SAW vs ERW and EFW Welded Steel Pipe

--An Expert Guide to Welding Processes, Applications, and Key Differences

Unravel the differences between SAW, ERW, and EFW welded pipes. Learn how SAW relates to EFW and compare fusion vs. resistance welding for your industrial project needs.

When selecting industrial welded steel pipes, the welding processes ERW, EFW, and SAW are frequently referenced. This article will delve into the fundamental distinctions and intrinsic connections between these three welded pipe types, ensuring the safety and economic viability of pipeline systems.

ERW Pipe

ERW (Electric Resistance Welding) pipe is a pressure welding process. It offers high production efficiency and low cost. It is widely used in general industrial applications such as medium and low-pressure fluid conveyance.

Relationship Between EFW and SAW

The SAW process involves igniting an arc beneath a flux layer to melt the filler metal and edges of the base material, forming a high-quality weld. Based on weld configuration, it is further categorised into Long Submerged Arc Welding (LSAW) and Spiral Submerged Arc Welding (SSAW). This represents the most characteristic and predominant form of EFW.

EFW (Electric Fusion Welding) broadly encompasses all fusion welding processes utilising an external heat source to melt metal for joining. Typically, when referring to EFW for pipeline manufacturing, it specifically denotes the SAW process.

SAW/EFW vs. ERW

Having clarified the relationship between EFW and SAW, we now compare SAW and EFW collectively against ERW.

Welding Principle

SAW/EFW relies on arc heat for fusion welding, requiring filler metal (welding wire). ERW relies on resistance heat for pressure welding. No filler metal is used.

Production Capacity and Dimensions

SAW/EFW is suitable for manufacturing large-diameter, thick-walled pipes. ERW is primarily used for producing small to medium-diameter pipes (typically less than 24 inches) with medium to thin wall thicknesses.

Weld Quality and Performance

SAW/EFW delivers superior weld quality with consistent performance, passing stringent non-destructive testing. ERW welds exhibit inferior quality compared to SAW/EFW and may become weak points under extreme environmental conditions.

Application Domains

SAW/EFW is suitable for high-pressure oil and gas transmission trunklines, offshore platforms, pressure vessels, and bridge structures. ERW dominates conventional industrial and civil projects.

ERW, EFW, and SAW represent distinct tiers and applications of welding technology. When selecting for a project, the most appropriate technical choice should be made based on specific pressure ratings, conveyed media, diameter requirements, and cost budgets.MTSCO offers fully fabricated welded steel pipes (including nickel alloys and duplex steel grades), providing bespoke selection solutions in accordance with ASTM and EN standards and project operating conditions to ensure precise alignment between materials and project requirements.