You drew the short straw and need to climb down into the guts of this low-pressure mill to inspect the steam extraction piping expansion joints.

That cover, together with the end rings, is firmly welded down to the piping. It’s not removable. If you wanted to know more about metallic expansion joints then you can take a look at Megaflexon Movement Joint.

expansion joints

A few facts to ponder while at the dark

The fixed covers are there for a purpose – to protect the bellows in the high velocity of this spent turbine steam. And to make sure they stay put, they are welded on solidly. This protection has a trade-off; the bellows cannot be readily inspected visually.

Those leaks are impacting the turbine’s efficiency.

Limited inspection methods

The figure below shows a normal cover arrangement. You need to be able to receive a borescope through the gap on one side. The scope will provide you some notion of the state of the bellows, but there’ll still be some difficulty in obtaining a fantastic peek down between the convolutions.

Start looking for indications of cover damage. Often the original designs had milder covers (and liners) which wouldn’t hold up under the high flow velocities.

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