Standards remain one of the most prevalent challenges in additive manufacturing (AM), especially in the highly regulated industries that the technology best serves. Speaking to TCT Magazine last year regarding the energy sector, shells Angeline Goh, head of 3D printing technology, explained how organizations responsible for setting international standards and legislation are “still catching up” when it comes to AM parts, but a recent milestone with LRQA (formerly Lloyd’s Register) could help speed things up.
The oil and gas giant recently worked with the global assurance provider to successfully certify a 3D printed pressure vessel under the European Pressure Equipment Directive (PED). The project, a first for the industry, went through four stages over four years, from design, to qualifying and printing facilities, to defining acceptance criteria, and culminating last year with testing and inspection.
To date, standards and legislation for AM pressure parts are lacking, and the need for regulation has generally prevented 3D printed pressure equipment from being permitted. The goal behind this project was to create a proof point that could inform the energy industry’s confidence in AM for future applications. It also emphasizes the ‘just in time rather than just in case’ parts supply method Goh also spoke last year as Shell explores alternatives to buying and stocking spares .
The vessel was designed for pressures up to 220 bar and was fabricated at Shell’s energy transition campus in Amsterdam using Powder Bed Fusion. Although this CE stamp represents a significant breakthrough for the energy sector, in a more recent Q&A session with TCT, Goh said there is still some way to go.
“The knowledge and data we have gained through this process is valuable for engaging with standards bodies and improving industry confidence in additive manufacturing,” Goh said. “This will allow us, over time, to further increase the scope of our inventory to just manufacture in time instead of stock, as well as increase our scope in innovative design and applications critical to our asset’s efforts to reduce operational greenhouse gas emissions.
Shell shared the three main challenges that arose during this project. The first was Primary Materials Approval, which meant printing test specimens next to the pressure vessel to test and approve material properties prior to formal approval through the Particular Materials Evaluation process ( LDCs).
Goh explained, “Unlike pre-tested, batch-purchased materials, with 3D printing, the part is created as the material is printed. Therefore, the formed material must be certified once the pressure vessel is already produced. »
They also needed to define inspection protocols that would detect defects caused by AM’s own “unique defects”. This included printing a dummy container with deliberate flaws and using a range of CT, dye penetrant and other non-destructive techniques to observe hard-to-detect flaws. Due to these unique defects, the usual acceptance criteria for welded pressure vessels were deemed inappropriate by the certifier. The team therefore had to model the intentional defects on the vessel’s performance to help define the maximum acceptable defects.
“The industry still lacks general acceptance criteria for defects in 3D printed pressure vessels,” Goh explained. “It took a lot of R&D time and effort from Shell and LRQA to be sure of the final product. Yet more data needs to be collected and shared by part manufacturers for standards bodies to define general defect acceptance criteria in 3D printed pressure vessels that can be adopted by certifiers in Europe and around the world. the world.
Data from this project can be used to support efforts to set standards for 3D printed pressure vessels under EN 13445 – Unfired Pressure Vessels. Shell is currently exploring the use of die-cast printing for its own experimental facility, focusing on R&D and design and process optimization “to improve the economics of printing critical parts, rather than large-scale manufacturing”.
Although the company says it will have more projects to showcase in the coming months, there are no immediate plans to have more parts certified. For now, more data and sharing of that data is needed.
Goh concluded, “We hope that other companies, research institutes and companies that have invested in similar research also see value in sharing their knowledge with standards bodies.”
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