Pittsburgh-based Buchanan Ingersoll & Rooney will merge Friday with Tampa-based Fowler White Boggs, creating a 530-lawyer firm that instantly becomes one of the 100 largest in the country.

Fowler White chair and CEO Rhea Law will stay on as chair of the new firm’s Florida operations and becomes a member of its board of directors. She was one of the few female managing partners of a sizable law firm in the country.