ASTM D4063-99(2022)

Standard Specification for Pressboard for Electrical Insulating Purposes

ABSTRACT
This specification covers pressboard for electrical insulating purposes as well as for dielectrical or structural purposes in transformers and other electrical apparatus. Pressboards under this specification are of three types: Type 1 consists of high-purity (Grade 1.1) calendered pressboards, while Type 2 consists of normal-purity (Grades 2.1.1, 2.2.1, 2.3.1, and 2.3.2) calendered pressboards. Precompressed pressboards (Grades 3.1.1, 3.2.1, and 3.3) fall under Type 3. Not included in this specification, however, are pressboards comprised of two or more sheets laminated together using an adhesive. Pressboards shall be manufactured from unbleached kraft pulp, cotton pulp, or a combination of both, and shall conform to the thickness, density, surface texture (smooth calendered surface for Types1 and 2, and fine-textured finish for Type 3), and color (from tan to blue-gray, depending on the pressboard's grade) requirements specified. The pressboard must also be free of dirt, metal particles, and other foreign material. Tests for apparent density, thickness, moisture and ash content, aqueous extract conductivity, chloride content, tensile strength, pH of aqueous extract, dielectric strength in air and in oil, shrinkage, and compressibility shall be performed and shall conform to the requirements specified.
SCOPE
1.1 This specification covers pressboard for electrical insulating purposes, manufactured from kraft, cotton, or kraft and cotton pulps. This board is intended for dielectrical or structural purposes in transformers and other electrical apparatus.  
1.2 Electrical insulating boards are most commonly referred to (and will be referred to herein) as pressboard. Other terms used for pressboard include transformer board, fuller board, and presspan.  
1.3 This specification covers pressboard having a nominal thickness of 0.030 to 0.315 in. (0.8 to 8.0 mm). For thinner material refer to Specification D1305.  
1.4 The maximum thickness available will differ with the type and the manufacturer. The maximum sheet size will differ with the thickness, type, and manufacturer.  
1.5 Pressboard shall normally be plied wet without pasting. Unless specified by the purchaser, this specification does not include pressboard comprised of two or more sheets that have been laminated together using an adhesive.
Note 1: The materials described in this specification are similar to corresponding types of pressboard described in IEC Specification 641-3, Sheet 1, Types B.0.1, B.2.1, B.2.3, B.3.1, and B.3.3.  
1.6 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.7 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: 30-Apr-2022
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.01 - Electrical Insulating Products

Relations

• Refers: ASTM D1711-24 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Mar-2024
• Refers: ASTM D1711-15 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2015
• Refers: ASTM D1711-14a - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2014
• Refers: ASTM D1711-14 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-May-2014
• Refers: ASTM D1711-13 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Nov-2013
• Refers: ASTM D1711-11a - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Aug-2011
• Refers: ASTM D3394-94(2009) - Standard Test Methods for Sampling and Testing Electrical Insulating Board
• Effective Date: 01-Oct-2009
• Refers: ASTM D1305-99(2009) - Standard Specification for Electrical Insulating Paper and Paperboard-Sulfate (Kraft) Layer Type
• Effective Date: 01-Oct-2009
• Refers: ASTM D1711-08 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-May-2008
• Refers: ASTM D3394-94(2005) - Standard Test Methods for Sampling and Testing Electrical Insulating Board
• Effective Date: 01-Sep-2005
• Refers: ASTM D1711-02 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 10-Mar-2002
• Refers: ASTM D3394-94(2000) - Standard Test Methods for Sampling and Testing Electrical Insulating Board
• Effective Date: 10-Apr-2000
• Refers: ASTM D1711-99 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 10-Oct-1999
• Refers: ASTM D1305-99(2004) - Standard Specification for Electrical Insulating Paper and Paperboard-Sulfate (Kraft) Layer Type
• Effective Date: 10-Mar-1999
• Refers: ASTM D1305-99 - Standard Specification for Electrical Insulating Paper and Paperboard-Sulfate (Kraft) Layer Type
• Effective Date: 10-Mar-1999

Overview

ASTM D4063-99(2022) is the international standard specification developed by ASTM International for pressboard used in electrical insulating applications. This standard provides comprehensive requirements for the material, manufacture, properties, and testing of pressboard intended for dielectric or structural purposes in transformers and various electrical apparatus. The specification addresses multiple types and grades of pressboard made from unbleached kraft pulp, cotton pulp, or their combination. It outlines requirements to ensure pressboard performance, such as thickness, density, dielectric strength, moisture content, and resistance to contaminants, which are crucial for maintaining the reliability and safety of electrical equipment.

Key Topics

• Types and Grades:
  ASTM D4063-99(2022) covers three main types of pressboard:
  • Type 1: High-purity calendered pressboard (Grade 1.1)
  • Type 2: Normal-purity calendered pressboard (Grades 2.1.1, 2.2.1, 2.3.1, 2.3.2)
  • Type 3: Precompressed pressboard (Grades 3.1.1, 3.2.1, 3.3)
• Material Composition:
  • Manufactured from unbleached kraft pulp, cotton pulp, or a combination
  • Trace amounts of one type of pulp are permitted in grades based on the other
• Physical and Electrical Properties:
  • Thickness range: 0.030 to 0.315 inches (0.8 to 8.0 mm)
  • Requirements for density, tensile strength (machine and cross-machine direction), compressibility, and shrinkage
  • Dielectric strength both in air and in oil, crucial for insulation integrity
  • Limits for moisture, ash, and chloride content, as well as aqueous extract conductivity and pH
• Surface and Appearance:
  • Types 1 and 2 feature smooth calendered surfaces; Type 3 has a fine-textured, press-dried finish
  • Color ranges from tan to blue-gray depending on the grade
  • Must be free from dirt, metal particles, and foreign matter

Applications

ASTM D4063-99(2022) pressboard is widely used in:

• Transformers:
  • As an electrical insulation component, especially for windings and core insulation
  • Used as spacers, barriers, and support structures due to high mechanical strength and dielectric properties
• Electrical Apparatus:
  • Applied in switchgear, reactors, and other high-voltage equipment where consistent electrical insulation is required
• Industries:
  • Power generation and distribution equipment manufacturing
  • Maintenance and repair of electrical transformers and related apparatus

Benefits of Compliance:

• Ensures electrical safety and reliability by specifying material integrity and performance
• Facilitates interoperability and material sourcing through clear product classification
• Reduces risk of equipment failure due to insulation breakdown

Related Standards

• ASTM D1305: Specification for Electrical Insulating Paper and Paperboard-Sulfate (Kraft) Layer Type, covering thinner insulating materials
• ASTM D1711: Standard Terminology Relating to Electrical Insulation, providing definitions relevant to insulating materials
• ASTM D3394: Test Methods for Sampling and Testing Electrical Insulating Board, referenced for evaluation procedures
• IEC 641-3: Specification for Pressboard and Presspaper for Electrical Purposes, offering international correlation for similar materials

Keywords: ASTM D4063, electrical pressboard, electrical insulation, transformer board, dielectric strength, kraft pulp, cotton pulp, precompressed pressboard, electrical apparatus insulation, insulating materials standards

By adhering to ASTM D4063-99(2022), manufacturers and users ensure pressboard insulation is optimized for electrical safety, mechanical stability, and longevity in demanding power system environments.

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:D4063 −99 (Reapproved 2022)
Standard Specification for
Pressboard for Electrical Insulating Purposes
This standard is issued under the fixed designation D4063; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This specification covers pressboard for electrical insu-
D1305 Specification for Electrical Insulating Paper and
lating purposes, manufactured from kraft, cotton, or kraft and
Paperboard—Sulfate (Kraft) Layer Type
cotton pulps. This board is intended for dielectrical or struc-
D1711 Terminology Relating to Electrical Insulation
tural purposes in transformers and other electrical apparatus.
D3394 Test Methods for Sampling and Testing Electrical
1.2 Electrical insulating boards are most commonly referred
Insulating Board
to (and will be referred to herein) as pressboard. Other terms
2.2 IEC Standards-Publication:
used for pressboard include transformer board, fuller board,
641-3, Specification for Pressboard and Presspaper for Elec-
and presspan.
trical Purposes–Part 3
1.3 This specification covers pressboard having a nominal
3. Terminology
thickness of 0.030 to 0.315 in. (0.8 to 8.0 mm). For thinner
3.1 Definitions:
material refer to Specification D1305.
3.1.1 For definitions of terms used in this specification refer
1.4 The maximum thickness available will differ with the to Terminology D1711.
type and the manufacturer. The maximum sheet size will differ 3.1.2 calendered pressboard, n—pressboard produced by
drying without restraint and then calendering between steel
with the thickness, type, and manufacturer.
rolls to obtain the desired thickness and density.
1.5 Pressboard shall normally be plied wet without pasting.
3.1.3 cotton pulp, n—cellulose fibers normally obtained by
Unless specified by the purchaser, this specification does not
pulping of new cotton garment cuttings.
include pressboard comprised of two or more sheets that have
3.1.3.1 Discussion—Included in cotton pulp is pulp called
been laminated together using an adhesive.
cotton-linter pulp which is derived from cotton fibers adhered
to cotton seed but separated from cotton seed subsequent to
NOTE 1—The materials described in this specification are similar to
corresponding types of pressboard described in IEC Specification 641-3,
ginning.
Sheet 1, Types B.0.1, B.2.1, B.2.3, B.3.1, and B.3.3.
3.1.4 kraft pulp, n (unbleached sulfate pulp)—cellulose
1.6 The values stated in inch-pound units are to be regarded fibers normally obtained from softwood (coniferous) trees
using the sulfate kraft process of cooking.
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
3.1.5 precompressed pressboard, n—pressboard produced
and are not considered standard.
by press-drying between heated platens to obtain desired
thickness and density.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Classification
ization established in the Decision on Principles for the
4.1 This specification covers the following three types of
Development of International Standards, Guides and Recom-
pressboard:
mendations issued by the World Trade Organization Technical
4.1.1 Type 1—High-purity calendered pressboard.
Barriers to Trade (TBT) Committee.
4.1.2 Type 2—Normal-purity calendered pressboard.
1 2
This specification is under the jurisdiction of ASTM Committee D09 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Electrical and Electronic Insulating Materials and is the direct responsibility of contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Subcommittee D09.01 on Electrical Insulating Products. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2022. Published May 2022. Originally the ASTM website.
approved in 1981. Last previous edition approved in 2016 as D4063 – 99 (2016). Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/D4063-99R22. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4063−99 (2022)
TABLE 2 Type 1–High-Purity Calendered Pressboard
4.1.3 Type 3—Precompressed pressboard.
Grade
Number 1.1.1
5. Ordering Information
Apparent density (Procedure A):
5.1 Orders for material furnished under this specification 3
0.030 to 0.050 in. (0.76 to 1.27 mm) g/cm 1.00 to 1.15
shall include: 0.051 to 0.090 in. (1.30 to 2.29 mm) g/cm 0.95 to 1.10
0.091 to 0.140 in. (2.32 to 3.65 mm) g/cm 0.90 to 1.05
5.1.1 Name of material,
>0.140 in. (3.56 mm) g/cm 0.90 to 1.05
5.1.2 Grade of pressboard (selected from Table 1),
Thickness:
5.1.3 Quantity (weight or number of sheets), 0.030 to 0.050 in. (0.76 to 1.27 mm) % ± 10
0.051 to 0.090 in. (1.30 to 2.29 mm) % ± 8
5.1.4 Dimensions (thickness, width, length), and
0.091 to 0.140 in. (2.32 to 3.65 mm) % ± 6
5.1.5 Additions or exceptions to the specification and
>0.140 in. (3.56 mm) % ± 6
Moisture % 4.0 to 8.0
supplementary requirements, if required, such as thermally
Ash % max 0.75
upgraded material.
Aqueous extract conductivity µS/cm max 20
Chloride content ppm max 8.0
6. Materials and Manufacture
Tensile strength, machine direction:
0.030 to 0.050 in. (0.76 to 1.27 mm) psi (MPa) min 9 000 (62)
6.1 The pressboard will be manufactured from unbleached
0.051 to 0.090 in. (1.30 to 2.29 mm) psi (MPa) min 8 000 (55)
0.091 to 0.140 in. (2.32 to 3.65 mm) psi (MPa) min 8 000 (55)
kraft pulp, cotton pulp, or a combination of unbleached kraft
>0.140 in. (3.56 mm) psi (MPa) min 7 000 (48)
pulp and cotton pulp.
Tensile strength, cross machine direction:
0.030 to 0.050 in. (0.76 to 1.27 mm) psi (MPa) min 5 000 (34)
6.2 The proportion of cotton pulp, by weight, will be as
0.051 to 0.090 in. (1.30 to 2.29 mm) psi (MPa) min 4 500 (31)
specified in Table 1.
0.091 to 0.140 in. (2.32 to 3.65 mm) psi (MPa) min 4 000 (28)
>0.140 in. (3.56 mm) psi (MPa) min 3 500 (24)
6.3 Cotton pulp in trace quantities in kraft pulp grades is
pH of aqueous extract: 6.0 to 9.0
permitted. Kraft pulp in trace quantities in cotton pulp grades
Dielectric strength in air:
0.030 to 0.050 in. (0.76 to 1.27 mm) V/mil (kV/mm) min 225 (9)
is permitted.
0.051 to 0.090 in. (1.30 to 2.29 mm) V/mil (kV/mm) min 200 (8)
6.4 No ingredients other than the cellulose fibers listed in
0.091 to 0.140 in. (2.32 to 3.65 mm) V/mil (kV/mm) min 200 (8)
>0.140 in. (3.56 mm) V/mil (kV/mm) min 175 (7)
6.1 or additions listed in 5.1.5 shall be permitted.
Dielectric strength in oil:
0.030 to 0.050 in. (0.76 to 1.27 mm) V/mil (kV/mm) min —
7. Property Requirements
0.051 to 0.090 in. (1.30 to 2.29 mm) V/mil (kV/mm) min —
0.091 to 0.140 in. (2.32 to 3.65 mm) V/mil (kV/mm) min —
7.1 Pressboard shall conform to the requirements listed in
>0.140 in. (3.56 mm) V/mil (kV/mm) min —
Tables 2-4 as applicable.
Shrinkage:
Machine direction % max 0.75
NOTE 2—Properties for grades listed in Table 1 but not established in
Cross-machine direction % max 1.25
Tables 2-4 are being considered.
Compressibility at 3 000 psi (21 MPa), % max 15
Procedure A
8. Workmanship, Finish, and Appearance
8.1 The pressboard will have the thickness, density, surface
texture, and color as agreed upon between the purchaser and 8.5 The presence of dirt and other foreign materials is
undesirable.Thepressboardwillbefreeofdirt,metalparticles,
the supplier.
and other foreign material.
8.2 Sheets shall be of width and length with dimensions
within limits agreed upon between the purchaser and the
9. Sampling
supplier.
9.1 Sample in accordance with Test Methods D3394.
8.3 Colorwillbetantoblue-gray,dependinguponthegrade
of pressboard.
10. Test Methods
8.4 Types 1 and 2 will have a smooth calendered surface.
10.1 Testinaccordanc
...