GS Entec has completed the conversion of its Yongjam Works in Ulsan into a dedicated, automated monopile production line, lifting annual capacity from 40,000 to 150,000 tonnes and shifting the company into the ultra-large foundation class needed for 15 MW-plus turbines. The roughly KRW 300 billion (about USD 210–220 million) project is the clearest example so far of a Korean heavy-equipment fabricator repurposing petrochemical-grade plate-forming competence for offshore wind — and it creates one of Asia's largest single points of demand for thick offshore-grade steel plate.
What has actually been built
Yongjam Works, in Nam-gu, Ulsan, spent more than three decades fabricating equipment for oil refining and petrochemical plants. GS Entec began renovating the site in October 2024 and finished roughly two years later, with completion reported by trade press in late October 2026 (Korean on-site coverage places the ceremony slightly earlier in the month).
| Parameter | Before | After (new line) |
|---|---|---|
| Annual monopile capacity | 40,000 t | 150,000 t |
| Monopile diameter | up to 10 m | up to 11 m |
| Unit weight | up to 2,000 t | up to 2,500 t |
| Length | up to 110 m | up to 100 m |
| Wall thickness | up to 113 mm | not publicly restated |
| Target turbine class | — | 15 MW and above |
Sources: GS Entec company specifications (pre-upgrade envelope), Seoul Economic Daily, Financial News, Offshore Wind.
The capacity figure is a nameplate, not a proven throughput; ramp-up to 150,000 t/yr has yet to be demonstrated. The wall-thickness figure of up to 113 mm comes from the company's earlier published envelope and has not been explicitly reconfirmed for the new line.
The Sif licence is the technical spine
The upgrade is not an organic effort. GS Entec's monopile capability rests on a licensing and technical partnership with Sif Holding N.V. of the Netherlands, one of the few foundation fabricators globally with deep accumulated process knowledge on large monopiles. A framework agreement was signed in July 2022, finalised in September 2023, and covers a 10-year, mutually exclusive Asian licence for Sif monopile and transition-piece technology — including an option to develop a further Korean plant. Sif receives a fixed one-off fee plus a per-monopile royalty and has supplied automation equipment and process expertise.
That structure matters commercially: it gives GS Entec a credible route into the technology but ties its Asian exclusivity and per-unit economics to a European partner whose own capacity decisions could shift. It also partly explains why no conventional EPC contractor has been publicly named for the conversion — the work appears to have been executed by GS Entec with Sif technical support rather than through a third-party EPC package.
Order book: one delivered, one contracted
Two references carry the commercial case.
Yeonggwang Nakwol (365 MW). GS Entec won a contract of roughly KRW 200 billion in 2023 to supply all 64 monopiles, and delivered them; installation was completed in mid-2026 by Samhae ENC with Toseong Construction and Hansan Maritime. The first unit shipped was 71.2 m long, 7.5 m in diameter and 895.6 t — sized for a 5.7 MW turbine. This is the proven-execution reference, and it predates the new high-capacity line.
Taean (504 MW). On 30 September 2026, GS Entec signed with Taean Wind Power to supply 37 monopiles totalling roughly 51,000 tonnes — about a third of the expanded nameplate capacity. Manufacturing is scheduled to begin in July 2027, with staged deliveries through August 2028; the wind farm targets construction in 2028 and completion in 2030. Contract value was not disclosed.
A third domestic project (Hanbit) is reportedly prospective but not contracted in public evidence.
Why the steel angle matters — and what is missing
At 150,000 t/yr nameplate, this is a concentrated demand point for high-thickness offshore plate, likely in the 60–113 mm range for primary monopile cans and heavier sections at the transition piece. A 51,000 t order for 37 units implies roughly 1,380 t per monopile on average, consistent with 15 MW-class dimensions.
What is not public: the plate mill, the steel grade specification, the tonnage contracted, and whether any steel supply agreement or qualification was tied to the facility upgrade. Korean reporting describes thick-plate forming and welding in detail without naming a supplier. POSCO's Pohang and Gwangyang plate mills hold renewable-energy and offshore-wind plate certifications and offer grades such as EN S355G7/G8+M from its own catalogue — a technically obvious candidate — but no public source links POSCO plate specifically to GS Entec monopiles. Readers should treat the identity of the plate supplier as an open question, not an established fact.
For steelmakers, the practical significance is twofold. Domestic Korean plate is the default assumption given freight economics and the Korean offshore-wind local-content push, but a 150,000 t/yr line is large enough that GS Entec could plausibly source from Japan or elsewhere if price or lead time demanded it. Either way, the plate grade qualification that matters here is not commodity structural plate — it is offshore-wind-certified heavy plate with tight toughness and weldability requirements, a narrower supply base.
Export ambitions and what to watch
GS Entec has explicitly flagged Japan as the next market, alongside wider Asia and Australia, and GS Group's chairman has framed the plant as part of the group's diversification. The near-term execution risks are:
- Ramp-up. Delivering 150,000 t/yr is a different operational challenge from delivering 64 monopiles on a 40,000 t line.
- Schedule sensitivity. Taean production starts only in July 2027, leaving the plant capacity-heavy and order-light in the interim unless further domestic contracts or exports land.
- Licence dependence. The Sif arrangement is the technology moat and the constraint simultaneously.
- Steel qualification. Whether GS Entec locks in a domestic plate partner or opens sourcing will shape the cost base of every subsequent bid.
For steel and fabrication professionals, the conclusion is straightforward: the facility's construction-phase procurement is finished and the plant is operational. The relevant forward question is not whether the plant will be built, but which plate mill secures a multi-year, qualified supply position behind a 150,000 t/yr monopile line — and that answer is not yet in the public record.