Vacuum Test
Pressure Vessel
Test to Destruction
Materials
Testing starts with the material itself,
although mechanical data is readily available for metals it is not always the case with plastics,
for this reason we use our own device for obtaining the Youngs modulus or stiffness of the plastics we use,
particularly because this value changes when the material is wet and when it is warm.
Leak Detection
The usual way to test for leaks is with a vacuum test. If glands fitted they would need to be blanked off, if cables are
installed within glands, a vacuum test will not be possible. Where subsea connectors have been installed a vacuum test can
easily be performed even if the cables are not fitted.
Pressure Resistance
To prove that a housing can withstand a given pressure we perform a hydrostatic test,
this involves applying water pressure to the outer surfaces of the housing within the confinement of a pressure vessel.
The pressure is normally measured in bar with one bar applied for every ten meters of water depth, plus a safety factor.
Our pressure vessel (see picture right) has an internal diameter of 820mm,
an internal height of 1500mm and can provide a pressure of 10 bar which is equivalent to 100 meters depth in water.
Test to Destruction
Occasionally it is important to prove the margin of safety, that is how much pressure can the housing take above working pressure before it will collapse,
this can only be done with a test to destruction causing the housing to implode.
In the case of the Sea Chest our calculations were confirmed by an implosion at fifty eight bar or seven times working pressure. At this pressure
the housing would have been significantly distorted with the equivalent of over one hundred tons applied to the largest face.
