Are mechanical snubbers preferable to hydraulic snubbers, which can suffer from oil leakage?

It is a fact that hydraulic snubbers require maintenance over a period of time in order to replenish the natural leakage of hydraulic fluid. Pipe Supports Limited is working towards a snubber design that will help to minimize the need for such maintenance. However, it cannot be totally eliminated.

In the USA, where there has been very long experience of operating nuclear power plant and where snubbers have been the subject of much discussion and review, there was a move towards mechanical rather than hydraulic snubbers. It was found, however, that a mechanical snubber is also subject to operational problems. The mechanism is prone to wear and fatigue and generally when a mechanical snubber fails in service it seizes and prevents the pipe from being able to move which in turn leads to damage to the piping and connected plant.

Hydraulic snubbers conversely fail in a ‘free’ state – the snubber continues to move with the pipe at the expense of slightly increased drag. However, the resultant stresses on the pipe during normal operation are insignificant. The problem with a ‘failed’ hydraulic snubber is that when the ‘event’ happens it can only provide notional damping by the air that is trapped within it.

Hence in the States there were significant efforts made to minimize the number of snubbers used.

Pipe Supports Group do not intend to manufacture mechanical snubbers; we do, however, have a relationship with a Japanese manufacturer who is willing to supply us mechanical snubbers, although our price will not be as competitive as it would be for hydraulic snubbers.