Hastelloy C-276 / C-22 / Alloy 2000 Forged Flanges & Fittings | ASME SB-462

When SB-462 is the correct specification

ASME SB-462 covers forged or rolled nickel alloy pipe flanges, forged fittings, valves and parts intended for corrosive high-temperature service. It is the specification that sits behind every Hastelloy C-276 weld neck flange and every C-22 forged elbow you will find in sour or acid service. The grades listed in SB-462 are N10276, N06022, N06200, N06030, N06035, N06044, N06059, N10362, N06686, N08031, N08020, N08367, N06045, N06025, N06699, N10665, N10675, N10629 and R20033.

One point worth flagging before you order: SB-462 is a material specification, not a dimensional one. The finished geometry still has to come from ASME B16.5 for flanges up to NPS 24 and ASME B16.47 above that, and fittings from ASME B16.9 for butt weld and B16.11 for socket weld and threaded. Buyers frequently ask us to confirm both numbers on the same line of the purchase order, and we recommend you do the same.

For the flange side of that pairing, the B16.5 flange dimensions for Class 150, 300, 600 and 900 give the outside diameter, hub and flange thickness, length through hub, thread length, bore and corner radius for every size from NPS 1/2 to NPS 24, in inches as ASME prints them.

Comparing the three grades you will specify most

All three are supplied in the solution annealed condition under SB-462. Recommended annealing temperatures followed by rapid cooling are 2025 to 2075 degrees F (1107 to 1135 degrees C) for C-276, 2025 to 2075 degrees F (1107 to 1135 degrees C) for C-22, and 2075 to 2125 degrees F (1135 to 1163 degrees C) for Alloy 2000.

The practical difference is the copper content. C-276 and C-22 are copper-free, so they hold their corrosion performance in strongly reducing acids. Alloy 2000 carries up to 0.3% copper and a nitrogen addition of 0.15 to 0.25%, which is what gives it its edge in sulphuric acid service. For reducing hydrochloric acid, C-276 is the safer default. For mixed oxidising acid, C-22 has the higher chromium and is the better performer. Where copper-bearing sulphuric acid dominates, specify Alloy 2000 and say so on the order.

Product forms and dimensional range

We supply SB-462 material as forged flanges in ASME B16.5 and B16.47 dimensions, and as forged fittings in ASME B16.9 (butt weld) and B16.11 (socket weld and threaded). Common forms include weld neck, socket weld, blind, lap joint and threaded flanges, plus elbows, tees, reducers, caps and stub ends. Sizes run NPS 1/2 through NPS 24 and above in pressure Classes 150, 300, 600, 900, 1500 and 2500, with Class 3000 and 6000 socket weld and threaded items on request. Wall thickness and diameter follow the applicable B16.5, B16.47, B16.9 and B16.11 tables.

Certification and inspection

Every order ships with an EN 10204 3.1 material test report carrying the heat number, the full ASME SB-462 Table 1 chemical analysis, and the mechanical properties for the grade and size ordered. On request we add hydrostatic testing, supplementary examination for weld repairs, and ferritic testing. For sour service we can supply ASTM G28 intergranular corrosion test results and NACE MR0175 / ISO 15156 documentation. Certificate of conformity to PED 2014/68/EU and UKCA can be issued for European and UK delivery. Third-party inspection by TUV, SGS, BV or Lloyd’s Register is arranged routinely and witnessed at our works before despatch.

Ordering information

Send us the grade, the product form, the nominal size, the pressure class, the dimensional standard (B16.5, B16.47, B16.9 or B16.11), the quantity and the delivery date. If you have a project drawing or a line list, attach it and we will return a quotation against it with the certificate package we will supply. Where the service condition is unusual, tell us the medium, the temperature and any chloride or oxidiser content, and our technical team will confirm whether C-276, C-22 or Alloy 2000 is the right material before you commit.