Corrosion Issues of Flanges

The corrosive action of chemicals, crevice corrosion, bimetallic corrosion, and high-pressure steam can result in the deterioration and subsequent leakage of flanges. The flange face is predominantly prone to crevice corrosion in extremely caustic environments. Crevice corrosion is a common damage mechanism where there is a concentration of corrosive substances in a localized area. Additionally, insufficient external flange protection can lead to rapid and more extensive damage to the flanges and fastenings that will accelerate the deterioration of the system’s integrity.

Over time, the corrosion started in the gap on the inside diameter of a flange can extend to the gasket area resulting in a loss of containment and release of a product with potentially catastrophic consequences. Consequently, loss of containment, whether in chemical lines such as hydrocarbons and gas systems or water distribution lines, will have significant environmental, operational, and commercial impacts.

Flange Protection Using Belzona Flange Face Forming Kit

Belzona Flange Face Forming Kit contents for flange protection
Belzona Flange Face Forming Kit Contents

Proven for over 10 years, Belzona’s flange protection systems eliminate the need for conventional cut and weld methods involving hot work and allow for a simple application in emergencies, especially in areas with limited access, such as on offshore platforms. Therefore, the Belzona Flange Face Forming kit is a unique repair kit developed to aid flange protection by combating the common problems with mating surfaces of flanged joints, such as heat distortion, corrosion, and erosion. In conjunction with Belzona 2-part epoxy repair composites such as Belzona 1111 (Super Metal), this flange repair kit provides a complete package solution that is cost-effective and simple to implement.

How To Use Belzona Flange Face Forming Kit

Step 1: Select the appropriate former from the guide provided and dry it.

Step 2: Dry fit the former to the damaged flange face to check the alignment of the raised face and particularly of the bolting holes.

Step 3: If successful, apply at least one coat of Belzona 9411 (Release Agent) to the former and all other surfaces to which Belzona product should not bond. Then, allow Belzona 9411 (Release Agent) to dry for at least 15 minutes at 68F (20C).

Step 4: All surfaces to be rebuilt should be roughened by either:

  • Grit blasting to give a surface finish of ISO 8501 – 1 Sa 2 ½, ensuring a minimum surface profile of 3 mils (75 microns) using an angular abrasive.
  • MBX bristle blaster
  • Rough grinding with handheld grinding equipment fitted with cutting discs

Step 5: Wash all prepared surfaces with Belzona 9111 (Cleaner Degreaser).

Step 6: Mix the selected Belzona product and apply a thin film of material to the damaged surface, pushing the material well into the prepared profile.

Step 7: Apply further material in a thin film to wet out the forming surface before applying the material in excess, to form a central peak with Belzona pre-cut applicator.

Step 8: Bring both surfaces together and once the correct level has been achieved, remove any excess material exuded from the joint area. Allow the Belzona product to cure.

Step 9: Once the product has sufficiently cured, dismantle the former and remove bolts. Take care not to damage the repaired area.

Step 10: Inspect the finished repair for defects: soft spots, differences in color, uneven thickness, and voids. Also, dress down any irregularities where required with emery paper.

Flange Protection Using Belzona 3412

Belzona 3412 is a liquid-applied membrane system that offers long-term flange protection from exterior damages. The durable system can be used for flange protection of different shapes, sizes, or configurations from crevice, galvanic and atmospheric corrosion and completely encapsulate the flange to exclude any moisture. When used in combination with the release agent/corrosion inhibitor, Belzona 8411, the coating can be easily cut, peeled back, and resealed to allow inspection and maintenance of fastenings. Once the required maintenance has been completed, the membranes will fold back to their original positions and can be sealed with a further quantity of Belzona 3412. The system can be brush- or spray-applied.

How To Brush Apply Belzona 3412

Step 1: Clean the surface of the pipe and flanged connections to remove all dirt, grease, and other surface contaminants.

Step 2: Thoroughly abrade the surface with abrasive paper (sandpaper) or wire brush to remove all gloss and provide a good key for the Belzona coating.

Step 3: Apply masking tape over the two bond areas to protect the pipe areas from accidental overspray.

Step 4: To allow assess to bolts and flanges in the event of required maintenance, we recommend the application of Belzona 8411 by brush or spray. This also provides an optimum level of corrosion protection.

Step 5: Once the Belzona 8411 is touch dry, remove the masking tape.

Step 6: Re-apply fresh masking tape.

Step 7: To seal the gap between the flange faces, cut a strip of Belzona 9341 to the correct width and apply it over the gap.

Step 8: Fit plastic caps over the nuts/bolts.

Step 9: Empty the entire contents of the Belzona 3412 base and solidifier and thoroughly mix in the bowl provided for at least three minutes.

Step 10: Using a spatula, transfer the mixed Belzona 3412 to the flange face and bolts.

Step 11: Using long, light strokes, brush the material over the entire area ensuring it does not extend outside the prepared area.

Step 12: While the first coat of Belzona 3412 is still wet, bed strips of Belzona 9311 around the circumference of both ends of the pipe and the flange.

Step 13: Mix and apply the second coat of Belzona 3412

How To Spray Apply Belzona 3412

Step 1: Clean the surface of the pipe and flanged connections to remove all dirt, grease, and other surface contaminants.

Step 2: Thoroughly abrade the surface with abrasive paper (sandpaper) or wire brush to remove all gloss and provide a good key for the Belzona coating.

Step 3: Apply masking tape over the two bond areas to protect the pipe areas from accidental overspray.

Step 4: To allow assess to bolts and flanges in the event of required maintenance, we recommend the application of Belzona 8411 by brush or spray. This also provides an optimum level of corrosion protection.

Step 5: Once the Belzona 8411 is touch dry, remove the masking tape.

Step 6: Re-apply fresh masking tape.

Step 7: To seal the gap between the flange faces, cut a strip of Belzona 9341 to the correct width and apply it over the gap.

Step 8: Fit plastic caps over the nuts/bolts.

Step 9: Empty the entire contents of the Belzona 3412 base and solidifier and thoroughly mix in the bowl provided for at least three minutes.

Step 10: Fill the cartridge of the Belzona Spray Gun.

Step 11: Spray the material over the entire area ensuring it does not extend outside the prepared area.

Step 12: While the first coat of Belzona 3412 is still wet, bed strips of Belzona 9311 around the circumference of both ends of the pipe and the flange.

Step 13: Mix and apply the second coat of Belzona 3412

Interested in purchasing Belzona’s repair composites and protective coatings?


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Alexander Ruiz

Jr. Copywriter, Belzona Inc., Miami, Florida

This Post Has One Comment

  1. Flanges

    Hi There,
    Thanks for sharing the blog and this great information. Which is definitely going to help us.
    Well done.

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