We like to draw following conclusions when discussing how to manage leaks in urea plants:
1. Leaks in the high-pressure synthesis section of a urea plant are always risky and the longer they last the more dangerous a leak will become. An early detection by means of a proper ammonia leak detection system is important.
2. The most safe option is to shut down the plant and solve the leak.
3. Perform always first a proper Risk Assessment and assure you know all the possible failure modes. Search for similar cases in the industry (AICHE, Incident Database UreaKnowHow.com, FIORDA), Perform all possible Non Destructive Testing inspections.
4. Never install a clamp on an ammonium carbamate or ammonia pipeline. Realize that the installation of clamps may create crevice corrosion risks and other risks due to the injection pressure and possible other forces on the leak area. Clamps when installed should always be considered a temporary solution and develop a procedure to check its integrity during installation.
5. Consider flushing instead of clamping. Monitor the leak and integrity of the leaking equipment continuously. Avoid that flushing liquid can drip of the carbon steel wall of a high-pressure equipment.
6. In case of a crack, shut down the plant.
7. In case of leak along a threaded connection, shut down the plant.
8. Take all possible preventive measures to avoid leaks.
9. Apply zero tolerance for any kind of leaks in urea plants.