KHIA headerKnow-How in Action


Belzona® Repairs Butterfly Valve Seals



General Industry (GIND)



Valves, Pipes and Fittings (VPF)


Customer Location:

Cement Industry, Nashville, TN, USA


Application Date:

February 2015


Application Situation:

Rubber gaskets on butterfly valves



The customer uses a cyclone and piping to move cement from barges to silos. Eroded areas at the edge of the valve flappers were allowing small amounts of cement and air to escape around the edges and further eroding the natural rubber.



Belzona 2311 (SR Elastomer)

Belzona 2911 (Elastomer QD Conditioner)



Natural Rubber


Application Method:

The application was carried out in accordance with Belzona Know-How System Leaflet VPF-1. The substrate was cleaned and roughened using a wire brush and a razor. The effect of the razor was to make dovetail like mechanical bonds. Belzona 2911 was used to condition the surface and allowed to dry for 30 minutes. The surface profile was rebuilt with Belzona 2311 using a Belzona applicator. Alternatively, a release agent could have been used on the flapper and the flapper could have been closed onto the still wet Belzona 2311 to create a perfect seal.


Belzona Facts:

Before the introduction of the Belzona solution, the customer was rebuilding the valves several times a year with new rubber gaskets that cost in excess of $450.00 each. A single pack of Belzona 2311 enabled the customer to repair two gaskets, saving the customer over $800.00 in total. Additionally, due to the abrasion resistance of Belzona elastomers, the customer gets a better service life out of the repairs than they were previously getting from new gaskets.


Photographs Description

  1. Erosion around the edges of the flapper
  2. Erosion more obvious with flapper removed
  3. Substrate cleaned and roughened, ready for conditioning
  4. Completed application, ready to go back into service
Case study pic one


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