How to Calculate Load Capacity for Industrial Grating
A practical step-by-step guide to calculating the correct bearing bar size and grating specification for your load requirements using ANSI/NAAMM standards.
Selecting the correct grating specification requires calculating the maximum load the grating will be subjected to, the clear span between supports, and the allowable deflection. This guide walks through the process using ANSI/NAAMM MBG 531 standards.
Step 1: Determine the Load Type
Industrial grating may be subjected to uniform distributed loads (e.g., general foot traffic at 4.8 kPa), concentrated loads (e.g., a vehicle axle or lifting equipment), or a combination of both. Identify the governing load case for your application.
Step 2: Measure the Clear Span
The clear span is the unsupported distance between bearing supports (typically steel beams or angles). Measure this accurately — a span of 1000mm requires very different grating to 1500mm under the same load.
Step 3: Apply the Load Table
ANSI/NAAMM MBG 531 provides load tables for standard bearing bar sizes at various spans. For example, at 1000mm span under 4.8 kPa UDL, a 25×5mm bearing bar at 30mm pitch is typically adequate with a deflection of approximately 6mm (L/165).
Step 4: Check Deflection
The accepted deflection limit for most applications is L/180 of the clear span (where L is the span in mm). For spans where aesthetics matter or where ponding of liquids would be a concern, a tighter limit of L/200 or L/240 is recommended.
Step 5: Account for Safety Factors
Apply the appropriate safety factor (typically 1.5 for structural applications) to your calculated load before selecting your specification. When in doubt, contact our engineering team for a free load calculation.
