In this both inner and outer surfaces of MS welded pipes are given a calorising treatment, under high temperature in which diffusion of aluminium takes place into the surface of the steel. Subsequently, the calorised pipes are given ceramic coating on both inner and outer surface. The calorising treatment and the ceramic coating give these pipes an extra ordinary higher life and resistance  to corrosion at high temperature than ordinary MS pipes and expensive stainless and alloy steel pipes normally used in oxygen lancing in electric arc furnaces and chemical factories and refineries. The average life of calorised and ceramic coated pipes is 7 - 9 times more than that of ordinary MS pipes and stainless steel pipes. Calorised and ceramic coated pipes are used in areas requiring high temperature and corrosive applications as follows:

  • Heat exchangers, handling hot and corrosive gas.

  • Finned Tubes.

  • Gas ducts for SO2 & H2S gases.

  • Reformer tubes.

  • Regenerator tubes.

  • Refinery flue gas tubes.

  • Ethylene Pyrolysis furnace tubes.

  • Oxygen lancing pipes in Alloy steel plants and copper smelters.


They are used as better and cheaper material of construction in the following equipments:

  • Boilers 
  • Burners
  • Recuperator
  • Thermowell
  • Soot blower
  • Air pre-heater
  • Transfer lines
  • Heat Exchangers
  • Refinery heater
  • Chemical reactors
  • Sulphur condensers
  • Fluidised bed exchanger


Type I Both ends threaded with one coupling and one plastic cap.

Type II Plain ends.

Type III Plain ends with one pressed coupling.

  1. The pipe is a low carbon special thin walled pipe, with high strength to weight ratio. The normal bore size and Wall thickness are as per standards.

  2. The calorising is upto a depth of 100 to 150 microns.

  3. The Refractory Ceramic coating is of special high Alumina materials to give higher resistance against spalling at high temperatures.

A comparison between ordinary steel pipes, expensive Alloy Steel Pipes and Stainless Steel pipes under different corrosive conditions is as follows:
It can be seen that calorised pipes are better and economical in comparison with ordinary or alloy steel pipes under various conditions of corrosion and use, which are encountered in different industries.

Why are Calorised Lance Pipes needed in oxygen steel making? In the process of steel manufacturing by open hearth or electric furnace, the consumption rate of lance pipes for oxygen injection sows rather high ratio owing to high temperature and severe oxidation. In general, steel pipes are used as lance pipes for oxygen injection. If MS pipes are treated by this process consumption rate of lance pipes will increase 6 - 7 times. It is necessary to make the pipe fireproof as a first step. Special treatment is then needed to protect the pipe from any falling-off or scaling-off by shock or by bending stress. As a result of research conducted over many years, it was discovered that the most effectual method is to diffuse aluminium into the pipe's surface, so as to promote wear proof properties on steel pipe. That is to say, calorising is to be carried at, in and outside of the steel pipe to promote wear and fire proof properties of the pipe. To enumerate, the advantages of oxygen steel making process:

  1. The exothermic reaction and agitation promote decarbonisation and heat rise in the furnace, while foaming slag can be eliminated.

  2. Fusion of sub material can be accelerated.

  3. Quality of steel will be improved.

  4. As the process raises the temperature.

  5. Selection of raw materials to be charged becomes easy.

  6. The process raises the production capacity of an electric furnace.

  7. Hydrogen, Nitrogen and non-metallic inclusions can be eliminated through oxidation.

  8. It makes it possible to recover chrome with the use of high chrome steel scrap.

Calorised lance pipes are prepared by rendering calorising finish to carbon steel in a thickness of 100-150 microns on both inner and outer surfaces and further coating with refractory materials in 200-300 microns thickness on both inner and outer surfaces. This metal diffusion treatment promotes the fireproof properties of steel pipes. The diffusion is an inter-metallic bond, which doesn't get damaged either by mechanical working like bending or straightening or by high temperatures. In the case of general fireproof pipes, oxidation takes place at that part of the surface in contact with the flame. In the case of these metal diffused pipes, the metal existing at the surface of the diffused zone is oxidised to its respective oxide, which prevents the further progress of oxidation and also melting. For instance, in calorising, aluminium is oxidised to alumina, which has a very high melting point 20500C compared to the melting point of aluminium, which is mere 6580C. 

As shown in the image the splashing action of high-pressure oxygen on molten steel is most severe at the upper inside part of the pipe ('A' point in the image). At this point the  following reaction takes place. 
4 Al + 3 O2 = 2 AL2O3 + 7.608 Calories

This is the essential difference between general fireproof pipes and metal diffused pipes. A more effective result is obtained by ceramic coating on the metal diffused zone. Ceramic means metallic oxides, carbides, nitrides and also fireproof clay. Alkaline silicates are added to improve the durability and tenacity. In the process of ceramic coating it is necessary that he surface of the metal is diffused zone is rough so that the ceramic coating has a good bonding and does not get peeled off.

Ceramic coating is carried out usually on the inside and outside of the pipe. The composition of the ceramic coating is as per the kind of furnace structure and the steel / metal produced. After cleaning the impurities on the surface of the pipe, aluminium powder or a mixture of aluminium and iron powder (to which halides are added as flux) is filled up inside and outside of the pipe and packed in a case. This then heated from outside. The illustration shows that the mettalic powder zone (2) adheres to the surface of metal alloy zone (1) on one side and to ceramic coating zone (3) on the other. Therefore the Ceramic coating never falls off or scales off from the pipe during the oxygen injection operation.

Comparison chart between MS pipe & Calorised pipe.

Oxygen Charge
Press. Kg/cm2
Oxygen flow
rate m3/min
Charge Time 
Length of consumption
Consumption rate mm/min. Type of Pipe Rate of MS Pipe to Calo. Lance
6.5-7 6.5-5 3 1950 650 MS 1
6.5-7 6.5-5 15 1290 86 CL 7.56
6.5-7 6.5-5 15 1420 94 CL 6.91
6 6 3 2430 809 MS 1
6 6 10 1150 115 CL 7.03
6 6 10 890 89 CL 9.03
5.5-6 5.5 3 1860 620 MS 1
5.5-6 5.5 10 840 84 CL 7.38
5.5-6 5.5 10 1070 107 CL 5.79
6.6 6.3 3 1830 610 MS 1
6.6 6.3 10 610 61 CL 10
6.6 6.3 10 1070 107 CL 5.70

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