What are the advantages and disadvantages of using welded valves in liquid ammonia pipelines?
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Previously, for a cold storage facility, the liquid ammonia and ammonia gas pipelines were equipped with J41B-40 flanged globe valves of DN32 to DN200 FM type; today, the client wants to replace them with welded valves. I rarely used welded valves before; they were only used for valves with small diameters. I would like to ask fellow professionals about the advantages and disadvantages of using welded valves for valves with large diameters, as well as the relevant standards
Liquid ammonia pipelines are considered pressure pipelines, and valves should be ammonia-specific stop valves
The J41B-40 model uses ammonia-rated stop valves with a PN40 rating. The client requested a specific connection method; the previous design used flange connections, but the client insisted on welding, stating that their pipelines were connected by welding in the past. Well, in the event that there’s a problem with the valve, and it needs to be replaced, it has to be cut out in order to replace it.