The parallel pipelines, which range between 12-20 inches, carry crude oil from the South Rumaila oilfield to the Zubeir One station, which pumps the crude to two Gulf terminals.
Iraqi oil exports from the southern terminals at Basra and Khor al-Amaya were running at slightly lower levels of 1.6 million barrels per day (bpd) on Thursday after pipeline attacks but will recover to full capacity soon, shippers and Iraqi oil officials said.
This compares with earlier estimates that the overnight explosions had halved exports to 1.1 million barrels per day (bpd). Officials had cautioned this could be due to the number of vessels loading rather than actual flows.
"The loading of vessels has not been affected by the attacks. All is normal," one shipping source at the region said, adding that loading was proceeding at 68,000 barrels per hour (bph) at Basra, or 1.6 million bpd.
Four vessels were alongside at Basra with two vessels loading, one completed and due to sail today and the other waiting to load. Six vessels are at anchor.
The smaller Khor al-Amaya terminal had finished loading one vessel, Kamlesh, at the normal rate of 20,000 bph and another vessel was now berthing to load, one agent said.
"Once that tanker starts loading, total rates at both ports will soon be back up to 80,000 bph," he said.
Iraq's south has been the focus of a US-led offensive aimed at crushing a Shia uprising led by anti-US cleric Moqtada al-Sadr.
Iraq's interior minister has said that the government has taken "extreme measures" to protect the infrastructure.
Attacks have continued unabated, including in the south, which accounts for virtually all of the country's oil exports.