Engineering and Technical Design Subsea BPR Pipeline Protection by Roger Fellows By protecting lines 2,000 to 10,000 feet below sea level, the Subsea Back Pressure Regulator (BPR) helps make oil and gas extraction more environmentally safe and productive. It counters chemical injection fluid siphoning in wells with low pressure. The novelty of this device is that the Subsea BPR throttles to create back pressure only when the pressure falls below a factory set pressure level. A hermetically sealed gas charge activates this first stage without power. More pressure causes a second stage to enact; allowing the product to handle additional pressure and debris.