Shrink-fit shear and seal integrity of tubular connections*

Make-up of threaded connections generates shrink-fit interference along the engaged thread length of pin and box. Pressure on the pin-box interface, together with Poisson's ratio, shortens the box and stretches the pin, creating shear and affecting sealability. This paper presents an analytical elastic solution of make-up with linear shear to help understand the physics of make-up and the unexpected consequences on leak. The model is driven and supported by results from FEA (finite element analysis) on an example API LTC connection. The main conclusion from the analysis is that make-up shear reduces leak resistance.