ASTM C537-87(2018)
(Test Method)Standard Test Method for Reliability of Glass Coatings on Glassed Steel Reaction Equipment by High Voltage
Standard Test Method for Reliability of Glass Coatings on Glassed Steel Reaction Equipment by High Voltage
SIGNIFICANCE AND USE
4.1 The widespread use of glassed-steel equipment in highly corrosive chemical processes has made it necessary to detect weak spots in the coating and repair them before catastrophic failure occurs in service. This test is intended to detect discontinuities and thin areas in a glass coating on metal to ensure that the coating is defect free and has sufficient thickness to withstand the prescribed service conditions. A test voltage may be selected at any desired value up to 20k V, thus making the test applicable to a wide range of thickness requirements. When, because of bubbles or defects, the thickness of glass at any spot is less than enough to withstand the applied voltage, a puncture results with an accompanying indication of a defect. Remedial action is then required to repair the defect before the equipment can be used for corrosive service. (When such defects are found before the equipment leaves the manufacturer's plant another application of glass can usually be applied and fired to become an integral part of the coating.)
SCOPE
1.1 This test method covers the determination of the reliability of glass coating on metal and is intended for use by manufacturers of equipment that is designed to withstand highly corrosive conditions where a failure of the coating in service would cause extreme damage to the exposed metal. Its use outside the manufacturer's plant is discouraged because improper or indiscriminate testing can cause punctures that are difficult to repair without returning the equipment to the manufacturer's plant. This test method detects not only existing discontinuities in the glass coating, but also areas where the glass may be thin enough to be likely to result in premature failure in service.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. For specific precautionary statements, see Section 7.
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.
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Designation: C537 − 87 (Reapproved 2018)
Standard Test Method for
Reliability of Glass Coatings on Glassed Steel Reaction
Equipment by High Voltage
This standard is issued under the fixed designation C537; 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.
INTRODUCTION
This test method covers the determination of the reliability of glass coating on metal using high
voltage. It is intended for use by manufacturers of equipment that is designed to withstand highly
corrosive conditions where a failure of the coating in service would cause extreme damage to the
exposed metal. The test method detects not only existing discontinuities in the glass coating, but also
areas where the glass coating may be thin enough to be likely to result in premature failure in service.
1. Scope 2. Terminology
1.1 This test method covers the determination of the reli- 2.1 Definitions:
ability of glass coating on metal and is intended for use by 2.1.1 glassed steel, glass-lined steel, or glass-coated steel—
manufacturers of equipment that is designed to withstand designations generally applied to a class of porcelain enamels
highly corrosive conditions where a failure of the coating in that have high resistance to chemical attack at elevated
service would cause extreme damage to the exposed metal. Its temperatures and pressures.
use outside the manufacturer’s plant is discouraged because
improper or indiscriminate testing can cause punctures that are 3. Summary of Test Method
difficult to repair without returning the equipment to the
3.1 This test method consists essentially of grounding the
manufacturer’s plant. This test method detects not only exist-
metal structure of the equipment to the ground side of a
ing discontinuities in the glass coating, but also areas where the
direct-current high-voltage generator and sweeping the glass
glass may be thin enough to be likely to result in premature
surface with a high-potential probe on the end of an insulated
failure in service.
handle and cable. Wherever a discontinuity exists or the
coating is thin enough (by reason of a concealed bubble or
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this conducting inclusion, etc.) so that the dielectric strength of the
remaining glass is less than some preset desired amount, the
standard.
dielectric strength of air-plus-remaining-glass breaks down and
1.3 This standard does not purport to address all of the
a discharge occurs. Built-in current-limiting devices ensure
safety concerns, if any, associated with its use. It is the
electrical safety to the operator. A variable voltage control
responsibility of the user of this standard to establish appro-
allows selection of a voltage which assures a predetermined
priate safety, health, and environmental practices and deter-
minimum thickness of glass.
mine the applicability of regulatory limitations prior to use.
For specific precautionary statements, see Section 7.
4. Significance and Use
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.1 The widespread use of glassed-steel equipment in highly
ization established in the Decision on Principles for the corrosive chemical processes has made it necessary to detect
Development of International Standards, Guides and Recom-
weak spots in the coating and repair them before catastrophic
mendations issued by the World Trade Organization Technical failure occurs in service. This test is intended to detect
Barriers to Trade (TBT) Committee.
discontinuities and thin areas in a glass coating on metal to
ensure that the coating is defect free and has sufficient
thickness to withstand the prescribed service conditions. A test
This test method is under the jurisdiction of ASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
voltage may be selected at any desired value up to 20k V, thus
Materials for Porcelain Enamel and Ceramic-Metal Systems.
making the test applicable to a wide range of thickness
Current edition approved Oct. 1, 2018. Published October 2018. Originally
ɛ1 requirements. When, because of bubbles or defects, the thick-
approved in 1964. Last previous edition approved in 2014 as C537 – 87 (2014) .
DOI: 10.1520/C0537-87R18. ness of glass at any spot is less than enough to withstand the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C537 − 87 (2018)
FIG. 1 Circuit Diagram, 20k V dc Tester
applied voltage, a puncture results with an accompanying sweeping larger surfaces of glass coating while the point probe
indication of a defect. Remedial action is then required to is better adapted to interior corners and the more restricted
repair the defect before the equipment can be used for
areas.
corrosive service. (When such defects are found before the
equipment leaves the manufacturer’s plant another application
7. Safety Precautions
of glass can usually be applied and fired to become an integral
7.1 The instrument and equipment being tested should be
part of the coating.)
well grounded both to a good ground and to each other. All
grounding contacts should be clean bare metal and not rusted
5. Interferences
or painted metal.
5.1 Since the test method is electrical, it is necessary to have
a good ground connection between the instrument and the 7.2 Handle the insulated probe handle so that the hand
metal substrate of the equipment being tested. It is also contacts the ground ring to prevent build-up of a static charge
necessary that the surface of the glass be reasonably clean and
which causes an unpleasant (although not dangerous) sensation
dry. A wet surface will conduct enough of the high voltage to on discharge.
any exposed metal, including the edges of the glass coating, so
7.3 Keep the probe electrode at least 305 mm (12 in.) away
that an indication of a “contact” may be obtained over a large
from conducting surfaces or personnel. Remember that con-
area instead of at localize
...
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: C537 − 87 (Reapproved 2014) C537 − 87 (Reapproved 2018)
Standard Test Method for
Reliability of Glass Coatings on Glassed Steel Reaction
Equipment by High Voltage
This standard is issued under the fixed designation C537; 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.
ε NOTE—Introduction added and unit abbreviation corrections made editorially in June 2014.
INTRODUCTION
This test method covers the determination of the reliability of glass coating on metal using high
voltage. It is intended for use by manufacturers of equipment that is designed to withstand highly
corrosive conditions where a failure of the coating in service would cause extreme damage to the
exposed metal. The test method detects not only existing discontinuities in the glass coating, but also
areas where the glass coating may be thin enough to be likely to result in premature failure in service.
1. Scope
1.1 This test method covers the determination of the reliability of glass coating on metal and is intended for use by
manufacturers of equipment that is designed to withstand highly corrosive conditions where a failure of the coating in service
would cause extreme damage to the exposed metal. Its use outside the manufacturer’s plant is discouraged because improper or
indiscriminate testing can cause punctures that are difficult to repair without returning the equipment to the manufacturer’s plant.
This test method detects not only existing discontinuities in the glass coating, but also areas where the glass may be thin enough
to be likely to result in premature failure in service.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. For specific precautionary statements, see Section 7.
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. Terminology
2.1 Definitions:
2.1.1 glassed steel, glass-lined steel, or glass-coated steel—designations generally applied to a class of porcelain enamels that
have high resistance to chemical attack at elevated temperatures and pressures.
3. Summary of Test Method
3.1 This test method consists essentially of grounding the metal structure of the equipment to the ground side of a direct-current
high-voltage generator and sweeping the glass surface with a high-potential probe on the end of an insulated handle and cable.
Wherever a discontinuity exists or the coating is thin enough (by reason of a concealed bubble or conducting inclusion, etc.) so
that the dielectric strength of the remaining glass is less than some preset desired amount, the dielectric strength of
air-plus-remaining-glass breaks down and a discharge occurs. Built-in current-limiting devices ensure electrical safety to the
operator. A variable voltage control allows selection of a voltage which assures a predetermined minimum thickness of glass.
This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
Materials for Porcelain Enamel and Ceramic-Metal Systems.
Current edition approved May 1, 2014Oct. 1, 2018. Published June 2014October 2018. Originally approved in 1964. Last previous edition approved in 20092014 as
ɛ1
C537 – 87 (2009).(2014) . DOI: 10.1520/C0537-87R14.10.1520/C0537-87R18.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C537 − 87 (2018)
FIG. 1 Circuit Diagram, 20k V dc Tester
4. Significance and Use
4.1 The widespread use of glassed-steel equipment in highly corrosive chemical processes has made it necessary to detect weak
spots in the coating and repair them before catastrophic failure occurs in service. This test is intended to detect discontinuities and
thin areas in a glass coating on metal to ensure that the coating is defect free and has sufficient thickness to withstand the prescribed
service conditions. A test voltage may be selected at any desired value up to 20k V, thus making the test applicable to a wide range
of thickness requirements. When, because of bubbles or defects, the thickness of glass at any spot is less than enough to withstand
the applied voltage, a puncture results with an accompanying indication of a defect. Remedial action is then required to repair the
defect before the equipment can be used for corrosive service. (When such defects are found before the equipment leaves the
manufacturer’s plant another application of glass can usually be applied and fired to become an integral part of the coating.)
5. Interferences
5.1 Since the test method is electrical, it is necessary to have a good ground connection between the instrument and the metal
substrate of the equipment being tested. It is also necessary that the surface of the glass be reasonably clean and dry. A wet surface
will conduct enough of the high voltage to any exposed metal, including the edges of the glass coating, so that an indication of
a “contact” may be obtained over a large area instead of at localized spots that can be marked and identified for repair.
6. Apparatus
6.1 The tester is composed of a source of high-voltage direct current with a suitable device to limit the current. A
constant-voltage transformer is used to supply a more uniform voltage source than the usual 115 V, 60 Hz line to which it is
connected. The power supply unit consists of a suitable step-up transformer along with a voltage-control device, a curren
...
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