There is unfortunately not a straight forward answer to this question, since it depends on how the suit has been used and stored. If the suit is obviously worn out, damaged beyond repair or has been in contact with undecontaminable chemicals, it should of course be taken out of service immediately, independently of age.
If, however, the suit has never been used but only been stored, the shelf life is minimum 5 years for any AlphaTec® (formerly known as TRELLCHEM®) suit, all provided the recommended storage conditions has been applied. Find more information on the shelf life for a specific AlphaTec® suit in the suit manual/Instructions for Use (IFU).
We recommend planning for replacement at an age of 10 years. This should be the wake-up call. There is no panic if the suit fulfils all criteria for re-use even after 10 years, but one must be aware that all polymer materials, no matter how resistant the material is, will eventually age by influence of heat, ozone, light etc. Therefore, even with a suit that looks OK, it should not be used much longer than 10 years. Suits which are 15 years old should be taken out of service. Any use after 15 years is at the risk of the user and we strongly advice against it.