Compact Double Block & Bleed Valve for Safe Depressurization in Oil & Gas Applications
Additive manufacturing enables a retrofit-ready DB&B solution, reducing component volume by over 70% while integrating full functionality into a 35 mm envelope, now deployed on one of Vår Energi’s offshore assets.
Ensuring safe and controlled depressurization of valve cavities remains a critical operational challenge in Oil & Gas environments. For installed systems, especially in gas service, retrofitting solutions must meet strict constraints in space, weight, and safety – without requiring costly replacement of existing infrastructure.
Valland S.p.A., an Italian manufacturer of custom valves, addressed this challenge with the development of the PVT Valve: a compact, additively manufactured Double Block & Bleed (DB&B) accessory valve designed for retrofit installation on existing main valves.
Produced by Valland’s additive manufacturing division, Valland3D, the component leverages metal AM on an EOS M 290 system, enabling a level of functional integration and compactness not achievable with conventional manufacturing.
Challenge
In double expanding gate valves, safely depressurizing the valve cavity posed both operational and safety challenges.
The existing setup lacked a DB&B configuration, making depressurization time-consuming, difficult to monitor, and a potential HSE risk, due to hydrocarbon exposure.
Additional complications arose in gas applications, where depressurization via standard drain ports could lead to hydrate formation, halting the process entirely.
From a mechanical perspective, the constraints were equally restrictive:
- Standard DB&B units were too heavy for existing ½" NPT threaded connections,
- increasing the risk of thread damage or failure,
- and making them unsuitable for retrofit deployment.
Critically, conventional manufacturing methods – machining, casting, or forging – were unable to deliver a design that combined full DB&B functionality, compact dimensions, and low weight within the required installation envelope.
As a result, operators were often left with only one alternative: replacement of the entire main valve, associated with significant cost and downtime.
Solution
To overcome these constraints, Valland developed an AM-native solution: the PVT Valve, designed from the ground up for additive manufacturing.
Using metal laser sintering on the EOS M 290 and super duplex F55 material, Valland3D engineered a compact accessory valve capable of delivering full DB&B functionality within an extremely limited design space. The design integrates a first pressure barrier, a drain channel, a second barrier, and an outlet, all within a total length of just 35 mm.
A key advantage of the additively manufactured design is the optimized mass distribution, which shifts the center of gravity closer to the main valve body. This reduces mechanical stress on the threaded connection and minimizes the risk of failure.
The manufacturing process, including printing and heat-treatment parameters, was developed in-house by Valland3D and qualified according to DNV-ST-B203, ensuring the component meets strict industry requirements for severe service conditions. The component was qualified to AMC Level 2 under the DNV framework, demonstrating that both the manufacturing process and quality assurance approach meet the requirements associated with safety- and performance-critical applications.
Against this background, the functional design of the PVT Valve plays a central role. The component is based on a Double Block & Bleed configuration, enabling safe isolation and controlled depressurization while maintaining compatibility with existing systems.
“Additive manufacturing allowed us to reduce the component volume by more than 70% compared with the smallest design we could reach with subtractive methods. Within only 35 mm of length we integrated four independent internal channels: first barrier, drain, second barrier and outlet. That is simply unfeasible with any traditional process.”
Gianluca Acquistapace, AM Manager, Valland3D
Results
The impact of the PVT Valve becomes most evident in its performance under real operating conditions. By enabling full Double Block & Bleed (DB&B) functionality within an extremely compact form factor, the solution addresses a long-standing field challenge that could not be solved with conventional approaches.
From an operational and safety perspective, the benefits are significant. The PVT Valve enables safe and monitored cavity depressurization, considerably reducing hydrocarbon exposure for operators. At the same time, it eliminates issues such as hydrate formation during depressurization, which can interrupt or delay the process. As a result, operators report a substantial reduction in the time required for each intervention, leading to more efficient and predictable field operations.
Beyond these operational improvements, the solution demonstrates full industrial readiness. The manufacturing process has been qualified according to DNV-ST-B203, and more than 100 units have already been produced, tested, and deployed in the field. Extensive validation, including pressure testing, fugitive emission testing, and fire-safe testing, confirms the component’s suitability for demanding Oil & Gas applications. Field deployment on one of Vår Energi's offshore assets further validates the solution's performance under real-world operating conditions.
The economic relevance of the solution lies primarily in its retrofit capability. By allowing installation on valves already in service, the PVT Valve eliminates the need for costly replacement of entire main valves. This not only reduces capital expenditure but also minimizes downtime and operational disruption.
“The PVT Valve uses a Double Block & Bleed configuration, with primary and secondary barriers formed by needle valves and a bleed plug between them. It can be designed with the same inlet interface as the valve it installs on, so it retrofits on equipment already in service.” Daniele Brambilla, Engineering Manager, Valland
Conclusion
With the PVT Valve, Valland demonstrates how additive manufacturing enables solutions that are not just incremental improvements, but previously unfeasible products.
By combining design freedom, material performance, and process qualification, Valland3D developed a compact, retrofit-ready DB&B valve that directly addresses real-world HSE and operational challenges in the Oil & Gas industry.
The project highlights the role of metal AM as an innovation driver for highly constrained applications, where conventional manufacturing reaches its limits.
