ASTM D3753-20

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D3753 − 19 D3753 − 20
Standard Specification for
Fiberglass (Glass-Fiber-Reinforced Thermosetting-Resin)
Manholes and Wetwells
This standard is issued under the fixed designation D3753; 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 “fiberglass” (glass fiber-reinforced thermosetting-resin) manholes and wetwells fabricated with
polyester, vinyl ester, or epoxy resin for use primarily in sanitary, storm, and industrial sewer applications.
1.2 The values given in inch-pound units are to be regarded as the standard. The values in parentheses are provided for information
purposes only.
1.3 The following precautionary caveat pertains only to the test methods portion, Section 8, of this specification: 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, health, and environmental practices and determine the applicability of regulatory
limitations prior to use.
NOTE 1—There is no known ISO equivalent to this 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.
2. Referenced Documents
2.1 ASTM Standards:
C581 Practice for Determining Chemical Resistance of Thermosetting Resins Used in Glass-Fiber-Reinforced Structures
Intended for Liquid Service
D695 Test Method for Compressive Properties of Rigid Plastics
D785 Test Method for Rockwell Hardness of Plastics and Electrical Insulating Materials
D790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
D883 Terminology Relating to Plastics
D1600 Terminology for Abbreviated Terms Relating to Plastics
D2412 Test Method for Determination of External Loading Characteristics of Plastic Pipe by Parallel-Plate Loading
D2583 Test Method for Indentation Hardness of Rigid Plastics by Means of a Barcol Impressor
D2584 Test Method for Ignition Loss of Cured Reinforced Resins
D3892 Practice for Packaging/Packing of Plastics
This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.23 on Reinforced Plastic
Thermosetting Resin Piping Systems and Chemical Equipment.
Current edition approved Sept. 1, 2019Dec. 1, 2020. Published September 2019December 2020. Originally approved in 1979. Last previous edition approved in 20122019
ε1
as D3753 – 12D3753 – 19. . DOI: 10.1520/D3753-19.10.1520/D3753-20.
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.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3753 − 20
3. Terminology
3.1 General—Definitions are in accordance with Terminology D883 and the abbreviations are in accordance with Terminology
D1600 unless otherwise indicated.
3.2 bench and invert, n—internal flow channel with a sloped bench extending from the edge of the flow channel to the manhole
wall designed to facilitate the flow of liquid through the manhole between the pipe connectors.
3.3 bottom, n—a flat, domed, dished, or other shaped bottom designed to make the manhole or wetwell watertight at its base.
3.4 expanded base manhole, n—a manhole with a larger diameter base section and reduced diameter riser section. (See Fig. 1 for
a typical manhole and an expanded base manhole.)
3.5 expanded base reducer, n—a portion of the manhole, between the manway reducer and bottom, that changes from one diameter
to another in the cylindrical portion of the structure.
3.6 manway reducer, n—the top portion of the manhole through which entrance to the manhole is made and where the diameter
increases from the entrance way to the larger manhole cylinder.
3.7 manhole, n—a constant diameter cylinder attached to a manway reducer designed to handle a manhole cover and ring.
3.8 manhole cover and frame, n—those accessories used with the manhole to close the manway entrance (includes grade
adjustment rings).
3.9 manhole cylinder, n—the portion below the manway reducer that extends in a constant diameter to the manhole base.
3.10 pipe connectors, n—connectors that provide access for the sewer pipe into the manhole.
3.11 resin rich, adj—describes that portion of the glass fiber-reinforced thermosetting-resin material where the resin-to-glass ratio
is significantly greater than in other portions of the manhole.
3.12 wetwell, n—a cylindrical structure which is permitted to be open at the top or include a top.
3.13 wetwell top, n—a flat, domed, dished or other shaped top attached at the top of a wetwell structure. The top may include ribs
FIG. 1 Typical Manhole and Expanded Base Manhole
D3753 − 20
or other structures to add stiffness. Stiffening features are permitted to be added to the interior or exterior surface, and may be
integral or added as a secondary feature. It is permitted to use a similar top on manholes.
4. Materials
4.1 Resin—The resins used shall be a commercial grade thermosetting unsaturated polyester, vinyl ester or epoxy resin.
4.2 Reinforcing Materials—The reinforcing materials shall be commercial grade of E-type glass fibers in the form of mat,
continuous roving, chopped roving, or roving fabric, having a coupling agent that will provide a suitable bond between the glass
reinforcement and the resin.
4.3 Surfacing Material—If reinforcing material is used on the surface exposed to the contained substance, it shall be a commercial
grade chemical-resistant glass or organic surfacing mat having a coupling agent that will provide a suitable bond with the resin.
4.4 Fillers and Additives—Fillers, such as sand, calcium carbonate, etc., when used, shall be inert to the environment and manhole
or wetwell construction. Additives, such as thixotropic agents, catalysts, promoters, pigments, etc., are permitted to be added as
required by the specific manufacturing process to be used to meet the requirements of this standard. The resulting reinforced-plastic
material shall meet the requirement of this specification. Use of fillers is permitted when agreed upon between fabricator and
purchaser. See Note 2.
NOTE 2—The use of paints, coatings, pigments, dyes, colorants and fillers may interfere with visual inspection of the laminate.
4.5 Other Materials—The use of polyester filaments, polyester scrim, glass fiber scrim, or similar material as processing aids is
permitted. The resulting reinforced-plastic material shall meet the requirement of this specification.
4.6 Ribs—When used, ribs are permitted to be manufactured as a solid construction or with materials applied over a structural or
non-structural form. The resulting reinforced-plastic material shall meet the requirement of this specification.
5. Manufacture
5.1 Manholes, wetwells, manway reducers, eccentric or concentric reducers, connectors, tops and bottoms shall be produced from
glass fiber-reinforced thermosetting resin with construction determined by the particular process of manufacture and configuration.
The process is permitted to include contact molding, compression molding, pultrusion, filament winding, resin transfer molding,
spray up, hand lay-up, centrifugal casting, vacuum bagging, or other methods. Ribs are permitted to be attached to the interior or
the exterior surface.
5.2 Interior Access—All manholes and wetwells shall be designed so that a ladder or step system can be supported by the installed
manhole or wetwell.
5.3 Manway Reducer—Manway reducers are permitted to be eccentric or concentric with respect to the larger portion of the
manhole.
5.4 Cover and Ring Support—Manholes shall provide an area from which a typical ring and cover plate can be supported without
damage to the manhole.
5.5 Assembly Joints—Product segments are permitted to be joined together to form a complete manhole or wetwell.
5.6 Manhole or Wetwell Bottom—Bottom shall be designed to be water tight and withstand the external hydraulic pressure of water
to grade. The bottom design is permitted to include methods to anchor the bottom to a concrete base or other external structure
to provide the required resistance to external pressure.
5.7 Bench and Invert—Bench and invert are permitted to be produced from glass fiber-reinforced thermosetting resin or other
material suitable for the contents of the manhole. The bench and invert are permitted to include one or more ⁄2-in. diameter ports
to allow the equalization of pressure between the manhole interior and the cavity under the bench and invert. Use of larger ports
is permitted to allow the field installation of concrete or grout in the cavity under the bench and invert.
D3753 − 20
6. Requirements
6.1 Workmanship:
6.1.1 Exterior Surface—The exterior surface shall be relatively smooth with no sharp projections. Hand-work finish is acceptable
if enough resin is present to saturate all fibers. The exterior surface shall be free of blisters larger than 0.5 in. (12.7 mm) in diameter
and delamination. Fibers loosely attached (can be removed with wire brush) are allowed if not excessive.
6.1.2 Exterior Paint or Pigmentation—Use of exterior paints, coatings, pigments and colorants is permitted when agreed upon
between fabricator and purchaser. See Note 2.
6.1.3 Interior Surface—The interior surface shall be resin rich with no exposed fibers. The surface shall be free of crazing,
delamination, blisters larger than 0.5 in. (12.7 mm) in diameter, and wrinkles of 0.125 in. (3.2 mm) or greater in depth. Surface
2 2
pits shall be permitted up to 6/ft (60/m ) if they are less than 0.75 in. (19 mm) in diameter and less than 0.0625 in. (1.6 mm)
deep. Voids that cannot be broken with finger pressure and that are entirely below the resin surface shall be permitted up to 4/ft
(40/m ) if they are less than 0.5 in. (12.7 mm) in diameter.
6.1.4 Interior Paint or Pigmentation—Use of interior paints, coatings, pigments, and colorants are permitted when agreed upon
between fabricator and purchaser. See Note 2.
6.1.5 Indentations—Indentations or other shape imperfections that will not affect performance are allowed.
6.2 Repairs—Any manhole or wetwell is permitted to be repaired to meet all requirements of this specification.
6.3 Dimensions—The dimensions shall be as shown below when measured in accordance with 8.3.1.
6.3.1 Minimum cylinder internal diameter of the manhole or wetwell shall be 42 in. (1057 mm). The minimum manway reducer
inside diameter shall be 21 in. (533 mm).
6.3.2 Manhole or wetwell lengths shall be in 6-in. (152-mm) increments 62 in. (51 mm).
6.3.3 Nominal inside diameters shall be 42 in. (1067 mm), 48 in. (1219 mm), 54 in. (1372 mm), 60 in. (1524 mm), 66 in. (1676
mm), and 72 in. (1829 mm). Tolerance on the inside diameter shall be 61 %. Other diameters are allowed and are covered by this
specification.
6.4 Manhole Performance Test—One complete manhole manufactured in a manner consistent in every way with this specification
shall meet the performance criteria in 6.4.1 – 6.4.3. If a change in materials or methods of manufacturing is made and that change
may affect the results of these tests, then the testing shall be repeated. These tests are to be conducted on a representative manhole
to qualify the finished product characteristics. They are not considered to be a quality control procedure and are not required for
production parts.
6.4.1 Load Rating—The complete manhole shall have a minimum dynamic-load rating of 16 000 lbf (71 172 N) when tested in
accordance with 8.4. To establish this rating, the complete manhole shall not leak, crack, or suffer other damage when load tested
to 40 000 lbf (177 929 N) and shall not deflect vertically downward more than 0.25 in. (6.35 mm) at the point of load application
when loaded to 24 000 lb (106 757 N).
6.4.2 Stiffness—The manhole cylinder shall have the minimum pipe-stiffness values shown in Table 1 when tested in accordance
with 8.5. It is permitted to interpolate stiffness requirements for other manhole lengths between the values in Table 1.
TABLE 1 Stiffness Requirements
Manhole or Wetwell Length, ft F/ΔY, psi (kPa)
(mm)
6 (1829) 0.72 (4.96)
12 (3658) 1.26 (8.69)
20 (6096) 2.01 (13.86)
25 (7620) 3.02 (20.82)
35 (10668) 5.24 (36.13)
50 (15240) 8.42 (58.81)
D3753 − 20
6.4.3 Soundness—The manholes shall not leak when tested in accordance with 8.6.
6.5 Wetwell Stiffness—The wetwell cylinder shall have the minimum pipe-stiffness value shown in Table 1 when tested in
accordance with 8.5. It is permitted to interpolate stiffness requirements for other wetwell lengths between the values in Table 1.
These tests are to be conducted on a representative wetwell to qualify the finished product characteristics. They are not considered
to be a quality control procedure and are not required for production parts.
NOTE 3—Table 1 values are based upon a surrounding soil modulus of 750 psi or greater. This value is representative of moderately compacted fine grain
sand.
6.6 Chemical Resistance—Manhole or wetwell samples manufactured in a manner consistent in every way with this specification
shall be tested in accordance with 8.7. The log of percent retention of each property after immersion testing when plotted against
the log of immersion time, and extrapolated to 100 000 h shall assure retention of at least 50 % of initial properties. If a change
is made in the manhole construction and that change may affect the results of the chemical resistance testing, then the testing shall
be repeated. Chemical testing is conducted to determine the applicability of the materials used in the manufacture of the manhole
to the specified use conditions. It is not considered to be a quality control procedure.
6.7 Material Properties—The following properties shall be established for each type of construction used in the manhole or
wetwell. If a change in materials or methods of manufacturing is made and that change may affect the results of the following tests,
then the testing shall be repeated. Material properties tests are conducted to qualify the finished product characteristics. They are
not considered to be a quality control procedure and are not required for production parts.
6.7.1 Material Composition—The material composition of the manhole or wetwell in percent by weight shall be determined in
accordance with 8.8.1.
6.7.2 Compressive Strength—The compressive strength in the hoop and axial directions of the manhole or wetwell shall be
determined in accordance with 8.8.2.
6.7.3 Flexural Strength and Modulus—The flexural strength and flexural modulus of elasticity, in the hoop and axial directions
of the manhole or wetwell, shall be determined in accordance with 8.8.3. Where component geometry will adversely affect the test
results (an example would be flexural testing on curved samples taken in the hoop direction), hand fabricated samples made
consistent with the materials and construction of the manhole or wetwell are permitted for testing.
6.8 Hardness—The surface hardness of the manhole or wetwell shall be determined in accordance with 8.8.4.
6.9 Thickness—The thickness of each manhole or wetwell component part shall be determined in accordance with 8.3.2.
6.10 Field Vacuum Test Capability—Each
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