Hello Pipe Enthusiasts!
Welcome back to #SEAPIPipeInsights! This time we will discuss the terms ERW and HFW that often appear in international steel pipe standards. Although SEAPI manufactures large‑diameter pipes using LSAW and HSAW/SSAW, it is still important to understand ERW and HFW so that we can read specifications across different standards more accurately.
What is ERW?
ERW (Electric Resistance Welded) is a general term for steel pipes joined using electric resistance current. The process uses electrical flow to heat the edges of steel plates until they fuse, producing a neat and consistent weld. ERW can be carried out at low, medium, or high frequency depending on production needs.
The term ERW appears in several standards, such as:
- ASTM A53 / ASTM A252 / ASTM A795 → carbon steel pipes for mechanical, utility, construction, piling, and fire protection applications.
- SNI 39:2024 → steel pipes for water supply and gas installation systems in Indonesia.
- JIS G3452 / JIS G3444 / JIS A5525 → Japanese standards recognizing ERW for ordinary piping, structural pipes, and steel pipe piles.
What is HFW?
HFW (High‑Frequency Welded), also commonly referred to as HF‑ERW, is an electric resistance welding process that uses high frequency (generally above 70 kHz). With this frequency, the heat generated is more concentrated, resulting in deeper weld penetration and more consistent quality compared to low‑frequency ERW.
In the API 5L standard, HFW is used specifically for oil and gas line pipes, where weld quality requirements are very strict because the pipes must withstand high pressure and demanding operating conditions. The HFW process ensures stronger welds, making it suitable for medium to large‑diameter pipelines. Interestingly, API also recognizes LFW (Low‑Frequency Welded) for large‑diameter pipes, but ASTM and other standards generally use the broader term ERW.
Conclusion
ERW and HFW are essentially the same electric resistance welding process, but the terminology differs depending on the standard. ASTM, SNI, and JIS generally use the term ERW, while API 5L is more specific with HFW to emphasize the use of high frequency.
For SEAPI, which produces large‑diameter steel pipes using LSAW and HSAW/SSAW, understanding ERW and HFW remains valuable as educational insight. It helps us interpret specifications across different standards correctly and demonstrates SEAPI’s awareness of the full spectrum of steel pipe welding technologies.
Southeast Asia Pipe Industries manufactures large‑diameter steel pipes according to international standards, supporting oil and gas, energy, and infrastructure projects in Indonesia and globally.
