Are there any requirements for the use of weld curtains to protect employees who pass by a welding area?

Yes. Under 1910.252(b)(2)(iii), “Protection from arc welding,” OSHA says “Where the work permits, the welder should be enclosed in an individual booth ... or shall be enclosed with noncombustible screens ... workers or other persons adjacent to the welding areas shall be protected from the rays by noncombustible or flameproof screens or shields or shall be required to wear appropriate goggles.”