Hydroprocessing Reactor Internals: Johnson Scallops, Center Pipe for Sale

In the high-stakes world of hydroprocessing, encompassing hydrotreating, hydrocracking, and hydrodesulfurization, reactor internals such as Johnson scallops and the center pipe are indispensable components. Their precision-engineered design directly influences catalyst usage, pressure drop, and process reliability. 

✔ Johnson Scallops

Johnson scallops are wedge-wire screen segments installed along the inner wall of radial-flow fixed-bed reactors. Shaped to match the vessel curvature, they guide reactants radially into and out of the catalyst bed, providing structural support, catalyst retention, and smooth flow distribution. Their V-wire profiles—and vertical slot orientation—ensure minimal abrasion, robust mechanical strength, and high open area for low pressure drop. 

✔ Center Pipe

The center pipe, often a cylindrical wedge-wire or perforated screen tube, sits at the core of the catalyst bed. It balances internal pressure, evenly collects or distributes process media, enhances flow uniformity, and prevents channeling—thereby safeguarding catalyst efficiency. Constructed from corrosion-resistant alloys such as stainless steel or Inconel, center pipes withstand the rigors of high-pressure and temperature environments.

Why They Matter in Hydroprocessing

Together, Johnson scallops and the center pipe form a high-integrity flow distribution system inside radial-flow reactor internals. Key advantages include:

• Improved flow uniformity across catalyst beds is vital for high yield and conversion rates. 

• Reduced pressure drop, thanks to high open area designs. 

• Enhanced durability under thermal cycling and mechanical stress, thanks to welded-wire construction that resists buckling or collapse. 

• Modular, easy installation and maintenance, reducing catalyst bed downtime during maintenance. 

These design benefits make Johnson scallops and center pipes ideal for hydrocracking, hydrotreating, catalytic reforming, and desulfurization processes in refineries and petrochemical units.

Technical Highlights & Custom Engineering

We offer tailored reactor internals to suit exact specifications:

• Material Choices: Stainless steels (304, 316, 321, 347), Duplex alloys, Hastelloy, Inconel 600 & 800. 

• Slot Size Control: From as small as 250 µm up in tight increments - ensuring precise catalyst retention. 

• Modular Fabrication: Components like scallops or center pipes can be sectioned to fit through manways for easier installation. 

• Installation Aids: Options such as cover plates, expander rings, and blank sections mitigate bed short-circuiting and secure assembly. 

• Quality Assurance: ISO-9001 certified manufacturing, mill certificates, welding specs, documentation, and field support services. 

Why Choose us?

▪ Proven OEM-grade manufacturing with extensive hydroprocessing expertise.

▪ Global delivery and support ensuring timely, installation-ready shipments. 

▪ Custom design services aligned to your reactor metrics—catalyst type, flow rates, pressure, temperature. 

▪ Robust QA&QC: material certifications, welding inspections, pressure testing, and assembly guidelines. 

Investing in premium Johnson scallops and wedge-wire center pipes elevates the performance and longevity of your hydroprocessing reactors. Designed for optimal flow distribution, reduced pressure loss, and durable operation, even under extreme conditions, they're indispensable for achieving operational efficiency and safety.

Contact Information

Email: sales@ubofilter.com

WhatsApp: 86 1353285589