Be cautious when using MSS-SP44. These flanges are not always compatible with an API 605 flange. ASME B16.47 lists both the MSS flanges (Series A) and the API 605 flanges (Series B). Ordering a 36" valve to the wrong series could be a very costly mistake! Unfortunately, I do not know of any online sources where you can get dimensions for each series, all my stuff is on paper.