Analysis on the current situation of domestic stan

Analysis of the current situation of domestic standards for thermosetting powder coatings

analysis of the current situation of domestic standards for thermosetting powder coatings

February 14, 2020

Abstract

this paper introduces the current situation of domestic standards for powder coatings and the differences in standards compared with liquid coatings, and emphasizes that the development of powder coatings industry is inseparable from the development of standards; The current situation of powder coating standards for domestic drinking water transmission and distribution equipment and the current situation of powder coating standards in the field of heavy corrosion prevention are analyzed

key words: powder coating; national standard; Industry standards; Standard for powder coatings for drinking water transmission and distribution equipment; Heavy duty anti-corrosion coating standards

Introduction

statistical data as of 2018 show that powder coatings still account for less than 10% of the entire coating market. With the increase of national policies and regulations on VOCs control, "oil to water", "oil to powder" and "high solid content" have become several hot topics. Although powder coatings are limited by high-temperature baking and substrate compared with water-based or high solid content paints, with the breakthrough of the technical bottleneck of powder coatings, its application prospect can not be underestimated

with the increase of powder coating application industry and the expansion of market field, the corresponding demand for standards follows. And standards are fundamental to lead and drive the development of the whole industry. Powder coating industry associations, manufacturing enterprises and relevant upstream and downstream enterprises have actively participated in or led the formulation and suggestions of powder coating related standards, so as to jointly create a good environment and atmosphere for the development of the industry. Leading the industry standard and being the industry benchmark should be the ultimate goal pursued by every excellent enterprise

looking at the relevant national standards for powder coatings

compared with oil-based coatings, powder coatings have a short history of development, low market share, relatively backward development in standards, and relatively few relevant standards. Up to now, among the national standards, there are only 35 current standards directly related to powder coatings, including 20 national standards, 13 industrial standards and 2 local standards; Industry standards specifically include four for the transportation industry, seven for the chemical industry, and one for non-ferrous metals and railway transportation. However, in fact, the application field of powder coatings is much wider than this. In other words, many industries lack the standard requirements of powder coatings

in recent years, national standards have also carried out a series of reforms. Among them, the National Standards Committee has proposed "Chinese standard 2035", which aims to reform, improve and optimize Chinese standards, so that Chinese standards can take the lead in the world. In April, 2017, the China Standards Committee for materials and testing groups (CSTM) was established in Beijing and has successively launched a sharing platform. The state vigorously promotes the development of group standards and closely integrates standards with market demand. On June 5, 2019, Zhongguancun material testing technology alliance released two group standard projects on powder coatings: professional operation vehicle powder coatings and selective ion electrode method for the determination of fluorine content in powder coatings. The former will be of great significance for standardizing and improving the level of powder coating for special operation vehicles, and the latter will lay the foundation for formulating the standard of fluorocarbon powder coating

in addition to the field of special operation vehicles and ultra weather resistant fluorocarbon powder coatings, powder coatings are also used in heavy corrosion protection, insulated electronics, insulated busbar, high reflection buildings, domestic and drinking water valve accessories, traffic and highway guardrails, auto parts, new energy vehicles, photovoltaic power generation, lighting and other industries. Because drinking water is closely related to people's livelihood, and in the field of heavy corrosion prevention, powder coatings, even the experimental curve, can provide a general outline, which has great potential. Therefore, the following focuses on the standards in these two fields

current situation of powder coating standards for drinking water transmission and distribution equipment

domestic standards related to protective coatings for water transmission and distribution equipment can be seen in Table 1

in the field of water transmission and distribution, coatings are protective materials for water transmission and distribution. In gb/t standard for safety evaluation of drinking water transmission and distribution equipment and protective materials, the Health Commission has stipulated the safety performance of protective materials, requiring the sprayed pipe fittings to be soaked and tested, and the soaked water must meet the toxicological requirements and water quality requirements in the national mandatory standard GB hygienic standard for drinking water

in China, each provincial Health Commission and Quality Supervision Bureau have their own "measures for the supervision and management of health administrative licensing" and "measures for the supervision and management of drinking water". What is related to coating is the need to conduct on-site audit of protective material production enterprises to ensure that the site selection, raw materials used, production and manufacturing process, as well as the quality and health conditions of workers meet the requirements. This really ensures the quality of drinking water in a great sense

however, after the pipes, valves and other accessories for water transmission and distribution are buried underground, in the actual soil environment, only a soaking toxicity test of pipe fittings before installation is not enough to ensure the long-term corrosion resistance. For the coating, the necessary mechanical properties can prevent the cracking of the coating after collision, and the necessary anti-corrosion properties can make the pipe fittings have a lasting protective effect on the metal in the buried environment. Moreover, a very important part of the protective performance of the coating is reflected in the spraying construction. How to ensure the correct pretreatment, apply the correct construction conditions, and apply the coating on the equipment and cure it is also missing in the current domestic certification system. In different industries and fields, there are basically standards for water transmission and distribution, but the requirements of the standards are uneven

in the hydraulic engineering industry, there is an important industry standard SL "Specification for corrosion protection of hydraulic metal structures", which stipulates the appearance, thickness and adhesion of pretreatment and coating film, but does not mention mechanical properties and corrosion resistance. Many landmarks in this field db13t/technical specification for cast iron gate in hydraulic engineering, db32t/2334 The requirements in SL are referenced in the coating involved in the code for inspection and evaluation of construction quality of hydraulic engineering, Part 3: metal structure and hydraulic machinery, and the national standard gb/t code for manufacture, installation and acceptance of steel gate in hydraulic and hydroelectric engineering

in the urban construction industry, the two industry standards cj/t "plastic coated composite steel pipe for water supply" and cj/t "soft seal gate valve for water supply and drainage" have requirements for coatings for steel pipes and gate valves: meet the requirements that do not affect water quality, thickness, hardness, adhesion and sanitary performance. Mechanical properties and corrosion resistance are not mentioned in the standard

in the field of iron and steel industry, gb/t "epoxy coating of ductile iron pipes, fittings and accessories" has carried out thickness, electric breakdown, MIBK wiping, adhesion, impact, indentation, hot water immersion Acid and alkali resistance "in order to find out problems in the initial stage of process development and carry out improvement, wear resistance and hygiene performance requirements, except for not mentioning the corrosion resistance performance, others are relatively comprehensive.

in the oil and gas industry, the requirements for the coating are the most stringent, and the internal coating and external coating of fusion sintered epoxy powder coating are specified respectively: sy/t" technical standard for fusion bonded epoxy powder internal anticorrosive coating of steel pipelines "and sy/t" Technical specification for fusion bonded epoxy powder coating of steel pipeline. The standard has made requirements for the performance of powder coating and coating: Taking the outer coating as an example, the performance requirements of powder: curing time, coking time, particle size, thermal characteristics, density, magnetic content; Coating performance requirements: appearance, thermal characteristics, cathodic stripping, bending resistance, impact resistance, porosity of bonding surface and section, scratch resistance, wear resistance, electrical strength, mentioned resistivity, cathodic stripping resistance and chemical corrosion resistance of the coating after bending. It can be said that the performance requirements have been very comprehensive and can be used as an important reference standard for improving the coating standard in the field of drinking water. However, the transportation requirements of oil and the transportation of water with a higher risk level need to be adjusted appropriately

however, since domestic steel pipelines are mainly coated with cement mortar oil paint inside and outside, the application of powder coating still needs more attempts and the development of supporting casting process. At present, the application of powder coating is mainly for iron castings such as valves, connectors and water storage tanks

to sum up, in order to improve the quality of drinking water, the industry standards for oil and gas pipelines can be used as an important reference to improve the coating standards in this field. At the same time, combined with the German DVGW certification system, the American NSF certification system and the Australian/New Zealand as/nzs4020 certification system, the certification system should be improved while the standards are improved

Table 1 list of relevant standards for coatings for domestic water transmission and distribution equipment

industry and field

standard number and standard name

requirements for coating performance

Health Department

GB sanitary standard for drinking water

reference gb/t

gb/t safety evaluation standard for drinking water transmission and distribution equipment and protective materials

hygienic requirements for soaking water (iron, manganese, copper, zinc, heavy metals, phenol, chloroform, fluoride, etc.)

water conservancy industry

SL should play a bridging role. 7 "Specification for corrosion protection of hydraulic metal structures"

apparent, film thickness, adhesion

DB 13T/Technical Specification for cast iron gate in hydraulic engineering "

refer to SL

DB 32t/2334 Code for inspection and evaluation of construction quality of hydraulic engineering Part 3 metal structure and hydraulic machinery

reference SL

gb/t code for manufacture, installation and acceptance of steel gate in hydraulic and hydroelectric engineering

reference SL

urban construction industry

urban construction industry standard cj/t water supply plastic coated composite steel pipe

does not affect water quality, thickness, hardness, adhesion Hygienic requirements (refer to gb/t 17219)

urban construction industry standard cj/t "soft seal gate valves for water supply and drainage"

does not affect water quality, thickness, hardness, adhesion, hygienic requirements (refer to gb/t 17219)

steel industry field

gb/t "ductile iron pipes, fittings and accessories epoxy coating"

thickness, electrical breakdown, MIBK wiping, adhesion, impact, indentation, hot water immersion, acid and alkali resistance, wear resistance Hygienic performance

oil and natural gas

sy/t technical specification for fusion bonded epoxy powder coating for steel pipelines

powder performance requirements: curing time, coking time, particle size, thermal characteristics, density, magnetic content

coating performance requirements: appearance, thermal characteristics, cathodic stripping, bending resistance, impact resistance, porosity of bonding surface and section, scratch resistance, wear resistance, electrical strength, resistivity After bending, the coating is resistant to cathodic stripping and chemical corrosion

SY/T technical standard for fusion bonded epoxy powder internal anticorrosion coating for steel pipelines

powder performance requirements: curing time, coking time, particle size, thermal characteristics, density, magnetic content

coating performance requirements: appearance, thermal characteristics, cathodic stripping, salt spray resistance, bending resistance, impact resistance, porosity of bonding surface and section, scratch resistance, wear resistance, electrical strength Referring to the current situation of powder coating standards in the field of resistivity, cathodic stripping resistance, chemical corrosion resistance, high temperature and high pressure resistance of the coating after bending

according to ISO, the atmospheric environment is divided into c1/c2/c3/c4/c5-i/c5-m different grades. With the development of powder coating technology, in the environment from C3 to c5-i, steel structures