Custom Designed Reactor: Process, Deliverables, and How to Specify One A custom designed reactor is a vessel engineered from your specific process duty rather than selected from a catalog. Catalog units suit standard, low-risk service; everything else, from an agitated hydrogenation vessel to a high-pressure synthesis autoclave, is custom by necessity. The value of custom design is fit: the reactor matches your chemistry, footprint, and code exactly. This article outlines the