Please help determine what media are suitable for each valve sealing surface

Generally, the choice of valve is determined based on the properties of the medium. Common sealing materials include 410, 440, 1Cr13, Hastelloy, Monel, etc., and these are selected according to the type of medium. 410 series materials are typically used for steam, Hastelloy for corrosive media, while Monel is used when wear resistance is required; 440 alloy or Stellite alloy can also be considered. So, there is no fixed combination for selecting valve seals; rather, it is determined by the physicochemical properties of the medium. If you have a specific medium, different material combinations will also be suggested based on the experience of various valve manufacturers. Hope this helps you

Q41F-16C features a valve seat seal made of PTFE, a material suitable for most types of media under normal operating conditions; its drawback is that it cannot withstand high temperatures. Q41F46-16C uses F46 as the material for its valve seat seal. Both of these are soft-sealing materials. Q41H-16C employs a 13Cr alloy as the material for its valve seat seal, which constitutes a hard-sealing material. However, valve manufacturers generally do not use 13Cr alloy in ball valves, instead opting to weld STL alloy onto the sealing surface

This post was last edited by wangsir85 on 2018-7-30 09:17. Attempting to answer your question: First of all, just looking at the model number isn’t enough to determine what medium it is intended for; other factors such as the materials of other components, the application environment, the switching frequency, the medium used, and temperature must also be taken into account. II. The meanings indicated by these models, as well as their typical areas of use: 1. 41 denotes a flange-mounted, straight-through floating ball valve, which indicates that the diameter cannot be too large. 2. F refers to the plastic valve seat of F4, a PTFE valve seat that can be used in most normal temperature operating conditions. 3. C denotes carbon steel, but there are many grades of carbon steel; it is the material of the valve body that plays a more significant role in determining the suitable medium for use. 4. H denotes valve seats made of Cr13 series stainless steel; in my opinion, both the ball and the valve seat are made of Cr13, resulting in a hard-to-hard seal. However, the sealing surfaces are not treated with cemented carbide materials such as STL, so their wear resistance is not good, and their sealing performance is inferior to that of soft seals. Of course, hard seals are more wear-resistant and temperature-resistant than soft seals. III. If we only consider this model, it is impossible to determine what type of medium it is suitable for: 1. In the cases of chemicals and petrochemical processing, it is not possible to make such a judgment; the actual medium and temperature must be taken into account. 2. Of course, the first two options are suitable for purifying natural gas, oils, air, and other substances where there is no requirement for corrosion resistance, as well as for valves that operate at normal temperatures; in such cases, carbon steel and floating ball valves are used. 3. The 41H type is suitable for ordinary valves used in refineries; there are no requirements regarding corrosion resistance or wear resistance, and the demands on sealing performance and wear resistance are very low – it is used in cases where carbon steel valves are chosen.

If it is a fire water pipeline, should Q41F or Q41H be used?

Either one will work; it is recommended to use Q41F, as its H-seal is not tight enough.

Well, there’s another question: are the Q41F and Q41H models different only in terms of their sealing surfaces, with everything else being the same (that is, the valve passages are identical)?

In terms of model, everything else is the same, but the specific material cannot be determined, as the model only indicates the material of the valve seat and the category of the valve body material.