Butt-Weld Pipe Fittings

Butt-weld fitting grades across carbon (A234 WPB / WPC), low-temperature (A420 WPL6 / WPL3 / WPL9), high-yield (A860 WPHY), Cr-Mo (A234 WP1–WP91 with class), austenitic stainless (A403), duplex / super duplex (A815), nickel alloys (B366) and titanium (B363). The material data on this page is representative, not an exhaustive record of every grade and size — the exact grade, class, UNS and edition are confirmed per order.

ASME B16.9 is the dimensional standard for factory-made wrought buttwelding fittings (NPS 1/2–48); short-radius elbows and returns formerly in B16.28 are now incorporated into B16.9. Weld-end preparation follows B16.25. B16.11 is not a butt-weld standard — it covers socket-welding and threaded forged fittings. Larger sizes use MSS SP-75 or SP-43 in their actual scope, or an approved design.

No. The centreline radius (1.0D for short radius, 1.5D for long radius) is not the same as the centre-to-end dimension. For a 90° elbow the centre-to-end equals the radius, but for a 45° elbow it is a different value, and small sizes have their own tabulated exceptions. The correct dimension is taken from the B16.9 table for the specific type, angle and size.

Grades such as A420 WPL6, WPL3 and WPL9 are impact-tested at specified Charpy test temperatures — these are test conditions, not automatic minimum design temperatures. The permissible design temperature depends on the applicable code, thickness, stress, heat treatment and testing provisions, confirmed for the actual application.

They are per ASTM B366, but the codes are easy to confuse: WPNCI is Inconel 600, WPNCMC is Alloy 625, and the WPNIC family (WPNIC / WPNIC10 / WPNIC11) is Incoloy 800 / 800H / 800HT. We confirm the exact designation, UNS and condition against the ordered B366 edition rather than assuming a suffix meaning.

Not automatically. Suitability for high-pressure or sour service depends on the qualified construction, grade, condition, toughness and the project’s design and testing requirements — not on seamless-versus-welded alone. A NACE reference or a high-strength grade is not by itself sour qualification; the actual environment (H&sub2;S, pH, temperature) and material condition govern.

Provide the fitting type, angle and radius, all end sizes and walls, the material grade and class, the standard and edition, seamless or welded construction, service and design conditions, required tests and certification, quantity and any drawing. Availability by grade, size and type is confirmed with the quotation.