Choosing a bulk storage vessel based on your mate- rial’s characteristics is the best way to ensure that the vessel will contain and discharge your material without problems. Here are 10 questions to answer about your material before you select a tank or silo, along with information about these vessel types, ex- amples showing how vessels were selected for differ- ent materials, and a sidebar describing discharge patterns in storage vessels. O ne of the most common mistakes in tank and silo selection is choosing a vessel based on a prefer- ence for a certain vessel type rather than on the stored material’ s requirements. While this approach may be easy for the vessel supplier —”I’m just giving my cus- tomers what they want!” — it can lead to unreliable dis- charge from the vessel, as well as other problems, including vessel wall damage and deformation and even complete vessel failure. A better approach is to base ves- sel selection on a sound understanding of your dry bulk material’s characteristics and to work closely with the supplier to design a vessel that can handle these character- istics. The result will be a bulk storage vessel that gives many years of trouble-free containment and smooth, reli- able discharge. 1 Before discussing the questions you need to answer about your material, let’s start by reviewing some tank and silo basics. About tanks and silos Tanks are typically constructed of coated carbon stee l, stainless steel, or, less often, aluminum, while silos are made of concrete. The tank and silo types most commonly used in bulk solids applications are described in the fol- lowing information. Which vessel can best handle your material depends primarily on your material’s characteris- tics and the volume of material you must store. [ Edit or’s note: The vessel capacitie s listed here are for hopper-bot- tom, rather than flat-bottom, vessels, because bulk solids storage vessels typically have hopper-bottom designs.] Shop-welded tank. A shop-welded tank, which consists ofwelded steel panels, as shown in Figure 1a, has a relatively small capacity of less than 10,000 cubic feet. The shop- welded tank is suitable for storing plastic resins, dry chem- icals, food products, minerals, wood waste, and other dry bulk materials. This tank is constructed entirely in the sup- plier’s factory and is then shipped on a truck trailer to the job site, where the tank is li fted by c rane from the trail er and placed on a foundation. Shop construction allows tight control of the tank’s welding quality and factory applica- tion of liquid surface finishes (such as a coati ng on the in- terior wall to prevent abrasion or corrosion, or a primer followed by an acrylic finish coat on the exterior wall for weather protection). The cost of shipping the one-piece tank to the job site is higher than for shipping parts for a site-built vessel, but the shop-welded tank has lower field installation costs. Bol ted fla t-pa nel tank . A bolted flat-panel tank (also called a bolted smooth-wall flat-panel tank to differentiate it from a tank with corrugated walls) has a capacity from 250 to 80,000 cubic feet. The bolted tank handles plastic resins, dry chemicals, minerals, wood waste, some food products, It’ s all about the material: T en questions to answer before selecting a bulk storage vessel Bill Neighbors T ank Connection
