ASTM E2981-21
(Guide)Standard Guide for Nondestructive Examination of Composite Overwraps in Filament Wound Pressure Vessels Used in Aerospace Applications
Standard Guide for Nondestructive Examination of Composite Overwraps in Filament Wound Pressure Vessels Used in Aerospace Applications
SIGNIFICANCE AND USE
4.1 The COPVs covered in this guide consist of a metallic liner overwrapped with high-strength fibers embedded in polymeric matrix resin (typically a thermoset) (Fig. 1). Metallic liners may be spun-formed from a deep drawn/extruded monolithic blank or may be fabricated by welding formed components. Designers often seek to minimize the liner thickness in the interest of weight reduction. COPV liner materials used can be aluminum alloys, titanium alloys, nickel-chromium alloys, and stainless steels, impermeable polymer liner such as high density polyethylene, or integrated composite materials. Fiber materials can be carbon, aramid, glass, PBO, metals, or hybrids (two or more types of fibers). Matrix resins include epoxies, cyanate esters, polyurethanes, phenolic resins, polyimides (including bismaleimides), polyamides, and other high performance polymers. Common bond line adhesives are FM-73, urethane, West 105, and Epon 862 with thicknesses ranging from 0.13 mm (0.005 in.) to 0.38 mm (0.015 in.). Metallic liner and composite overwrap materials requirements are found in ANSI/AIAA S-080 and ANSI/AIAA S-081, respectively.
Note 6: When carbon fiber is used, galvanic protection should be provided for the metallic liner using a physical barrier such as glass cloth in a resin matrix, or similarly, a bond line adhesive.
Note 7: Per the discretion of the cognizant engineering organization, composite materials not developed and qualified in accordance with the guidelines in MIL-HDBK-17, Volumes 1 and 3 should have an approved material usage agreement.
FIG. 1 Typical Carbon Fiber Reinforced COPVs (NASA)
4.2 The as-wound COPV is then cured and an autofrettage/proof cycle is performed to evaluate performance and increase fatigue characteristics.
4.3 The strong drive to reduce weight and spatial needs in aerospace applications has pushed designers to adopt COPVs constructed with high modulus carbon fibers embedded in an epoxy matrix. Unfortunately, high modulus fiber...
SCOPE
1.1 This guide discusses current and potential nondestructive testing (NDT) procedures for finding indications of discontinuities and accumulated damage in the composite overwrap of filament wound pressure vessels, also known as composite overwrapped pressure vessels (COPVs). In general, these vessels have metallic liner thicknesses less than 2.3 mm (0.090 in.), and fiber loadings in the composite overwrap greater than 60 % by weight. In COPVs, the composite overwrap thickness will be of the order of 2.0 mm (0.080 in.) for smaller vessels and up to 20 mm (0.80 in.) for larger ones.
1.2 This guide focuses on COPVs with nonload-sharing metallic liners used at ambient temperature, which most closely represents a Compressed Gas Association (CGA) Type III metal-lined composite tank. However, it also has relevance to (1) monolithic metallic pressure vessels (PVs) (CGA Type I), (2) metal-lined hoop-wrapped COPVs (CGA Type II), (3) plastic-lined composite pressure vessels (CPVs) with a nonload-sharing liner (CGA Type IV), and (4) an all-composite, linerless COPV (undefined Type). This guide also has relevance to COPVs used at cryogenic temperatures.
1.3 The vessels covered by this guide are used in aerospace applications; therefore, the inspection requirements for discontinuities and inspection points will in general be different and more stringent than for vessels used in non aerospace applications.
1.4 This guide applies to (1) low pressure COPVs used for storing aerospace media at maximum allowable working pressures (MAWPs) up to 3.5 MPa (500 psia) and volumes up to 2 L (70 ft3), and (2) high pressure COPVs used for storing compressed gases at MAWPs up to 70 MPa (10 000 psia) and volumes down to 8 L (500 in.3). Internal vacuum storage or exposure is not considered appropriate for any vessel size.
Note 1: Some vessels are evacuated during filling operations, requiring the tank to withstand external (atmospheric) pre...
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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: E2981 − 21
Standard Guide for
Nondestructive Examination of Composite Overwraps in
Filament Wound Pressure Vessels Used in Aerospace
1
Applications
This standard is issued under the fixed designation E2981; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
NOTE 1—Some vessels are evacuated during filling operations, requir-
1. Scope
ing the tank to withstand external (atmospheric) pressure, while other
1.1 This guide discusses current and potential nondestruc-
vessels may either contain or be immersed in cryogenic fluids, or both,
tive testing (NDT) procedures for finding indications of dis- requiring the tanks to withstand any potentially deleterious effects of
differential thermal contraction.
continuities and accumulated damage in the composite over-
wrap of filament wound pressure vessels, also known as
1.5 The composite overwraps under consideration include,
composite overwrapped pressure vessels (COPVs). In general,
but are not limited to, ones made from various polymer matrix
these vessels have metallic liner thicknesses less than 2.3 mm
resins (for example, epoxies, cyanate esters, polyurethanes,
(0.090 in.), and fiber loadings in the composite overwrap
phenolic resins, polyimides (including bismaleimides), and
greater than 60 % by weight. In COPVs, the composite
polyamides)withcontinuousfiberreinforcement(forexample,
overwrap thickness will be of the order of 2.0 mm (0.080 in.)
carbon, aramid, glass, or poly-(phenylenebenzobisoxazole)
for smaller vessels and up to 20 mm (0.80 in.) for larger ones.
(PBO)). The metallic liners under consideration include, but
are not limited to, aluminum alloys, titanium alloys, nickel-
1.2 This guide focuses on COPVs with nonload-sharing
chromium alloys, and stainless steels.
metallic liners used at ambient temperature, which most
closely represents a Compressed GasAssociation (CGA) Type
1.6 ThisguidedescribestheapplicationofestablishedNDT
III metal-lined composite tank. However, it also has relevance
methods; namely, Acoustic Emission (AE, Section 7), Eddy
to (1) monolithic metallic pressure vessels (PVs) (CGA Type
Current Testing (ET, Section 8), Laser Shearography (Section
I), (2) metal-lined hoop-wrapped COPVs (CGA Type II), (3)
9), Radiographic Testing (RT, Section 10), Infrared Thermog-
plastic-lined composite pressure vessels (CPVs) with a
raphy (IRT, Section 11), Ultrasonic Testing (UT, Section 12),
nonload-sharing liner (CGA Type IV), and (4) an all-
and Visual Testing (VT, Section 13). These methods can be
composite, linerless COPV (undefined Type). This guide also
used by cognizant engineering organizations for detecting and
has relevance to COPVs used at cryogenic temperatures.
evaluating flaws, defects, and accumulated damage in the
1.3 The vessels covered by this guide are used in aerospace composite overwrap of new and in-service COPVs.
applications; therefore, the inspection requirements for discon-
NOTE 2—Although visual testing is discussed and required by current
tinuities and inspection points will in general be different and
range standards, emphasis is placed on complementary NDT procedures
more stringent than for vessels used in non aerospace applica-
that are sensitive to detecting flaws, defects, and damage that leave no
tions.
visible indication on the COPV surface.
NOTE 3—In aerospace applications, a high priority is placed on light
1.4 This guide applies to (1) low pressure COPVs used for
weight material, while in commercial applications, weight is typically
storing aerospace media at maximum allowable working pres-
sacrificed to obtain increased robustness. Accordingly, the need to detect
sures (MAWPs) up to 3.5 MPa (500 psia) and volumes up to
damagebelowthevisualdamagethresholdismoreimportantinaerospace
3
vessels.
2L (70 ft ), and (2) high pressure COPVs used for storing
NOTE 4—Currently, no determination of residual strength can be made
compressed gases at MAWPs up to 70 MPa (10000 psia) and
3
by any NDT method.
volumes down to 8L (500 in. ). Internal vacuum storage or
exposure is not considered appropriate for any vessel size.
1.7 All methods discussed in this guide (AE, ET,
shearography, RT, IRT, UT, and VT) are performed on the
composite overwrap after overwrapping and structural cure.
1
For NDT procedures for detecting discontinuities in thin-
This guide is under the jurisdiction of ASTM Committee E07 on Nondestruc-
tive Testing and is the direct responsibility of Subco
...
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.
´1
Designation: E2981 − 15 E2981 − 21
Standard Guide for
Nondestructive TestingExamination of the Composite
Overwraps in Filament Wound Pressure Vessels Used in
1
Aerospace Applications
This standard is issued under the fixed designation E2981; 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
ε NOTE—Fig. 2 and the definition in 3.4.3 were updated editorially in April 2019.
1. Scope
1.1 This guide discusses current and potential nondestructive testing (NDT) procedures for finding indications of discontinuities
and accumulated damage in the composite overwrap of filament wound pressure vessels, also known as composite overwrapped
pressure vessels (COPVs). In general, these vessels have metallic liner thicknesses less than 2.3 mm (0.090 in.), and fiber loadings
in the composite overwrap greater than 60 percent% by weight. In COPVs, the composite overwrap thickness will be of the order
of 2.0 mm (0.080 in.) for smaller vessels and up to 20 mm (0.80 in.) for larger ones.
1.2 This guide focuses on COPVs with nonload-sharing metallic liners used at ambient temperature, which most closely represents
a Compressed Gas Association (CGA) Type III metal-lined composite tank. However, it also has relevance to 1)(1) monolithic
metallic pressure vessels (PVs) (CGA Type I), 2)(2) metal-lined hoop-wrapped COPVs (CGA Type II), 3)(3) plastic-lined
composite pressure vessels (CPVs) with a nonload-sharing liner (CGA Type IV), and 4)(4) an all-composite, linerless COPV
(undefined Type). This guide also has relevance to COPVs used at cryogenic temperatures.
1.3 The vessels covered by this guide are used in aerospace applications; therefore, the inspection requirements for discontinuities
and inspection points will in general be different and more stringent than for vessels used in non aerospace applications.
1.4 This guide applies to 1)(1) low pressure COPVs used for storing aerospace media at maximum allowable working pressures
3 3
(MAWPs) up to 3.5 MPa (500 psia) and volumes up to 2 m2 L (70 ft ), and 2)(2) high pressure COPVs used for storing
3 3
compressed gases at MAWPs up to 70 MPa (10,000(10 000 psia) and volumes down to 8000 cm8 L (500 in. ). Internal vacuum
storage or exposure is not considered appropriate for any vessel size.
NOTE 1—Some vessels are evacuated during filling operations, requiring the tank to withstand external (atmospheric) pressure, while other vessels may
either contain or be immersed in cryogenic fluids, or both, requiring the tanks to withstand any potentially deleterious effects of differential thermal
contraction.
1.5 The composite overwraps under consideration include, but are not limited to, ones made from various polymer matrix resins
(for example, epoxies, cyanate esters, polyurethanes, phenolic resins, polyimides (including bismaleimides), and polyamides) with
1
This test method guide is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.10 on
Specialized NDT Methods.
Current edition approved July 1, 2015Feb. 1, 2021. Published September 2015February 2021. Originally approved in 2015. Last previous edition approved in 2015 as
ε1
E2981 – 15 . DOI: 10.1520/E2981-15E01.10.1520/E2981-21.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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E2981 − 21
continuous fiber reinforcement (for example, carbon, aramid, glass, or poly-(phenylenebenzobisoxazole) (PBO)). The metallic
liners under consideration include, but are not limited to, aluminum alloys, titanium alloys, nickel-chromium alloys, and stainless
steels.
1.6 This guide describes the application of established NDT methods; namely, Acoustic Emission (AE, Section 7), Eddy Current
Testing (ECT,(ET, Section 8), Laser Shearography (Section 9), RadiologicRadiographic Testing (RT, Section 10), Thermographic
Testing (TT,Infrared Thermography (IRT, Section 11), Ultrasonic Testing (UT, Section 12), and Visual Testing (VT, Section 13).
These methods can be used by cognizant engineering organizations for detecting and evaluating flaws, defects, and accumulated
damage in the composite overwrap of new and in-service COPVs.
NOTE 2—Although visual testing is discussed and required by current r
...
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