Safety & PPE Reference Library · Sizing, Fit & Identification

Identifying Hard Hat Date Codes

How to read the molded date clock and other shell markings inside a hard hat to find when it was made and what it is rated for.

Ref SP-0310ANSI/ISEA Z89.1

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

ANSI/ISEA Z89.1 requires the date of manufacture to be marked on the helmet. Most makers mold a small "date clock" into the underside of the brim or the inside of the shell. Suspensions often carry their own date. Knowing the age matters because plastics degrade with sunlight, heat, chemicals and time, and makers set service lives from the date of manufacture or date placed in service.

How to read a date clock

Remove the suspension if needed and look under the brim and inside the crown.
Find a circle divided into 12 segments, numbered 1 to 12 for the months.
Read the number in the center. This is the year, usually the last two digits.
Read the month the arrow points to. Some makers use a second ring of dots or a small arrow for the quarter or week instead.
If the code is unclear, check the maker's guide to its date marking.

Shell and suspension markings

Marking	Where	What it tells you
Date clock or printed date	Under brim, inside shell	Month and year of manufacture
ANSI/ISEA Z89.1 and year	Inside shell label or molding	Standard edition the helmet was tested to
Type I or Type II	Inside shell	Top impact only, or top and lateral
Class G, E or C	Inside shell	Electrical class
Size range	Inside shell or suspension	Head sizes the suspension fits
LT, HT, HV	Inside shell	Low temp, high temp, high visibility options
Reverse-donning arrows	Inside shell	May be worn backward with suspension reversed
Suspension date	On the headband or crown straps	Age of the suspension, separate from the shell

Key points

Follow the maker's service life. It may be counted from manufacture or from first use; read the instructions.
Write the in-service date with a permanent marker where the maker allows, or log it.
Chalky surface, fading, cracks and stiffness mean replace, whatever the date.
Any helmet that has taken a significant impact should be removed from service.

Common mistakes

Reading the center number as the month.
Using the shell date for the suspension, or the reverse.
Keeping old stock on the shelf for years and then selling it as new without checking dates.
Scratching or engraving the shell to record dates.

Governing standards: ANSI/ISEA Z89.1; 29 CFR 1910.135.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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