Hdpe Wye piece preffered on the pipeline to give new lines with the some angles which is most reliable as hdpe 45 degree why fittings. Some of purpose of the pe wye pieces is to reduce of the pe pipelines with the bigger diameter to smaller diameter lines to reduce the lines, or to change the way of the lines over the pipeline. HDPE Wye fittings connection type is butt welding type by the hdpe butt fusion welding machines for the polyethylene pipeline.