A plant is constructed with hoppers (silos) to store the finished dry resin product. The silos are 8900 cu. ft. capacity, SA516 gr 70 material, design pressure 3.6 psi, static head 24 psi. The silo was constructed per API 620, and is ASME code-stamped. Material is pneumatically conveyed to the silos and a dust collector is provided on top of each that vents to the atmosphere. My question is, is a PVSV still required? Or maybe just good safe practice? I have worked in PVC, and all silos had at least pressure relief on a separate nozzle in addition to the dust collectors, even if the dust collectors had high differential pressure alarms.
