19-W-4 describes a welded bar grating spacing arrangement. It does not, by itself, specify the bearing bar depth, thickness, material or load capacity.
Read the three parts of the designation
- 19: bearing bar centres at 19/16 inch, or 1-3/16 inch.
- W: welded construction.
- 4: cross bar centres at 4 inches.
The NAAMM Metal Bar Grating Manual, MBG 531-24 explains the marking system and shows the equivalent ordering form W-19-4.
Pitch is different from the clear opening
Pitch is measured from one bar centre to the next. For a simple parallel rectangular-bar arrangement, the nominal clear distance between adjacent bearing bars is the pitch minus the bar thickness. Consequently, changing the bar thickness changes the opening even when the spacing designation stays the same.
Keep unit conversions explicit
One and three-sixteenths inches converts mathematically to 30.1625 mm; four inches converts to 101.6 mm. A drawing may use rounded metric designations, so agree the actual specified dimensions and tolerances instead of assuming every rounded label is an exact manufacturing dimension.
Complete the order description
Add the bearing bar depth and thickness, material, finish, surface, panel dimensions and quantities. Show bearing direction, supports and project load requirements on the drawing. Two panels both labelled 19-W-4 can still have different sections and performance.
Use the 19-W-4 measurement checklist to review an existing panel and the load-table reading guide for performance information. See steel grating spacing for the wider specification context.
