This document discusses key considerations for planning and life safety in flour milling facilities. It covers regulatory codes around occupancy, construction type, height and area restrictions. Grain storage, cleaning towers, tempering bins and mills often use slipformed concrete construction. The document outlines the flour milling process and notes facilities must plan for flexible layouts and changing technology. Life safety focuses on OSHA, FDA, NFPA codes around equipment access, building envelope, fire protection and loads in mill structures. Sanitary construction aims to allow durable, cleanable surfaces throughout facilities.

1. Design Considerations for the Construction and Operation of Flour Milling Facilities. Part I Planning, Structural, and Life Safety Gregory D Williams, Ph.D., P.E., S.E. Kurt Rosentrater, Ph.D

2. Introduction 26,000 flour mills in late 1800’s 336 flour mills in 2002 Larger more complex facilities with higher outputs 26.5 million tons of output Design Information is limited and not documented

3. Flour Milling Process Break system Separates wheat into components Purification system Sorts particles based on size, air resistance, and specific gravity Reduction system Fine grinding system Finishes flour Tailings Unwanted components

4. Elements of Flour Milling Facility Grain Receiving, Storage & Handling Grain Cleaning Pre-clean Storage Tempering Milling Finished Flour Warehousing & Packaging

5. Flour Milling Process

6. Flour Milling Process

7. Facility Planning Long Range Planning Strategic vision Organizational objectives Grain Supply Local farm sources Geographic area Wheat types Economic factors Local Grain types and volumes Global Population trends Demographics ROI

8. Facility Planning Regulatory Issues Good Manufacturing Practices (GMP’s) Identity Preservation Location/Site Transportation and Infrastructure Utilities Roads Rails/Trucking Site Properties Soil Bearing Drainage Expansion/New Construction Upgrading or expanding existing facility

9. Facility Planning Technology Constantly Changing Must be flexible and adaptable Facility Layout Key to efficiency Coordinate with design team

10. Facility Layout Start with block flow diagrams Buildings determined by like unit operations Layout buildings around unit operations and vessels Work integrally with process design for final layout that is compliant with building codes and OSHA

11. Flour Milling Process

12. Life Safety Design Considerations Model Building Code (2003 IBC) FDA OSHA NFPA

13. Model Building Codes International Building Code Occupancy Construction type Height and floor area Location on site Special requirements Design Details

14. Occupancy Group B – Business Offices Group H-2 – Hazardous – Grain storage Grain Cleaning Milling areas Group F1 - Factory and Industrial Further processing areas Group S – Storage Warehouse areas

15. Fire Rated Construction Types Types I to V Types I & II are least combustible Concrete and steel construction Types III,IV, & V are more combustible Includes wood structures Most Flour Mills are Type I construction Details – Chapter 7 of the International Building Code Floors, partitions, exterior walls, barriers, etc

16. Height and Floor Areas Function of occupancy type and construction type Frontage area and sprinkler systems can increase allowable area Unlimited Area buildings can be built if certain height, sprinkler, and frontage requirements are met

17. Location on Site Grain elevators (storage) must be 30 ft from adjacent structures of different use or property lines Other facility locations are determined by exterior wall fire ratings and site space. Chapter 6 of the IBC

18. Equipment Access Platforms Special case of mezzanine No more than 2/3 the area of floors Access or egress to or from shall not serve as egress for building system

19. Building Envelope No particular national energy conservation requirements for industrial buildings Good business practice dictates energy efficient building design for economical reasons ASRAE requirements can serve as guidelines

20. OSHA Title 29 of the Code of Federal Regulations - OSHA Access Stairs Fixed Ladders Guardrails Equipment Access

21. FDA Title 21 of the Code of Federal Regulations Site Maintained in a manner such that it is not a source of contamination Building Floors walls and ceilings easily cleaned Utilities Water and Drains for cleaing Lighting and Ventilation

22. NFPA NFPA 68 Guide for Venting Deflagrations Explosion venting is required in flour mills NFPA 69 Standard on explosion prevention systems NFPA 61 Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Product Facilities NFPA 85 Boiler and Combustion Systems Hazards Code NFPA 13 Fire Sprinklers

23. Loads Live Loads Dead Loads Loads due to Grain, Flour ect Janssen's Equation Mass Flow – first in first out Wind Seismic

24. Grain Storage Concrete or Steel Construction Raw grain stored in slip form concrete or corrugated steel bins. Large volume bins Details of construction in Williams and Rosentrater 2004 Major elements include reclaim, storage, and distribution system

25. Cleaning Tower Houses raw gain cleaning equipment Often constructed integral with grain storage 5 to 7 stories high Slip formed concrete or steel tower Slip formed concrete tower cast integrally with the pilasters Concrete construction is more common ACI 313 or AISC Steel manual

26. Tempering Bins Slip formed concrete bins Steel silos Mass Flow Adjust Grain MC

27. Finished Flour Bins Smooth wall concrete or steel bins Mass flow design for first in first out flow Concrete bins are rectangular Steel bins are round Pneumatic pressures are possible

28. Flour Bins

29. Mill Construction Large mills are slipform construction Small mills are steel construction Slipformed structures are designed using ACI 313 and ACI318 Bins can integrally with slipform Mat foundations are typical Pilasters are wall stiffening elements that carry vertical load Concrete design done using ACI 313 and ACI 318 Steel design done using AISC documents

30. Mill Pilaster Arrangements

31. Packaging & Warehouse Precast concrete or steel construction Fire code dictates construction type Precast or steel construction

32. Sanitary Construction Coving or Curbing Sanitary Structural Shapes No Ledges No Voids Durable Cleanable Coatings for Floors and Walls Clean Storage for Final Product Openings should be cleanable

33. Summary Brief overview of planning and life safety considerations for Flour Milling Facilities Refer to paper for specific details and code sections Excellent opportunities for Agricultural Engineers