Inconel is a high nickel containing alloy. It consists of the maximum nickel content and offers resistance specifically at the elevated temperatures. It is an excellent material for use in the sulfur free conditions.

Inconel alloy can be utilized from cryogenic to above 1200oF. It is broadly utilized in the chemical plants. The applications include heaters, stills, bubble towers, condensers for processing fatty acids,evaporator tubes, tube sheets, flaking trays for the production of sodium sulfide and equipment for handling abietic acid in the production of paper pulp. The strength and oxidation resistance properties at the elevated temperatures make Inconel highly purposeful for the several applications in the heat processing plants. Inconel alloy is a standard material for using in the nuclear reactors; it offers superior resistance to corrosion by high purity water and no signs of stress corrosion cracking in reactor water systems.

Inconel alloy is resistant to the different corrosive conditions. It acts well in the oxidizing and reducing conditions. The high concentration of nickel offers superior resistance to the alkaline solutions.The Inconel alloy has adequate resistance to strong oxidizing acid solutions. The oxidizing effect of dissolved air solely is adequate to insure full passivity and freedom from corrosion by air saturated mineral acids and specific concentrated organic acids.

Chromium-Nickel stainless steels fail catastrophically sometimes due to stress corrosion cracking. This kind of damage is often associated with the conditions containing chlorides and stress water, dissolved oxygen and other factors.Inconel alloy is virtually immune to chloride ion stress corrosion cracking.

Sulfur compounds: Inconel alloy offers resistance at the moderate temperatures, but is exposed to sulfidation in the elevated temperatures.

Marine conditions: Inconel is slightly superior to Monel alloy. Inconel alloy offers outstanding resistance to sea water conditions.

Water: Inconel alloy is superiorly resistant to running sea water and salt water spray, it is practically free from corrosion due to fresh water as well as the corrosive natural waters. Inconel alloy offers outstanding resistance to corrosion by primary and secondary coolants in the nuclear reactors. Galvanic coupling of the alloy to steel or stainless steel does not increase the corrosion on the any element of couple.

Steam: Inconel alloy is fully resistant to the whole combinations of steam air and carbon dioxide and is specifically useful for contact with steam at the elevated temperatures. Steam does not impair the spring features of Inconel alloy.

Acids: generally, Inconel alloy offers significant resistance in the oxidizing and reducing conditions. It is not resistant to the solutions having significant magnitudes of sulfur dioxide,however it is effectively resistant to tarnishing by the dilute solutions that occur in the food processing.

Sulfuric acid: Inconel alloy provides adequate resistance at room temperature and low resistance at the boiling temperatures.Monel and few other stainless steel alloys offer superior resistance to Inconel.

Hydrochloric Acid: Medium resistance in the dilute mixtures, not preferred in warm and concentrated solutions.

Hydrofluoric acid : medium resistance, poor resistance in the vapor phase.

Phosphoric acid: Inconel alloy offers excellent resistance to entire concentrations at room temperatures. Corrosion is quick at the elevated temperatures and magnitudes above 50%.

Nitric Acid: Inconel alloy offers poor resistance

Organic acids:: Inconel alloy has actually good resistance to corrosion by organic acids as these occur in the food products and alcoholic beverages. Acetic and formic acids at the room temperatures do not influence Inconel. The resistance is only adequate at the high temperatures.Outstanding resistance can be received with warm fatty acids such as oleic, stearic, linoleic and abietic. Good outcomes in the medicine applications where product purity is important have been found. 

Hastelloy C alloys

Strength – 100,000 psi, yield strength 47,000 psi

Highest application temperature : 427oC or 800oF

Hastelloy alloy C is a relatively high nickel alloy that is primarily utilized for offering excellent corrosion resistance features. It has the maximum tensile strength. It is introduced in wrought or cast forms. Fabrication, machining and welding are easily done without any issues. It offers resistance to whole concentration percentages of HCl at room temperatureas well as wet or dry chlorine conditions. The alloy C offers outstanding resistance to pitting, stress corrosion cracking and to oxidizing conditions about 1900oF.

Hastelloy alloy C offers resistance to corrosion by ferric andcupric chlorides, hot polluted mixed acids, solvents, chloride contaminated conditions, chlorine, formic acid, acetic acid, acetic anhydride and ocean water.

Uses of Hastelloy C

• Herbicide units- process equipment lines
• Hydrochloric acid operations – pump lines and check valves
• Research-hydrochloric acid operations
• Super phosphoric plants- hot acid service
• Petrochem plant- warm sulfuric acid service
• Chemical plant- check valves on chlorine injection pump applications
• Sulfuric acid – Hastelloy alloy C is preferred for boiling sulfuric acid about 10% content. It is worthy in resisting the entire contents of acid at room temperatures to 160oF. At the room temperature the corrosion rate in the whole content percentages is generally lower than 3 mpy.
• Hydrochloric acid- Hastelloy C alloy offers resistance to all concentrations of HCl at room temperatures and is successfully utilized up to 120oF.
• Hydrofluoric acid: Linings of Hastelloy alloy C have provided three years service in the HF furnace units.