Steel Pipes used in Process Industries

What are Pipes?

Long, hollow steel pipes are used in various situations for various purposes. Pipes are the steel industry’s most successful product due to their versatility. They are frequently used to carry small solid particles and fluid substances that can flow. They are also used in construction for activities like heating and plumping or underground transportation of water and gas through cities because of their extraordinary strength.

What are Steel Pipes?

Steel pipes have had more strength and durability than iron pipes because they are composed of metal alloys of iron and other metals, such as aluminum, manganese, etc. They are galvanized by applying a layer of zinc to it in a hot zinc bath or by an electroplating process, and they are either seamless or welded across the length of the pipe. Zinc is a suitable metal for coating water pipes as it is non-toxic to humans.

How is steel pipe used?

Structures, transportation, and manufacturing all employ pipes. The inner diameter fluctuates depending on the wall thickness, and they’re sized based on their outer diameter. Depending on the pressures the pipe must endure, some applications require thicker walls than others.

Structural Use of steel pipe

  • Construction Piles
  • Scaffolding Poles

Manufacturing Use of  steel pipe

  • Guard rails
  • Bollards
  • Bike racks
  • Transport Use

Most Common Steels Used in Process Piping Industry

The steel used in the pipework is available in various varieties. Due to its superior corrosion resistance properties, stainless steel is the second most widely used material in process industries after carbon steel.

Carbon Steel

  • Carbon steel is the most common type of steel used in the pipeline industry. Process plants, general refinery factories, and the chemical industry all utilize carbon steel pipe fittings.
  • They are also utilized in the production of neutral or aqueous solutions.
  • The working temperature of carbon steel generally ranges from -29 °C to 427 °C.
  • In addition to low-temperature carbon steel (LTCS), high-strength carbon steels are also accessible in carbon steel materials. Low-temperature carbon steels can be used at temperatures down to -46°C.
  • One kind of high-quality steel is called “killed carbon steel,” when it is melted, it is entirely deoxidized.
  • The materials of killed carbon steel are more precise and of excellent quality than those used for standard carbon steel; they also generally have less air.

Alloy Steel

  • Steels with specific amounts of alloying elements are known as—alloy steels. In general, alloying elements enhance steel’s strength and stress or shock resistance. 
  • While nickel, chromium, molybdenum, manganese, silicon, and copper are the most prominent alloying elements, numerous additional chemicals are also used in the steel-making process.
  • In the industrialized world, countless alloy and concentration combinations are used, each of which is designed to produce a particular characteristic.
  • In the piping industry, high-alloy steel types are recommended for use in situations that must resist brutal environments, including intense heat or cold.
  • This is so that strong yet flexible pipes that can resist damage can be created with the proper use of chemistry and heat treatment. Because of its durability, alloy pipe is commonly used in the oil and gas and power generation industries.
  • Steel pipe gets enhanced corrosion resistance owing to alloying materials. Due to this, chemical industries also prefer it significantly.

Stainless Steel

Besides carbon steel and alloy steel, traditional piping materials comprise stainless steel. They could be easily fabricated into varying styles, are resistant to corrosion, and typically function within -257 and 538 ° C. Stainless steel is available in three varieties: 

a) Martensitic stainless steel – Martensitic alloys have a controlled amount of carbon and other additives, in addition to 12–20% Cr. The typical material for this task is Type 410. Heat treatment can harden fibers, improving their tensile strength. Austenitic stainless steels have excellent corrosion resistance and are typically used in moderately corrosive environments.

b)Ferritic stainless steel – Low carbon content (0.1%) & 15–30% Cr both are included in ferritic steel. The corrosion resistance is enhanced either by higher Chloride concentration. Type 430 is a typical ferritic stainless steel. These can be reinforced through cold working but not by heat treatment. Plants that generate nitric acid frequently use type 430. It is also resistant to scale and elevated oxidation up to 800 °C.

c) Austenitic stainless steel – Austenitic steel has had the most excellent corrosion resistance of the three classifications. 16–26% Cr & 6-22% Ni are found in these steels. Low carbon content (0.08% maximum) minimizes carbide precipitation Welding may lead to Cr carbide precipitation, which reduces the alloy’s chromium content and diminishes its resistance to corrosion in some particular environments, most notably nitric acid. Heat treatment aids in the removal of the carbide precipitation (solution annealing). Special steels stabilized with titanium, niobium, or tantalum have been developed to avoid precipitation (Types 321,347 & 348). Another solution is to use low-carbon stainless steel, such as types 304L & 316L, with a calorific value of only more than 3%.

d) Precipitation Hardened stainless steel– Precipitation Due to its high strength, heat treatability, and magnetic properties, hardened stainless steel offers excellent corrosion resistance and a very high strength-to-weight ratio. It is used in the manufacturing of springs and aerospace parts. 17-7PH and 17-4PH are two types of precipitation-hardened stainless steel.

e) Duplex / Super Duplex stainless steel –Duplex and Super Duplex stainless steel composition include both Austenite and Ferrite. Because of its structural makeup, this grade provides the benefits of both austenite and ferrite stainless steel. Good resistance to corrosion in cracks and pitting. High resistance to stress corrosion cracking and high strength. They are used in heat exchangers, structural applications, and seawater systems. Duplex and Super Duplex stainless steel are EX- UNS S32205, S31803, and S32760.

Learn more about types of steel in piping

Even though the complex chemistry and metallurgy involved in steel manufacturing can be challenging to comprehend, it has helped various industries polish and improve their essential processes.

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