What are the differences between ERW and HFW steel pipe? ERW steel pipe manufacturing process includes HFW. ERW have low, medium, high-frequency welding processes. And HFW are especially for high-frequency electric resistance welding.
ERW and HFW do not have very big different. Because EFW is a type of ERW process for ordinary and thin-wall thickness steel pipes. We could see its differences as below.
Definition For ERW Steel Pipe and HFW Steel Pipe
ERW pipe: Electric Resistance Welded Pipe
HFW pipe: High-Frequency Welding pipe
What is the HFW Steel Pipe?
It noted that HFW pipe is a type of ERW pipe. HFW steel pipe is ERW pipe produced with a welding current frequency equal to or greater than 70 kHz. Through high-frequency current welding resistance, the heat generated in the contact objects. So the objected surface heated to the plastic state. Then with or without forging to achieve a combination of steels.
HFW is a solid resistance heat energy. The high-frequency current pass through the metal conductor. It will produce two peculiar effects, skin effect and proximity effect.
HFW process is to use the skin effect to concentrated on the steel object surface. It used proximity effects to control the position. And the power of the high-frequency electric current flow path. Since the speed is very high, the contacted plate edge could heated and melted inshore time. Then extruded through the docking process.
Welding Processes of the ERW and HFW
ERW welding process refers to the heat generated by the resistance to current flow that passes through the jointed metals. So a large current needed to electrify the whole surface of the steel plate or coil to the length of welding. In the ERW welding process, the electric current that passes through the entire conductor is at 50/60 Hz.
HFW welding process is not the same case with the high-frequency process. Since it’s only a section of the steel metals heated by the induction of electric coil. High-frequency generated by either AC or DC current. In these cases, two generator used. One is the constant current welding generator. And the other one is constant voltage high-frequency welding generator.
HFW is Required in API 5L PSL2 ERW Steel Pipe
According to the API 5L and ISO 3183 specification. PSL 2 pipes in welded process, the HFW welding is a mandatory need for ERW steel pipes. As it is an improvement from the inherent problems of hardness. It lack of fusion and susceptibility of stress corrosion cracking (SCC).
ERW steel pipe includes HFW steel pipe
ERW is the general designation of resistance welded steel pipes. It sorted into two types: alternated current welding (AC) and direct current welding (DC).
According to different frequencies, AC welding can divided into different welding type. Such as, low-frequency welding, intermediate frequency welding, ultra frequency welding, and high-frequency welding.
The high-frequency welding (HFW) used in ordinary or thin wall steel pipe. It includes contact welding and induction welding. Direct current welding is generally used for small-caliber steel tubes.
In general, HFW is one of ERW production methods. It adopts the high-frequency welding process. So, the ERW steel pipe includes the HFW steel pipe.
ERW steel pipe application and usage
ERW steel pipe used for transporting gas and liquid objects. Such as oil and gas could meet the low and high-pressureneedt. In recent years, with the development of ERW technology, more and more ERW steel pipes used manu field. Such as in the oil and gas fields, the automobile industry and so on.
Advantages of ERW pipe and HFW pipe
ERW pipes’ advantage is high efficiency, low cost, material saving, easy automation.
In the welding process, HFW steel pipes do not need to add filling meta. So it has fast welding speed and high efficiency in production. HFW pipe used in the fields in oil and gas transportation. In oil well pipeline, building structure and various kinds of mechanical pipe.
But, HFW steel pipe quality affected by many factors, such as raw material and process. And the production quality control become difficult. So the yield and welding process still needs to improved.
And Winsteel Group is professional LSAW pipe manufacturer. We have got API 5L PSL 1 and PSL 2 certificate for decades years. If you need a quotation of our products or have any questions, please contact me. I will do my best to support you.