Zhang Lian
(Langfang Donghua Anti-corrosion Engineering Co., Ltd. Langfang, Hebei Province, 065000)
A, history
Epoxy coal asphalt coatings 1974, the first generation of products developed successfully, 1979, the second generation of products developed successfully in 1987, the Ministry of Petroleum, the Ministry of Petroleum compiled the "buried steel pipelines, coal-oxygen coal asphalt anti-corrosion layer technical standards" SYJ 28-87, 1991 developed the "buried steel pipeline construction and acceptance of epoxy coal asphalt layer The Ministry of Petroleum prepared the "buried steel pipeline epoxy coal asphalt anticorrosion layer technical standards" SYJ 28-87, 1991 developed the "buried steel pipeline epoxy coal asphalt anticorrosion layer construction and acceptance specifications" SYJ 4047-90, 1996 Ministry of Petroleum of the above two standards were re-amended to merge and promulgate China's petroleum and natural gas industry standards SY/T 0447-96, * * * * has experienced 22 years.
Epoxy coal asphalt coating the first batch of test pieces buried in 1974 in Daqing, Qinhuangdao, Zhengzhou, Wuhan and Zhanjiang, etc., the second generation of products GH2 type in 1982 for the Qinhuangdao oil company's first station station 11 kilometers of Φ720 ㎜ pipeline anticorrosive, is the first time the largest industrial use, and so far is still effective, the coatings bonded tightly, hard as before.
The use of epoxy coal asphalt coating anticorrosion typical projects include Beijing Water Company Military Museum in front of the underground water pipeline, Harbin city gas pipeline network *** 450 kilometers, the first and second phase of the Beijing Water Nine Plant project of more than 40 kilometers of 2.2m diameter water supply pipelines, etc., have been in normal use for nearly 20 years for China's large-caliber water supply pipeline corrosion set a precedent for the external.
Epoxy coal asphalt coatings used in oil storage tanks and other petrochemical equipment corrosion examples include the Shengli Oilfield Binnan station in 1990, 11 5000 cubic meters of oil tank top corrosion overhaul, 89 years of the Asian Games Village Sewage Treatment Plant activated sludge tanks (concrete tanks) corrosion, the Beijing Gao Beidian Sewage Treatment Plant activated sludge tanks and sewage pipeline corrosion and the first phase of the project of the Shijingshan Power Plant in 1986, the circulating water pipeline and cool water tower. Shijingshan Power Plant Phase I project in 1986, circulating water pipeline and cool water tower corrosion, so far, have more than 10 years of history, the use of good results.
At present, epoxy coal asphalt coating has been in the petroleum, chemical, electric power, urban utilities and other industries of water, gas, natural gas, heating and other kinds of pipeline use, is the use of our country's wider range of anticorrosion coatings.
Two, experience
After more than twenty years of application practice, summarizes the epoxy coal asphalt coating has the following advantages and disadvantages.
Advantages:
1, anti-corrosion layer performance is stable, long service life.
2, construction is more convenient, the coating natural curing, no heating equipment, can be mechanized, semi-mechanized or manual construction.
3, the coating cost is low, in the same conditions of descaling, its comprehensive cost (including transportation, processing, loss, etc.) is lower than all
all anticorrosion materials, similar to petroleum asphalt.
4, after more than twenty years of experience, the petroleum sector has developed a set of epoxy coal asphalt anti-corrosion from design to construction of
technical standards, indicating that its technology is mature and reliable.
Disadvantages:
1, the coating curing reaction is affected by the temperature, low temperature (below 10 ℃) curing slower, the northern winter construction is limited.
2, the coating manufacturers throughout the country, low-priced low-quality products impact on the market, affecting the quality of the project, damage to the image of epoxy coal asphalt.
3, due to the construction of a small amount of solvent can be added, it is easy for some construction units to provide jerry-built (excess solvent added to dilute the coating in order to reduce the cost) opportunities.
4, because it is a two-component, on-site construction of the curing agent ratio is not allowed or uneven mixing often results in poor curing or uneven quality after curing.
5, the coating of glass cloth, glass cloth contains wax, affecting the interlayer adhesion.
Three, innovation
Donghua general manager, senior engineer Zhang Lianyuan is the second generation of epoxy coal asphalt product development project leader, summed up more than two decades of experience and lessons learned from the application of practice, the invention of a new type of epoxy coal asphalt anticorrosion materials - epoxy coal asphalt cold wrapped tape, and obtained a patent in China (Patent No. ZL) 98205622.2).
The epoxy coal asphalt cold wrapping tape consists of two parts: cold wrapping tape and molding rubber. The cold-wrapped tape is made of polypropylene non-woven felt impregnated with epoxy coal asphalt paint, after slitting and winding, with standard slitting widths of 125㎜ and 250㎜, and lengths of 20m and 40m per roll (which can be adjusted according to the special requirements of the users), and is divided into two kinds of reinforced and extra-strengthened grades according to the thickness. The shaping adhesive is composed of A and B components, and is divided into two types according to the temperature of use: the warm type (used at temperatures above 5℃) and the low temperature type (used only at temperatures below 5℃). Cold wrapping tape and shaping glue supporting the supply of products from the factory, the construction of the shaping glue A, B component equal amount of mixing, and then according to the structure of shaping glue - cold wrapping tape - shaping glue on the surface of the protected object, after leaving the natural curing of the formation of epoxy coal asphalt corrosion-resistant layer.
The characteristics of epoxy coal asphalt cold wrapping tape are:
1, cold wrapping tape substrate selection of polypropylene non-woven felt, the material is a high mechanical strength, corrosion resistance of very good synthetic fibers, and the surface of the non-wax, the thickness of the uniformity of the anti-corrosion layer, so the surface of the flat, strong adhesion, pinhole less, excellent electrical properties and anticorrosive properties.
2, shaping glue using a special formula, the anticorrosion layer curing speed, short construction period, can be normal construction throughout the year, solving the winter construction problems.
3, construction is convenient and fast. A coating can achieve China's oil and gas industry standard SY/T 0447-96 requirements of the strengthened level or special strengthened level of anti-corrosion layer, than the use of epoxy coal asphalt paint plus glass cloth labor-saving, convenient.
Four, technical performance
Referring to China's oil and gas industry standard SY/T 0447-96, respectively, by the China Petroleum and Natural Gas Pipeline Research Institute (August 1999) and Henan Product Quality Supervision and Inspection Institute (November 2000) test, confirming that the epoxy-coal asphalt cold-wrapped tape of the technical performance in line with the requirements of industry standards.
Table I Cold-wrapped tape combination performance (shaping rubber - cold-wrapped tape - shaping rubber structure)
No. Item Unit Line standard Product indexes Pipeline Research Institute test results Henan Quality Supervision Institute
Test results
1 Drying Surface drying h ≤4 ≤1 1 ______
Solid drying h ≤16 ≤6 4 ______
2 Color and Appearance Black glossy Black glossy,
surface flat
No hollow drums, bonded tightly Black glossy,
surface flat Conforms to the standard
Requirements
3 Thickness Reinforced grade ㎜ ≥0.4 ≥0.4 0.59 ______
The special Strengthening grade ≥0.6 ≥0.6 0.71 ______
4 Leakage detection by electric spark Strengthening grade kV ≥2.5 ≥2.5 3.0 _______
Special Strengthening grade ≥3.0 ≥3.0 5.0 _______
5 Adhesion
(180°peeling) N/㎝ ≥12 20.2～21.7 _______
6 Impact resistance ㎏? ㎝ ≥50 _____ 50 ______
7 Industrial frequency electrical strength MV/m ≥20 _____ ______ ＞20
8 Volumetric resistivity Ω?m ≥1×1010 _____ ______ 2.9×1012
Five, use method
1, surface treatment. Remove the oil and dust and other loose material on the surface of steel, wood and cement to reveal a flat and solid surface. Poor treatment will affect the adhesion, reduce the quality of the coating, the higher the quality of surface treatment, the coating help life longer.
2, coated with molding glue. Styling glue is divided into A and B components, mixed at a ratio of 1:1, stirred evenly after painting, to be coated evenly, full, and shall not miss the coating.
3, wrap the cold wrapping tape. Styling glue coated immediately after winding or pasting cold wrapping tape, must maintain the adhesive state of the styling glue, if the styling glue painting time is too long has been dry, must be painted again before wrapping the tape. After the cold wrapping tape is wrapped, apply the shaping adhesive again. If the corrosive environment is bad, need higher insulation performance or require the protection of backfill under the ditch, you can wrap a layer of cold wrapped tape or coated with a stereotypes of adhesive, the construction method as above, to play the role of double-layer protection.
Sixth, economic indicators
Epoxy coal asphalt cold wrapped tape construction method is relatively simple, a sticky that can save a lot of labor costs and the corresponding management fees (secondary fees). A layer of reinforced cold-wrapped tape can reach the reinforced level stipulated in the petroleum industry standard SY/T 0447-96, and a layer of special reinforced cold-wrapped tape can reach the special reinforced standard. (See Table 2)
Table 2
SY/T 0447-96 Standard Requirements GH4 Type Cold Wrap Tape
Anti-corrosive Grade Coating Thickness
(㎜) Detection Resistance Voltage
(V) Model Resistance to Detection Voltage
(V) Coating Thickness
(㎜)
Strengthening Grade ≥0.4 2500 Strengthening grade 2500 0.4
Extra-strengthening grade ≥0.6 3000 Extra-strengthening grade 3000 0.6
Commonly used at home and abroad pipeline anticorrosive layer comprehensive cost analysis. (See Table III)
Table III
Serial No. Species Manufacturing method Comprehensive cost (yuan/m2)
1 Polyethylene Jacket Melt Extrusion 65-75
2 Powdered Epoxy Polyethylene Jacket Three-layer Coating Electrostatic Spraying, Melt Extrusion 90-100
3 Polyethylene Adhesive Belt Rubber-based binder plus polyethylene belt 55-65
4 coal tar enamel hot coating plus non-woven glass felt 70-80
5 petroleum asphalt coating hot coating plus glass cloth 55-65
6 coal epoxy asphalt coating cold coated plus glass cloth 50-60
7 coal epoxy asphalt cold-wound tape cold-wound tape plus shaping adhesive 50-55
Seven, the comprehensive performance of the pipeline external corrosion-resistant layer comparison
Practice has proved that various kinds of anti-corrosion layer, the rubber binder plus polyethylene belt, the corrosion of the pipeline, the corrosion of the pipe and the corrosion of the pipeline. p>Practice has proved that: all kinds of anti-corrosion layer has its own unique advantages and disadvantages and applicable conditions, each anti-corrosion project should be based on its corrosive environment, climatic conditions, the working conditions of the transport medium, the service life requirements, the ability to afford the investment, the availability of sources of supply, and other factors, to carry out a comprehensive validation and selection of the best.
The main performance comparison of the above seven anti-corrosion layer is listed in Table IV
Table IV Comprehensive performance comparison of pipeline external anti-corrosion layer
Materials
Projects Petroleum asphalt anti-corrosion layer polyethylene
Adhesive tape Extruded poly
Ethylene layer Fused epoxy
Powder layer Coal tar
Porcelain enamel layer Coal epoxy
Bitumen layer Epoxide
Bitumen layer Epoxide layer Epoxide layer Epoxide layer Epoxide layer Epoxide layer Epoxide layer Epoxy layer Epoxy layer
Asphalt layer Coal Tar Epoxy Cold Strip
Electrical insulation properties Medium Excellent Excellent Excellent Excellent Excellent Excellent
Cathodic protection shielding Poor Excellent Excellent Excellent
Chemical stability Medium Excellent Excellent Excellent Excellent
Mechanical properties Poor Excellent Excellent Medium Excellent
Resistance to microbial erosion Poor Excellent Excellent Excellent Excellent Excellent
Depositioning and repairing Medium Excellent Excellent Medium Excellent Excellent Excellent
Eco-environmental resistance: poor, excellent, good, medium, good, good
Life: poor, medium, good, good, good, good
Comprehensive cost: low, medium (two-layer), medium
(three-layer), high, high, medium, low, low
Note: Comparison of the performance of excellent, good, medium, and poor in the order of performance; comparison of the cost of the comprehensive cost in the order of high, medium, and low.
VIII. Conclusion
Epoxy Coal Asphalt Cold Strip has been awarded a national patent (Patent No. ZL 98205622.2), Langfang City, issued a production license (Langong Gongxu Office Word No. 1106) from 1996 has been mass production in 2001 Langfang City, the technical supervision department as a quality trustworthy products.
Epoxy Coal Asphalt Cold Strip is cheaper, easy to construct, a paste that is, after the curing of the coating of high mechanical strength, electrical and chemical properties, can be constructed at low temperatures and humid conditions, the thickness of the coating is uniform, the quality of the construction is stable, the coating has anticorrosive, waterproof, acid and alkali resistance, impact resistance, resistance to low temperatures and high temperatures and other properties.
The cold-wrapped tape can be widely used in oil, gas, water and road, chemical plants, sewage treatment plants, tank bottom, crude oil tank corrosion, can also be used for roof waterproofing, basement waterproofing and moisture-proofing projects.