SRP Completes Initial Titanium SHRINK-FIT Testing

The SHRINK-FIT taper joint allows high-strength thick-wall pipe to be machined in a tapered profile before applying the end flanges or couplings. With shrink-fit technology it becomes possible to use different materials for end flanges and pipe, allowing for example combinations such as titanium pipe and steel flanges.  Such a combination is particularly attractive for riser taper joints, giving a very efficient (and hence reduced length) joint, together with a simplified interface with the rest of the riser and avoid large titanium forgings.

To qualify these designs, initial testing of scaled shrink-fit components has now been conducted.  Shrink-fit assemblies composed of a titanium alloy metal shaft and a nickel alloy metal hub were tested for their pull out load resistance.  The testing has yielded valuable information regarding the frictional resistance between the two metals for a range of conditions.

The science behind SRP’s patented shrink-fit connection is well understood and SRP’s theoretical modelling enabled pull-out loads to be estimated before testing, which were found to correlate well with test results.

These experiments confirm the belief of the reinforcement in frictional force provided by the shrink fit connection (under increasing pull-out load) on the onset of surface damage between the two mating metal pieces.