KEPCO GS-5445 Tubular Steel Pole Specification Updated — Suppliers Eye Galvanizing Standards and Module Length Compliance

I. GS-5445: The “Entry Passport” to Korea‘s Steel Pole Market

For any B2B supplier seeking to enter South Korea’s transmission steel pole market, KEPCO‘s GS-5445 “Tubular Steel Pole” General Technical Specification represents an unavoidable technical threshold. Published in 2018, this document constitutes KEPCO‘s most current technical requirements for steel pole products.

It is important to understand that GS-5445 does not exist in isolation. It complements DS-1111 “Design Standard of Transmission Tower” — another core document within KEPCO’s design standards framework. DS-1111 governs the structural design methodology and load calculation principles for transmission towers, while GS-5445 further specifies material, manufacturing, inspection, and supply requirements specific to tubular steel poles. Together, these two standards form the complete technical specification chain from design to delivery.

GS-5445 covers multiple voltage levels across Korea‘s transmission backbone. Public literature indicates that the standard applies to both 154kV double-circuit and 345kV four-conductor configurations. For higher voltage levels, KEPCO has also issued derivative specifications such as GS-5445-0009 for 765kV double-circuit transmission lines.

II. Three Key Technical Points Suppliers Must Address

2.1 Module Length: The Logistics-Economics Equation of 9m to 12m

GS-5445 specifies a modular segmentation length range of 9m to 12m for steel poles. This specification is not arbitrary — it is grounded in the practical constraints of Korea‘s road transportation conditions.

Mountainous roads in Korea feature numerous tunnels with clearance heights typically limited to 4.0–4.5m. As voltage levels increase, the base diameter of steel poles has expanded correspondingly — for 154kV and above, base diameters can exceed 2.6m — making conventional integral transport through tunnels impossible. Segmented design ensures that each pole section’s length and diameter remain within the capacity of standard flatbed trailers.

For suppliers, module length directly impacts costs at two levels:

• Transportation costs: The 9–12m range aligns with Korea‘s road transport clearances, eliminating the need for oversize permits or detours, keeping logistics costs.

• Site installation costs: Shorter modules increase the number of connection points and extend on-site construction time; longer modules may exceed transport equipment capacity. The 9–12m range specified in GS-5445 represents the optimum validated through years of KEPCO engineering practice.

2.2 Galvanizing Corrosion Protection: The Compliance Threshold of KS D ISO 1461:2013

Corrosion protection is a key item in KEPCO‘s supplier qualification process. GS-5445 requires that hot-dip galvanizing for steel poles comply with KS D ISO 1461:2013. This standard is identical to international standard ISO 1461:1999, specifying technical requirements and test methods for hot-dip galvanized coatings on fabricated steel articles.

In practice, Korean suppliers must also meet the additional requirements of KEPCO‘s internal specification KRS PW 0058. Zinc bath temperature is controlled at 450–480℃, and coating thickness is graded based on steel thickness to ensure long-term corrosion resistance in Korea’s coastal high-humidity and high-salinity environments.

For international suppliers, KS D ISO 1461 is technically equivalent to ASTM A123 (the U.S. hot-dip galvanizing standard). Suppliers already holding ASTM A123 compliance in other markets face manageable challenges in transitioning to KS D ISO 1461 certification. However, KEPCO‘s inspection criteria and acceptance procedures for galvanizing quality — including coating uniformity, adhesion, and surface defect — have unique requirements that must be addressed through internal process adjustments prior to delivery.

2.3 Structural Design: International Alignment with ASCE/SEI 48-11

GS-5445 references the American Society of Civil Engineers‘ standard ASCE/SEI 48-11 “Design of Steel Transmission Pole Structures” in its structural design methodology. This alignment:

• Korean steel pole design load calculation methods are consistent with mainstream international standards;

• Suppliers already designing to ASCE/SEI 48-11 in other markets will find their technical approaches readily adaptable to the Korean market.

However, suppliers should note that GS-5445 also incorporates KEPCO‘s specific requirements based on Korea’s local meteorological conditions and seismic design criteria — international standard parameters cannot be applied without adjustment.

III. Market Dynamics and Implications for Suppliers

Recent procurement activity in the Korean market demonstrates the practical application of GS-5445. In September 2024, KEPCO initiated procurement of approximately 5,277 tons of steel pipe towers for the 500kV HVDC Donghaean-Singapyeong line. That same month, KOSDAQ-listed Boseong Powertech signed a KRW 24.4 billion contract with KEPCO for steel tower pole supply on the East Coast-Singapyeong transmission line. All these projects are benchmarked against GS-5445.