Standard for Anticorrosive Coating of Steel Pipeline Polyethylene Adhesive Tape
The scope stipulates that the maximum operating temperature of polyethylene adhesive tape anticorrosive coating pipes should not exceed 70°C. The minimum operating temperature is no longer specified. With the development of polyolefin adhesive tape technology, some companies have introduced several polypropylene adhesive tape products, which have been applied in some projects. In order to facilitate the engineering design and application of polypropylene adhesive tape, it is stipulated that the anticorrosive layer of polypropylene adhesive tape can be implemented with reference to this standard, but the design and application unit should propose the specific technical performance requirements of polypropylene adhesive tape according to the application environment and product characteristics. To meet the needs of pipeline corrosion protection.
3. Anticorrosive layer structure and grade
3.1 The structure of the anti-corrosion layer is divided into:
1. A composite structure composed of primer, anticorrosive adhesive tape (inner tape) and protective adhesive tape (outer tape);
2. Anti-corrosion layer structure composed of primer and anti-corrosion adhesive tape. At present, the anti-corrosion layer structure of domestic polyethylene adhesive tape has a primer + inner tape + outer tape anti-corrosion layer structure, and there is also a primer wrapper
Anti-corrosion layer structure of polyolefin adhesive tape. The foreign standards DIN30672 and BSEN12068 do not specify the structure and grade of the anti-corrosion layer, only the performance of the anti-corrosion layer; the anti-corrosion structure specified by AWWAC209 is the structure of the primer and the anti-corrosion tape; AWWAC214 specifies that the anti-corrosion layer of the factory-prepared tape is primer + inner tape +External anti-corrosion layer structure. Therefore, this standard revises the structure of the anti-corrosion layer, and the two structures are selected by the design according to the engineering requirements and the characteristics of the selected products.
3.2 Anti-corrosion layer grade
According to the feedback during the implementation of SY/T0414-98, this standard stipulates that the thickness of ordinary grade anticorrosion layer shall not be less than 0.7mm, the thickness of reinforced grade shall not be less than 1.0mm, and the thickness of special reinforced grade shall not be less than 1.4mm. /T0414-93 is consistent with regulations. However, considering that the corrosion environment of buried pipelines is more complicated, it is stipulated that the anti-corrosion layer level of buried pipelines should not be lower than the reinforced level.
3.3 Pipelines laid in the open air should use special weatherproof protective tape, mainly to determine the light aging resistance of the outdoor tape.
4. Anti-corrosion layer material
4.2 Specifications and performance of adhesive tape
The properties of the protective adhesive tapes, splicing adhesive tapes and anticorrosive adhesive tapes specified in the original industry standard SY/T0414-98 are only different in thickness, and there is basically no difference in other properties. Therefore, this standard no longer lists protective adhesives. The performance requirements of adhesive tape and patch tape stipulate that the performance of protective adhesive tape and patch tape should meet the requirements of anti-corrosion adhesive tape, but the protective adhesive tape does not specify the peel strength of primer steel. The thickness of the adhesive tape is determined by The design selects the corresponding product specifications of the manufacturer according to the selected anti-corrosion layer structure, and the inspection should be carried out according to the specification data stated by the manufacturer during acceptance.
Other performance changes are mainly as follows:
1) The thickness of the tape is no longer specified. Due to the diverse specifications and types of adhesive tape products, the applicable anti-corrosion layer structure is different, and its thickness varies greatly, so this standard no longer specifies the thickness range of adhesive tape products. The design should determine the structure of the anti-corrosion layer according to the requirements of the anti-corrosion grade, and then select the adhesive tape product. The acceptance inspection is mainly to check whether the production quality of the supplied products is stable, so the inspection index is specified as the deviation requirement of the manufacturer's specified value.
2) The peel strength requirements have been adjusted: the peel strength requirements of the tape for the primer steel are improved; the peel strength values u200bu200bof the tape to the backing material of different products are respectively specified according to the product characteristics and packaging form of the tape.
3) Increased the performance requirements of the anti-corrosion coating system. According to the requirements of DIN30672 and EN12068, the performance requirements of anti-corrosion layer impact resistance, peeling strength at service temperature, cathodic stripping and other performance requirements have been increased. These performance requirements shall be tested with the anti-corrosion layer pipe section prepared in the laboratory, and the structure level shall be tested according to the design or engineering requirements, or according to the manufacturer's recommendation.
5. Construction of anti-corrosion layer
5,3.2 Apply the primer in accordance with the primer instructions provided by the manufacturer. The manufacturer's primer specification should state the primer application method, the amount of primer per unit painted area, and the drying requirements.
5.4.1 The minimum temperature for unwinding the adhesive tape should not be lower than the minimum temperature specified in the product manual. Unwinding at too low a temperature will cause damage to the adhesive tape.
Tape winding method: It is advisable to use a special winding machine or a manual winding machine for winding. During the winding process, a consistent winding tension of the adhesive tape should be maintained to ensure the overlap and parallelism of the adhesive tape and avoid wrinkles in the anti-corrosion layer.
7, quality inspection
7.2 Appearance inspection of the anti-corrosion layer The appearance quality of the anti-corrosion layer depends on the quality of the tape winding. Frequent defects are wrinkles, uneven laps, cracks, and bulges. As long as the winding tool is suitable and carefully operated, these defects can be avoided. Regarding the bubbles generated during the winding process: when the weather is hot or the tape is wound in sufficient sunlight, bubbles are often generated. Due to the elasticity and self-repairing ability of the adhesive tape itself, these bubbles can disappear by themselves. This situation should not be regarded as a quality problem. If permanent bubbles are generated, like wrinkles, they should be removed and repaired.
7.5 Peel strength inspection The on-site peel strength inspection is used to inspect the adhesion to steel pipes. The inspection should be carried out 24 hours after the tape is wrapped.