American Petroleum Institute defines standards for oil and natural gas industry. There is standards for various types of valves and equipments used in oil and gas industry. This results is uniform design of equipments and parts with replaceability across various manufacturers. Here is a list of such standards.
| Sr. | Number | Title |
| 1 | API 526 | Flanged Steel Pressure-Relief Valves |
| 2 | API 560 | Fired Heaters for General Refinery Services |
| 3 | API 594 | Wafer and Wafer-Lug Check Valves |
| 4 | API 599 | Metal Plug Valves |
| 5 | API 600 | Bolted Bonnet Steel Gate Valves for Petroleum and Natural Gas Industries |
| 6 | API 602 | Compact Steel Gate Valves |
| 7 | API 603 | Class 150, Cast, Corrosion-Resistant, Flanged-End Gate Valves |
| 8 | API 605 | Large Diameter Carbon-Steel Flanges (NPS 26-60, class 75, 150, 300, 400, 600 and 900 |
| 9 | API 608 | Metal Ball Valves |
| 10 | API 609 | Butterfly Valves: Double Flanged, Lug- and Wafer-Type |
| 11 | API 610 | Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries |
| 12 | API 611 | General Purpose Steam Turbines for Petroleum, Chemical, Gas Industry Services |
| 13 | API 612 | Special Purpose Steam Turbines For Petroleum, Chemical, Gas Industry Services |
| 14 | API 616 | Gas Turbines For |
| 15 | API 617 | Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services |
| 16 | API 618 | Reciprocating Compressors |
| 17 | API 619 | Screw Compressors |
| 18 | API 620 | Design and Construction of Large, Welded, Low Pressure Storage Tanks |
| 19 | API 621 | Reconditioning metallic gate, globe, and check valves. |
| 20 | API 650 | Welded Steel Tanks for Oil Storage |
| 21 | API 660 | Shell-and-tube Heat Exchangers |
| 22 | API 661 | Air-Cooled Heat Exchangers for General Refinery Service |
| 23 | API 662 | Plate Heat Exchangers for General Refinery Services |