Figure 16 - The 8-inch (203.2 mm) diameter bore hydraulic pressure pipe for the moveable tips at Penarth Dock. Each is to be tested to 2,500 lbs. per square inch. There is a discrepancy in the dimensions shown at the bottom left enlarged view of the water and pressure tight connection. It is actually an error of 5/32" or approx. 4 mm so I decided to create a 3D CAD model to check the error and to gain better understanding of how such a simple joint could possibly work under the extreme hydraulic pressure of 170 Bar. [178]

A 3D CAD model in SolidWorks, thanks to Rota Design Limited [108] which shows a cross section through the pipe flange and jointing area. There is a 1/16" gap but the sealing faces are dependant upon the radial clearance and possibly gutta-percha packing or similar. Assuming each pipe is made from grey cast iron and, as per the drawing above, is 9 feet (2,743.2 mm) long. Consequently, each nine foot length of pipe weighs just over 800 Kg! Today there are many grades of ductile cast iron suitable for the application but at the turn of the 20th century the grades were somewhat limited and the methodology for checking the quality of the casting was simple; you either cut it up to see the inclusions and faults, or tapped it with a hammer to make it ring; just like a wheeltapper did on the railways to check the integrity of railway wheels and their tyres !

An enlarged section (with colourised version) of a photograph featuring H.M.S. Guardian moored up at the northern quayside of Penarth Dock during April 1959 shows sections of hydraulic pipe with identical flanges to those above. Maybe these have been recovered from the moveable tips which were situated at the other side of the basin. The four tips numbers 15 -18 were removed towards the end of the 1930's. [001] [20170922]