By Russell Hillenburg, President & CEO of Woven Metal Products
As you think of your reactors, towers and drums, many people don’t think about what goes on inside of them. Leading a metal fabrication company focused on the internals inside those structures, I think about what you can’t see: the components that power the processes. Internals selection is important across all towers, drums and reactors, but I’ll focus on reactor internals specifically.
Reactors used for example in hydrotreating, hydrocracking, or catalytic reforming, house internals such as screens, trays, scallops, center pipes, and outlet support grids that help to distribute fluids or gases evenly, hold catalyst or other media in place, and prevent costly losses downstream.
These components must perform under punishing conditions: extreme heat, crushing pressures, demanding schedules, and constant exposure to corrosive chemicals. This makes the selection of internals and how they work together critical. It’s never a one-size-fits-all, it’s a customized engineering exercise.
For most reactor internals, fabricators typically choose between wire mesh, profile wire, and perforated plate for filtration, separation or catalyst containment needs. Each option has distinct advantages and tradeoffs.
A typical wire mesh screen, used to contain catalyst
Wire mesh remains a proven, cost-effective solution in many applications. For example, wire mesh is often used in catalyst hold-down screens at the top of axial flow reactors. These screens need very high open area to minimize pressure drop, must be lightweight so they don’t crush catalyst, and should be easy to remove during turnarounds. In applications like these, wire mesh can perform exceptionally well, sometimes for decades, without any reason to upgrade.
Profile wire, which has largely replaced wire mesh in some applications over the last 30 years, offers excellent strength and highly predictable open area. It’s commonly used in radial reactor components like center pipes and scallops, where mechanical strength is critical. However, stronger isn’t always better. If a scallop is designed too strong, the load may shift and cause the center pipe to become the weak point. Profile wire can also be more expensive, so its benefits must justify the potential increased cost.
Center pipes made of profile wire
Perforated plate has come a long way thanks to advances in laser cutting, water jet cutting, and improved punching tolerances. Today, perforated plate is frequently used in scallops, outlet components, and support grids where cleanability, durability or precise hole sizing is important. In some outlet designs, perforated plate is preferred because larger holes make inspection and cleaning easier during maintenance.
Examples of various patterns in perforated plate
So how do you decide if wire mesh, profile wire or perforated plate is best for filtration or separation?
It starts with understanding what the internal product needs to do. Strength requirements, open area, pressure drop, temperature and containment size all matter. Pressure drop is directly tied to open area: the more open the structure, the lower the pressure drop. But increasing open area often reduces mechanical strength, creating a constant balance between process and structural needs.
Cost and timing also play a major role. Many reactor internals are fabricated from high-alloy materials with long lead times. In emergency turnarounds, material availability may dictate the solution. However, with proper advance planning, our team at Woven Metal Products can help optimize not just performance, but also cost, schedule and long-term reliability.
From our perspective, the real value comes from engineering collaboration.
Because we work extensively with wire mesh, profile wire, and perforated plate, we can act as solution providers and advisors, not just suppliers. Sometimes the right solution is an upgrade. Other times, it’s simply changing metallurgy or refining an existing design rather than spending more on new material.
We have also co-developed solutions working with our partners to create the best solution for their process need. One example of using different products based on the process condition needed comes from our own patented Outlet Support Grid (OSG).
WMP OSG made with profile wire
WMP OSG made with wire mesh
When we developed this patented solution to replace traditional catalyst support grids, we used a variety of separation options for containment. All work well in different conditions, while holding more catalysts and achieving a lower pressure drop than traditional support grids.
In reactor internals, the best answer is rarely universal.
That’s why it pays to work with a fabrication partner who understands the options, the tradeoffs, asks the right questions, and helps you choose the solution that truly fits your process.
Our internal engineering department can help you determine the best solution for your need and work with your engineers to discuss issues and provide alternative solutions or simply offer replacement in-kind solutions.
Reach out to our team at Woven Metal Products to find your solution: wovenmetal.com/contact.