Objective / Scope
Conventional design of offshore facilities has relied on using standard steel profiles having either welded/bolted connections for topside structural design. Structural plates have also been used for girders and for rolling tubular profiles to make up for nonstandard sizes mandated by design. In case of steel structures required for supporting piping, electrical and instrumentation trays, standard steel profile is the default option and other options have been less explored. These support structures constitute nearly 1.5% of the entire topside weight. On a 1000MT topside, supports for piping, E&I weigh nearly 15MT. For fabricating this 1.5% of steel, engineering teams produce massive documentation (at least 20% of the detail engineering deliverables) which is generally redundant once the facility is installed and spend an equal amount of time amidst ever-compressing schedules.
The advent of 3D printing technologies opens the frontier for 3D printing of these elements directly from the 3D model. Since 3D printing allows for seamless generation of shapes, the intermediate joints/ welds within the support can be eliminated and the weight of the support steel can be optimized.
Methods / Process
To check for feasibility, 2 piping supports (one L-frame and one goal-post with a brace) and 1 goal post type cable tray support were chosen from an ongoing project. These structures would normally be made up of standard steel profiles welded together based on the support detail drawings generated from 3D model.
For this exercise, these were assumed to be produced from additive manufacturing methods (3D printing) eliminating joints and minimizing geometrical discontinuities. The loads considered for traditional support design have been applied on the optimized ‘structure for 3D printing’ using FEM software ANSYS. It was observed that it is feasible to reduce at least 30% of material for the 3D printed structure and still the structural integrity of the support structure was within safe limits. With the deployment of 3D printing techniques, supports can be designed aesthetically allowing for future additions to be made to the support.
Currently, EPC industry develops pipe and tray support standards using standard steel profiles and some efforts need to be put in to deploy FEM techniques. While this may lead to more engineering hours initially, it can be easily optimized. Real benefit is expected by totally avoiding all the documentation that gets generated as 3D printing machines and FEM software can directly read from industry-standard 3D models.
Results / Conclusions
Considering the multiple topsides loaded out each year, a typical yard in a calendar year fabricates more than 300MT of piping/tray supports. There is enough economy of scale available to deploy assets required for 3D printing techniques and optimize the engineering & fabrication costs.
However, this may require re-writing of some client specifications and standards to allow for 3D printing technologies to be deployed. This also opens avenues for digitalization of the facilities since 3D printing machines interface directly from 3D computer models.
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