Jun-2017

3D metal printing in plant engineering

A tailor-made spare part, produced just a few minutes ago by a 3D metal printer, fits seamlessly into the natural gas liquefaction plant. Now, the plant can resume operations, after minimal downtime and at minimum cost.

Linde Engineering

Article Summary

Experts test additive manufacturing. This way of manufacturing spare parts is still in the realms of fiction. However, a team of experts at Linde Engineering is already working on turning it into reality. Dr Martin Hock, Senior Consultant for Materials and Corrosion at Linde Engineering, is in charge of all activities related to this manufacturing process. Although it is still in its infancy, this technology is opening up completely new application possibilities and product opportunities for many industry sectors. Additive manufacturing, also called 3D printing, encompasses a number of different processes. However, they all have one thing in common: They all use digital 3D design data to build three-dimensional objects, one layer of metal at a time.

No limits to the design possibilities
“As a rule, the more complicated a component is, the more benefits additive manufacturing brings to the production process,” explains Hock. “Complexity doesn’t automatically result in higher costs, as is often the case with other processes.” Conventional processes struggle with complex designs such as interlocking hollow parts, double-walled components with mesh structures or solid elements with integrated cooling coils. They either cannot produce them or can only do it with a huge amount of effort. With additive manufacturing, however, there are no limits to the design possibilities, almost anything is possible. “We are currently focusing intensively on technical feasibility and assessing which of the different processes are best suited to our needs,” adds Hock. “At the moment, we are collecting, documenting and evaluating promising ideas and looking to see which plant components are even suitable for 3D printing. It goes without saying that we are also keeping a close eye on technical developments,” continues the head of the project’s five-person team.
 
More compact, more functionality
Additive manufacturing is a particularly effective way of creating delicate structures and lightweight parts, which are not particularly common in plant engineering. Nevertheless, 3D printing could mark a huge advance in the production of heat exchangers, which are at the heart of natural gas liquefaction plants. “We are looking at how elements created using additive manufacturing could improve heat transfer. This could reduce the surface area required for exchanging heat, enabling us to build more compact heat exchangers, which, in turn, would save space, material and costs.” In addition to this, the Linde experts are concentrating on plant components that until now could only be manufactured using complicated welding processes. They are also looking to identify process components that could truly harness the benefits of 3D printing; in other words, components where cavities, cooling coils or catalytic structures are already integrated in the design.

However, even supposedly simple plant elements could be promising candidates for additive manufacturing. Tapering pipe components, also known as reducer fittings, are a prime example here. These elements increase or decrease the diameter of a pipe. “It would be a huge benefit if we could manufacture these components ourselves, exactly the way we want them, when we want them,” explains Hock. Additive manufacturing could also be used to build components made of different metals. A metallurgically tight Joint would be much too complex for conventional methods – but not for 3D printing. Particularly expensive metals, for instance, could be limited to the interfaces where they are actually necessary.

Driving the industrialisation of 3D printing
Plant elements also have to meet certain standards – usually very exacting ones. In addition, they have to withstand extreme temperatures and pressures. This is why pressure vessels, for example, can only be approved for use if they comply with specific guidelines and regulations. For conventional production processes, manufacturers can rely on references, characteristic values, standard sizes and calculations to establish that a container is in full compliance. “This now needs to be developed for AM components,” continues the Linde engineer. “Material properties cannot be evaluated in advance because the material doesn’t exist until the element is actually being produced one layer at a time,” adds Hock, highlighting one of the key challenges here. The Linde team has therefore joined a working group in Germany’s Mechanical Engineering Industry Association (VDMA) that aims to develop standards for the approval of load-bearing components created using additive manufacturing and thus to drive industrialisation of this process.

3D printing could also bring major benefits to spare parts production. “If we could manufacture parts tailored exactly to our needs then we would be able to replace defective components in our process units much more quickly,” enthuses the Linde engineer. Every day that an industrial plant is offline, it incurs losses. By ensuring faster delivery times, 3D printers could save real money and make industrial production more cost-effective.