ASME B16.9 Buttweld Pipe Fittings ASTM B366 UNS N10276 / C276 Eccentric Reducer

Buttweld fittings are welded to the pipe, providing a strong, leak-proof connection. Used in high-pressure systems. Eccentric reducer—different from concentric. Eccentric has one side flat, used to maintain the bottom or top of the pipe level when changing pipe sizes. Applications in pipelines where you need to avoid trapping air or sediment. Applications of this fitting would be in industries like chemical processing, oil and gas, pharmaceuticals, where corrosive materials are handled. Manufacturing process—probably involves forming, welding, heat treatment, testing.

Equivalent Grades of ASTM B366 C276 Buttweld Pipe Fitting

Mechanical Properties of ASTM B366 C276 Buttweld Pipe Fitting

• Excellent corrosion resistance in harsh environments (e.g., sulfuric acid, hydrochloric acid, chlorine).

• Resists pitting, crevice corrosion, and stress-corrosion cracking.

• Performs well in high-temperature and high-pressure conditions.

Chemical Composition of ASTM B366 C276 Buttweld Pipe Fitting

Compare with other common materials --- Vs. Stainless Steels (e.g., 316/316L, 304):

• C276 excels in resisting both oxidizing and reducing acids (e.g., sulfuric, hydrochloric, phosphoric) and chloride-induced corrosion (pitting, crevice corrosion).

• Stainless steels (SS 316/304) fail in concentrated HCl, hot sulfuric acid, or high-chloride environments (e.g., seawater), whereas C276 handles these with ease.

• Key advantage: C276 avoids catastrophic failure in acidic, chloride-rich, or sour gas (H₂S) environments where stainless steels corrode rapidly.

Vs. Duplex Stainless Steels (e.g., 2205, 2507):

• Duplex steels offer better strength and chloride resistance than standard SS but struggle with non-oxidizing acids (e.g., HCl) and high-temperature chlorides.

• C276 outperforms duplex steels in reducing acids and mixed acid systems (e.g., HNO₃ + HCl).

Vs. Other Nickel Alloys (e.g., Inconel 625, Hastelloy C22):

• Inconel 625 has good oxidation resistance but lacks molybdenum (Mo) content (9% vs. 15-17% in C276), making C276 superior in reducing acid environments.

• Hastelloy C22 offers broader corrosion resistance (e.g., nitric acid) due to higher chromium (Cr: 22% vs. 15% in C276), but C276 is more cost-effective for applications where extreme Cr resistance isn’t critical.

Applications

• Chemical Processing: Reactors, scrubbers, and piping handling sulfuric, hydrochloric, or phosphoric acids.

• Oil & Gas: Sour gas (H₂S/CO₂) pipelines, offshore platforms.

• Pollution Control: Flue gas desulfurization (FGD) systems with hot chlorides.

• Pharmaceuticals: Aggressive solvent handling.