The sale of almost any valve has a technical aspect. Even the most basic commodity valve transaction, where a small on/off industrial valve for low-pressure water service is purchased off-the-shelf requires a working knowledge. For example, a low-pressure, manual industrial valve would require the seller to know about fluid flow, piping, metallurgy and other materials of construction.
Also, the technical complexity scale escalates quickly when talking about more complex valves. A seller needs a high level of know-how for understanding larger diameter high-temperature, high-pressure automated valves manufactured from high alloys for critical service applications in refineries and petrochemical plants; control valves in power plants; remote emergency shutdown valves on an interstate pipeline; or reliable hardened containment vent systems in Mark I and II boiling-water reactor nuclear plants (as mandated by the Nuclear Regulatory Commission after the Fukushima disaster in 2011), among many others.