The most economic way to install a subsea pipeline in deepwater is using Slay method because of the lay speed, due to number of workstations. But on Slay method, the lay vessel requires a massive structure which we called "Stinger" to guide the pipe down to seabed. A Stinger is an extension structure at the stern of the vessel which used to support pipeline on its way to seabed. This stinger is also used to control the strain level by controlling the stinger radius. The length and the radius of the stinger will govern the pipe departure angles which in the end, it will govern the length of pipe span on catenary as well as the tension require for pipe laying.

Typically modern stinger consists of one, two or three space frame and hold by stinger holding frame and stinger hitch. On each of the space frame, the pipeline will be supported on few number of roller supports. These supports are called "Roller Box". The Stinger radius are adjusted by setting the "Roller Box" at certain heights and also set the angles between Stinger Sections.

Typically during Pipelay analyses, Stinger was assumed to be fixed, at certain extent, this rigid assumption is valid. Many Pipelay operations have been analyzed based on this assumption. The pipeline is becoming deeper and deeper and the deeper pipeline required longer stinger and typically the un-supported part of the stinger also become longer which make the stinger does not stiff enough or it will deflect much more compare to shorter stinger.

This study is about using Pipelay Analyses Software and Structural Analyses Program to calculate the displacement of the Stinger based on Reaction Load on the Roller Box taken from Pipelay Analyses. And the interaction between the two softwares was used to predict appropriate stiffness of the stinger. In the end of the study, comparison using Rigid Assumptions and Non Rigid Assumption on Pipelay Analyses was drawn to understand the effect of the stain level, tension required and the gap on stinger last roller.

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