The owner/operator requires an NPS 3 ½ nozzle to be installed in an in-service tank. The tank is 110 feet in diameter, 60 feet maximum fill height, shell thickness at the point of hot tap is .75", and the material is of unknown toughness with a minimum design metal temperature of 38F. This nozzle is to be installed adjacent to an existing nozzle. What is the minimum spacing between these nozzles?