Graduation assignment - Post-weld improvement
The Swiss-based Allseas Group, founded in 1985 and headed by Edward Heerema, is a global leader in offshore pipeline installation and subsea construction. Allseas Engineering, located in Delft, provides project management and engineering services to other subsidiaries of the Allseas Group.
Assignment: Post-weld improvement of the weld root inside the pipe
The girth welds of high strength steel gas and oil pipelines must survive the fatigue loadings that occur during pipeline operation and installation. Although the tolerance in pipe roundness and wall thickness is carefully controlled during pipeline fabrication, certain misalignment of the pipes after welding can persist, which is sometimes difficult to tolerate with respect to fatigue resistance of the weldments.
The effect of misalignment from outside can be diminished by polishing a weld cap out, thereby making the transition from one pipe to another smoother, which cannot be done easily from inside the pipe. That is why other possibilities need to be investigated. One of the fatigue improvement post-weld treatment techniques is impact peening. There might be pneumatic or ultrasonic peening, which have different manners of load transfer from the energy source to pin(s) that at the end impacts a treated surface. Through these impacts plastic deformation is introduced in the thin layer of the material surface reducing the tensile residual stresses and improving the geometry of the weld toe. The effect of impact treatment is finally in the enhanced fatigue resistance of the weld.
The graduation assignment comprises investigating the effects of impact treatment techniques on high strength pipeline weld root, performing fatigue tests – on treated and as-welded specimens cut out from the test pipe – and analysing the results. In addition, all advantages and disadvantages of the impact treatment techniques must be critically reviewed and suggestions made for a concept design of a tool that might be used inside the pipe.
We are looking for a student with affinity for real-world applications. During the course of this project you will develop both your engineering and your scientific skillset. The assignment requires both an analytical mind and a hands-on attitude.
This graduation assignment is available for a period of 9 to 12 months.
For further information, please contact Susie Toppler, Recruitment at Allseas Engineering B.V.: +31 15 268 1800.
Candidates fulfilling the requirements who are interested in an internship within the Innovations Department may use the online application form.