Ceylon Steel has invested around 10 billion in expansion of its facilities in Oruwala, just outside Sri Lanka's capital Colombo, officials said.
Chairman Nandana Jayadeva Lokuvithana said the firm can cater to the entire domestic demand.
The firm sells under the brand 'Lanwa' a diminutive based on a Sinhalese language term for Lanka Steel.
It is not clear whether GI pipes have import tax protection.
Sri Lanka has been raising import taxes on various steel products making house building more expensive to citizens who are trying to build a roof over their heads, especially at a time when war refugees are re-building their homes.
Most home citizens get into debt to build houses. The state has also jacked up taxes on bathroom fittings and ceramic products in the past year.Even in the budget for 2013 presented last week, import taxes on several types of steel products were raised.