SPECIFICATIONS:

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.