The other electric utility projects that boilermakers work on include such projects as routine maintenance at operating plants and new plant construction, which account for approximately 13,500,000 man-hours of
Plants require routine maintenance every 6 months and the boilermakers do this specific task. 
mnli hypothesis: Plants require routine maintenance every 6 months and the boilermakers do this specific task.  premise: The other electric utility projects that boilermakers work on include such projects as routine maintenance at operating plants and new plant construction, which account for approximately 13,500,000 man-hours of