A welded shop-fabricated silo is a single-piece cylindrical storage vessel with a conical discharge hopper, fully welded and finished in the workshop before delivery. Transport limits diameter to about 4 m. It offers leak-proof, crevice-free construction in SS 304, SS 316L, or mild steel with epoxy lining, serving food, pharma, chemical, and plastics powder storage from 5 to 150 m3.
Powder enters through a top inlet by pneumatic conveying line or bucket elevator. A reverse-jet filter on the roof vents conveying air while retaining fines. Material is held in the cylindrical shell and flows by gravity through the 60 degree cone to a discharge valve, rotary airlock, or screw feeder. Level transmitters and high-level switches control filling and prevent overfill.
Challenges
Transport Envelope Limitation
Road transport restricts shell diameter to roughly 4 m and overall length to about 20 m, capping single-piece capacity near 150 m3 and constraining site access routing.
Weld Seam Corrosion in Hygroscopic Duty
Continuous exposure to hygroscopic powders and washdown moisture attacks weld heat-affected zones, initiating pitting and product contamination over time.
Condensation Inside the Shell
Day-night temperature swings condense moisture on the inner wall, causing powder caking, lump formation, and blocked discharge cones.
Funnel Flow in Standard Cones
Cone angles shallower than the powder wall friction limit produce funnel flow, leaving stagnant annular material that ages, cakes, and contaminates later batches.
Overpressure During Pneumatic Filling
Blocked or undersized roof filters during tanker blow-in raise internal pressure beyond the shell design limit, risking roof deformation.
Solutions
- Modular Flanged Shell Sections: Splitting tall silos into flanged, gasketed shell sections keeps each transport piece within road limits and allows site bolting with full weld quality retained in each section.
- Pickled and Passivated Weld Finishing: Full pickling and passivation of all internal welds restores the chromium oxide layer on SS surfaces, preventing preferential weld-zone corrosion in humid powder service.
- Insulation Cladding or Trace Heating: External mineral wool insulation with aluminium cladding, or low-watt trace heating on the cone, keeps the inner wall above dew point and stops condensation caking.
- Mass Flow Cone Verified by Shear Testing: Selecting cone angle and outlet size from measured wall friction and flow function data guarantees first-in first-out mass flow for the stated powder.
- Pressure Relief Valve with Filter Monitoring: A calibrated pressure-vacuum relief valve plus differential pressure monitoring across the roof filter protects the shell during tanker filling and signals filter cleaning.
Applications
- Wheat Flour and Bakery Ingredient Storage: Bulk storage of flour, semolina, and improver premixes feeding dosing screws on bakery and biscuit production lines.
- Sugar and Dairy Powder Buffering: Storage of crystal sugar, icing sugar, skimmed milk powder, and whey powder ahead of blending and packing operations.
- Detergent Base Powder Storage: Holding of spray-dried detergent base powder and soda ash between tower discharge and post-dosing lines in home care plants.
- Plastic Resin and Masterbatch Storage: Storage of PP, PE, and PVC resin powders and granules feeding extrusion and compounding lines.
- Pharmaceutical Excipient Bulk Storage: Bulk holding of lactose, MCC, and starch excipients supplying dispensing booths in solid dosage facilities.
Model Range and Capacity: JBM-WS Series
Basis: 60 degree cone, 300 mm outlet, working volume 90 percent of gross.
| Model | Dia (m) | Cyl. Ht (m) | Overall Ht (m) | Gross Vol (m3) | Working Vol (m3) | Capacity (t) @ 0.6 t/m3 |
|---|---|---|---|---|---|---|
| JBM-WS-06 | 1.6 | 2.5 | 4.1 | 5.9 | 5.4 | 3.2 |
| JBM-WS-13 | 2.0 | 3.5 | 5.5 | 12.8 | 11.5 | 6.9 |
| JBM-WS-25 | 2.5 | 4.5 | 6.9 | 25.6 | 23.1 | 13.8 |
| JBM-WS-50 | 3.0 | 6.0 | 8.8 | 48.5 | 43.7 | 26.2 |
| JBM-WS-85 | 3.5 | 8.0 | 11.3 | 86.7 | 78.0 | 46.8 |
| JBM-WS-140 | 4.0 | 10.0 | 13.7 | 140.2 | 126.2 | 75.7 |