Multiple benefits from FBS application

The FBS (Full Bolting Service) program aims at improving the reliability of bolted flanged joints with interposed gaskets, in any situation whether they are for lines, equipment or instrumentation, and make them efficient and reliable in order to not allow any leaks in any operating conditions.


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It is common to find joints in the system that let the product flow from the inside to the outside and this is due to the more or less high pressure at which the joint is applied (leak).

The leaking product could be dangerous for the environment and health and sometimes give rise to situations of high risk with even catastrophic consequences.

The reasons why there is product leakage through a joint can be many and almost always attributable to incorrect maintenance, a consequence of an approach that does not appropriately identify and evaluate the elements that have the greatest influence in achieving the final objective, “the tightness under pressure “.

Therefore it is considered necessary to implement a maintenance program that minimizes the losses from the flanged joints.


Why a joint does not seal?

The seal through a joint occurs if, during any operating conditions, the residual load on the gasket is such that over its entire development, it is not less than the minimum required, a function of the pressure, of the gasket and of the finish of the contact surfaces. of the flanges.

If in a portion, even a small one, this condition does not occur, the leak begins which may undergo variations in flow rate, usually increasing, sometimes it could even disappear and then reappear and sometimes disappear completely (thermomechanical actions).

Briefly we will say that to have internal pressure tightness it is sufficient that the residual load on the gasket is never less than the minimum necessary.

Of some joints that have historically shown leaks despite having previously been treated with particular attention, a careful and accurate analysis will be carried out and they will be redesigned, with the study of the installed gasket and if it is deemed necessary to replace it with another technologically more performing.

It could be considered necessary to make some observations on the joint and the gasket removed, all elements that will increase the information and the quality of them in order to be able to produce an intervention project which will lead to the achievement of the best result.


A redesign intervention can concern one or more of the following elements:

  • Change of material quality of bolts, tie rods and nuts;
  • Introduction of washers under the nuts;
  • Change of the finish of the seal seats;
  • Change of the type of gasket or of the simple geometry of the mounted one;
  • Change of the face of the flanges;
  • Elimination of damage caused by nuts embedded in the flanges;
  • Special instructions for assembling the joint;
  • Calculation of particular tightening loads and sequence of application;
  • Indications for monitoring the joint during operation and control interventions following shutdowns and before restarting or following reductions in operating conditions.

The items recalled are the most immediate ones but others can be added to them.