25.220.50 - Enamels

This document specifies a simulating method of test for determination of the release of metal-ions from enamelled articles, which are intended to come into contact with food.
This document also specifies limits for the release of metal-ions from enamelled articles, which are intended to come into contact with food.
This document is applicable to enamelled articles, including tanks and vessels, which are intended to be used for the preparation, cooking, serving and storage of food.

Specifies the requirements for the testing apparatus to be used. Includes a general description and figures.

This document specifies a test method for determining the resistance of vitreous and porcelain enamel coatings to abrasion by rubbing, grinding or other mechanical effects.

ISO 28706-2:2017 specifies a test method for the determination of the resistance of flat surfaces of vitreous and porcelain enamels to boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours.
This method allows the determination of the resistance of vitreous and porcelain enamels to the liquid and vapour phases of the corrosive medium simultaneously.

EN-ISO 8289-1 specifies two low voltage tests for detecting and locating defects that extend to the basis metal in vitreous and porcelain enamel coatings.Method A (electrical) is applicable to the rapid detection and determination of the general location of defects. Method B (optical), based on colour effects, is applicable to the more precise detection of defects and their exact locations. Both methods are commonly applied to flat surfaces. For more intricate shapes, such as undulated and/or corrugated surfaces, ISO 8289-2 is applicable.

This document specifies two low voltage tests for detecting and locating defects that extend to the basis metal in vitreous and porcelain enamel coatings.
Method A (electrical) is applicable to the rapid detection and determination of the general location of defects. Method B (optical), based on colour effects, is applicable to the more precise detection of defects and their exact locations. Both methods are commonly applied to flat surfaces. For more intricate shapes, such as undulated and/or corrugated surfaces, ISO 8289-2 is applicable.
NOTE 1  Selection of the correct test method is critical to distinguish the areas of increased conductivity detected by method B from actual pores that extend to the basis metal, which can be detected by both methods.
NOTE 2  The low voltage test is a non-destructive method of detecting defects and, therefore, is completely different from the high voltage test specified in ISO 2746. The results of the high and low voltage tests are not comparable and will differ.

This document specifies two low voltage tests for detecting and locating defects that extend to the basis metal in vitreous and porcelain enamel coatings. Method A (electrical) is applicable to the rapid detection and determination of the general location of defects. Method B (optical), based on colour effects, is applicable to the more precise detection of defects and their exact locations. Both methods are commonly applied to flat surfaces. For more intricate shapes, such as undulated and/or corrugated surfaces, ISO 8289-2 is applicable. NOTE 1 Selection of the correct test method is critical to distinguish the areas of increased conductivity detected by method B from actual pores that extend to the basis metal, which can be detected by both methods. NOTE 2 The low voltage test is a non-destructive method of detecting defects and, therefore, is completely different from the high voltage test specified in ISO 2746. The results of the high and low voltage tests are not comparable and will differ.

This document specifies a test method for determining the resistance of vitreous and porcelain enamel coatings to abrasion by rubbing, grinding or other mechanical effects.

This document specifies the quality requirements for apparatus, components, appliances and accessories of glass-lined steel (including semi-crystallized enamel coatings) and glass-lined steel castings used for process plants. It specifies the quality requirements and the tests to be carried out by the manufacturer as well as the actions to be taken to repair defects. It is also applicable to glass-lined pumps, pump components and fittings. It does not apply to glass-lined flanged steel pipes or glass-lined flanged steel fittings. The test methods specified cover checking the enamel, the dimensional accuracy and the performance of apparatus and components. This document is applicable to new apparatus and components as well as used items that have been re-enamelled. It does not contain requirements regarding the chemical or physical properties of vitreous and porcelain enamels.

This document specifies the minimum requirements and the functional characteristics of enamel coatings applied by any process, such as wet dipping, wet flow-coating, wet spraying, wet electrostatic spraying, wet electrodeposition or dry-powder electrostatic spraying, to profiled steel heat exchanger panels in regenerative heat exchangers, before and after packing in baskets. For very severe service conditions, or to obtain extended operational life, more stringent limits can be agreed between customer and supplier.

This document specifies the quality requirements for apparatus, components, appliances and accessories of glass-lined steel (including semi-crystallized enamel coatings) and glass-lined steel castings used for process plants. It specifies the quality requirements and the tests to be carried out by the manufacturer as well as the actions to be taken to repair defects.
It is also applicable to glass-lined pumps, pump components and fittings.
It does not apply to glass-lined flanged steel pipes or glass-lined flanged steel fittings.
NOTE 1  Provisions for glass-lined flanged steel pipes and glass-lined flanged steel fittings are given in ISO 28721-4.
The test methods specified cover checking the enamel, the dimensional accuracy and the performance of apparatus and components.
This document is applicable to new apparatus and components as well as used items that have been re-enamelled.
It does not contain requirements regarding the chemical or physical properties of vitreous and porcelain enamels.
NOTE 2  Examples of test reports are given in Annex A.

This document specifies the minimum requirements and the functional characteristics of enamel coatings applied by any process, such as wet dipping, wet flow-coating, wet spraying, wet electrostatic spraying, wet electrodeposition or dry-powder electrostatic spraying, to profiled steel heat exchanger panels in regenerative heat exchangers, before and after packing in baskets.
For very severe service conditions, or to obtain extended operational life, more stringent limits can be agreed between customer and supplier.

This document specifies the quality requirements for apparatus, components, appliances and accessories of glass-lined steel (including semi-crystallized enamel coatings) and glass-lined steel castings used for process plants. It specifies the quality requirements and the tests to be carried out by the manufacturer as well as the actions to be taken to repair defects. It is also applicable to glass-lined pumps, pump components and fittings. It does not apply to glass-lined flanged steel pipes or glass-lined flanged steel fittings. NOTE 1 Provisions for glass-lined flanged steel pipes and glass-lined flanged steel fittings are given in ISO 28721-4. The test methods specified cover checking the enamel, the dimensional accuracy and the performance of apparatus and components. This document is applicable to new apparatus and components as well as used items that have been re-enamelled. It does not contain requirements regarding the chemical or physical properties of vitreous and porcelain enamels. NOTE 2 Examples of test reports are given in Annex A.

This document specifies the minimum requirements and the functional characteristics of enamel coatings applied by any process, such as wet dipping, wet flow-coating, wet spraying, wet electrostatic spraying, wet electrodeposition or dry-powder electrostatic spraying, to profiled steel heat exchanger panels in regenerative heat exchangers, before and after packing in baskets. For very severe service conditions, or to obtain extended operational life, more stringent limits can be agreed between customer and supplier.

This standard specifies a low-voltage test method for detecting and locating defects (pores, cracks or pop-offs) which occur in enamel coatings of corrugated and/or undulated profiles and which extend down to the metal base.

This document specifies the requirements for product quality and product testing of enamelled valves
and pressure pipe fittings for untreated and potable water supply.
It does not apply to chemical service glass-enamel and apparatus enamel.

This document specifies a low-voltage test method for detecting and locating defects (pores, cracks or pop-offs) that occur in enamel coatings of corrugated and/or undulated profiles and that extend down to the metal base.
The method is based on colour effects (optical method) and is applicable to the precise detection of defects and their exact position. It can be used for non-flat, more profiled shapes such as corrugated or undulated surfaces.
NOTE       The low-voltage test is a non-destructive test for detecting defects extending down to the metal base and is, therefore, completely different in comparison to the high-voltage test in accordance with ISO 2746.

This document specifies the requirements for product quality and product testing of enamelled valves and pressure pipe fittings for untreated and potable water supply.
It does not apply to chemical service glass-enamel and apparatus enamel.

This document specifies a low-voltage test method for detecting and locating defects (pores, cracks or pop-offs) that occur in enamel coatings of corrugated and/or undulated profiles and that extend down to the metal base. The method is based on colour effects (optical method) and is applicable to the precise detection of defects and their exact position. It can be used for non-flat, more profiled shapes such as corrugated or undulated surfaces. NOTE The low-voltage test is a non-destructive test for detecting defects extending down to the metal base and is, therefore, completely different in comparison to the high-voltage test in accordance with ISO 2746.

This document specifies the requirements for product quality and product testing of enamelled valves and pressure pipe fittings for untreated and potable water supply. It does not apply to chemical service glass-enamel and apparatus enamel.

This document specifies a simulating method of test for determination of the release of metal-ions from enamelled articles, which are intended to come into contact with food. It also specifies limits for the release of metal-ions from enamelled articles, which are intended to come into contact with food. It is applicable to enamelled articles, including tanks and vessels, which are intended to be used for the preparation, cooking, serving and storage of food.

This document describes a test method for the determination of the resistance of vitreous and porcelain
enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The apparatus
used is a hexagonal vessel in which six enamelled specimens or a tetragonal glass bottle in which four
enamelled specimens are simultaneously tested.
NOTE 1 The resistance to any alkaline liquid can be determined. However, the test method was originally used
for the determination of the resistance to hot detergent solutions, within the neutral and alkaline range, used for
washing textiles.
NOTE 2 Since detergents are continually subject to alterations in their composition, a standard test solution
is specified which, in respect to its alkalinity, wetting properties and complexing behaviour, can be considered
as a typical composition for the detergents present on the market. The pH value and alkalinity of the standard
test solution depend on the proportions of sodium tripolyphosphate, sodium carbonate and sodium perborate
present; sodium tripolyphosphate acts simultaneously as a complexing agent. The wetting properties of the
standard test solution are obtained by the addition of alkylsulfonate. A higher sodium perborate content is not
considered necessary since the effect of oxygen on enamel is unimportant and an increase in the perborate
content does not cause any significant alteration in the alkalinity of the standard test solution. The testing of
different enamels using this standard test solution and other test solutions (including 5 % sodium pyrophosphate
solution) has justified the use of this standard test solution for determining the resistance of enamels to hot
detergent solutions.

ISO 28706-3:2017 describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The apparatus used is a hexagonal vessel in which six enamelled specimens or a tetragonal glass bottle in which four enamelled specimens are simultaneously tested.
NOTE 1    The resistance to any alkaline liquid can be determined. However, the test method was originally used for the determination of the resistance to hot detergent solutions, within the neutral and alkaline range, used for washing textiles.
NOTE 2    Since detergents are continually subject to alterations in their composition, a standard test solution is specified which, in respect to its alkalinity, wetting properties and complexing behaviour, can be considered as a typical composition for the detergents present on the market. The pH value and alkalinity of the standard test solution depend on the proportions of sodium tripolyphosphate, sodium carbonate and sodium perborate present; sodium tripolyphosphate acts simultaneously as a complexing agent. The wetting properties of the standard test solution are obtained by the addition of alkylsulfonate. A higher sodium perborate content is not considered necessary since the effect of oxygen on enamel is unimportant and an increase in the perborate content does not cause any significant alteration in the alkalinity of the standard test solution. The testing of different enamels using this standard test solution and other test solutions (including 5 % sodium pyrophosphate solution) has justified the use of this standard test solution for determining the resistance of enamels to hot detergent solutions.

ISO 28706-3:2017 describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The apparatus used is a hexagonal vessel in which six enamelled specimens or a tetragonal glass bottle in which four enamelled specimens are simultaneously tested. NOTE 1 The resistance to any alkaline liquid can be determined. However, the test method was originally used for the determination of the resistance to hot detergent solutions, within the neutral and alkaline range, used for washing textiles. NOTE 2 Since detergents are continually subject to alterations in their composition, a standard test solution is specified which, in respect to its alkalinity, wetting properties and complexing behaviour, can be considered as a typical composition for the detergents present on the market. The pH value and alkalinity of the standard test solution depend on the proportions of sodium tripolyphosphate, sodium carbonate and sodium perborate present; sodium tripolyphosphate acts simultaneously as a complexing agent. The wetting properties of the standard test solution are obtained by the addition of alkylsulfonate. A higher sodium perborate content is not considered necessary since the effect of oxygen on enamel is unimportant and an increase in the perborate content does not cause any significant alteration in the alkalinity of the standard test solution. The testing of different enamels using this standard test solution and other test solutions (including 5 % sodium pyrophosphate solution) has justified the use of this standard test solution for determining the resistance of enamels to hot detergent solutions.

This standard specifies the procedures for the preparation of enamel samples for measurement of the thermal dilatation and calculation of the thermal expansion coefficient.

ISO 20274:2017 specifies the procedures for the preparation of enamel samples for measurement of the thermal length change and calculation of the thermal expansion coefficient.

ISO 20274:2017 specifies the procedures for the preparation of enamel samples for measurement of the thermal length change and calculation of the thermal expansion coefficient.

This European Standard defines a number of terms relating to vitreous and porcelain enamels and their technology. This list is not complete and only comprises those terms for which the definition is considered necessary for correct and adequate understanding in order to clarify these processes.
It should be understood that the interpretations given are those corresponding to the practical usage in this field and that they do not necessarily coincide with those used in other fields.
For purposes of clarification, the term Vitreous Enamel, used throughout this European Standard, is synonymous with Porcelain Enamel, the term favoured in the United States and some other countries.

This standard establishes a system for the cataloguing of defects in sheet steel
enamelling. It serves for a consistent language use concerning the designation and
characterization of enamelling defects. This standard is limited to detectable defects and
does not purport to fully take into consideration all occurring types of defects. It does not
evaluate enamelling defects; the classification carried out serves for the conveyance or
practical knowledge.

This document specifies a test method for the determination of the resistance of flat surfaces of vitreous
and porcelain enamels to boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours.
This method allows the determination of the resistance of vitreous and porcelain enamels to the liquid
and vapour phases of the corrosive medium simultaneously.

ISO 19496-1:2017 defines a number of terms relating to vitreous and porcelain enamels and their technology. This list is not complete and only comprises those terms for which the definition is considered necessary for correct and adequate understanding in order to clarify these processes.
The interpretations given are those corresponding to the practical usage in this field and they do not necessarily coincide with those used in other fields.
For purposes of clarification, the term "vitreous enamel", used throughout this document, is synonymous with "porcelain enamel", the term favoured in the United States and some other countries.

ISO 19496-2:2017 establishes a system for the cataloguing of defects in sheet steel enamelling. It serves for a consistent language use concerning the designation and characterization of enamelling defects. This document is limited to detectable defects and does not purport to fully take into consideration all occurring types of defects. It does not evaluate enamelling defects; the classification carried out serves for the conveyance of practical knowledge.

ISO 28706-2:2017 specifies a test method for the determination of the resistance of flat surfaces of vitreous and porcelain enamels to boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours.
This method allows the determination of the resistance of vitreous and porcelain enamels to the liquid and vapour phases of the corrosive medium simultaneously.

ISO 19496-1:2017 defines a number of terms relating to vitreous and porcelain enamels and their technology. This list is not complete and only comprises those terms for which the definition is considered necessary for correct and adequate understanding in order to clarify these processes. The interpretations given are those corresponding to the practical usage in this field and they do not necessarily coincide with those used in other fields. For purposes of clarification, the term "vitreous enamel", used throughout this document, is synonymous with "porcelain enamel", the term favoured in the United States and some other countries.

ISO 19496-2:2017 establishes a system for the cataloguing of defects in sheet steel enamelling. It serves for a consistent language use concerning the designation and characterization of enamelling defects. This document is limited to detectable defects and does not purport to fully take into consideration all occurring types of defects. It does not evaluate enamelling defects; the classification carried out serves for the conveyance of practical knowledge.

ISO 28706-2:2017 specifies a test method for the determination of the resistance of flat surfaces of vitreous and porcelain enamels to boiling acids, boiling neutral liquids, alkaline liquids and/or their vapours. This method allows the determination of the resistance of vitreous and porcelain enamels to the liquid and vapour phases of the corrosive medium simultaneously.

This International Standard specifies a method for non-destructive measurements of the thickness of
non-magnetizable coatings on magnetizable base metals.
The measurements are tactile and non-destructive on typical coatings. The probe or an instrument with
integrated probe is placed directly on the coating to be measured. The coating thickness is displayed on
the instrument.
In this International Standard the term “coating” is used for material such as, for example, paints and
varnishes, electroplated coatings, enamel coatings, plastic coatings, powder coatings, claddings.
NOTE This method can also be applied to the measurement of magnetizable coatings on non-magnetizable
base metals or other materials (see ISO 2361).

ISO 2178:2016 specifies a method for non-destructive measurements of the thickness of non-magnetizable coatings on magnetizable base metals.
The measurements are tactile and non-destructive on typical coatings. The probe or an instrument with integrated probe is placed directly on the coating to be measured. The coating thickness is displayed on the instrument.
In ISO 2178:2016 the term "coating" is used for material such as, for example, paints and varnishes, electroplated coatings, enamel coatings, plastic coatings, powder coatings, claddings.
NOTE          This method can also be applied to the measurement of magnetizable coatings on non-magnetizable base metals or other materials (see ISO 2361).

This standard establishes a system for the cataloguing of defects in enamellings for chemical service and vessels; in addition, it describes some types of areas in which defects have been treated and which can easily be confounded with enamelling defects.
It serves for a consistent language use concerning the designation and characterization of enamelling defects. This standard is limited to detectable defects and does not purport to fully take into consideration all occurring types of defects. It does not evaluate
enamelling defects; the classification carried out is based on experience and corresponds, as far as possible, to ISO 28721-1.
NOTE Regarding the acceptance of glass lined equipment for use in process engineering, ISO 28721-1 applies.

ISO 2178:2016 specifies a method for non-destructive measurements of the thickness of non-magnetizable coatings on magnetizable base metals. The measurements are tactile and non-destructive on typical coatings. The probe or an instrument with integrated probe is placed directly on the coating to be measured. The coating thickness is displayed on the instrument. In ISO 2178:2016 the term "coating" is used for material such as, for example, paints and varnishes, electroplated coatings, enamel coatings, plastic coatings, powder coatings, claddings. NOTE This method can also be applied to the measurement of magnetizable coatings on non-magnetizable base metals or other materials (see ISO 2361).

This part of ISO 28706 describes a test method for the determination of the resistance of vitreous and
porcelain enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The
apparatus used is a cylindrical vessel in which only one enamelled specimen is tested.
NOTE 1 The test method was initially set up for determination of the resistance of vitreous and porcelain
enamels to a hot sodium hydroxide solution. Within the scope of this part of ISO 28706, the resistance of other
alkaline liquids can be tested.
NOTE 2 This part of ISO 28706, which uses a cylindrical vessel, is generally used for tests carried out on
vitreous and porcelain enamel coatings for the chemical industry.

ISO 28721-5:2016 establishes a system for the cataloguing of defects in enamellings for chemical service and vessels. In addition, it describes some types of areas in which defects have been treated and which can easily be confounded with enamelling defects. It serves for a consistent language use concerning the designation and characterization of enamelling defects.
ISO 28721-5:2016 is limited to detectable defects and does not purport to fully take into consideration all occurring types of defects. It does not evaluate enamelling defects; the classification carried out is based on experience and corresponds, as far as possible, to ISO 28721-1.
NOTE          Regarding the acceptance of glass lined equipment for use in process engineering, ISO 28721-1 applies.

This International Standard establishes the requirements for the design and use of vitreous-enamelcoated
bolted cylindrical steel tanks for the storage or treatment of water or municipal or industrial
effluents and sludges.
It applies to the design of the tank and any associated roof and gives guidance on the requirements for
the design of the foundation.
It applies where
a) the tank is cylindrical and is mounted on a load-bearing base substantially at or above ground level;
b) the product of the tank diameter in metres and the wall height in metres lies within the range 5 to 500;
c) the tank diameter does not exceed 100 m and the total wall height does not exceed 50 m;
d) the stored material has the characteristics of a liquid, exerting a negligible frictional force on the
tank wall; the stored material may be undergoing treatment as part of a municipal or industrial
effluent treatment process;
e) the internal pressure in the headspace above the liquid does not exceed 50 kPa and the internal
partial vacuum above the liquid does not exceed 10 kPa;
f) the walls of the tank are vertical;
g) the floor of the tank is substantially flat at its intersection with the wall; the floor of the tank may
have a rise or fall built in to allow complete emptying of the tank contents, the slope of which does
not exceed 1:100;
h) there is negligible inertial and impact load due to tank filling;
i) the minimum thickness of the tank shell is 1,5 mm;
j) the material used for the manufacture of the steel sheets is carbon steel (tanks constructed of sheets
made from aluminium or stainless steel are outside the scope of this International Standard);
k) the temperature of the tank wall during operation is within the range −50 °C to +100 °C under all
operating conditions.
This International Standard also gives details of procedures to be followed during installation on site
and for inspection and maintenance of the installed tank.
It does not apply to chemical-reaction vessels.
It does not cover resistance to fire.

ISO 28721-5:2016 establishes a system for the cataloguing of defects in enamellings for chemical service and vessels. In addition, it describes some types of areas in which defects have been treated and which can easily be confounded with enamelling defects. It serves for a consistent language use concerning the designation and characterization of enamelling defects. ISO 28721-5:2016 is limited to detectable defects and does not purport to fully take into consideration all occurring types of defects. It does not evaluate enamelling defects; the classification carried out is based on experience and corresponds, as far as possible, to ISO 28721-1. NOTE Regarding the acceptance of glass lined equipment for use in process engineering, ISO 28721-1 applies.

ISO 28765:2016 establishes the requirements for the design and use of vitreous-enamel-coated bolted cylindrical steel tanks for the storage or treatment of water or municipal or industrial effluents and sludges.
It applies to the design of the tank and any associated roof and gives guidance on the requirements for the design of the foundation.
It applies where
a)    the tank is cylindrical and is mounted on a load-bearing base substantially at or above ground level;
b)    the product of the tank diameter in metres and the wall height in metres lies within the range 5 to 500;
c)    the tank diameter does not exceed 100 m and the total wall height does not exceed 50 m;
d)    the stored material has the characteristics of a liquid, exerting a negligible frictional force on the tank wall; the stored material may be undergoing treatment as part of a municipal or industrial effluent treatment process;
e)    the internal pressure in the headspace above the liquid does not exceed 50 kPa and the internal partial vacuum above the liquid does not exceed 10 kPa;
f)     the walls of the tank are vertical;
g)    the floor of the tank is substantially flat at its intersection with the wall; the floor of the tank may have a rise or fall built in to allow complete emptying of the tank contents, the slope of which does not exceed 1:100;
h)    there is negligible inertial and impact load due to tank filling;
i)     the minimum thickness of the tank shell is 1,5 mm;
j)     the material used for the manufacture of the steel sheets is carbon steel (tanks constructed of sheets made from aluminium or stainless steel are outside the scope of this International Standard);
k)    the temperature of the tank wall during operation is within the range −50 °C to +100 °C under all operating conditions.
ISO 28765:2016 also gives details of procedures to be followed during installation on site and for inspection and maintenance of the installed tank.
It does not apply to chemical-reaction vessels.
It does not cover resistance to fire.

ISO 28706-4:2016 describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The apparatus used is a cylindrical vessel in which only one enamelled specimen is tested.
NOTE 1       The test method was initially set up for determination of the resistance of vitreous and porcelain enamels to a hot sodium hydroxide solution. Within the scope of this part of ISO 28706, the resistance of other alkaline liquids can be tested.
NOTE 2       This part of ISO 28706, which uses a cylindrical vessel, is generally used for tests carried out on vitreous and porcelain enamel coatings for the chemical industry.

This part of ISO 28721 specifies requirements for the resistance to chemical attack and thermal shock
of chemical enamels and their designation for ordering purposes.
It is applicable to enamelled apparatus, piping and other components primarily used for process
equipment in chemical plants.
It only applies to unalloyed and low-alloy carbon steels suitable for enamelling.
NOTE The main criteria for assessing enamel quality are the resistance to chemical attack and thermal
shock and the structure of the cover coat enamel.

ISO 28765:2016 establishes the requirements for the design and use of vitreous-enamel-coated bolted cylindrical steel tanks for the storage or treatment of water or municipal or industrial effluents and sludges. It applies to the design of the tank and any associated roof and gives guidance on the requirements for the design of the foundation. It applies where a) the tank is cylindrical and is mounted on a load-bearing base substantially at or above ground level; b) the product of the tank diameter in metres and the wall height in metres lies within the range 5 to 500; c) the tank diameter does not exceed 100 m and the total wall height does not exceed 50 m; d) the stored material has the characteristics of a liquid, exerting a negligible frictional force on the tank wall; the stored material may be undergoing treatment as part of a municipal or industrial effluent treatment process; e) the internal pressure in the headspace above the liquid does not exceed 50 kPa and the internal partial vacuum above the liquid does not exceed 10 kPa; f) the walls of the tank are vertical; g) the floor of the tank is substantially flat at its intersection with the wall; the floor of the tank may have a rise or fall built in to allow complete emptying of the tank contents, the slope of which does not exceed 1:100; h) there is negligible inertial and impact load due to tank filling; i) the minimum thickness of the tank shell is 1,5 mm; j) the material used for the manufacture of the steel sheets is carbon steel (tanks constructed of sheets made from aluminium or stainless steel are outside the scope of this International Standard); k) the temperature of the tank wall during operation is within the range −50 °C to +100 °C under all operating conditions. ISO 28765:2016 also gives details of procedures to be followed during installation on site and for inspection and maintenance of the installed tank. It does not apply to chemical-reaction vessels. It does not cover resistance to fire.

ISO 28706-4:2016 describes a test method for the determination of the resistance of vitreous and porcelain enamelled articles to attack by alkaline liquids at temperatures between 25 °C and 95 °C. The apparatus used is a cylindrical vessel in which only one enamelled specimen is tested. NOTE 1 The test method was initially set up for determination of the resistance of vitreous and porcelain enamels to a hot sodium hydroxide solution. Within the scope of this part of ISO 28706, the resistance of other alkaline liquids can be tested. NOTE 2 This part of ISO 28706, which uses a cylindrical vessel, is generally used for tests carried out on vitreous and porcelain enamel coatings for the chemical industry.

ISO 28721-2:2015 specifies requirements for the resistance to chemical attack and thermal shock of chemical enamels and their designation for ordering purposes.
It is applicable to enamelled apparatus, piping and other components primarily used for process equipment in chemical plants.
It only applies to unalloyed and low-alloy carbon steels suitable for enamelling.
NOTE          The main criteria for assessing enamel quality are the resistance to chemical attack and thermal shock and the structure of the cover coat enamel.