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How to apply pipe anticorrosion tape

Author : Date : 7/4/2013 3:30:33 AM

                                                                Underground Pipeline anticorrosion tape application technical

1,General rule

1.1 In strong sand environment ( weather filled with sandy ,maybe there is some dust, sand on the surface of pipeline ,primer ,tape )please don’t brush primer and wrap tape when there is no reliable protection measures.

1.2 when air humidity is higher than 80% or in a rainy day ,prohibit to brush primer and wrap tape 1.3 Anticorrosion tape General Construction technology:

 2、Pipe Pretreatment Pretreatment should do with following rule :

1.Clean welding slag,burr,oil and dust and other attachments from surface of pipeline When Pipeline anticorrosion coating need heavy repair,you should use the appropriate method to remove the original coating and residue.

2.Use mechanical or sandblasting the projectile rust method (if specified sandblasted ),its quality should reach to St3 level or St2 level ,reach
the national standard rule from Rust grades and preparation grades of steel surfaces before application of paints and related products
GB/T8923-1998 (Level standard refer to attach)

3.After Rust,defects which exposed on the surface of the steel pipe should be processed, dust attached to the surface and abrasive should be
removed ,keep pipeline surface dry.When rust again or surface contamination , must pretreat surface again.                         3.Brush Liquid Adhesive, Primer Properties

3.1  Steel surface must dry,without dust(when wind&sand strong or air humidity higher,must wrap tape at once )If exceed 4 hours or overnight,should brush primer again before wrap tape. The best effect time is after brush primer ,when surface dry ,wrap tape at once .
Primer should be stirred in a vessel uniform. If primer thicker ,mix diluent ,can start work when dilute to right viscosity Clean hairbrush ,rollers,or other mechanical method can be used for brushing primer .

3.3 Brushing primer on the pipe should be without missing brush ,no bubbles,clots and sagging defects, should form a uniform film. Thickness
should be greater than or equal to 30 microns. Carefully brushing the weld to leak painted.Subject to the primer is dry (at room temperature
and the air under natural flow conditions, it normally takes 3-5 minutes), then wrapped around the tape.Special attention should be low temperature or in the groove construction, longer dry time to ensure that the lower half of the table dry pipe. When brush primer should pay attention to safety, to prevent splashing, and should stay away from sources of ignition. Primer, the primer should be the remaining iron back into the container and sealed containers to prevent evaporation waste primer

3.6  The amount of primer is per square pipe is 0.12 kg.

4  How to warp tape

4.1 Tape volume solution temperature must be above 5 ℃, application temperature should be carried out at 5 ℃ above.(Experience has shown that tapes can be at a lower temperature -30 ℃ when application , but to ensure unwinding temperature.)  When the weather is very bad, the ambient temperature is below 10 ℃ or at the beginning of the tape wrapped around a hard layer, in order to ensure the tape has good adhesion strength, while wipe the surface of the water vapor pipe, should adopt a blowtorch when exposed to heat pipe surface (if necessary, require bake per header of the roll) to ensure winding effect   
 
4.2.For welds,if necessary,to use the 30-50 mm wide strip tape reinforcement, the first covering the weld and smooth by hand or wooden tools compaction. 

4.  Use the appropriate mechanical or hand tools, in good primer coating on the pipe by overlap requirements spiral wound tape, the tape should maintain a certain tension force, force should be uniform, to make the tape layer of tight junctions . Side seam tape should be parallel, not twisted folds. Phase at both ends of the tape should be more than 100 mm of the overlap . When necessary, the front end of a tape base film brushing primer or fully baked until dry overlap after another period starting end of the tape. End and beginning sleek wooden tools should be used so as not to tilt tightly pressed against.

4.4 Use tape winding machine is to ensure the quality of effective measures, hands wrapped around the tape is difficult to achieve uniform surface quality and consistent tension force, and only in exceptional circumstances, mechanical construction can not be carried out only when hand wrapping, but it should be using a narrow width tape.                                                                                      

5、Coating quality standards and inspection methods Tape coating shall meet the following requirements:

5.1 Apparent:  Visual inspection of pipelines across the board for the precast plant should be visually inspected by the root,fill the mouth, fill the wound should be checked one by one, the coating surface should be smooth, overlap uniform, no wrinkles, no permanent bubbles, no damage. It should be specified that: When the weather is hot or sunny, the wound tape often have bubbles. Since the tape itself has a certain degree of flexibility and ability to repair itself, these bubbles can disappear on their own, so this should not be taken as quality problems. Should produce permanent bubbles, like wrinkles, as it should eradicate processing. Visual inspection of pipelines across the board for the precast plant should be visually inspected by the root, fill the mouth, fill the wound should be checked one by one, the coating surface should be smooth, overlap uniform, no wrinkles,no permanent bubbles, no damage.

It should be specified that: When the weather is hot or sunny, the wound tape often have bubbles.Since the tape itself has a certain degree of flexibility and ability to repair itself, these bubbles can disappear on their own, sothis should not be taken as quality problems. Should produce permanent bubbles, like wrinkles, as it should eradicate processing. If the application of the air humidity, temperature, etc.

There are a series of water vapor causes the pipe surface, after wrapping, and because of the sealing tape is good, resulting in water vapor for a long period of time, not through the coating, causing bubbles . As long as the construction of attention, this problem can be avoided.          Because the pipe is endothermic, and anti-corrosion tape black more endothermic, so the tube corrosion ban after exposure, should be stored according to requirements. Such as normal temperature at 20 ℃, the temperature of steel is certainly above 30 ℃, which is contrary to the standards and construction requirements

5.2 Thickness: Depend on SY/T0414-98 "destructive pipeline coating thickness measurement method (magnetic method)" measure. Thickness shall meet
the standards requirements. Measurement when there is damage to the coating equipment should not be used. Tape thickness greatly affect the quality of the corrosion, increase the corrosion resistance of the tape thickness is increased, when the tape type, the structure is determined, the total thickness of the coating can be determined

5.3  Peel strength: This indicator is directly related to the quality of the coating, the penetration of water and the tape and the adhesive force between the pipes, it should ensure a sufficient adhesion strength steel. In our standard SY/T0414-07, the peel strength measurements were carried out using the following methods: a knife to cut open along the ring 10 mm in width, length greater than 100 mm layer of tape until the tube. With a spring balance and a 90 degree angle from the wall opened, opened speed is not greater than 300mm/min, the tests should be carried out after 24 hours.

 As shown below: We can also according to the U.S. ASTM-1000 standards, 3kg copper weights hanging method test method to check for: the vertical sides of the pipe coating cut open a wide 5cm, 10cm long tape layer 180 degrees overhanging 3kg weight at 10 min decreased from less than 10cm is qualified,and such tape is in general fall within 10 minutes are less than the distance 3cm, the above test time and should be at room temperature (5-20 ℃), humidity is less than 75% after 24 hours when finished wrapping .