Discussion on the material selection for valve pressure control components
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This post was last edited by wangsir85 on 2018-8-11 at 19:06. For example, in the case of a ball valve that is designed and manufactured in strict accordance with ASME B16.34, the material used for the valve body will certainly be one of those specified in B16.34, such as WCB, F304, etc., and the temperature and pressure ratings are determined in line with B16.34. However, do the materials for the valve stem and ball not need to comply with those specified in B16.34? For example, in the following two situations: 1. Suppose I choose AISI 4140 for my valve stem; this material is not specified in B16.34, as B16.34 only specifies the materials for the valve body, valve cover, and valve disc. Is this in compliance with the B16.34 standard? 2. If A182 F304 balls and valve stems are chosen, but the temperature is 600°C. On B16.34, A182 F304 is specified; of course, if F304 is used for the valve body at the flange end, the temperature cannot exceed 538°C – that’s definitely not acceptable ； But using F304 for the valve stem or ball at 600°C – does this meet the B16.34 standard? I hope everyone will kindly share their insights and engage in active discussions.
1. For valves designed and manufactured in accordance with ASME B16.34, materials that meet the requirements of Volume II of ASME BVPC-II, as described in Chapter 5-5.1 of B16.34, may also be used. This applies to the valve body and the valve cover. Excluding the internal components such as the spheres you mentioned, the “Cover” referred to in the standards is the valve cover of check valves. 2. For the internal components of valves, such as the ball and valve stem materials, the material selection principle, as described in Chapter 5 – 5.1.1 and 5.2 of B16.34, is to ensure compliance with the applicable valve pressure-temperature ratings. No specific requirements are specified for the materials; it is recommended to refer to ASME B31.3, App-D of ASME BPVC-II, and App-W of BPVC-III-1 to determine the suitability of the materials. 3. For valve stem AISI 4140, this is equivalent to grade 4140 as specified in ASME SA29/SA29M; this standard corresponds to ASTM A29/A29M-2005. It is suitable for CS valve bodies and can also be used for certain SS valve bodies, depending on the specific operational requirements. 4. The applicable temperature of a valve depends not only on materials such as the internal components but also takes into full account the valve’s structure, in order to ensure normal operation at the operating temperatures. The above content is provided for mutual discussion and reference only.
Thank you so much for your guidance, I really appreciate it!