Posted to News on 11th Nov 2025, 11:30
Two pressure relief valves in series deliver twice the protection
The Lee Company has come up with an interesting solution to the problem of handling high cracking pressures in downhole oil and gas applications, by using two pressure relief valves in series.
Whether downhole or subsea, the required levels of safety can be difficult to achieve, especially in the oil and gas industries. Sudden, or unexpected pressure spikes can cause considerable damage to equipment, resulting in production stoppages, or in extreme cases more serious consequences. Effective protection starts at the component level, and this is where pressure relief valves come into play.
The Lee Company has been providing solutions helping customers solve the toughest fluid control challenges for over 75 years and today offers robust and reliable relief valves in three main varieties. Firstly, the safety relief valves are designed to be exercised for intermittent 'pop-off' applications, while the pressure regulating valves are intended to operate more continuously with stable performance throughout the operating range.
Finally, thermal relief valves relieve a few droplets of fluid from a trapped volume expanding due to rising temperatures. Each type of valve plays an essential role in downhole oil tool applications and is manufactured to the exacting tolerances required.
In some applications, such as customers making downhole oil tools, there is the possibility of extreme cracking pressures occurring up to 10,000 psid and beyond. The Lee Company manufactures 0.281" diameter high pressure relief valves with cracking pressures up to 5,9000psid, so two in series could offer pressure relief as high as 11,800psid, enabling users to handle double the cracking pressure. This may seem implausible but when you think about how the valves operate you can appreciate why it's an ideal solution.
For example, where the first valve just cracks open, typically the pressure isn't enough to open the second valve, so the spring will try to close it. If the pressure is then increased further to the sum of the two valves cracking pressures, both valves will open, and each valve will take its own pressure drop across it. A simple solution but highly effective and ideal for customers making downhole oil tools.
Like all products from The Lee Company, pressure relief valves are small, lightweight, and incredibly durable, enough to serve out the entire lifespan of an oil tool. In addition, these products are available in a range of sizes and cracking pressures. For example, we offer sizes from 0.187-inch diameter relief valves up to the 0.812-inch threaded line removable units (LRUs) to ensure proper flow and precise opening pressures to meet the specific needs of an application. Zero leak options are available for applications in which eliminating any leakage is critical.
Pressure relief valves can be created in custom envelopes and configurations with unique cracking pressures, flow rates, leakage specifications, and a range of materials.
