Viscotaq - Protecting Buried Flanges
From Corrosion Control
Buried flanges can often be difficult to protect against corrosion. VISCOTAQ provides an easy solution for corrosion prevention. VISCOTAQ Products can be molded around the bolts and uneven surface. They bond at a molecular level creating a coating that is impermeable to moisture & oxygen; thus protecting the substrate against corrosion.
- Materials necessary
- VISCOTAQ VISCOWRAP
- VISCOTAQ VISCOPASTE
- VISCOTAQ VISCOSEALANT
- OUTER WRAP
The surface area to be coated should be inspected prior to coating; known defects must be documented and photographed prior to application.
- In case of rehabilitation, the old coating should be removed. Remove loose parts, grease, debris and moisture.
- The minimum surface should be ST2/ SSPC-SP2 (Hand Tool Clean), however where possible prepare to ST3/SSPC-SP3 (Power Tool Clean). In order to obtain best values blast the pipe to a surface level near white metal SA 2.5/SSPC-10.
- Remove sharps edges on the welds. This can be accomplished with a grinding machine.
- Bevel the factory/adjacent coating of the pipeline to which a connection must be made to an angle of 45 degrees.
- The adjacent coating should be roughened by means of sand paper or a grinding machine. Advised overlaps onto the existing pipe coating: < 30” pipelines 4”overlap, > 30” pipelines 6” overlap.
- Keep the working area clean and dry at all times. Avoid the presence of water.
- Regularly check to make sure the surface of the pipeline is 4°F+ above the dew point.
- Protect the working area from rain and other moisture
- The existing factory coating must be beveled at an angle of 45 degrees (if applicable). In case of thick coatings, like bitumen or coal tar enamel, a bridge should be made on the bare steel onto the coating transition with
- a irst straight circumference wrap. This will allow for proper wrapping over the 45 degree angle.
- Start wrapping the VISCOWRAP material as near to the lange as possible. The irst wrap must be straight. The irst wrap must be at least in a vertical position under the bolts.
- Wrap into the direction of the factory coating and end straight with an overlap onto the factory coating.
- Wrap the VISCOTAQ VISCOWRAP with slight tension and a minimum 1 cm/ 1/2” overlap.
- Advised overlaps onto the existing pipe coating: < 30” pipelines 4”overlap, > 30” pipelines 6” overlap.
- VISCOSEALANT is to be applied into the gap between the flange faces if the space is large enough for sealant to it.
- For optimum application of VISCOSEALANT, preheat material to 35°C/90°F.
- Apply the VISCOSEALANT all the way around the flange pushing the sealant as far in the gap as possible.
- Smooth the surface with a putty knife, removing excessive material.
- For optimum application of VISCOPASTE, the material should have a temperature 25°C/77°F.
- The material should not be cold otherwise the material will be stiff and have a viscosity too low for application to difficult to reach areas.
- Cut the VISCOPASTE material into small pieces that can be easily molded to protect the flange bolts and irregular surfaces.
- Use gloves and a putty knife and knead the VISCOPASTE at a 45 degree angle from the flange rim toward the pipeline.
- All bolts and nuts or other exposed objects should be covered with
- Avoid inclusion of air and moisture.
VISCOTAQ VISCOWRAP on the flange outer rim
Install Viscotaq ViscoWrap from pipe to pipe over the Viscopaste and flange to protect the outer edge of the flange and to insure substrate is protected.
Install viscowrap with a minimum of a 1/2’” overlap.
Option 2- for less critical areas.
Wrap one layer of VISCOTAQ VISCOWRAP material along the circumference of the flange. End with a circumference overlap >5 cm/2”. In cases of multiple circumference wraps, ending overlaps should be staggered.
The VISCOPASTE material should have a smooth and uniform structure and by preference a 45 degrees angle from the flange top to the pipeline.
- Start wrapping the PE Outer Wrap on the flange rim to one side and wrap down with a 75% overlap. After finishing make the same wrap to the other side and end in the same way.
- Make sure that the last wrap is applied without tension and smoothly ix the PE end to the pipe.
- A 6 mm / ¼” section of VISCOWRAP material should always be visible after the PE Outer Wrap had been applied.