In the HDD crossing of Liaohe River for Qinhuangdao-Shenyang Gas Pipeline, Huayuan used forward thrusting devices and techniques for the first time domestically to assist back-pulling of the pipeline into the borehole, setting a domestic HDD record of 1578m length of φ1016mm pipeline installed in medium to coarse sand strata which possesses inherent risks of higher resistance.
(translation of the chinese texts in the figure:
Liaohe River HDD Crossing: Qinhuangdao - Shenyang Natural Gas Pipeline Project
1. The formation is mainly composed of coarse to medium coarse sand, which is most likely to cause the risk of gripping and locking the drill pipe down inside the borehole.
2. The diameter of the product pipeline is φ1016mm, and the length of the crossing section is 1570m. When back pulling, the extra resistance exerted on the pipeline due to the vast existence of coarse and medium coarse sand, exceeded the pulling force of the capacity of the main rig (HY-9800 Type Drill Rig). But with the assistance of the thruster with ~500 tonnes of thrusting capacity, the pipeline was successfully installed.)