I've read that it is best to replace seatbelts after about 15 years, if they are never crashed. Is this accurate?
Ultimately, like anything, the answer yes; seatbelts "wear out". However in the average life of a typical ‘modern’ vehicle the aging of seatbelts is a non-issue. However the critical part of this is ‘modern’. With regard to older vehicles there may well be a strong argument for replacing the seatbelts. Many years ago webbing was constructed very differently to how it is today. The old style construction is inferior when compared to modern standards and thus such belts dating from certain periods could have degraded and become unsafe.
First (as I’m sure all CPSTs are well aware) it is most important to regularly inspect seatbelts for any signs of wear, odd looking deposits or general damage. In the same way it is good practice (essential in all honesty) to regularly inspect tyres, brakes etc, do the same with seatbelts. I would be very surprised if a vehicle manual did not recommend these regular checks.
Clearly there are some practices that will cause a seatbelt to become unusable or unsafe. For example, the incorrect installation of a car seat, securing items by knotting the belt, getting the belt trapped in a door and thus exposing it to the outside atmosphere while driving, etc. Such misuse could cause the webbing to wear excessively or inconsistently and create a weakness. Nonetheless, such misuse would have to take place over a prolonged period of time.
In the case of a given vehicle under the inspection of a CPST, unless damage to the belt is obvious, I suspect (although I don’t know for certain) the only way to ascertain whether or not the seatbelt requires replacement is to contact the vehicle manufacturer. From a practical viewpoint, it is extremely unlikely that they would be able to tell you and almost certainly could not do so in the timeframe available at the check.
That said, there are a couple of basic observations that can be made that will help identify if a seatbelt is of an antiquated design and thus might need replacement. Foremost the buckle design. Older style seatbelts often have ‘latch’ or ‘lift’ buckles (similar to that of an aircraft seatbelt) which would suggest that the seatbelt is (at minimum) a few decades old and thus is quite likely to have degraded with the continual changes in temperature, exposure to sunlight and general wear. Often these buckles feature the vehicle manufacturer’s company logo (from when seatbelts were a real “selling point”!!). These are some examples:
Old Kangol Seat Belt Buckles
Old Kangol Latch Buckle
Old Britax Inertia Belt Buckle
(Some old vehicles from the 1960s even had ‘magnetic’ buckles to help keep the belt latched!)
Second, look at the ‘weave’ of the seatbelt.
This picture shows an old style of weave which in the UK at least, has not been fitted in new vehicles for at least 35 years (I don’t whether this is true for North American vehicles).
So in a check situation with an older car that would need a BSC, or just giving someone advice, would a CPST inform the caregiver that they need to have the seatbelts replaced?
From a personal viewpoint, if I had to advise someone whether or not the belt needed to be replaced, if it was an original “pebble weave” style belt or featured a buckle similar to those above, I would recommend replacement.
I hope this helps.