Just as employers must provide for their workers, companies cannot unilaterally disclaim any liability for visitor safety. Apart from any governance applicable under OSHA regulations, neglecting visitors' safety could see you embroiled in a mess of trouble under common law or tort law. A sensible approach then would be to adopt policies designed to safeguard visitors and ensure their enforcement and effectiveness - just as you would for your own workers. Be aware too that simply posting notices stating that visitors "visit at their own risk" won't cut it in court. Disclaiming in advance and requiring acceptance as a condition of entry simply carries no weight. It would be wise then to craft a safety policy for visitors along the same lines as employers do for workplaces.
1- Visitors must be notified of any hazards they might encounter.
2- They must be made aware of all protocols and procedures in the event of an emergency.
3- All visitors must sign-in and sign-out of your facility.
4- Similar to all workplaces, must be provided with the appropriate personal protective equipment (PPE) and on its use and reason for it.
5- Care must be taken to ensure proper fit and use of the PPE.
6- Visitors must be oriented properly and advised on the basics of behaviour during the visit.
When developing a visitors safety policy it is important to factor-in the type of industry you are in and any special features of your facility. It is important also to particular attention to the suitability of any PPE provided. For example, if the hazard assessment only calls for 'toe protection' the protective footwear cannot be ill-fitting or so awkward to wear that it constitutes a hazard in itself!
While it may never be possible to avoid liability for visitors' safety entirely it may be possible to do so if you can prove that your safety policies were not adhered to. Just as with workers' safety you are only required to behave responsibly as any reasonable person should. If your visitors safety policies are communicated properly and enforced consistently you should be able to avoid injuries and nasty lawsuits.