Nickel Alloy: Hastelloy C-276 (UNS N10276)
UNS N10276 or DIN 2.4819, Hastelloy C-276 (also known as Alloy C-276), is a nickel-molybdenum-chromium-iron-tungsten alloy which is among the most corrosion-resistant alloys currently available. The high molybdenum content imparts resistance to localized corrosion such as pitting. The low carbon minimizes carbide precipitation during welding to maintain resistance to intergranular attack in heat affected zones of welding joints.
|Nominal Chemical Composition of Hastelloy C-276, %|
|Density||Melting Range||Specific Heat||Magnetic Permeability|
|lb/in3||g/cm3||°F||°C||Btu/lb.°F||J/kg*°C||200 oersted||15.9 kA/m|
|Product Form||Tensile (ksi)||.2% Yield (ksi)||Elongation %|
|Tube & Pipe||105.4||45.4||70|
|Sheet, Plate & Strip||ASTM B575|
|Billet, Rod & Bar||ASTM B472|
|Coated Electrodes||DIN 2.4887|
|Bare Welding Rods & Wire||DIN 2.4886|
|Seamless Pipe & Tube||ASTM B983|
|Welded Pipe & Tube||ASTM B619/B626|
*The mechanical properties vary in different product forms and heat treatment conditions.
Alloy C276 nickel alloy plate is one of the premier corrosion resistant materials that performs exceptionally well in both oxidizing and reducing environments. It resists chloride stress corrosion cracking, pitting, crevice and general corrosion. The alloy is also resistant to carbide precipitation during welding enabling it to be utilized in the as-welded condition.
In chemical processing applications, the alloy has exceptional resistance to sulfuric, hydrochloric, formic, acetic and phosphoric acids. Alloy C276 nickel alloy plate performs well in environments containing acid chlorides, solvents and acetic anhydride, The alloy is one of the few grades that withstands wet chlorine gas, hypochlorite and chlorine dioxide solutions.
Alloy C276 nickel alloy plate is highly resistant to concentrated solutions of oxidizing salts including iron and copper chloride. It also performs well in seawater, especially under crevice conditions where other frequently used alloys such as stainless steel, Alloy 400 and Alloy 625 fail.
The operating conditions of flue gas desulfurization systems offer a challenging environment for corrosion resistant materials. Scrubber liquors and gas condensates often contain chlorides. Alloy C276 nickel alloy plate nickel alloy plate has been shown to withstand higher chloride levels than other grades before the onset of localized corrosion in these systems.
Alloy C276 nickel alloy plate is used extensively in the recovery and processing of sour natural gas which contains hydrogen sulfide along with carbon dioxide and chlorides. Carbon and alloy steels cannot withstand this corrosive environment. They are subject to failure by sulfide stress cracking or stress corrosion cracking. The rich chemistry of Alloy C276 nickel alloy plate makes it resistant to sour environments even at high temperatures in deep wells.
Corrosion Resistance of Hastelloy C-276 to Hydrochloric Acid
Hastelloy C-276 has outstanding resistance to hydrochloric acid. It is resistant to all concentrations of hydrochloric acid at room temperature, and can be employed successfully up to about 120°F [49°C].
Diagram A illustrates the corrosion resistance of Hastelloy C-276 in hydrochloric acid. There are 4 lines that indicates specific corrosion rate at corresponding temperature and acid concentration. The extra line is the boiling point curve of hydrochloric acid. Take line-“5 mpy” for example, it represents the combination of HCl acid concentration and temperature at which a corrosion rate 5 mpy (0.13 mm/year) is expected. Below the line, the corrosion rate of 0~5 mpy (0~0.13 mm/year) is expected. Between line-“5 mpy” and line-“20 mpy”, a corrosion rate of 5~20 mpy (0.13~0.51 mm/year) may be expected.
Diagram B illustrates the corrosion resistance of Hastelloy C-276 to hydrochloric acids that are purged with oxygen. Oxygen dissolved in HCl solution may drastically accelerate the corrosion attack since it is not a strong enough oxidizer to passivate Alloy C-276.
Diagram C illustrates the corrosion resistance of Hastelloy C-276 to hydrochloric acid purged with nitrogen. Nitrogen dissolved in HCl solution may effectively inhibit the corrosion attack to some extent. Thus, the corrosion rate will decrease comparatively under the same condition.
Corrosion Resistance of Hastelloy C-276 to Sulfuric Acid
Hastelloy C-276, UNS N10276 or W.Nr. 2.4819, is the most universally corrosion-resistant nickel alloy. It is widely used in various applications involving sulfuric acid of an extensive range of concentrations and temperatures. The two isocorrosion diagrams shown below illustrate relative corrosion resistance of Hastelloy C-276 material to sulfuric acid or sulfuric acid with 200 ppm chloride ions, respectively. The two diagrams are based on corrosion tests conducted on Hastelloy C-276 specimens(ASTM B575 Gr. N10276 plates) which are solution heat treated and in unwelded condition.
Diagram A is the isocorrosion diagram for Hastelloy C-276 in sulfuric acids. It has 5 lines which are marked as “5 mpy”, “20 mpy”, “50 mpy”, “200 mpy”, and “boiling point curve” respectively. Take line-“5 mpy” for example, it represents those combinations of sulfuric acid concentration and temperature at which a corrosion rate of 5 mpy(0.13 mm/year) is expected. Below the line, rates between 0~5 mpy(0~0.13 mm/year) are expected. Between line-“5 mpy” and line-“20 mpy”, corrosion rates of 5~20 mpy(0.13~0.51 mm) are expected. Above/below the “boiling point curve” line, the lines reflect the corrosion rates in gaseous or aqueous H2SO4 respectively.
Compared to Diagram A, Diagram B provides the comparison of isocorrosion lines for Hastelloy C-276 in sulfuric acid with 200 ppm chloride ions and isocorrosion lines for Hastelloy C-276 in sulfuric acid. Both tests shall be conducted in aqueous solution of H2SO4. This diagram illustrates that chloride ions contained in the sulfuric acid, even in very small amount, may significantly accelerate the corrosion rate of Hastelloy C-276.
Thermal Expansion Coefficients for Hastelloy C276 at Elevated Temperatures
The thermal expansion coefficients for Hastelloy C-276(UNS N10276) are provided in below tables. All tabulated values are abstracted from ASME BPVC Section II Part D (Properties).
1. Instantaneous Coefficient of Thermal Expansion for Hastelloy C-276
*Temp.: temperature, unit: °F. *Coefficient A: instantaneous coefficient of thermal expansion, unit: 10-6inch/inch/°F.
2. Mean Coefficient of Thermal Expansion for Hastelloy C276
*Temp.: temperature, unit: °F.
*Coefficient B: mean coefficient of thermal expansion in going from 70°F to indicated temperature, unit: 10-6inch/inch/°F.
3. Linear Thermal Expansion for Hastelloy C-276
*Temp.: temperature, unit: °F.
*Coefficient C: linear thermal expansion in going from 70°F to indicated temperature, unit: inch/100 ft.
Maximum Allowable Stress of Hastelloy C-276 at Elevated Temperatures
Hastelloy C-276 fittings manufactured to ASTM B366 Gr. N10276 can be furnished in either seamless or weld types. Its nominal composition is 54Ni-16Mo-15Cr and the fittings shall be solution annealed. The fittings can be used for a plurality of applications based on ASME Boiler and Pressure Vessel Codes. Generally, these applications can be classified into two conditions: Condition A & Condition B. Condition A refers to Hastelloy C-276 fittings used for ASME BPVC Section I, Section VIII Division 1, and Section XII. Condition B refers to Hastelloy C-276 seamless or welded fittings used for ASME BPVC Section VIII Division 2 respectively. The maximum allowable stress of ASTM B366 Gr. N10276 at elevated temperatures are listed in below 3 tables.
1. Maximum Allowable Stress of Hastelloy C-276 Fittings in Condition A
*Temp.: metal temperature, °F, not exceeding; *MAS: maximum allowable stress, ksi. For both seamless & welded fittings.
*The maximum applicable temperatures of Hastelloy C-276 fittings for Section I, Section VIII-1, and Section IX shall be 1000°F, 1250°F, and 650°F, respectively.
2. Maximum Allowable Stress of Hastelloy C-276 Fittings in Condition B
*Temp.: metal temperature, °F, not exceeding; The maximum applicable temperature for Section VIII-2 is 800°F.
*MAS-1: The maximum allowable stress of Hastelloy C-276 welded fittings at elevated temperatures.
*MAS-2: The maximum allowable stress of Hastelloy C-276 seamless fittings at elevated temperatures.
Air Pollution Control – flue gas desulfurization systems – stack liners, absorbers, ducts, dampers, stack gas re-heaters and fans
Flue gas desulfurization (FGD) uses technologies to remove sulfur dioxide from exhaust gases in coal-fired power plants. Air pollution control in power generation and industrial environments is crucial due to strict air quality control laws and regulations. High concentrates of chlorides are found in the gases that are emitted from these plants. Other grades of alloys cannot withstand these higher chloride levels. Moreover, other conditions found in FGD systems, such as high temperatures, acidity, halides other than chlorides, wet and dry conditions, mineral deposits, and dew points, contribute to corrosion of FGD materials. Nickel alloy C276 (c-276) plate and sheet materials are ideal choices for air pollution control components found in flue gas desulfurization systems such as stack liners, absorbers, ducts, dampers, and stack gas reheaters and fans. Considered the “workhorse” alloy of the FGD industry, Nickel alloy C276 (c-276) offers reliable and low-maintenance services for corrosive-resistant air pollution control components.
Chemical Processing – heat exchangers, pressure vessels, tanks, evaporators, piping, flanges and fittings, pumps and valves
Chemical processing is a method of changing one or more chemicals or compounds using chemical reactions into another. Chemical processing utilizes equipment such as heat exchangers, pressure vessels, tanks, evaporators, piping, flanges and fittings, pumps, and valves. Due to the harsh operating conditions often found in and solutions used in the chemical processing industry, a high performance nickel alloy, such as C276 (c-276), that possesses superior corrosion-resistant properties, may be required. Sulfuric, acetic, phosphoric, formic, nitric, and hydrochloric acids, as well as hydrofluoric compounds, can be found in chemical processing environments and, nickel alloy C276 (c-276) displays excellent resistance to these substances. C276 (c-276) alloy also resists the formation of grain-boundary precipitates in the weld heat affected zone, making it suitable for the fabrication of chemical process equipment.
Oil and Gas Production – sour gas service components
Sour gas is natural gas that contains large amounts of hydrogen sulfide. Natural gas is considered sour if there are more than 5.7 milligrams of hydrogen sulfide per cubic meter of natural gas. Natural gas fields that are expected to be used as energy are becoming increasingly sour. Hydrogen sulfide is corrosive, toxic, and lethal, therefore certain materials must be used to ensure safety when compressing gas that contains hydrogen sulfide. C276 (c-276) nickel alloy is a wise choice for sour gas service components because of its ability to resist corrosion, and subsequently, promote the future of the oil and gas industry. Hydrogen sulfide is especially corrosive when it is present in water. This causes sulfide stress cracking which can significantly damage equipment. Compressors for sour gas services must be able to resist corrosion in order to keep up with the demand for natural gas as a source of energy. The removal of hydrogen sulfide in oil refineries or natural gas production plants is referred to as “sweetening,” and must be done before the raw natural gas can be used. The properties of nickel alloy C276 (c-276) make it resistant to sour environments, even at high temperatures.
Pharmaceutical Production – reactor vessels, piping, flanges and fittings, pumps and valves
High purity and process control are essential in the production of pharmaceuticals. Pharmaceutical production equipment must be made of a non-corrosive material so drugs are not contaminated with metallic impurities. Cleanability is also an important factor in pharmaceutical production equipment. Materials for equipment in pharmaceutical industries must be corrosion resistant to high purity water as well as buffer solutions used in preparation of products and cleaning supplies. C276 (c-276) nickel alloy plate is a superior choice for pharmaceutical production equipment because it is able to resist corrosion from the raw materials used in the production of pharmaceuticals, specifically those containing chlorides. Alloy C276 (c-276) has excellent corrosion resistance in a wide range of chloride-bearing environments, both acidic and alkaline. Furthermore, C276 (c-276) nickel alloy has excellent corrosion resistance over a great range of temperatures.
Pulp and Paper – bleaching vessels and digesters
The pulp and paper industry uses wood as a raw material to produce pulp, paper, board, and other cellulose-based products using bleaching vessels and digesters. Bleaching vessels are where wood pulp is bleached, making it appear whiter. Digesters are where wood chips are heated to high temperatures with sodium hydroxide and sodium sulfide to change them into pulp by dissolving the wood’s lignin binder. Black and white liquors contained in this cooking process are corrosive materials that can attack the internal walls of the digester. Both the bleaching and digesting processes include chlorine and chlorine-based materials as well as sulfur, hydrogen sulfide, and sulfur dioxide. Nickel alloy C276 (c-276) pipe, plate, and sheet material have excellent corrosion resistance in a wide range of chloride-bearing environments, both acidic and alkaline, which makes them excellent choices for bleaching vessel and digester materials.
Waste Treatment – incinerators for toxic, industrial and municipal waste
Incineration is a waste treatment process that destroys waste by converting the organic material to carbon dioxide and water vapor through exposure to high temperatures. Incinerators are used for toxic, industrial, and municipal waste, and are important because they destroy potentially harmful substances. Waste materials may contain chlorinated organics, fluorocarbons, sulfur, and brominated compounds. When these are oxidized at extreme temperatures in the incinerator, nitrogen oxides, hydrogen halides, sulfur oxides, and acidic gasses are produced, thus making incinerator material selection difficult. C276 (c-276) is an alloy that can withstand these harsh environments and is a great choice for incinerator materials.
Ore processing involves mineral extraction that separates ore into valuable substances. Chemically aggressive solids and fluids are used in the extraction process. Selecting a corrosion-resistant material for ore processing equipment is very important. Pitting, or localized corrosion leading to small holes in metal, is a major concern with ore processing because of the presence of thiosulfates. For this reason, nickel alloy C276 (c-276) pipe and plate are premier materials for ore processing equipment. The alloy’s ability to withstand harsh chemical environments makes it an ideal material for ore processing equipment.
Hastelloy C-276 Fittings (ASTM B366 UNS N10276)
Hastelloy C-276 pipe fittings refer to factory-made wrought nickel alloy fittings manufactured to ASTM B366 UNS N10276. It can be designated as CRHC276(corrosion resistant fittings) or WPHC276(ASME pressure fittings). The fittings can be manufactured from pipe or tube of ASTM B619, B622, B626 UNS N10276, plate, sheet or strip of ASTM B575 UNS N10276, forging or bar of ASTM B564, B462, B472, B574 Gr. N10276. The Hastelloy C-276 fittings are mainly furnished in 3 connection types: butt welding, threaded, socket welding, covering a variety of standard specifications.
Dimensional Standards for Hastelloy C-276 Fittings
|ASME B16.9||Hastelloy C-276 butt welding pipe fittings|
|ASME B16.11||Hastelloy C-276 high pressure forged fittings|
|MSS SP-43||Hastelloy C-276 butt welding pipe fittings|
|MSS SP-95||Hastelloy C-276 swage nipples and bull plugs|
|MSS SP-97||Hastelloy C-276 forged branch outlets|
*Hastelloy C-276 fittings shall be solution annealed. The minimum heat treatment temperature shall be 2050°F[1121°C].
Hastelloy C-276 Sheets Used for Plate Heat Exchangers
Hastelloy C-276 sheets manufactured to ASTM B575 Gr. UNS N10276 can be used for the construction of plate heat exchangers. The plate heat exchanger include “standard plate heat exchanger”, “semi-welded heat exchanger”, and “brazed plate heat exchanger”. Hastelloy C-276 is a low-carbon nickel-chromium-molybdenum-tungsten alloy which has universal resistance to almost all corrosion.
In the plate heat exchanger industry, Hastelloy C-276 plates or sheets are rolled to corrugated style. It can be used in applications involving wet oxygen, sulfuric acid, sulfurous acid, acetic acid, formic acid, hypochlorite, and other reducing or oxidizing acids.
The standard plate heat exchangers shown above are designed for the application involving sulfuric acid at 165°C and 0.85 MPa. Its heat exchanging area is 41 square meters. The flanges, outlets, columns, and guide rails are made of carbon steels. The corrugated plates are made of ASTM B575 UNS N10276 sheets with the thickness of 0.7mm.
The hot-working temperature range for Alloy C276 nickel alloy plate is 1600 – 2250°F (870 – 1230°C). The alloy should be water quenched after hot working. Heat treatment is recommended after hot working to ensure maximum corrosion resistance.
Alloy C276 nickel alloy plate should be in the annealed condition for cold working. The alloy has a higher work-hardening rate than the austenitic stainless steels which should be taken into consideration. An in-process anneal may be necessary with a high degree of cold working. If the alloy undergoes greater than 15% deformation during cold working, a solution anneal may be necessary.
Alloy C276 nickel alloy plate can be readily welded by most standard processes including GTAW (TIG), PLASMA, GMAW (MIG/MAG) and SMAW (MMA). A post weld heat treatment is not necessary. Brushing with a stainless steel wire brush after welding will remove the heat tint and produce a surface area that does not require additional pickling.
Alloy C276 nickel alloy plate should preferably be machined in the annealed condition. Since Alloy C276 nickel alloy plate is prone to work–hardening, only low cutting speeds should be used and the cutting tool should be engaged at all times. Adequate cut depth is necessary to assure avoiding contact with the previously formed work-hardened zone.
Prices for Hastelloy C-276 Materials
- Hastelloy C-276 seamless pipes, ASTM B622 Gr. N10276, size: 1-1/2″~6″, wall thickness: 2 mm ~ 8mm; unit price FOB Shanghai Port: USD 67.80 per kg.
- Hastelloy C-276 bars / rods, ASTM B574 Gr. N10276, size: 15 mm ~ 65 mm, length: 0.5 m ~ 3 m; unit price FOB Shanghai Port: USD 32.50 per kg.
- Hastelloy C-276 plate, sheet & strip, ASTM B575 Gr. N10276, size: 0.5 mm ~ 6.0 mm thick; unit price FOB Shanghai Port: USD 36.80 per kg.
- Validity: 15 days. The prices provided are only for reference since it may be subject to raw material fluctuation, specific quantity, specific dimension, etc.
- Payment Term: T/T or L/C.
Source: China Alloy C-276 Pipe Fittings Manufacturer – Yaang Pipe Industry (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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