The Difference Between API 5L ERW and EFW Steel Pipe

　　Differences between API 5L ERW Steel Pipe and API 5L EFW Steel Pipe

　　Two of the most common methods to produce pipe are API 5L Electric Resistance Welding (ERW), and Electric Fusion Welding (EFW). Both processes involve a coil of steel being continuously fed through a series of rollers/dies which shape the flat steel into the desired shape of the pipe.

　　The welding method of ERW pipe and submerged arc welded pipe is significantly different. The pressure welding method without filler metal is adopted. The weld is not filled with other components, and the skin effect and the proximity effect of the high frequency current are used to instantaneously heat the edge of the plate.

　　At the soldering temperature, the weld of the forged structure is extruded by a squeeze roll. High-quality steel pipes require heat treatment on the weld line or off-line to refine the microstructure of the weld zone. The weld of the high-quality ERW welded pipe can reach the same level of toughness as the base metal, which cannot be achieved by the submerged arc welding process.

　　What is ERW Pipe Used For?

　　Just as ERW is the predominant pipe manufacturing process, ERW pipe can be found in just about every industry where fluid/media needs to be moved from one location to another.

　　Common industries where you would find ERW pipe include: plumbing, HVAC, fire suppression, commercial, aviation, aerospace, automotive, rail, electronics, energy, oil & gas, and industrial.

　　What is EFW Pipe Used For?

　　Being viewed as a cost-effective alternative to seamless pipe means that EFW can be used in higher pressure, more corrosive applications where ERW could not be considered. Industries such as petrochemical, textile, food & processing and chemical processing can utilize EFW in areas of their pipelines.

　　ERW Pipe Specifications

　　ERW pipe sizes range from ½” – 48”

　　Manufactured in several schedulesranging from schedule 5 to schedule 160 as well as schedule XXS and XS. The schedule used is dependent upon the application and pressure of the piping system.

　　The most common alloys ERW pipe is manufactured from are stainless steel and carbon steel.

　　Ends: plain, bevelled, threaded

　　Industry Standards & Specifications:

　　ASTM A178: Standard Specification for Electric-Resistance-Welded Carbon Steel and Carbon-Manganese Steel Boiler and Superheater Tubes

　　EFW Pipe Specifications

　　EFW pipe sizes range from 1/8” through 100”.   The availability of these diameters depends on the ASTM specification.

　　Manufactured in several schedules including schedule 10, schedule 40 and schedule 80, etc. These schedules are used in different applications based on the pressure requirements of the system they will be used in.

　　Available in several alloys such as stainless steel, high nickel alloy and carbon steel. This gives flexibility to those installing piping systems.

　　Surface finishes: HF pickled, matt polish, sandblast

　　Ends: plain, bevelled, threaded

　　Industry Standards & Specifications:

　　ASTM A672: Standard Specification for Electric-Fusion-Welded Steel Pipe for High-Pressure Service at Moderate Temperatures

　　ASTM A691: Standard Specification for Carbon and Alloy Steel Pipe, Electric-Fusion-Welded for High-Pressure Service at High Temperatures

　　API 5L EFW is the abbreviation of electric fusion welding.

　　One of submerged arc welding (SAW)-electric welding (EFW) is a process in which metal is heated by one or several consumable electrodes and a workpiece to heat the metal, and the arc is used to make the metal and fill. The material is fully melted and does not require pressurization.

　　The part of the filling metal is all from the electrode. Melt Gas Shielded Welding (GMAW)-A type of electrofusion welding (EFW) that is similar to submerged arc welding, but its protection comes from inert gases and works better.

　　Shengtian Group distributes an extensive selection of API 5L welded pipe, including Electric Resistance Welded (ERW) and Double Submerged Arc Welded (DSAW) carbon steel pipe — along with their respective flanges and fittings.