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Advanced technology of making electric welded
tubes equivalent by their quality to seamless tubes

F. Davydov,
Expert of Corporation "Delta-service" (Dnepropetrovsk, Ukraine)

The technology under consideration has been proposed by F. Davidov well known Ukrainian specialist in the tube manufacture. It is offered to commercialize the technology by means of its realization.

The existing procedures of the roll- profile calculation used in the strip forming and welding operations and in sizing the welded tubes tale into account one of the three main deformations acting in above processes. This does not allow to use them in the development of analysis process simulation models with the purpose of their integration into the tube making technology.

The project authors propose a new analytical procedure for the calculation of the roll profile which takes into account all three main deformations, Cubic strain problem has been solved for the first time and this allows to extend the technology potentials and get new production results by the development of the process simulation model and its integration into the production flow.

Application of the new procedure ensures the following:

  • Adjustment parameters obtained are such, that they guarantee a cardinal improvement in the tube quality of pipes and all technical-and-economic indices of the equipment operation.
  • Simulation models realize a continuous control of the technology parameters in the line of the electric-weld tube unit and ensure longitudinal stability of the tube
  • In addition to the calculation of the roll design for making tubes of new sizes, existing roll designs can be examined for making a decision regarding their suitability or giving a recommendation of their correction.

Competitiveness of the new technology is ensured by the following:

  • High-frequency electric welded tubes made by the new technology meet the international standard requirements to seamless tubes and can be used in heavy-duty installations.
  • Owing to the higher stability of the tube making schedule and reduced equipment stops, technical-and-economic indices of the tube manufacture enhance significantly (10% to12% shorter equipment down-time, 10% to 12% lower metal consumption and 10% to15%. Higher labor productivity.
  • Owing to a higher precision of coordination between the velocity of the strip of which the tubes are formed and the peripheral velocity of the roll relation, the roll wear can be reduced by more than 50% and the tube cost can be cut by 10%.
  • Technological flexibility improves and therefore influence of the servicing personnel qualifications and experience is practically excluded.

The technology commercialization is assumed to be carried out in one of the following ways (other variants of commercialization are possible as well):

  • Transfer of know-how, including the procedure of the forming, welding and sizing stand roll profiles; the procedure of calculation of the adjustments parameters; the method of a continuous process parameters control in the line of the tube mill; the examination procedure for existing roll designs. For a pre-sale approval of the know-how being commercialized, the project authors will carry-out, free of charge, a demonstrational checking of a roll design for one or two sizes with giving just the calculation results.
  • Founding a joint-venture enterprise with following main functions:
    • Executing orders of examination of the roll design made earlier and giving conclusions on the basis of the results obtained.
    • Correction of the existing roll designs.
    • Calculation of the roll designs for new tube sizes and giving the roll pass drawings and adjustment parameters.
    • Participation in the utilization of the new technology in the production conditions.

The project realization terms are determined by the chosen direction of commercialization but they are not long in any option (e.g. not longer than one week of calculation per one size).

The project cost in case of its commercialization will be defined considering the following:

  • When using an existing set of rolls, only new adjustment parameters should be defined are used ( new roll manufacture cost is not necessary),
  • For the continuous control of the process parameters in the line of the tube mill, installation of three instruments will be necessary. By the Ukrainian experts evaluation, their total cost does not exceed $5,000 to $6,000,
  • Cost of the know-how proper, like the investment shares in founding a joint-venture enterprise are a subject of negotiations with the potential buyers.

All know-how of this project have no patent protection.

The project realization will bring about changes at the tube market owing to the improvement in the consumer-oriented qualities and competitiveness.

Besides, high-frequency electric welded tubes made by the new technology meet the requirements of international standards to seamless tubes and that will allow to raise their consumer market costs.

More information about this technology you can have from "Steel in Translation" (Vol.23, No.9, pp.32-33, 1993; Vol.26, No.1, pp.59-61, 1996; Vol.26, No.8, pp.71-74, 1996; Vol.26, No.11, pp.71-74, 1996; Vol.27, No.4, pp.50-54, 1997).

For further information please contact:

Attn: F. Davydov
Addr. Post Box 603, Dnepropetrovsk, 5, Ukraine, 49005
Phone: + 380 562 470813
Phone/Fax: + 380 562 322767/322768/373800 clossary

Further information also available:

Ukrainian State University of Chemical Engineering
Pridneprovie Cleaner Production Center
Attn: Prof.William Zadorsky

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