Racking is unlikely to fail by fatigue loading. Fatigue failure requires a load to be applied many times (often thousands) before fatigue failure is likely. The mode of failure is more likely to be over load causing structural failure (buckling of structural members) or failure of pin joints etc by shear or bending stresses. Impact by fork trucks etc, leaving dents/impact increases the risk of buckling (coke can effect). Missing pins/locking devices is also a likely way to cause failure. There is a trade body releated to warehouse racking - sorry can't remember the name. Also it is likely there will be a British Standard to work to for your particular type of racking. I would guess something like monthly visual inspections by locally trained staff and an annual formal inspection by a suitably competent engineer will be a good starting point.

We designed a range of racking tagging and inspection systems last year with great results. Feel free to drop me a line if you want any info sent over.

As part of good practice we check our racking monthly, completed by on site racking inspectors trained by SESS. An annual inspection is completed by an independent body (SESS)