What Do Steel Grating Designations Mean? G325/30/100 (YB/T 4001) vs 19-W-4 (ANSI/NAAMM MBG 531) vs BS 4592

Short answer

A steel grating designation tells you the bearing bar size, the bearing bar spacing and the cross bar spacing. In the Chinese standard YB/T 4001.1 a welded grating is written like G325/30/100: G for welded grating, 32 mm bearing bar height and 5 mm thickness, 30 mm bearing bar pitch, and 100 mm cross bar pitch. In ANSI/NAAMM MBG 531 a grating is written like 19-W-4: bearing bars at 19/16 in (1-3/16 in) centres, welded (W), and cross bars at 4 in centres, with the bar size stated separately. BS 4592 covers industrial open-bar flooring and stair treads in the UK. Grating size, load and finish are confirmed per drawing.

YB/T 4001.1 (China)

• Covers steel grating: welded and press-locked types, materials, dimensions, tolerances, surface finish and inspection.
• Designation pattern: type letter, bearing bar height and thickness, bearing bar pitch, cross bar pitch.
• Commonly quoted bearing bar pitches include 30 mm and 40 mm; cross bar pitches include 50 mm and 100 mm.
• Hot-dip galvanizing is the usual finish for carbon steel grating.

ANSI/NAAMM MBG 531 (North America)

• The Metal Bar Grating Manual published by NAAMM. It defines terminology, designations, tolerances and published load tables for steel and aluminium bar grating.
• Designation pattern: bearing bar spacing in sixteenths of an inch, manufacturing type (W welded, P pressure-locked, S swage-locked), cross bar spacing in inches, then bearing bar size (for example 19-W-4, 1-1/4 x 3/16).
• 19-W-4 and 15-W-4 are common industrial designations; 15/16 in spacing is often chosen where smaller openings are needed.
• MBG 532 covers heavy-duty bar grating.

BS 4592 (United Kingdom)

• BS 4592-1 is the specification for metal open bar gratings used as industrial flooring and stair treads. Other parts of the series cover other flooring types.
• UK projects often specify panel size, bar size, nosing for stair treads and serrated or plain surface with reference to this series.

How to choose and specify

1. State the standard the drawing follows and the grating designation.
2. Give the span direction, the clear span and the loads; the designer selects the bar size from the relevant load tables. Loads are confirmed per drawing.
3. Choose the surface: plain or serrated.
4. Choose the material and finish: hot-dip galvanized carbon steel (for example to ASTM A123), stainless steel, aluminium or FRP.
5. Choose the fixing: saddle clips, M-clips or welded fixing; see our grating fasteners page.

We supply steel grating, stair treads and fasteners to the designation and drawing you send. MTC is provided per order, and third-party inspection can be arranged per order.

FAQ

What does G325/30/100 mean?

Welded steel grating with 32 x 5 mm bearing bars at 30 mm pitch and cross bars at 100 mm pitch, written to the YB/T 4001.1 pattern.

What does 19-W-4 mean?

Bearing bars at 19/16 in centres, welded, with cross bars at 4 in centres, as defined in ANSI/NAAMM MBG 531. The bearing bar size is stated after it.

Can a YB/T 4001 grating replace an MBG 531 grating?

Only if the designer checks the bar size, spacing and load for the project. The two standards use different size series and units.

Which standard covers galvanizing?

Projects commonly reference ASTM A123 for hot-dip galvanized coatings on steel products. The required coating is confirmed per order.

Do you supply aluminium and FRP grating too?

Yes. SHEDAR is a manufacturer of aluminium grating, and we supply FRP grating. Specifications are confirmed per order.

Related products

• Steel Grating
• Stair Treads
• Grating Fasteners
• Aluminium Grating
• FRP Grating