effective Date: 01-Nov-2012

Overview

ASTM D4731-13(2020) is the internationally recognized standard developed by ASTM for hot-application filling compounds intended for use in telecommunications wire and cable. This specification details requirements for petroleum-based and other compounds used to fill air spaces in both electrical and fiber optic cables. The primary purpose of these filling compounds is to prevent the ingress and migration of water and other undesirable fluids within the cable structure, preserving cable integrity and functionality in varied installation environments, such as aerial, buried, or underground settings.

Key Topics

• Types of Filling Compounds

  • Type I (General Purpose): Suitable for cables not subject to electrical stress, including most fiber optic cables and loose buffer tubes.
  • Type II (Electrical): Designed for wires and cables that must function fully or partially under electrical stress, with specific electrical properties.

• Core Requirements

  • Corrosion Inhibition: Compounds must protect metallic cable elements from corrosion.
  • Moisture Barrier: Must act as a longitudinal and radial barrier against fluid entry.
  • Compatibility: Should not degrade the performance of any cable component it contacts.
  • Adhesion: Required to provide strong adhesion between metallic sheath elements and outer cable jacket materials.

• Physical and Chemical Properties

  • Compounds are tested for homogeneity, color and opacity, color stability, presence of foreign materials, volatility, thermal oxidative stability, and overall corrosion prevention.
  • Temperature characteristics such as pour point, drop-melting point, viscosity, and congealing point must meet agreed-upon criteria to ensure reliable performance during manufacturing and over the cable’s lifetime.

• Certification and Quality Assurance

  • All products must conform to these requirements and may be provided with certification upon request.
  • Producers must maintain written nominal values and tolerances for quality control, and any significant changes require purchaser approval.

Applications

• Telecommunications Wire and Cable Protection

  • Used in both electrical and fiber optic cables to fill voids and block moisture, ensuring cable longevity and signal reliability.
  • Applicable in harsh environments where resistance to water, chemicals, and environmental stress is essential.
  • Suitable for cables installed aerially, underground, or in buried conduits, where moisture ingress protection is critical.

• Cable Manufacturing

  • The standard supports manufacturers in selecting and specifying appropriate filling materials for their cable products, whether for general-purpose or high-voltage electrical applications.
  • Promotes consistency and performance reliability in end-use products by outlining minimum property requirements and compatible test methods.

Related Standards

• ASTM D4730 - Specification for Flooding Compounds for Telecommunications Wire and Cable
• ASTM D4732 - Specification for Cool-Application Filling Compounds for Telecommunications Wire and Cable
• ASTM D4568 - Test Methods for Evaluating Compatibility Between Cable Filling and Flooding Compounds and Polyolefin Wire and Cable Materials
• ASTM D445, D97, D127, D1500, D257, D92, and others - Test methods referenced for evaluating key physical, chemical, and electrical properties of filling compounds.

Practical Value

Implementing ASTM D4731-13(2020) enhances the moisture and corrosion resistance of telecommunications cables, supporting long-term performance and reducing maintenance due to water ingress or component degradation. The standard ensures material consistency and quality, providing a solid reference for cable manufacturers, installers, and specifiers in the telecommunications sector who seek durable and reliable cable protection solutions. By adhering to these guidelines, stakeholders can confidently address environmental risks and maintain high standards in communication infrastructure.

Standards Content (Sample)

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.
Designation: D4731 −13 (Reapproved 2020)
Standard Specification for
Hot-Application Filling Compounds for Telecommunications
Wire and Cable
This standard is issued under the fixed designation D4731; 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 D257 Test Methods for DC Resistance or Conductance of
Insulating Materials
1.1 This specification covers a variety of petroleum-based
D445 Test Method for Kinematic Viscosity of Transparent
and other compounds used for filling the air spaces in telecom-
and Opaque Liquids (and Calculation of Dynamic Viscos-
munications wires and cables (both electrical and fiber optic)
ity)
forthepurposeofpreventingwaterandotherundesirablefluids
D938 Test Method for Congealing Point of Petroleum
from entering or migrating through the cable structure. (For
Waxes, Including Petrolatum
related standards see Specifications D4730 and D4732).
D1500 Test Method forASTM Color of Petroleum Products
1.2 A hot-application compound is a material that requires
(ASTM Color Scale)
melting in order to be applied as a liquid and its melting point
D2161 Practice for Conversion of Kinematic Viscosity to
affects its performance in the finished cable product.
Saybolt Universal Viscosity or to Saybolt Furol Viscosity
D3895 Test Method for Oxidative-Induction Time of Poly-
1.3 The values stated in SI units are to be regarded as
standard. The values given in parentheses after SI units are olefins by Differential Scanning Calorimetry
D3954 Test Method for Dropping Point of Waxes
provided for information only and are not considered standard.
D4565 Test Methods for Physical and Environmental Per-
1.4 This international standard was developed in accor-
formance Properties of Insulations and Jackets for Tele-
dance with internationally recognized principles on standard-
communications Wire and Cable
ization established in the Decision on Principles for the
D4568 Test Methods for Evaluating Compatibility Between
Development of International Standards, Guides and Recom-
Cable Filling and Flooding Compounds and Polyolefin
mendations issued by the World Trade Organization Technical
Wire and Cable Materials
Barriers to Trade (TBT) Committee.
D4730 Specification for Flooding Compounds for Telecom-
munications Wire and Cable
2. Referenced Documents
D4732 Specification for Cool-Application Filling Com-
2.1 ASTM Standards:
pounds for Telecommunications Wire and Cable
D6 Test Method for Loss on Heating of Oil and Asphaltic
D4872 Test Method for DielectricTesting ofWire and Cable
Compounds
Filling Compounds
D92 Test Method for Flash and Fire Points by Cleveland
Open Cup Tester
3. Terminology
D97 Test Method for Pour Point of Petroleum Products
D127 Test Method for Drop Melting Point of Petroleum 3.1 Definitions of Terms Specific to This Standard:
3.1.1 filling material, n—anyofseveralmaterialsusedtofill
Wax, Including Petrolatum
D150 Test Methods forAC Loss Characteristics and Permit- the air spaces in the cores of multi-conductor insulated wires
and cables, or between buffer tubes covering optical fibers, or
tivity (Dielectric Constant) of Solid Electrical Insulation
within such buffer tubes, or any combination of these configu-
rations and any other cable components, for the purpose of
This specification is under the jurisdiction of ASTM Committee D09 on
excluding water and other undesirable fluids; especially with
Electrical and Electronic Insulating Materials and is the direct responsibility of
regard to telecommunications wire and cable, including optical
Subcommittee D09.07 on Electrical Insulating Materials. Subcommittee D02.10
contributed in the development of this standard. cable, intended for outside aerial, buried, or underground
Current edition approved Aug. 1, 2020. Published September 2020. Originally
installations.
approved in 1987. Last previous edition approved in 2013 as D4731 – 13. DOI:
3.1.2 producer, n—the primary manufacturer of the mate-
10.1520/D4731-13R20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
rial.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3.1.3 suppliers, n—jobbers and distributors as distinct from
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. producers.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4731 − 13 (2020)
4. Classification 8.1.1 When tested, in accordance with Test Methods D150
or D4872, at a temperature of 23 6 3 °C, the dissipation factor
4.1 Two basic types of filling compounds are covered, as
shall not exceed 0.0010 at a frequency of 1 MHz and the
follows:
permittivity shall not exceed 2.30.
4.1.1 Type I—General-purpose filling compounds include
8.1.1.1 Warning—If any bubbles are formed in melting the
all materials to be used for filling cables that are not required
compound to prepare the specimen for test, the sample shall be
to function under electrical stress (for example, all dielectric
discarded and a new sample selected.
fiber-optic cable), including filling compounds for fiber-optic
8.1.2 When tested, in accordance with Test Methods D257,
loose buffer tubes.
at a temperature of 23 6 3 °C, the volume resistivity shall be
4.1.2 Type II—Electrical-type filling compounds include
not less than 10 Ω·cm.
materials having prescribed electrical properties and used for
filling wires and cables that are required to function fully or
9. Physical Properties
partially under electrical stress (including hybrid fiber-optic
cable).
9.1 Filling compound furnished under this specification
shall inhibit the corrosion of any metallic wire and cable
5. Ordering Information
elements with which it comes in contact, while serving as a
5.1 Orders for material under this specification shall include
radial and longitudinal barrier to moisture transmission. Con-
the following information:
tact of the filling compound with any cable component shall
5.1.1 Quantity (mass or volume) of each item,
not cause degradation of performance of the cable component.
5.1.2 Generic name of the material, such as hot-application
The filling compound shall display adhesive properties to
cable filling material,
provide adhesion between metallic sheath elements and the
5.1.3 Type of material: Type I, General Purpose or Type II,
outer jacket materials of wire and cable.
Electrical,
9.2 Other Physical Properties:
5.1.4 How furnished: drums or barrels, tank cars or tank
9.2.1 Other property requirements such as Flash Point (for
trucks, and the like,
example, Test Method D92), high-temperature drip/oil separa-
5.1.5 Certification, if required (Section 14).
tion (syneresis) in the raw material state, and the like, shall be
5.1.6 This specification designation, and
as agreed upon between the producer and the purchaser.
5.1.7 Any special requirements, as listed in 7.2, 9.2, 10.2,
(Additional information on oil separation is given in the
and Sections 11 and 12 that apply.
appendix of this specification.)
6. Materials and Manufacture
10. General Requirements
6.1 The material and manufacturing methods used shall be
such that the resulting products will conform to the properties 10.1 All filling compounds manufactured in accordance
and characteristics prescribed in this specification. with this specification shall meet the following requirements:
10.1.1 Homogeneity—The compound shall be homoge-
7. Chemical Composition
neous and free of agglomerates.
7.1 The chemical composition of these materials is not 10.1.2 Color and Opacity—The compound shall be as
specified. The material shall be of a chemical composition nearlycolorlessasiscommerciallyfeasible,consistentwiththe
suitable for the intended purpose and that meets the require- requirements of the end products for which the filling com-
ments of this specification as hereinafter stated. pound is intended. In general, identification of cable members
coated with filling compound shall not be significantly inhib-
7.2 When agreed upon between the producer and the
ited because of filling-compound color or opacity.
purchaser, antioxidant stabilizing additives shall be included in
10.1.3 Color Stability—After aging a specimen of filling
thecompoundformulationtoassurespecifiedresultsinthermal
compound in a suitable container for a period of 120 61h
oxidative stability testing.
(5days)atatemperatureof266°F(130°C)inastaticairoven,
7.3 Once established, the producer shall not change the
measure the compound color in accordance with Test Method
composition of the compound in successive lots of material
D1500. Unless otherwise specified, the color of the aged
without prior approval of the purchaser.
compound shall not exceed 2.5.
10.1.4 Foreign Material—The compounds shall b
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