Alloy Pipes

What is alloy？

Alloy steel is a specific type of steel that undergoes alloying with elements such as molybdenum, manganese, nickel, chromium, vanadium, silicon, and boron. These alloying elements are introduced to improve the steel's strength, hardness, wear resistance, and toughness. The amount of alloying metals can vary from 1% to 50%.But Stainless steel is a type of steel that has been mixed with other metals. It has only 10.5% chromium, which makes just resistant to rust.

Creating alloys scientists to combine the properties of different metals. They often made to alter the mechanical properties of the base metal, to induce hardness, toughness, ductility, or other desired properties. If a heavy, strong metal is mixed with a light, weak metal in the correct amounts, the result is a light, strong metal.

Alloys have molecules of varying sizes since they are made up of a variety of components combined. Iron and a small amount of carbon are the two main components of steel. The most common extra element added to steel is chromium, which makes it resistant to corrosion. Manganese, molybdenum, nickel, titanium, tungsten, and vanadium are some other elements that can be added to steel to make it stronger.  The classification of alloys is determined by how these elements mix and combine. In metal chemistry, an alloy can also be categorized as either a transition metal or interstitial, depending on the arrangement of its constituent atoms.

Alloy steels are classified into two categories: low alloy steel and high alloy steel. The key distinction between them is typically a 5% content of alloying elements. In practical terms, low alloy steel is generally considered equivalent to alloy steel, particularly in the oil and gas sector.

Characteristics of alloys

An alloy is a substance that has metallic properties and is composed of two or more elements, out of which at least one is a metal. Metals are generally malleable, when different ratios of metals are combined as alloys, it modifies the original properties of metals to give desirable characteristics. Therefore, alloying of metal helps us to use the metal in daily life application. Properties of alloy steel may vary depending on the alloy composition. For example:

0.95-1.3 wt. % of aluminum is used as an alloying element to nitriding steels.

0.001-0.003% of boron is used to improve hardenability.

0.5-2.0% of chromium is used to improve hardenability.

4-18% of chromium is used for corrosion resistance.

0.25-0.40 % of manganese along with sulfur is used to prevent brittleness.

Which alloys can be made into steel tubes？

Alloys are made by melting and mixing the base metal and additional elements (metals and/or non-metals) and allowing them to cool. The atoms of the alloying elements occupy, or substitute, the same sites the atoms of the base material would occupy in its lattice structure. After mixing, the alloys can be cast or wrought into ingots, rods, bars, or plates. There are many different types of metal alloys, and the combinations within are nearly endless. Here are some of the most popular alloys and their applications.

Hastelloy steel: Hastelloy is a nickel-based alloy that exhibits excellent resistance to corrosion and high temperatures.The composition of Hastelloy includes nickel, molybdenum, chromium, tungsten, and cobalt. It has available in a variety of forms, including plate, sheet, bar, tubing, and forgings.The high nickel content of Hastelloy provides good resistance to chloride-induced stress corrosion cracking.The chromium content of Hastelloy provides good resistance to oxidation at high. The molybdenum content of Hastelloy provides good resistance to pitting and crevice corrosion.

Inconel steel: Nickel is the base composition of Inconel alloys. Its ability to maintain a stable austenite structure at any temperature is the guarantee of high temperature resistance of all Inconel alloys.Chromium is also important to Inconel. It can form a protective film on the surface of the alloy. This protective film protects the alloy from corrosive substances. If your project requires materials with very high strength, Inconel alloys should be preferred.

Incoloy steel: With the higher ferrous content and lower cost Incoloy makes it the ideal material in elevated temperature but less critical in applications. The further feature of incoloy is its relative ease of fabrication, employing the same machines and processes used for stainless steel. The outstanding property of Incoloy is corrosion resistance. In reducing & oxidising conditions, Incoloy resists general corrosion, pitting & crevice corrosion, intergranular corrosion and stress corrosion cracking. It is particularly useful in sulphuric & phosphoric acids, sulphur containing flue gases, sour gas and oil wells and sea water. It has a high nickel content, sufficient to resist chloride ion stress corrosion cracking, and a very stable austenite structure. The levels of molybdenum and copper enable the alloy to resist reducing agents and acids. Chromium gives resistance to oxidising conditions. The alloy is titanium stabilised to resist pitting and intergranular attack after fabrication, particularly welding, which includes heating in the critical sensitisation temperature range ( 650°C – 760°C ).

Monel steel:Monel is a single-phase, solid-solution binary alloy with excellent mechanical properties at subzero temperatures. With a specific gravity of 8.80, the Monel alloy 400 has a melting temperature range of 1300–1350 °C and a Poisson ratio of 0.32. Monel is well known as a corrosion strong, rust-resistant material. It is resistant to corrosion and acids, and monel  alloys can withstand a fire in pure oxygen.

Nickel Alloy: Nickel alloy sheet’s high-temperature strength makes it an excellent material for manufacturing components in various high-temperature environments, including gas turbines, jet engines and chemical plants. Even at temperatures exceeding 1000°C, nickel alloy sheet remains stable and retains its strength, creating a robust and reliable material option. Nickel alloys exhibit excellent ductility and toughness, even at high strength levels and these properties are retained up to low temperatures. Nickel reduces thermal expansion for better dimensional stability. Nickel alloys also have good resistance to oxidation. This prevents the formation of oxide layers on the surface. Nickel alloys have good oxidation resistance even at high temperatures. This oxidation resistance property allows them to maintain their mechanical and chemical properties in oxidizing environments.

Use of the alloy steel pipe

• Feed water and steam generator tubing
  

• Brine heaters, sea water scrubbers in tanker inert gas systems

• Sulfuric acid and hydrofluoric acid alkylation plants

• Pickling bat heating coils

• Heat exchangers in a variety of industries

• Transfer piping from oil refinery crude columns

• Plant for the refining of uranium and isotope separation in the production of nuclear fuel

• Monoethanolamine (MEA) reboiling tube

• Cladding for the upper areas of oil refinery crude columns