Are you wishing to print something hollow with no vertical seam? This can be achieved by selecting the setting "Vase Mode" in Simplify3D. With this setting activated, the printer will disregard your outline/perimeters setting and any solid parts of your model. It only print with one perimeter and no retraction, and therefore no vertical seam. It is great for thin-walled, decorative parts such as vases, planters, and small containers.
It can be selected by going into the layer tab of the Simplify3D process settings and checking the box shown below:
We would also recommend selecting additional settings of 0 top layers and 3 bottom layers found under the "Layer" tab, and the setting "Merge all outlines into a single solid model" which is found under the "Advanced" tab which will also heal additional error in your mesh.