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What is Api 6a Flange?
API flanges refer to flanges that meet the standards set by the American Petroleum Institute (API). These flanges are typically used in applications related to the oil and gas industry, including pipelines, refineries, and petrochemical plants.
API flanges come in various sizes and pressure ratings, and are available in different materials such as carbon steel, stainless steel, and alloy steel. The most commonly used API flanges are the API 6A and API 16A flanges.
API 6A flanges are used for wellhead and Christmas tree equipment, while API 16A flanges are used for blowout preventers (BOPs) and their associated equipment. These flanges are designed to withstand high pressure and temperature conditions, and are subject to rigorous testing and certification procedures to ensure their safety and reliability.
API flanges are typically connected using bolts and nuts, and the sealing surfaces are usually machined to ensure a tight and leak-free connection. Proper installation and maintenance of API flanges are crucial to ensure their performance and safety in high-pressure applications.
About ASTM A694 F60
ASTM A694 F60 is a carbon steel material specification standard. Specifically:
ASTM A694 is a standard established by the American Society for Testing and Materials (ASTM), which specifies the chemical composition, mechanical properties, and other requirements for carbon steel forged flanges and fittings.
F60 is a material grade within the ASTM A694 standard. The “F60” designation indicates a minimum yield strength of 60,000 psi (approximately 414 MPa).
In other words, ASTM A694 F60 refers to a carbon steel material with a minimum yield strength of 60,000 psi, used for manufacturing flanges, fittings, and other equipment in the oil and gas industry.
This high-strength material is suitable for applications that require the ability to withstand high pressure and temperature conditions. It is widely used in oil and gas pipelines, refining equipment, petrochemical facilities, and other similar applications.

API 6A Weld Neck / Blind / RTJ Flange Dimensions
| Sizes | B | OD (Outside Daimeter) | C | E1 | Q | G | K | T | J1 | J2 | J3 | J4 | R | BC | N | H | BX |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 13/16″ | 46.8 | 185 | 3 | – | 5.56 | 77.77 | 105 | 42.1 | 88.9 | 65.1 | 48.5 | – | 10 | 146.1 | 8 | 23 | 151 |
| 2 1/16″ | 53.2 | 200 | 3 | – | 5.95 | 86.23 | 111 | 44.1 | 100 | 74.7 | 51.6 | – | 10 | 158.8 | 8 | 23 | 152 |
| 2 9/16″ | 65.9 | 230 | 3 | – | 6.75 | 102.77 | 132 | 51.2 | 120.7 | 92.1 | 57.2 | – | 10 | 184.2 | 8 | 26 | 153 |
| 3 1/16″ | 78.6 | 270 | 3 | – | 7.54 | 119 | 152 | 58.4 | 142.1 | 110.2 | 63.5 | – | 10 | 215.9 | 8 | 29 | 154 |
| 4 1/16″ | 104 | 315 | 3 | – | 8.33 | 150.62 | 185 | 70.3 | 182.6 | 146.1 | 73.1 | – | 10 | 258.8 | 8 | 32 | 155 |
| 5 1/8″ | 131 | 360 | 3 | 9.5 | 9.53 | 176.66 | 221 | 79.4 | 223.8 | 182.6 | 81 | 6.4 | 10 | 300 | 12 | 32 | 169 |
| 7 1/16″ | 180.2 | 480 | 6 | 11.1 | 11.11 | 241.83 | 302 | 103.2 | 301.6 | 254 | 95.3 | 9.7 | 16 | 403.2 | 12 | 42 | 156 |
| 9 “ | 229.4 | 550 | 6 | 12.7 | 12.7 | 299.06 | 359 | 123.9 | 374.7 | 327.1 | 93.7 | 9.7 | 16 | 476.3 | 16 | 42 | 157 |
| 11″ | 280.2 | 655 | 6 | 14.3 | 14.29 | 357.23 | 429 | 141.3 | 450.9 | 400.1 | 103.2 | 14.2 | 16 | 565.2 | 16 | 48 | 158 |
| 13 5/8″ | 346.9 | 770 | 6 | 15.9 | 15.88 | 432.64 | 518 | 168.3 | 552.5 | 495.3 | 114.3 | 17.5 | 16 | 673.1 | 20 | 51 | 159 |
| 16 3/4″ | 426.2 | 870 | 6 | 8.3 | 8.33 | 478.33 | 576 | 168.3 | 655.6 | 601.7 | 76.2 | 30.2 | 19 | 776.3 | 24 | 51 | 162 |
| 18 3/4″ | 477 | 1040 | 6 | 18.3 | 18.26 | 577.9 | 697 | 223.1 | 752.5 | 674.7 | 155.6 | 25.4 | 16 | 925.5 | 24 | 61 | 164 |
| 21 1/4″ | 540.5 | 1145 | 6 | 19.1 | 19.05 | 647.88 | 781 | 241.3 | 847.7 | 762 | 165.1 | 31.8 | 21 | 1022.4 | 24 | 67 | 166 |
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