Johnson Screens - Perforated Plate Scallops

Insights

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.