THE Department of Trade and Industry (DTI) on Monday denied allegations made by a former lawmaker and a structural engineer late last week that quenched and tempered (QT) steel bars were unsafe for constructing tall buildings.
In an online statement, DTI said it found no “factual or technical basis to support the allegation that QT steel is unsafe for high-rise construction” after consulting with the Philippine Constructors Association (PCA), Philippine Iron and Steel Institute (PISI), Association of Structural Engineers of the Philippines (ASEP), and other stakeholders.
The bars are manufactured by rapidly cooling plain carbon steel with a fine water spray, resulting in a bar with a higher composite yield and tensile strength than the parent material.
In a press briefing in Quezon City last Thursday, former Sen. Anna Dominique “Nikki” Coseteng and Emilio Morales, former chairman of ASEP’s National Structural Code Committee, claimed that butt-wielding, treading, hotbending, galvanizing, and heating QT steel could result in property damage and endanger lives—which the DTI refuted.
The quenchtempering and thermomechanical treatment that QT bars received “passed all chemical, physical, and mechanical requirements,” the Trade deparment said, citing a Department of Science and Technology-Metal Industry Research and Development Center (DoST-MIRDC) study titled “Characterization of Locally Manufactured Quenched and Self-Tempered Reinforcing Steel Bars”.
This study also found that a QT steel bar, when heated up to 500 degrees Celsius, “does not impose any change in its microstructure,” it added.
“Although this exceeds the restriction set at 275 degrees Celsius in the National Structural Code of the Philippines (NSCP) 2015 edition, DoST-MIRDC explained that this may be a very conservative cap on welding temperature to ensure safety,” DTI said.
The PCA said butt-wielding was not used for construction, and PISI said galvanizing was not performed on rebars, it added.
Some local steel manufacturers perform roll treading on the bars, which only reduce about 0.1 percent of the steel, but still retain their strength, the department noted.
“DTI-Bureau of Philippine Standards (BPS) strongly upholds its stance that the use of QT steel bars in construction is safe, even stressing that the DoST-MIRDC study in itself confirms this, provided that restrictions on welding, hot bending, treading, and galvanizing are strictly followed,” it said.
The department also said BPS’ Technical Committee on Long Steel would require QT bars to be embossed to let consumers know what kind of steel they are.
A “massive information and education campaign on steel bars will [also]be conducted for the benefit of consumers, constructors, and all other concerned industry practitioners,” it added.