Four Decades of Rail Welding at CFR

This year?s autumn it has been four decades since the Rail Welding Department started to function. It is a specialized unit conceived for modernizing the railway infrastructure. The unit it is now called Group of Rail Welding Works CF SUDAREC.
For almost a century railways used to be made of rail-tracks tied up with screws with spaces between their bottom, in order to permit dilatation during very hot weather, connections called joints. This classical system of making railways had at first some exploitation disadvantages, because of the joints that were sensitive parts of the railway, due to the socks and vibrations that act together on the rail- rolling stock material, causing failure of the comfort degree of the trip. From statistics we also find out that the average cost for the maintenance of such joints at the panels of 10-15 m long, reaches up to 45/50% of the total expenses of maintenance works.
Even from the beginning of our century, technicians and railway scientists studied and experimented the possibility of building continuous, joint-less rails. Progresses achieved in the realization of rail superstructure -and especially perfecting the modality of connecting rails to the slippers - led gradually to the possibility of using certain rail-tracks, whose length doesn?t matter, obtained by welding them progressively.
The jointless railway presents certain advantages also from the economic perspective, due to the prolongation of the railway material duration in time (rail-tracks, slippers, connecting elements, ballast prism) and to the reduction of maintenance costs both for the rails and for the rolling stock material, to the reduction of the necessary energy for train traction and as a consequence of all these, to the possibility of increasing trains? traffic speed.
Today we cannot make any railway for large speed with joints, just without them.
    Building continuous railways generally presuppose two fundamental issues:
        • Realization of the main rail welding by different technological procedures;
         • Building and maintaining rail platforms in different conditions of temperature and exploitation.
In our country there were, over the times, certain intense preoccupations in respect to the two directions I mentioned above that were later concretized in theoretical and experimental works. Thus, in 1937, Professors Corneliu Miclosi and C.C. Teodorescu created the work called Welding Industrial Procedures, the first specialized treaty ever issued in Romania.
The first welding works using incendiary substances were realized at Bucharest Trams Company (STB) even from 1920, as well as at the trams in Timisoara, using an electrical welding device by compression, procedure created by Professor C. Miclosi, known under the name of TAURUS.
This kind of attempts by CFR took place for the first time in 1933, by welding rails of type 45 in Timis tunnel, on route Ploiesti-Brasov, on a distance of 975 m, using thermal methods, whereas between 1935-1936, using the blue light welding method of rails type 40, on platforms of 30-60 m long between Bucharest Filaret - Jilava railway stations.
After the War, neighborhood countries create the first welded railways, by different procedures, of which the most used ones being thermal and electrical welding procedures.
In 1957, as a consequence of an Agreement with the Railway Company of the Czech Republic (CSD), the first experimental platform was completed, using the electrode electrical welding procedure, on route Bucharest - Urziceni, between Moldoveni - Armanesti railway stations. On this experimental platform measurements were taken, and constituting the research fundament for the work of CC Teodorscu, called Theory of Jointless Rails Submitted to Temperature Variations.
At the same time, Romanian railway specialists intensify their study and documentary activity here and abroad, analyzing all the possibilities of creating in our country all the equipment devices necessary to rail welding process. Helped by the Welding Center from Timisoara, led at that time by professor C. Miclosi, the first welding electrical installations by contact and pressurized procedures, special mushroom bolts used in transportation of the welded rail-tracks, as well as the equipment for treating the welding work (i.e.grinders) will be ever designed at IPCF and realized at IMMR Brasov.
In the same time, rails that were to be welded had to fulfill certain quality conditions, as for example: verification of the rails with the defect detector, complete connections, slippers and ballast prism to be in accordance with the standards, geometry of the rails to be perfect, etc. The welded rails belonging to long distance platforms had to be supervised and maintained according to rigorous terms in order not to prejudice the stability by dilatation during raised temperatures or by braking them during temperature bellow 0 degrees.
That is why, establishing the temperature while fixing the platforms was a very important process. Taking into account the big temperature differences in Romania, in order to maintain an equilibrium between the compressor forces acting in summer time and the traction forces during winter time, they established that platforms should be fixed on a temperature that represents the differences average quantum, meaning +60º+(-30º)=15 ºC
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This neutral temperature was extended, out of practical reasons, to an initial difference pattern, from +12 C to +22 C, and finally from +17C to +27C.
In order to exemplify what risks could be assumed unless these prescriptions are followed, it would suffice to say that should the rails be fixed on slippers at +5C, and temperature increase during summer time to more than +55C, the rail type 49 would support an axial compressive force up to 78.000 kgf, whereas the force for the rail type 65 would be of 95.000 kgf. Needless to say that in certain building conditions or inadequate rail maintenance works, this could cause the rail to loose its stability (phenomenon called flammable process).
The specialized unit in rail welding works, created 40 years ago, acknowledged a dynamic increase of activity during the four decades of existence.
Having the chance of being one of the first leaders, I started my activity only with six echelons for pressurized electrical welding, with six echelons for electrical arch welding, one thermal welding installation and one single equipment maintenance atelier. Latter on, the unit became a site, and today it is a company with all the necessary logistic departments that we use in order to perform some works that could reach to more than 500 km of welded rail per year.
The necessary equipment of our unit was supplied in time, both in quality and in quantity. The initial TAURUS installations on manual command were replaced by import installation type PRSM -3, with K 335 welding bottoms, completely automated, fact that lead to an increase of productivity per machine, from 3.5 welding works /hour to 7 welding works /hour. In point of quality, the number of damaged rail stabilized at just 0.12 breaking rails per 1.000 welding works in one year. Today, the number of welded rails for the CFR network covers more that 70% of the normal capacity, fact that places CFR in the group of medium developed European countries.
We also have to point out the contribution of the researchers of the former ICPTT, and of certain professors from colleges in the field in Bucharest and in the country. By theoretical studies, experiments on Pipera stand, or on the trying platform in Faurei, or on other experimental sectors, all these maintenance and repairing conditions were consolidated, elaborating technical prescriptions and norms (Norm 341 related to the creation, maintenance and supervision of jointless rails); they made possible for us to be able to exploit our railway system in normal conditions, without no unpleasant malfunctioning of the latter. Among the resolved solution we could add the following:
        Rail welding in tight curves;
        Provisions for fixing and re-fixing jointless railways;
        Rail welding in the underground;
        Welding of rail installations;
        Welding of rails on metallic bridges;
        Realization of the equipment necessary for thermal welding;
        Welding of rails with pressure and gas;
        Modern technologies of welding of rails in ateliers;
        Modern equipment for the Rail Regeneration Atelier from Ploiesti;
        Establishing the minimum weight necessary for insuring the lateral resistance of the rail;
        Rail repairing by electrical welding;
        Prefabricated fabrics for thermal welding of rails in short duration rail closures;
        Equipment for maintenance of welded rails and others.
In the same time, we have to remember the contribution of the Romanian railway professionals during the lectures of the 9 Commission of the OSJD Committee, under the theme Jointless Railway, or during the sessions of the UICORE Committee.
Presently, SUDAREC is developing welding works to the main thoroughfare rails according to the approved programs.
Under the present circumstances, with a better organization of works, the average physical productivity (Km of welded rail/ man) during the last years has increased to 20% in comparison with that from the last decade.
For the future we intend to impose certain measures of modernizing the existing equipment, fact that will lead to a significant improvement in quality (mainly a significant reduction of welded rail breaking), as well to a superior productivity. From this point of view, CFR-SA will be able to enter the family of the first class European railway administrations.

Engineer Ion Stafie reporting