The bidders were local firms Conta Walter Mario and Mega, offering 53.3mn pesos (US$17.3mn) and 50.1mn pesos respectively.
Both offers fell below the project's official 55mn-peso budget.
The province will evaluate the bids before pre-awarding the concession in roughly two weeks, a source at Salta's production ministry told BNamericas.
Following the pre-awarding of the concession, the losing bidder will have several days to file queries, complaints or presentations before the works are officially awarded, the source said.
Originally the province had planned for the pipeline to stretch 175km, but reformulated the distance during the tender process.
The pipeline will provide gas to La Candelaria, El Tala, El Jardin, Potrerillos, Tolombon, Cafayate, Animana and San Carlos.
Construction is due to require seven months once the project and EIS have been approved by natural gas regulator Enargas.
Construction is expected to begin 60-90 days after the signing of the contract, BNamericas reported previously.
The pipeline will include a valve in Tolombon, meaning the provinces to Salta's south could connect to the line.
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