Every hard hat has the date of manufacture imprinted on the inside rim of the hat itself.
You should see a circle similar to the one pictured above. To read the date of manufacture, the arrow points to the month and the number in the center is the year. This particular hard hat was manufactured in September 2004 making it 7 years old in September of 2011. It is recommended that hard hats be replaced no later than every five years due to natural degradation over time. Some hard hats will need to be replaced as early as every two years especially if you work outside a considerable portion of the day since ultraviolet radiation degrades the plastic much faster than normal wear.
One good test for degradation, regardless of the date of manufacture, is the “crackle test”. To perform the crackle test, hold your hard hat upside down and squeeze the sides together gently. If you hear a crackle when you do this, your hard had should be replaced because it no longer provides the level of protection that you will need in the event of impact.
The webbing inside of your hat should be replaced every 12 months. This is the “shock absorber” for the impact resistance system and it is also the part that suffers the most wear and tear. The webbing pops in and out easily and can be replaced in a matter of minutes. The minute that it takes to replace it can mean the difference between a near miss and a debilitating injury!
David Carter, CSP