Technical requirements of the API St 605 standard for large diameter flanges
The API St 605 standard defines technical regulations and manufacturing tolerances for carbon steel welding neck flanges equipped with a connecting face. The standard covers products with a nominal pipe size (NPS) ranging from 26 to 60 inches for pressure classes 75, 150, 300, 400, and 600. For products in the NPS 26-48 range, the standard also regulates parameters for pressure class 900. EV Group China ensures the supply of products that fully comply with these specifications, including cast and forged non-removable flanges used as structural elements for valves, fittings, or nozzles.
The nominal flange dimensions regulated by API St 605 are synchronized with pipe fitting sizes, ensuring joint tightness during installation. The product range includes a two-inch size increment for the entire diameter range (from 26 to 60 inches) and pressure classes from 75 to 600, as well as for the 26-48 inch range at pressure class 900.
Technical characteristics monitored by EV Group China specialists during production and supply according to API St 605 include:
- Geometric parameters (including weld end configuration and mating surfaces);
- Manufacturing tolerances and deviations;
- Physicochemical properties of the carbon steel grades used;
- Tabular values for operating pressures and temperature limits;
- Specifications for fasteners and gaskets;
- Product marking standards for batch identification.