Interview to the Engineer Silvia Purificato,
Manager of Quality of Metal Structures DIN S.A
by Johanna De Luca
Tell us, please Silvia. What is this project about?
This work is the new departure terminal hall of Ezeiza Airport Ministro Pistarini. First of all, we have to say that, in the jargon, it is usually known as “Zeppelin”, obviously because of its shape. The concept lying behind Argentine Airports 2000 is a modernization of the whole airport whose beginning is just this new Zeppelin: there will be only one departure terminal with this and the Zeppelin will be the place where all the passengers will have to go through to be able to board.
Metal Structures DIN SA took part of the quotation of which it was the winner and from that moment, it worked very closely with the staff of ORSNA and Argentine Airports 2000 so as to do the Detail Engineering of this structure. What in any work is called “columns”, here it is called “little angels” and from there the so called “little arms” are born. When they get together the “little hand” or” little palm” are formed and from there it joins the main beams and the secondary beams to make up the union of the different pieces. In Plant, the main beams, the secondary beams, “the little arms” and the “little angels” were done but the structure as a whole was not done there. The pieces arrive at the work site separately, they are assembled there and then welded and obviously a touch-up of the corrosion protection system is done. It is a very difficult task because tolerances that are common at any work, here they are not: each of the pieces that I mentioned previously has a unique spatial position in three directions and any deformation causes the loss of the final shape leading, therefore, to its invalidation. We have been the pioneers not only in the calculations, in the construction of each one of the pieces, in the assembly and in the weld but also in the tolerances that the work has to carry. Actually, from Bravo River downward there is no other work like this.
It is important to outline that our client was a great support, Argentine Airport 2000, staff from ORSNA and Ministry of Planification and Public Works. Although it has obviously played the role of a client, it has also given us significant support in our basic contacts with the Engineer Dendi, the Engineer Cordone, the Engineer Torres Carbonell and the Engineer Carlos Figueroa, who represented a great guide and help. It is also necessary to note the work of the topographers who were permanently on-site measuring each one of the parts that make up the Zeppelin to check its correct spatial position.
What welding process was used to perform this great work?
When having to choose a process not only the thickness and the type of material; that is the quality of what is going to be welded, is taken into account but also the structure that is going to be welded , the functionality of the structure and where it is going to be welded. Although it is hard to do, for example, a “little angel” in our Plant as was done by our assemblers and welders, the advantage they had is that they were able to put it on the beds and worked in a closed and controlled place. Instead, in the worksite, it is open, in movement, with dust, wind, sun and rain. We think that the SMAW process (the famous electrode) was the best choice of the whole work because it allowed us enough mobility to reach the place we had to weld without any major inconveniences, with only one electrode holder plier and a ground wire to be able to weld the huge amount of welds that had to be welded. And it was not only to reach the floor level as when welding the base to the anchor but also to reach, for example, the union of the main beams that are more than 12 meters high. We have also had the unconditional and great technical, administrative and emotional support of our electrodes supplier that has been ESAB Conarco. This is a project that requires this and more than this and we have had this from all our suppliers, but in particular from ESAB .
It is a work of structural and architectural complexity. Structural because the work cannot afford any problem since people are constantly passing by. And it is more complex than any other work because the type of design demands that, apart from supporting itself, the structure has to support 340 tons of glass and continue being well, structurally sound, without any problem.
Unlike other common projects, this structure has the characteristic that if there were a structural problem, for example, if the weld cracked, this wouldn’t remain only in the fissured seam. As the structure is chained in itself, this fissure would be transmitted throughout the whole structure. From the architectural-aesthetic point of view, it has to meet World Class levels, which guarantees flawless finishes. Apart from strong planning, technical support from our suppliers is required.
What electrodes have you used?
We have used Conarco 6010 and 7018 electrodes (cellulosic and basic) of a diameter of 3,25.4 and 5 mm. Obviously backed by the corresponding welding procedures, using the material prequalified by AWS . I insist: the result is clearly visible. There is one thing that is clear….. the work needed productivity with quality. It is known that DIN has always worked with two or three top suppliers. It wouldn’t have been possible to reach the productivity and quality levels achieved in this work without a star product, it would be impossible, and it has been achieved.
It should be noted that the selected consumables are 100% national product, which is something we are proud of. The project has as a whole 100% Argentine labour, and that means 100% responsibility, 100% effort, 100% knowledge and 100% expertise placed by each one of those who have been working directly or indirectly in this project.
How many tons of consumables did you use?
1.6 mm tubular wire was used in the Plant , it works extremely well. Here on site, around 8 tons of electrodes as a minimum. ..and we go on welding !
What is your reflection on the welders involved in the project?
All of our welders are rated by AWS with the maximum rating that is 4G, this means they can weld in all positions. Actually, all positions have to be used because there is no other way of having access to be able to weld each of the parts. It must be taken into account that they are welding in a very complicated work. It is an open worksite, we are not alone as there are other suppliers working alongside us, next to us, above us or below us. So it is impossible to work if it is not done with great professionalism and great human vision too. The product can be good, the machine can be very good, the process can be very good, the calculation can be very good, the plan can be very good, but if there is not that plus given by the person, that love, that responsibility, that pride…. The work will not have the same result, it will not be achieved.
It is important to stress that because of the type of deformations that the work has to have, which are practically minimal (that is, no tolerance or any distortion in a standard work applies here), there was necessity to weld in triple phase sequenced in the weld seam, in each seam and between seams with each other to make the resulting deformation minimal or zero. A post wend treatment was not necessary, but precautions were taken in each one of the seams of each of the welds.
How did you control the welds ?
First, each liquid pool of each weld seam is controlled. Then, the visual of each seam was controlled and they were measured to guarantee each engineering calculation because it must be remembered that each weld must support the structure that is being welded apart from the one of its surrounding. Then we did non-destructive tests with penetrating liquids with a level 2 certified by INTI.
