Wireless sensor networks are used to monitor water/oil pipelines. The excising schemes for pipeline monitoring are not energy efficient. Network operators have to daily travel across pipelines to change batteries of sensor nodes. In this paper, we propose a novel sensorbased pipeline monitoring protocol called FPMN. FPMN utilizes float nodes to reduce energy consumption in sensor nodes by reducing tasks of sensor nodes. FPMN tries to spread best route information along the pipelines in a way to reduce bandwidth and energy consumption. Our simulation experiments show that FPMN reduces energy consumption by 68.3% without change in packet delay and network traffic.