ASTM C537-87(2014)e1
(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 and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 7.
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´1
Designation: C537 − 87 (Reapproved 2014)
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 2.1.1 glassed steel, glass-lined steel, or glass-coated steel—
designations generally applied to a class of porcelain enamels
1.1 This test method covers the determination of the reli-
that have high resistance to chemical attack at elevated
ability of glass coating on metal and is intended for use by
temperatures and pressures.
manufacturers of equipment that is designed to withstand
highly corrosive conditions where a failure of the coating in
3. Summary of Test Method
service would cause extreme damage to the exposed metal. Its
3.1 This test method consists essentially of grounding the
use outside the manufacturer’s plant is discouraged because
metal structure of the equipment to the ground side of a
improper or indiscriminate testing can cause punctures that are
direct-current high-voltage generator and sweeping the glass
difficult to repair without returning the equipment to the
surface with a high-potential probe on the end of an insulated
manufacturer’s plant. This test method detects not only exist-
handle and cable. Wherever a discontinuity exists or the
ingdiscontinuitiesintheglasscoating,butalsoareaswherethe
coating is thin enough (by reason of a concealed bubble or
glass may be thin enough to be likely to result in premature
conducting inclusion, etc.) so that the dielectric strength of the
failure in service.
remaining glass is less than some preset desired amount, the
1.2 The values stated in SI units are to be regarded as
dielectric strength of air-plus-remaining-glass breaks down and
standard. No other units of measurement are included in this
a discharge occurs. Built-in current-limiting devices ensure
standard.
electrical safety to the operator. A variable voltage control
1.3 This standard does not purport to address all of the
allows selection of a voltage which assures a predetermined
safety concerns, if any, associated with its use. It is the
minimum thickness of glass.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Significance and Use
bility of regulatory limitations prior to use. For specific
4.1 Thewidespreaduseofglassed-steelequipmentinhighly
precautionary statements, see Section 7.
corrosive chemical processes has made it necessary to detect
weak spots in the coating and repair them before catastrophic
2. Terminology
failure occurs in service. This test is intended to detect
2.1 Definitions:
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.Atest
voltage may be selected at any desired value up to 20k V, thus
This test method is under the jurisdiction ofASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
making the test applicable to a wide range of thickness
Materials for Porcelain Enamel and Ceramic-Metal Systems.
requirements. When, because of bubbles or defects, the thick-
Current edition approved May 1, 2014. Published June 2014. Originally
ness of glass at any spot is less than enough to withstand the
approved in 1964. Last previous edition approved in 2009 as C537 – 87 (2009).
DOI: 10.1520/C0537-87R14. applied voltage, a puncture results with an accompanying
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
C537 − 87 (2014)
FIG. 1 Circuit Diagram, 20k V dc Tester
indication of a defect. Remedial action is then required to 7. Safety Precautions
repair the defect before the equipment can be used for
7.1 The instrument and equipment being tested should be
corrosive service. (When such defects are found before the
well grounded both to a good ground and to each other. All
equipment leaves the manufacturer’s plant another application
grounding contacts should be clean bare metal and not rusted
of glass can usually be applied and fired to become an integral
or painted metal.
part of the coating.)
7.2 Handle the insulated probe handle so that the hand
contacts the ground ring to prevent build-up of a static charge
5. Interferences
which causes an unpleasant (although not dangerous) sensation
5.1 Sincethetestmethodiselectrical,itisnecessarytohave
on discharge.
a good ground connection between the instrument and the
7.3 Keep the probe electrode at least 305 mm (12 in.) away
metal substrate of the equipment being tested. It is also
from conducting surfaces or personnel. Remember that con-
necessary that the surface of the glass be reasonably clean and
ducting surfaces may lead to personnel at some distance from
dry. A wet surface will conduct enough of the high voltage to
the probe. Discharge the probe tip by grounding it after turning
any exposed metal, including the edges of the glass coating, so
offtheinstrumentandbeforechangingprobetips.Althoughthe
that an indication of a “contact” may be obtained over a large
current is low enough to be electrically safe, th
...
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 2009) C537 − 87 (Reapproved 2014)
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 and health practices and determine the applicability of regulatory
limitations prior to use. For specific precautionary statements, see Section 7.
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.
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
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 April 15, 2009May 1, 2014. Published June 2009June 2014. Originally approved in 1964. Last previous edition approved in 20042009 as
ε1
C537 – 87 (2004)(2009). . DOI: 10.1520/C0537-87R09.10.1520/C0537-87R14.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
C537 − 87 (2014)
FIG. 1 Circuit Diagram, 20 000-V D-C 20k V dc Tester
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 20 00020k 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 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
current-limiting rheostat, a rectifier, and appropriate safety and remote control relays, meters, as well as an insulated cable and
probe (see Fig
...
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