Flanges on glass lined equipment are vulnerable to failure. This begins the downward cycle toward eventual replacement of the equipment often sooner rather than later. Failure at the flange is among the most frequent cause for equipment replacement or re-glass leading to costly equipment repairs, downtime, and replacement. There are two primary causes of flange damage. Sharing this information with operators and maintenance technicians can catch these problems in its early stages.
Flanges are the weak link in the system, a failed gasket resulting in a very small leak that will corrode the carbon steel flange from the outside. Often the flange was not properly shimmed during assembly. Proper gasket use of is of utmost importance. If you are unsure of proper gasketing feel free to call or email. We can provide specifications.
Since glass lined equipment has been fired at 1500F several times during the enameling process slight distortion in the flange face can occur. During assembly it is imperative to check the flange for shimming. Improper or lack of shimming will lead to glass failure as mechanical stresses are introduced to the flange when the clamps are torqued.
The first sign of a problem is a slight leak at the flange joint. The first and worst response is usually to tighten the clamps to stop the leak. The CRT gasket will have lost its compressibility so the force is then transferred directly to the flange. The induced stress results in the glass fracturing.
A standard repair is a tantalum overlay repair. This method requires a specially formed patch to conform to multiple radii and seal along the flange face. See the overlay photos below. A secondary repair is a Teflon or tantalum outside sleeve, these are very expensive often above $15,000 plus installation costs.