Contact: Cheng Huiqiang
Address：No. 333, Jinxian Road, Jinjiaba, FENHU Town, Wujiang District, Suzhou City, Jiangsu Province
Applicability of cold-wrapped tape in overhaul of anticorrosive layer
1. Product classification
At present, the classification of cold-wound tape products has not been conducted in China, and there is no corresponding evaluation basis for the selection of anticorrosive overhaul materials. The problems that occur in some cases are actually related to the field applicability of the product. Foreign countries have performed classification and performance tests on cold-wound tapes in BS EN 12068 according to resistance to mechanical damage, operating temperature or special installation conditions, and give technical specifications for different grades of products, for example, BS EN 12068 cathodic protection- Together with cathodic protection, organic coatings—tape and shrink material—provide protection against external corrosion of buried or underwater steel pipelines .
一分彩(1) Resistance to mechanical damage is divided into A-level (low-level mechanical damage resistance), B-level (medium mechanical resistance resistance) and C-level (high mechanical resistance resistance) .The difference lies in resistance to cathodic peeling, interlayer peeling, and tube metal. Stripping requirements between surface and factory-prefabricated coatings are different. It can perform performance tests on its impact resistance, indentation resistance, insulation resistance, cathodic peel resistance, interlayer peel strength, and peel strength with the surface of the pipe body and the factory-prefabricated coating.
一分彩(2) The operating temperature can be divided into 30 levels (applicable to continuous operation temperature of 30 ° C), 50 levels (applicable to continuous operation temperature of 50 ° C), and high temperature levels (applicable to continuous operation temperature exceeding 50 ° C) according to high continuous operation temperature. Among them, the high temperature grade product is increased by 10 ° C, and the temperature must be marked on the bracket, and it resists indentation, resistance to cathodic peeling, interlayer peeling strength, peeling strength to the surface of the pipe and the coating of the pipe, and overlap shear Performance test for strength and heat aging resistance.
(3) The installation conditions of special beads can be divided into L grade (for -20 ℃ ～ -5 ℃), VL grade (for extremely low temperature below -20 ℃) and UV grade (suitable for long-term storage under sunlight and UV resistance required). Among them, L or VL grades should be able to handle products and coated tubes below -5 ° C; the handling and laying temperature of VL grade products should be determined by the manufacturer and the user and should be marked on the bracket. (Anticorrosive tape)
General coatings require sandblasting, but currently domestic cold-wound tape products generally require St3 treatment. Although it can reduce construction costs, from the perspective of overall performance and long-term protection, it may not be able to ensure long-term performance of the coating. In addition, for the petroleum asphalt remaining on the pipeline surface, it will be difficult to completely remove the surface with diesel cleaning, especially the residual oil stains in the corrosion pits or rough welds will affect the adhesiveness of the tape.
一分彩Most of the cold-wound tapes based on polyethylene film have good high insulation properties. If the coating is intact without peeling, the pipe body will be well protected. If there are defects such as wrinkles and peeling, and groundwater penetrates into the defect site at the same time, the shielding of the polyethylene tape may cause the tube body of the attachment at the defect site to be unprotected and corrode. For this type of material, the main purpose is to ensure the adhesion of the tape to the pipe body and the interlayer adhesion, without peeling and delamination; on the other hand, a double-layer inner tape anti-corrosion coating based on polypropylene woven fiber web Layer, although there is no cathodic protection shielding problem, its insulation performance decreases rapidly.
4. Service life
Laboratory thermal aging test results show that the life of cold-wrapped tapes generally does not exceed 800h (the general requirement is 2400h), and the corresponding cold-wound tapes for cold oil pipelines abroad are tested every 15 years.
一分彩(1) Classify and classify such products in China to facilitate the selection of anticorrosive coating overhaul materials.
(2) Replace automatic tools with automatic winding equipment to reduce construction defects.
(3) The surface of the pipe body is sandblasted, and the rust removal level is increased to Sa2.5 level to enhance the adhesion of the cold-wound tape to the pipe body.
(4) Before backfilling the anti-corrosion overhaul pipe section under the trench, sandbags should be placed at a certain distance from the suspended section to reduce the settlement of the pipeline.
(5) Improve the performance of cold-wrapped tape, improve the adhesion of polyethylene tape to the pipe body and its resistance to mechanical damage, resistance to water vapor penetration of polypropylene tape (plant root penetration), and pressure resistance.
(6) Carry out research on the service life of cold-wrapped tape in pipelines, especially hot oil pipelines.
Contact: Cheng Huiqiang
|Contact : Li Cong|
|Address: No. 333, Jinxian Road, Jinjiaba, Wujiang District, Suzhou, Jiangsu|