| NOMINAL PIPE SIZE | PRESSURE CLASSES | ||||||||||||||
| ASME B16.5 | API 6B | ASME B16.47 Series A | |||||||||||||
| 150# | 300# – 600# | 900# | 1500# | 2500# | 720# - 960# (1) | 2000# | 3000# | 5000# | 10000# | 150# | 300# - 600# | 900# | |||
| ½” | - | R-11 | R-12 | R-12 | R-13 | - | - | - | - | - | - | - | - | ||
| ¾” | - | R-13 | R-14 | R-14 | R-16 | - | - | - | - | - | - | - | - | ||
| 1” | R-15 | R-16 | R-16 | R-16 | R-18 | R-16 | R-16 | R-16 | R-16 | R-82 | - | - | - | ||
| 1 ¼” | R-17 | R-18 | R-18 | R-18 | R-21 | R-18 | R-18 | R-18 | R-18 | - | - | - | - | ||
| 1 ½” | R-19 | R-20 | R-20 | R-20 | R-23 | R-20 | R-20 | R-20 | R-20 | R-84 | - | - | - | ||
| 2” | R-22 | R-23 | R-24 | R-24 | R-26 | R-23 | R-23 | R-23 | R-24 | R-85 | - | - | - | ||
| 2 ½” | R-25 | R-26 | R-27 | R-27 | R-28 | R-26 | R-26 | R-26 | R-27 | R-86 | - | - | - | ||
| 3” | R-29 | R-31 | R-31 | R-35 | R-32 | R-31 | R-31 | R-31 | R-35 | R-87 | - | - | - | ||
| 3 ½” | R-33 | R-34 | - | - | - | - | - | - | R-37 | R-89 | - | - | - | ||
| 4” | R-36 | R-37 | R-37 | R-39 | R-38 | R-37 | R-37 | R-37 | R-39 | R-88 | - | - | - | ||
| 5” | R-40 | R-41 | R-41 | R-44 | R-42 | R-41 | R-41 | R-41 | R-44 | R-90 | - | - | - | ||
| 6” | R-43 | R-45 | R-45 | R-46 | R-47 | R-45 | R-45 | R-45 | R-46 | - | - | - | - | ||
| 8” | R-48 | R-49 | R-49 | R-50 | R-51 | R-49 | R-49 | R-49 | R-50 | - | - | - | - | ||
| 10” | R-52 | R-53 | R-53 | R-54 | R-55 | R-53 | R-53 | R-53 | R-54 | R-91 | - | - | - | ||
| 12” | R-56 | R-57 | R-57 | R-58 | R-60 | R-57 | R-57 | R-57 | - | - | - | R-57 | R-57 | ||
| 14” | R-59 | R-61 | R-62 | R-63 | - | R-61 | R-61 | R-61 | - | - | - | R-61 | R-62 | ||
| 16” | R-64 | R-65 | R-66 | R-67 | - | R-65 | R-65 | R-65 | - | - | - | R-65 | R-66 | ||
| 18” | R-68 | R-69 | R-70 | R-71 | - | R-69 | R-69 | R-69 | - | - | - | R-69 | R-70 | ||
| 20” | R-72 | R-73 | R-74 | R-75 | - | R-73 | R-73 | R-73 | - | - | - | R-73 | R-74 | ||
| 22” | - | - | - | - | - | - | - | - | - | - | R-80 | R-81 | - | ||
| 24” | R-76 | R-77 | R-78 | R-79 | - | - | - | - | - | - | - | R-77 | R-78 | ||
| 26” | - | - | - | - | - | - | - | - | - | - | - | R-93 | R-100 | ||
| 28” | - | - | - | - | - | - | - | - | - | - | - | R-94 | R-101 | ||
| 30” | - | - | - | - | - | - | - | - | - | - | - | R-95 | R-102 | ||
| 32” | - | - | - | - | - | - | - | - | - | - | - | R-96 | R-103 | ||
| 34” | - | - | - | - | - | - | - | - | - | - | - | R-97 | R-104 | ||
| 36” | - | - | - | - | - | - | - | - | - | - | - | R-98 | R-105 | ||
| Notes: (1) - Class 720, 960, 10000 and 2900 flanges to API 6B are obselete. Data is for informational purposes only. | |||||||||||||||
| (2) - R-30 is for lapped joint only. | |||||||||||||||