Gate and ball valves are commonly selected for isolation, while butterfly valves may provide compact isolation and, in some designs, limited throttling capability. Globe or purpose-designed control valves are generally more suitable where accurate flow regulation is required. The choice should consider shutoff tightness, pressure drop, operating frequency, pipe size, fluid condition, and maintenance access. A pipe valve should not be selected by valve type alone.

Start with the design pressure and temperature, not only the normal operating pressure. Then confirm the valve size, material pressure-temperature rating, flange class or PN rating, and the connected pipe or flange standard. Flanged, wafer, lug, threaded, and welded-end valves are not automatically interchangeable. Face-to-face dimensions, flange drilling, sealing surface, flow direction, and space for operation should be checked before ordering.

Material selection depends on the fluid composition, solids, corrosion potential, temperature, pressure, and required shutoff performance. Carbon steel, stainless steel, elastomers, and metal seats each have different operating limits. Check the body, stem, disc or ball, trim, seat, seals, and any coating as a complete material combination. If the medium is corrosive, abrasive, very hot, or chemically complex, request a compatibility review rather than relying on the body material alone.

A lever or handwheel may be adequate for accessible valves that are operated infrequently and within manageable torque limits. Gear operators can reduce manual effort on larger valves. Electric or pneumatic actuators may be considered for remote operation, automation, frequent cycling, or defined fail positions. Selection should account for required torque, cycle time, power or air supply, enclosure rating, control signal, emergency operation, and the project's safety philosophy.

Depending on the valve and project, buyers may request shell and seat leakage test records, material certificates, dimensional reports, coating records, actuator data, drawings, and certificates tied to the exact model. API 598 is one commonly specified valve inspection and pressure-testing standard, but other standards may govern the order. State the test method, pressure, duration, leakage acceptance criterion, witnessing requirement, and document format before production.