High-Pressure Flanges

Wellhead and pressure-control flanges manufactured to API Spec 6A, using ring-joint sealing. 6B types cover lower pressure classes (2,000-5,000 psi) while 6BX types are used for higher ratings (10,000-20,000 psi) with raised-face hub geometry.

Pipe flanges in sizes NPS 1/2 through NPS 24 conforming to ASME B16.5, available in pressure classes from 150 through 2500. High-pressure service in this category centers on Class 600, 900, 1500, and 2500.

Flanges for sizes NPS 26 and larger covered by ASME B16.47, offered in Series A and Series B layouts. Used on large pressure vessels and big-bore manifold connections beyond the range of B16.5.

Flanges with a tapered hub butt-welded to the adjoining pipe, transferring stress smoothly into the pipe wall. Preferred for high-pressure and cyclic service because the bore matches the pipe and the joint is fully radiographable.

Flanges forged from carbon steel (e.g. ASTM A105) or low-alloy steel (ASTM A182) for strength and grain flow. Forging is the standard production route for high-pressure flanges across both API and ASME ranges.

Flanges made from stainless grades (ASTM A182 F304/F316) or corrosion-resistant nickel alloys, or carbon-steel bodies with a nickel-alloy weld overlay on wetted surfaces. Selected for sour (H2S) or corrosive service per NACE MR0175 / ISO 15156.

Threaded stud bolts with heavy hex nuts that clamp flange pairs, typically ASTM A193 grade bolting with A194 nuts. High-pressure classes such as Class 1500 and 2500 require larger-diameter, higher-strength bolting sets.

Quick-connect figure-number unions (e.g. 1502, 2202) used on temporary high-pressure flow iron and frac equipment as an alternative to bolted flanges. The figure number indicates the union's cold working pressure rating.