How to choose ammonia valves

It depends on the specific application; for example, the material and cost of construction (there are options that are relatively suitable and cheaper, as well as better ones that are more expensive). Such valves must also have good sealing properties to prevent leaks. Different pipe diameters (flow rates) dictate certain preferences when choosing a valve – diaphragm valves can be used for smaller diameters, while they’re not suitable for larger ones. The pressure difference is another factor that influences the choice of valve.

Valves with babbitt cores should be used, and the valve bodies should not be made of cast iron.

It is best to have the ammonia tank manufacturers provide or recommend them as well. This valve requires a high standard of quality – it must not only be resistant to corrosion but also able to withstand pressures of around 20 kg.

There is a dedicated ammonia shut-off valve, J41B-25, which can be used for both liquid ammonia and gaseous ammonia； Ammonia solution may require preservatives (depending on its concentration)

I think the corrosiveness of ammonia mainly affects copper. Is it non-corrosive to ordinary carbon steel or 304? I also read many discussions on the forum. There are now three options: 1. Butterfly valve with PTFE sealing surface (what about using rubber instead?) ) 2. Ball valve with PTFE seal 3. Globe valve with PTFE seal. What are your thoughts on these options? Please share your opinions

Is there anyone else who wants to discuss it? ? ?

Ammonia water, also known as ammonium hydroxide, has a certain degree of corrosiveness; ammonia carbonate water is even more corrosive. It has a strong corrosive effect on copper, a weaker effect on steel, and little corrosive effect on cement. It also has a certain corrosive effect on wood. For valves used in such media, the cheapest materials for manufacturing them are cast iron and cast steel; for higher-quality valves, stainless steel ball valves are used. By mixing liquid ammonia or gaseous ammonia with water, ammonia solution can be obtained, so the same types of valves that can be used with ammonia solution can certainly be used with gaseous and liquid ammonia as well! In addition to being produced in ammonia synthesis plants, ammonia solutions of varying concentrations can also be produced as by-products in coking plants, coal carbonization processes, and the petroleum industry. 　　Ammonia-containing off-gases from the ammonia processing process in nitrogen fertilizer plants can also be utilized; after being absorbed with water, they yield dilute ammonia solutions with a nitrogen content of 1% to 3%. These solutions are inexpensive and suitable for application in nearby areas. A few days ago, I just sold several pneumatic ball valves for a urea processing unit! QQ: 928976489 (Your control valve consultant)

For those equipped with dedicated valves, carbon steel is no problem; the key issue is whether the packing is corrosion-resistant. I’ve used both ordinary valves and those made of 304 material, and in all cases leakage occurred at the packing area. It's better to have a dedicated one. In the case of liquid ammonia, it is best to connect an ammonia pressure regulator.

Globe valves are commonly used for ammonia pipelines, while butterfly valves are prone to internal leakage; if the sealing surface is made of rubber, it tends to age quickly

It’s possible to use all-stainless steel, with the valve disc plus STL alloy welded on; the results are quite good!

The stainless steel bellows globe valves produced by Zhejiang Wanlong Machinery Co., Ltd. are designed specifically for use in ammonia handling systems

Choose duplex steel; it’s somewhat similar to the medium used in urea.