An undetected leak in a well head flange connection can lead to complete loss of pressure control. Even a very small leak between flanges can grow into a great disaster during well operations.
A flange joint that leaks on test will become a failed joint if it is sent to the field without correction. A leaking joint does not mean a leaking gasket, as the joint consists of the gasket, two flanges and a set of bolts. The gasket condition, the flange sealing groove condition, the bolt and nut condition along with lubrication, the cleanliness of all the parts mentioned, and finally the correct tension in the tightened bolts will determine the success of the flange connection, over time, in the field.
When assembling Ring Gasket sealed connections, every precaution should be taken to assure that the ring grooves are clean and free of damage and corrosion, and the ring gaskets are new and undamaged.
Every made-up connection should be tightened in compliance with API specifications and tested before use. Special care should be taken to observe any leak. Any leak must be stopped by retightening or if necessary, by complete disassembly, making necessary corrections, replacing the Ring Gasket with a new Ring Gasket (inspect the new Ring Gasket for any handling damage), and reassembly of that connection, followed by a successful hydro test.
The photograph below illustrates the destructive power of high pressure fluid flowing against steel. A small leak will grow as the steel washes away, allowing uncontrolled release of the pressurized fluid.