Double Ball

Double-ball ball valves are used in industrial piping systems where isolation requires two independent sealing points and controlled venting of the intermediate cavity. The double block and bleed arrangement allows leakage verification, depressurization before maintenance, and safer isolation of process equipment in liquid, gas, utility, and transmission lines.

Selection between floating ball and trunnion mounted construction depends on valve size, operating pressure, required torque, and cycling frequency. Trunnion mounted designs are generally specified for larger diameters or higher pressure classes, while compact manifold configurations reduce installation length and limit potential external leakage points compared with assemblies using multiple separate valves.

Available configurations include self-relieving seats for cavity pressure relief, DIB arrangements for defined upstream/downstream sealing logic, and secondary soft seats for additional sealing capability. Body materials may include carbon steel, stainless steel, or alloy steel, depending on the process medium, temperature range, corrosion allowance, and material compatibility requirements. For pipeline applications, special constructions for pig launching and pig receiving are also used, with bore geometry suitable for pig passage without restriction of the flow path.

During technical specification, the engineer should evaluate ASME or PN pressure class, end connection type, fire-safe and anti-static requirements, cavity relief philosophy, bleed valve accessibility, stem sealing maintenance, and acceptable seat leakage according to the operating scenario of the installation.