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Johnson Screens Perforated Plate Scallops

Johnson Screens' perforated plate scallops are an economical approach for retaining catalyst and protecting against catalyst leakage in a radial flow unit. The perforated scallops are light weight and easy to install in your reforming unit.


Each licensor of radial flow units has critical perforation size specifications and characteristic end assembly details. Scallops are typically fabricated from 1200µm sheet in 321H SS material and custom built for your particular unit's needs. Scallops fabricated from 1570 µm sheet are available for operators looking for a more rugged design. Johnson Screens is fully qualified for all licensors' scallop specifications. 

Material in 321H SS is maintained in inventory to allow emergency replacement of components damaged during operation. Our field service crews are also available to maintain your perforated scallops to quickly get your unit back online.

Scallops are installed as a partner to a centerpipe in a reformer. As thermal expansion and contraction of the vessel occurs, loads are exerted on the surfaces of the scallops and centerpipe. Perforated scallops are designed to deform under extreme load, acting as a safety valve to protect the centerpipe and reduce the chance for catalyst leakage into heaters or exchangers. Proper functioning as a safety device requires the scallop to be fabricated to specific tolerances and uniform shape. Johnson Screens scallops meet all these requirements.

Locations and Contact


Aqseptence Group Japan Limited, Susono

Manufacturing Location
A138 Kanezawa, Susono
410-1106 Shizuoka

Tel: +81 55 997 8511

Fax: +81 55 997 8514



Aqseptence Group (India) Private Limited, Ahmedabad

Sales and Manufacturing Location
E-540, GIDC, Sanand-II Industrial Estate,
Village: Bol, Tak: Sanand,
Gujarat 382170, Ahmedabad

Tel: +91 2717 618000



Aqseptence Group Pty Ltd., Brisbane

Sales and Manufacturing Location
88 Brickyard Road,
Geebung 4034 QLD
PO Box 85, Virginia DC,
QLD 4014

Tel: +61 7 3867 5555

Fax: +61 7 3867 5566



Aqseptence Group SAS, Availles-en-Chatellerault

Sales and Manufacturing Location
Zone Industrielle
86530 Availles-en-Châtellerault

Tel: +33 5 4902 1600

Fax: +33 5 4902 1616



Aqseptence Group SAS, Soissons

Sales and Manufacturing Location
108 route de Reims
02200 Billy-sur-Aisne

Tel: +33 3 23 75 05 42

Fax: +33 3 23 75 05 43


North America

Aqseptence Group, Inc., New Brighton, MN

Sales and Manufacturing Location
1950 Old Hwy 8 NW,
New Brighton, MN 55112

Tel: +1 651 636 3900

Fax: +1 651 638 3171


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