Csub (Norway)

Abstract CSUB has developed a modular and adjustable Pipeline Crossing/Freespan Support designed to support pipelines subjected to freespan due to uneven seabeds or scouring. This support can also be used for crossing supports of rigid pipelines. CSUB has qualified the use of Glass Fiber Reinforced Polyester (GRP) material in accordance with DNV standards, leveraging over three decades of extensive use. The main findings indicate that high-quality GRP is environmentally benign, exhibits very low degradation in seawater, and is well-suited for offshore applications. These conclusions are corroborated by independent third-party evaluations from organizations such as DNV. The Adjustable Pipeline Crossing/Freespan Support is patent pending. CSUB wish to acknowledge Mr. Qasim Saleem at Offshore Pipeline Department of Aramco for valuable insight and contribution during the development and testing of the Adjustable Pipeline Crossing/Freespan Support. The Adjustable Freespan Support was tested at CSUB's factory in Arendal in 2023. The tests involved pulling the foundation under the pipe on a concrete floor, installing wedges, and securing them using a threaded mechanism. The objective was to demonstrate the functionality of the support and measure the operational loads. Tests were conducted using 8" (1250 kg) and 28" (4840 kg) pipes with two sets of wedges, 15 degrees and 30 degrees. The recorded loads for maneuvering the freespan support equipment are as follows: Table 1Recorded loads for maneuvering of freespan support equipmentTaskMaximum forceCorresponding friction factorPulling foundation under pipeline1160 kg0.62Moving wedge into position, manually55 kg0.34Table 2Measured torque/load taken from 28" pipeline with weight of 4840 kg and maximum lifting height of pipeWedgeTorque appliedResulting lifting forceMax. lifting height15° Wedge100 Nm4840 kg220mm30° Wedge100 Nm2220 kg645mm150 Nm3640 kg200 Nm4840 kg The tests proved that the Pipeline Freespan Support operates as intended for: Movement of assembly under pipeline Wedge operation, including connection to the threaded rod and lift mechanism, effectively transferring the pipeline load to the support.

This article presents a feasibility study where fibre-reinforced structural elements are assembled into long slender columns using adhesive bonding. The columns are intended to be part of an externally guyed high-voltage transmission tower where they are subjected to a combination of compressive and transverse loads. The article has shown that 25-m long poles can be made with small tolerances in both angularity and concentricity. Previous published scientific work on buckling of composite columns was applied to predict the behaviour of the pole as it was being loaded in compression to 1200 kN or within 5% of its critical load in a bespoke horizontal test jig. The confidence in the material, the structural elements, the analysis method and the quality of the test equipment has shown that there is a potential in further optimization of the structure that will ultimately be a part of a high-voltage composite tower.