Damage to the wave-shaped gasket N08800+ and flexible graphite led to a fire
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A heat exchanger with a maximum operating temperature of 454 degrees in the tube side, a pressure of 0.25 MPa, and a design temperature of 488 degrees. The shell side operates at 482 degrees, with a pressure of 0.11, and the design temperature is 510 degrees. An expansion joint is installed in the shell side, the gasket at the connection between the tube box flange and the tube sheet is a corrugated gasket (N08800 + flexible graphite), and the fasteners are made of 25Cr2MoVA. After running for 2 months, the unit was stopped without disassembly; when it was started up again, feed was introduced first to the shell side. There were 2 instances of thermal tightening. After fluid began to flow in the tube side, leakage was detected at the junction between the tube box flange and the tube sheet, and the graphite on the surface of the gasket had deteriorated into slag. There is another heat exchanger with similar operating conditions; the temperature in the tube side is only 30 degrees lower, spiral gaskets are used, and no problems have occurred. I now wish to replace the wave-shaped gasket of this device, which is experiencing leaks, with a wound gasket. However, the strength of the tube box flange is insufficient, and the calculations do not pass. I would like to ask everyone: how can this problem be solved without replacing the device’s flange (made of material N08800)?
This post was last edited by ywyyxj on 2025-12-22 at 16:31. Now, every two months when the vehicle is parked, the gaskets must be replaced; otherwise, leaks occur, which increases maintenance costs. Constant monitoring is required, as it poses a significant safety risk. Manufacturer’s solution: Option 1: Replace the equipment flange and use wound gaskets in place of the standard gaskets ； Option 2: The shims still use wave-toothed shims, but high-temperature disc springs are added to alleviate temperature-induced stress.