There is no specific limit. However, a good general practice for commonly used bolting materials is to torque them to a preload stress value of 50,000 psi. The amount of torque to achieve that will depend upon lubrication and bolt diameter, and whether the nut to flange contact surface is also properly lubricated. A good reference on bolting flanged joints is an ASME document, PCC-1 Guidelines for Pressure Boundary Bolted Flange Assembly.