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The Department of Trade and Industry (DTI) finds no factual or technical basis to support the allegation that quenched and tempered (QT) steel is unsafe for high-rise construction, following a series of consultations conducted with the Philippine Constructors Association (PCA), Philippine Iron and Steel Institute (PISI), Association of Structural Engineers of the Philippines (ASEP), and other relevant stakeholders. It was learned in the studies and researches made by the DTI that the process of quenching and tempering steel is being used by more than 190 countries across the globe for the last thirty (30) years.

Among the allegations made is that the processes of butt-wielding, treading, hotbending, galvanizing, and heating of QT steel can result to damage of property thereby endangering the lives of the general public. However, in a study conducted by the Department of Science and Technology – Metal Industry Research and Development Center (DOST-MIRDC) entitled, “Characterization of Locally-Manufactured Quenched and Self-Tempered Reinforcing Steel Bars,” the rebar process through quenchtempering and thermomechanical treatment passed all the chemical, physical, and mechanical requirements.

The said study also indicates that a QT steel bar, when heated up to a temperature of 500-degrees Celsius, does not impose any change in its microstructure. Although this exceeds the restriction set at 275-degrees Celsius in the National Structural Code of the Philippines (NSCP) 2015 edition, the DOST-MIRDC explained that this may be a very conservative cap on welding temperature to ensure safety.

The PCA also clarified that butt-wielding is not even used for construction while PISI mentioned that galvanizing is not performed on rebars. In terms of treading, or the process of creating a screw tread to mechanically connect two rebars, some local steel manufacturers said that they perform roll treading to do this. They explained that this process only diminishes about 0.1% of the steel bar which does not at all affect the strength of the rebar. This practice is also commonly used in the construction industry across the globe, including high-rise construction.

The 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. The discussions during the consultations that were convened also coincide with Philippine National Standard (PNS) 49:2002 on steel bars for concrete reinforcement. The quenching and tempering methodology indicated in the PNS likewise adheres to the principles of the American Society of Testing Materials that is accepted worldwide.

As a way forward, the DTI-Bureau of Philippine Standards Technical Committee on Long Steel (TC11) has established an embossed permanent marking for QT steel bars to inform consumers that they are purchasing such kind of steel. The same is likewise proposed for micro-alloyed rebars. All these changes shall form part of the revisions to PNS 49. The DOST-MIRDC also committed to conduct new tests and research to validate the restrictions set in the NSCP which will be witnessed by the DTI-BPS.

In addition, massive information and education campaign on steel bars will be conducted for the benefit of consumers, constructors, and all other concerned industry practitioners. The DTI continues to ensure quality and safety of products, particularly construction materials used in the Golden Age of Infrastructure with the national government’s Build, Build, Build program.♦

Date of release: 04 June 2018

 

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