The current standards and test methods of high temperature anti-corrosion paint are reviewed

For a range of protective coating systems, there is a sound testing system, including how to recommend the coating system, and put forward a pre-certified method. For example, for anti-corrosion coatings, there are ISO 12944, ISO 20340, Norsok M501, ASTM D5894, ASTM B117 standards. For lining coatings, there are NACE TM-01-74, NACE TM-1085, ISO 2812, ASTMD5499 standard
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. For fire-resistant coatings, there are BS476, EN 13881, ASTM E119/ANSI UL263, UL1709, GB 14907. However, for high-temperature coatings, whether domestic or foreign, the standard is very limited, one is widely accepted the number of standards is relatively small, and the high temperature coating pre-certification method is also very limited. In this paper, some standards and test methods related to high temperature paint are collated and summarized to facilitate the reference of personnel in the high temperature paint industry.
1 Domestic high temperature paint-related standards
1.1 SH/T 3022-2011 "Petrochemical equipment and pipeline coating corrosion-resistant design specifications
in this standard mentioned six types of high-temperature coatings, respectively, inorganic zinc-rich coatings, epoxy phenolic resin coatings, silicone coatings, cold-sprayed aluminum coatings, thermal aluminum (zinc), applicable to the occasion see Table 1.
the technical requirements and test methods of various heat-resistant coatings are also put forward in this standard. This article is described in more detail in subsequent test methods. In this standard, the default is as long as the nominated type can be applied to high temperature occasions. The temperature tolerance of the product is not clearly required or tested in the technical requirements. The test method of thermal shock and corrosion protection under the insulation layer is not proposed.
also recommended coating kits in this standard, as in Table 2.
SH/T 3022 on the application of high temperature paint, SH/T 3022 coating matching recommendations
this table identifies the different temperature ranges, different operating conditions can be used in the high temperature paint varieties. The number of construction channels and the thickness of each paint dry film are proposed, and the requirements of the total thickness of dry film are also put forward. It is a good reference for engineers.
1.2 GB 50393-2008 "Steel oil storage tank corrosion prevention engineering technical specifications
in this standard mentioned that the outer wall primer of the crude oil storage tank with insulation layer should be rich in zinc-based anti-corrosion paint, finish should be water-resistant anti-corrosion coating, dry film thickness should not be less than 150 m.
the outer wall primer of the crude oil storage tank without insulation layer should adopt zinc-rich anti-corrosion coating, the paint can use fluorocarbons, acrylic-polyurethane and other water-resistant weather-resistant anti-corrosion coating, dry film thickness should not be less than 200 m.
heating tube should be based on the temperature of the heating medium, choose a suitable anti-corrosion coating, dry film thickness should not be less than 250 m, in general, the use of silicone coating more, there is the use of epoxy phenolic.
also put forward performance index requirements for silicone anti-corrosion coatings. The performance indicators inside are not exhaustive for high temperature paint, and some indicators are not suitable.
the zinc-rich paint referred to in this standard is used under the insulation layer, while zinc-rich paint is not explicitly recommended under the insulation layer in NACE 0198. Performance indicators for silicone corrosion-resistant coatings such as surface resistance, acid resistance (5% sulphuric acid, 720 h) are difficult to achieve. This environment is not the main environment faced by silicone-type high temperature anti-corrosion paint. Overall, in the high temperature paint industry, less reference to this standard. In addition, GB 50393 has initiated a new revision process, some of which may change in this revision.
1.3 DL/T 5072-2007 Thermal Power Plant Insulation Paint Design Code
The supporting coating recommended by this procedure is in Table 3. The standard does not specify the performance index of high temperature paint, nor does it specify the performance index of high temperature paint.
DL/T 5072 Companion Coatings Recommended
1.4 HG/T 4565-2013 "Boiler and Auxiliary Equipment High Temperature Resistant Coatings"
defines two types of high temperature coatings in this standard: Class A for heat treatment protection coatings and Category B for the use of protective coatings, respectively, for Class A and Class B coatings. The technical requirements of high temperature coatings are enriched in this standard, including not only the regular drying time and adhesion level, but also the requirements for heat resistance, post-heat salt spray testing and sudden cold resistance. Two of these test methods were first seen in domestic standards, one for sudden cold tests and one for post-heat salt spray tests. Specific test requirements can be seen in the Later Test Methods section of this article. The standard currently refers to fewer people in the country.
1.5 HG/T 3362-2003 "Aluminum powder silicone drying heat-resistant paint
the standard for two-part aluminum powder silicone drying heat-resistant paint proposed performance indicators. Details can be referred to in the later test methods section.2 Foreign Standard
2.1 NACE SP0198-2010 (Control of Corrosion Under Thermal Insulation and Fireproofing Materials
a typical corrosion protection system for carbon steel under the insulation layer, as shown in Table 4.
addition, in CS-8 also mentioned that inorganic zinc-rich can be used in the environment of -45 to 400 degrees C, but also with other types of high-temperature paint. Anti-corrosion systems for stainless steel are recommended as listed in Table 5.
as can be seen from Tables 4 and 5, the standard specifies the type of coating, the applicable temperature range, and the thickness of each coating, which is of strong reference in design. In this standard, that is, the default paint type can be used in this environment, there is no specific testing requirements for coatings.
2.2 Norsok M501
In Norsok M501 Edition6, System No.6C mentions that stainless steel uses 2 epoxy phenolic coatings at temperatures less than 150 degrees C, each at 125 m.
noted in System No.9 that carbon steels less than 150 degrees C can use two epoxy phenol coatings, each at 150 m. It is important to note that both NACE0198 and Norsok M501 suggest that stainless steel under the insulation layer should be coated with high temperature corrosion protection coatings.3 Normal test method for high temperature paint
High temperature paint is also a coating, many physical mechanical performance test methods and conventional anti-corrosion paint test methods consistent.
3.1 Status in the container
mentioned in HG/T 4565, visually determined, requires normality.
: open the container, mix with a knife or stir bar, allowing the bottom of the container to have precipitation, if stirred easily mixed evenly, then rated as "normal."
in SH/T 3022 mentioned with visual judgment, requires a well-stirred after no hard blocks, in a uniform state.
3.2 drying time
HG/T 4565 requires: table dry 2 h, do 24 h, dry 30min.
SH/T 3022 requirements: silicone aluminum powder heat-resistant paint table dry 2 h, dry 6 h; acrylic modified silicone heat-resistant paint table dry 2 h, dry 6h; cold spray aluminum paint table dry 2 h, dry 16 h; HG/T 3362 requirements: at 150 degrees C, dry 2 h.
test methods mentioned above are GB/T 1728
3.3 coating appearance
HG/T 4565 requirements are normal. Specifically described as: in scattered sunlight visual observation, Class A coatings should be applied uniformly, no pinholes, cracking and peeling phenomenon. Class B coatings should be applied uniformly, without hanging, flowering, pinholes, cracking and peeling phenomena.
requirements in HG/T 3362: silver grey, paint film flat.
3.4 Adhesion
As mentioned in SH/T 3022, with reference to GB/T 1728, silicone aluminum powder heat-resistant paint: 3 MPa; acrylic modified silicone heat-resistant paint: 3 MPa; cold-sprayed aluminum paint: 4 MPa
requires adhesion of 1 level in HG/T 4565, reference standard GB/T 9286-1998.
requires adhesion level 2 in HG/T 336≤2, refer to GB/T1720.
note that, in our experience, some types of high-temperature paint are not suitable for pulling. For example, cold-sprayed aluminum coatings are recommended to test adhesion with a cross-cut method based on ISO 2409, with a grade of 0, 1 or 2, or 5A, 4A or 3A according to ASTM D3359.
this is due to the flexible properties of cold-sprayed aluminum coatings, the value of the pull adhesion (according to ISO 4624) cannot be compared with other standard anti-corrosion coatings on the market.
when a pull-out adhesion test is performed, the value may be between 1 and 5 MPa, depending on the temperature exposed to the cold-sprayed aluminum coating. Because the coating will be cohesive damage rather than bonding damage between the substrate, the pull-out adhesion test does not represent the actual cold-sprayed aluminum coating and the adhesion between the substrate. Since the coating is cohesively damaged in the pull-out adhesion test, the coating is considered to have sufficient adhesion.
3.5 hardness
hardness is not a particularly important indicator for high temperature paint, so there is no requirement in the standard, many times this data is measured only as a reference. We've seen references to the ASTM D3363 pencil hardness method to test hardness, as well as Fischer 100 diamond hardness.
3.6 Bending
is mentioned in SH/T 3022 and refers to GB/T 6742, which requires silicone aluminum powder heat-resistant paint: ≤2 mm; acrylic modified silicone heat-resistant paint: ≤2 mm; and cold-sprayed aluminum paint: ≤2 mm. Flexibility is required in HG/T 3362 up to ≤ mm, with reference GB/T 1731.
3.7 Non-volatile content
in SH/T 3022 requires silicone aluminum powder heat-resistant paint ≥45%; acrylic modified silicone heat-resistant paint ≥35%; cold-sprayed aluminum paint ≥60%. In HG/T 3362, a 34% ≥ is required, and the reference methods are GB 1725.
3.8 Impact resistance
requires 35 cm in≥ HG/T 3362, refer to GB/T 1732.
3.9 Water Resistance
mentioned in HG/T 3362, immersed in distilled water 24 h, removed and placed 2 h after observation, requires the appearance of the paint film unchanged, reference GB/T 1733.
3.10 Gasoline resistance
mentioned in HG/T 3362, immersed in RH-75 gasoline 24 h, removed and placed 1 h after observation, requires the paint film is non-foaming, unchanged soft, reference GB/T 1734.
3.11 chloride ion content test
we know that chlorine ions can cause corrosion in stainless steel, which is why many stainless steels need to be painted. Sometimes the matching will require the content of chlorine ions in the paint. Chloride ion testing can be carried out with reference to ASTM C871-04. 4 Special testing program for high temperature paint
Many tests are specific to high temperature paint, such as heat resistance, heat impact resistance and corrosion resistance testing under the insulation layer.
4.1 Heat Resistance
is mentioned in HG/T 4565, with reference to GB/T 1735-2009 at 400 degrees C, 24 h, no foaming, no wrinkle, no shedding, no cracking, powdering ≤2 level, rowing test ≤2 level.
GB 50393 is proposed, according to GB/T 1735 at 180 degrees C 24 h≥;
tests are tested at different temperatures, between thermostats and heating processes.
: GB 1735 is the test standard for high temperature anti-corrosion paints. The test method is to prepare the paint film on 4 thin steel plates, and after the paint film is dry, place 3 paint samples in a blowing thermostat or high temperature furnace at a set temperature. After reaching the specified temperature, the model will be taken out, compared with the original model, while checking whether there are layers, wrinkles, blisters, cracking, color change and other phenomena.
4.2 Salt-resistant
requires 240 h in HG/T 4565 to be non-foaming, non-wrinkled, non-falling off, not cracking, reference GB/T 1771-2007.
resistance to salt spray usually indicates corrosion resistance of the coating, 240 h is indeed short. In some of our in-product internal tests, a neutral salt mist test of up to 5,000 h is performed at 35 degrees C, based on ISO7253, and then foaming and rusting are measured. For example, epoxy phenol aldehyde resistant to high temperature paint.
4.3 Post-Heat-resistant Salt Mist Test
In the HG 4565 standard, the test plate is d?boarded into a high-temperature furnace for five consecutive heating tests under 200 degrees C/8 h, 250 degrees C/16 h, 300 degrees C. /8 h, 350 degrees C/16 h, 400 degrees C/8 h, heating model at 23 degrees C placed 1 h, according to GB 1771-2007 salt spray test 24 h, requires no foaming, no wrinkle, no shedding, no cracking.
Again, for certain coatings, such as epoxy phenol-resistant high-temperature paint, there will be more rigorous testing within our company, with a salt spray test of 5,000 h at 230 degrees C and 16h at room temperature, after 3 cycles.
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