When a flange connection starts leaking, the first reaction is often simple: tighten the bolts again.
It feels practical. It feels fast. And sometimes, the visible leak even disappears.
But that does not mean the problem is solved.
In many cases, retightening only hides the real cause of leakage. The connection may still be unevenly loaded, the gasket may already be damaged, or the operating conditions may simply be too demanding for the selected sealing solution.
More Torque Is Not the Same as More Safety
A common mistake is to assume that more torque automatically creates a better seal.
In reality, torque is only an indirect value. The actual bolt load depends on friction, lubrication, surface condition, assembly sequence and gasket behavior. Two bolts tightened with the same torque can still generate very different clamping forces.
That is why retightening individual bolts can create new problems instead of solving the original one. One area of the gasket may be overloaded, while another remains under-compressed. The result: temporary tightness, but no reliable sealing integrity.
The Leak Is Only the Symptom
Flange leakage rarely happens without a reason. Often, the root cause lies deeper:
· insufficient gasket stress
· unsuitable gasket material
· uneven bolt load
· relaxation after installation
· flange or surface damage
· operating conditions not considered during design
If these factors are not understood, retightening becomes a maintenance routine instead of a solution.
Reliable Sealing Starts Before the Wrench Is Used
A safe flange connection begins with the right gasket, the right data and the right engineering approach.
For critical applications, EN 1591-1 calculations help evaluate whether a flange connection can achieve the required tightness under real operating conditions. Using certified EN 13555 gasket data, pressure, temperature and bolt load can be assessed before problems occur in operation. This engineering-based approach is also used in Revoseal’s TA-Luft compliance communication.
Engineering Instead of Retightening
Retightening may help in the moment. But it should never become the sealing strategy.
True reliability comes from controlled bolt load, suitable gasket technology and a flange connection that is designed for the actual operating conditions.
For critical flange connections, the actual bolt load can be verified using load cells instead of relying solely on torque values. Combined with proper engineering and flange calculations, this provides a clear understanding of the connection’s sealing integrity and helps identify potential issues before they lead to recurring leakage.
Critical flange connections require particular attention throughout design, assembly and operation. Revoseal supports plant operators with engineering expertise, bolt load measurements and sealing solutions to achieve reliable, long-term sealing performance in demanding applications.
