Gas wells, oil wells, and their production facilities use many heavy-duty valves. There is enormous pressure on underground natural gas and oil, and oil and gas can be sprayed into the air up to a hundred meters high. The combination of valves and special accessories can withstand pressures above 10000 psi. This type of pressure is rare on land and is quite common in deep-sea oil wells. Valves used for wellhead equipment must withstand high temperatures and extremely high pressures. Valve pipeline combinations typically include special globe valves (called throttle valves) and gate valves. A special shut-off valve is used to regulate the flow from the well. In addition to the wellhead, there are facilities that require valves in natural gas and oil fields. This includes L-process equipment used for pre-treatment of natural gas or oil. These valves are usually made of carbon steel material with lower grades.