The chemical industry is a big user of valves of all types and materials. From small batch plants to the huge petrochemical complexes found on the Gulf Coast, valves are a huge part of chemical process piping systems.

Most applications in chemical processes are lower in pressure than many refining processes and power generation. The most popular pressure classes for chemical plant valves and piping are Classes 150 and 300. Chemical plants have also been the biggest driver of the market share takeover that ball valves have wrestled from linear valves over the past 40 years. The resilient-seated ball valve, with its zero-leakage shutoff, is a perfect fit for many chemical plant applications. The compact size of the ball valve is a popular feature as well.

There are still some chemical plants and plant processes where linear valves are preferred. In these cases, the popular API 603-designed valves, with thinner walls and lighter weights, are usually the gate or globe valve of choice. Control of some chemicals is also effectively accomplished with diaphragm or pinch valves.

Because of the corrosive nature of many chemicals and chemical-making processes, material selection is critical. The defacto material is the 316/316L grade of austenitic stainless steel. This material works well to fight corrosion from a host of sometimes nasty fluids.

For some tougher corrosive applications, more protection is needed. Other high-performance grades of austenitic stainless steel, such 317, 347 and 321 are often chosen in these situations. Other alloys that are used from time to time to control chemical fluids include Monel, Alloy 20, Inconel and 17-4 PH.