Tekfen's first assignments focused on construction work that did not require special expertise, such as basic construction and excavation. Tekfen subsequently took part as a subcontractor in a project led by the Williams Brothers firm to build two 6-inch fuel oil pipelines under the Bosphorus. This was Tekfen's first acquaintance with pipeline projects, and the first step in a process that has culminated in Tekfen emerging as an esteemed brand among the worlds' pipeline contractors.
In the early 1960s, Turkey was witnessing a great deal of investment in heavy industry as well as medium and light industry, and this led Tekfen to focus more on industrial and infrastructural construction. In this period, Tekfen executed some of the basic construction work in the building of the Ereğli Iron-Steel Factory, which started in 1961 with the purpose of meeting Turkey's need for rolled iron-steel. Tekfen also undertook the construction of the Gülüç Dam, which provided the factory's water for cooling and consumption. This was one of the most extensive projects executed by Tekfen up to that date.
Tekfen carried out most of its initial work in the field of pipelines and oil-gas facilities as a subcontractor of foreign companies. The superior performance displayed combined with the experience obtained from these projects opened up new opportunities for the company. For instance, the 4.5-inch 10 km long collection pipelines at Bulgurdağı and the 8-inch Kürkan-Pirinçlik pipeline were among some of the first pipelines Tekfen constructed independently, and served as preparation for bigger projects that were to be undertaken in later years. The construction of the Istanbul Oil Refinery (İpraş), one of Turkey's biggest petrochemical plants, was also commenced in the same period. This is one of the many plants that carry the mark of Tekfen to every corner of Turkey.
Connecting the oil field in Batman with İskenderun Bay, the 493 km long Batman-İskenderun Crude Oil Pipeline project began in 1965. As the biggest pipeline constructed in Turkey thus far, it takes its place among Tekfen's noteworthy enterprises. Continuously expanding its experience in the fields of pipelines, liquid and gas storage tanks and industrial plants as well as improving its equipment, Tekfen was also greatly commended by the employers at a time when the number of companies that were able to offer these types of services were only but a few, and the company soon attained the status of an indispensable choice for both local and foreign project owners.