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Text: James Woodcock
On double expanding gate valves, depressurizing the cavity has been slow, hard to monitor and a hydrocarbon exposure risk, because the installed setup carries no double block and bleed configuration. Standard DB&B units are too heavy for the existing half-inch NPT connections, and venting through standard drain ports can form hydrates that halt the process. Operators were left replacing the whole main valve.
Italian valve maker Valland and its additive division Valland3D have answered with the PVT Valve, delivering full DB&B functionality inside 35 millimeters. Four independent channels run through that space: first barrier, drain, second barrier and outlet, with needle valves forming the barriers around a bleed plug. Volume is down more than 70 percent against the smallest design reachable by subtractive methods.
The part is printed in super duplex F55 stainless steel on an EOS M 290, with print and heat treatment parameters developed in-house. Additive design also shifted mass so the center of gravity sits closer to the body, easing load on the thread.
Valland has qualified the process to DNV-ST-B203 at Additive Manufacturing Component Level 2, and over 100 units have passed pressure, fugitive emission and fire testing, with field units at a Vår Energi offshore asset. Because the inlet interface matches the host valve, it retrofits onto equipment already in service.
