Analysis of the Changes and Impacts of the New National Standard for Ribbed Reinforcing Bars in Hot Rolling
Jul 12, 2024
On June 25, 2024, the State Administration for Market Regulation and the Standardization Administration of China officially released the new national standard "Steel for Reinforced Concrete Part 2: Ribbed Reinforcing Bars in Hot Rolling" GB 1499.2-2024. This is the sixth revision and will be implemented from September 25, 2024, replacing the previous national standard GB/T 1499.2-2018. This new standard is proposed by the Ministry of Industry and Information Technology and is executed by the National Technical Committee for Steel Standardization of Reinforced Concrete.
Compared to GB/T 1499.2-2018, in addition to structural adjustments and editorial changes, this new standard has made significant technical changes in terms of weight tolerance, fatigue requirements, inspection items, and sampling quantities.
The "shape and dimensional tolerances" have been adjusted, with the nominal rib spacing not exceeding 70% of the bar's nominal diameter. The weight tolerance has been tightened significantly, with 6-12 mm diameter bars allowed a deviation of ±5.5%, 14-20 mm at ±4.5%, and 22-50 mm at ±3.5%.
For steel produced by converter or electric arc furnace, the new standard specifies that specific materials such as HRB500E, HRBF500E, HRB600 should undergo ladle refining. Higher nitrogen content is permitted in the "reinforcing steel chemical composition," promoting the development of high-strength reinforcing steel.
New fatigue performance requirements have been added, particularly for concrete structures or components subjected to dynamic cyclic loading, such as highway culverts, railway culverts, and urban rail transit underground structures. The fatigue performance test should be conducted according to GB/T28900, with 5 samples taken from different bars (coils).
For HRB600 rebars, the new standard recommends mechanical connections and also allows for welding connections.
The new standard sets more refined requirements for the chemical composition and mechanical properties of rebars. If surface defects do not meet the mechanical or process performance requirements, the surface quality is deemed unqualified.
The new standard updates the reverse bending test, allowing factory inspections to be conducted directly at room temperature. An additional reverse bending test sample is added for rebar grades with "E".
The new standard is more precise, changing the total weight measurement accuracy from not greater than 1% of the total weight to accurate to 1 gram.
Besides the previous marking on the surface of the rebar with grade marks, manufacturer serial numbers, and nominal diameter millimeter numbers, the new standard allows for the marking of registered factory names or trademarks instead of the first two digits of the administrative division code. It also allows for the inclusion of barcodes and QR codes containing product information on the packaging, nameplates, and quality certificates of rebars.
Since the first release of the national standard for ribbed reinforcing bars in 1979, it has been revised every 5-10 years, and this is the sixth revision, 6 years after the last implementation date. The main changes in the new standard are as follows:
1️⃣ For the rebar product itself, the new standard is more stringent in terms of weight tolerance, fatigue performance, surface quality, and weight accuracy, further improving the quality of rebar products.
2️⃣ For production enterprises, to meet the technical requirements of the new standard, they may need to upgrade or transform production equipment or invest in research and development, which will increase production costs. Additionally, the new fatigue performance and sampling tests will increase the investment in rebar testing, further increasing operational costs.
3️⃣ For high-strength rebar grades, the new standard requires the addition of ladle refining processes and welding connection methods, which will greatly improve the quality and performance stability of high-strength rebars.
4️⃣ For the market itself, the implementation of the new standard will increase production costs in the short term and also improve the quality of rebar products. With the improvement of standards, the market demand for high-quality rebar will increase, and rebars that meet the new standard will be favored by users, with a certain quality "premium".
5️⃣ The new standard is a mandatory standard that must be implemented. Production enterprises should familiarize themselves with the changes in the standard and adjust production processes before the standard is implemented. Considering the inventory digestion cycle, old standard rebar products accumulated by distributors after the implementation of the standard cannot be sold.
6️⃣ Faced with the challenges and opportunities brought by the new standard, steel production enterprises should accelerate production technology transformation in the short term to meet the strict requirements of the new standard; at the same time, they should plan production reasonably, and balance the inventory structure of old and new products at the beginning of the standard implementation.
7️⃣ The implementation of the new standard will undoubtedly bring profound changes to China's rebar industry. Although in the short term, rebar enterprises may face the dual pressures of rising costs and market adjustments, in the medium and long term, this standard may promote related production enterprises to improve product quality and safety, create a standardized and orderly market environment, and is conducive to building a modern industrial system that is autonomously controllable, safe and reliable, and has strong quality competitiveness, promoting the industry to the high end. With technological innovation to consolidate the core competitiveness of products, accelerate the transformation to high-end, green, efficient, and intelligent, and then achieve high-quality development and improve the overall competitiveness of the industry.
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