2025-05-29
In ASTM A312 stainless steel pipe specifications, two commonly referenced terms are AW (As Welded) and WM (Welded and Machined). Understanding their differences is important when selecting the appropriate material for specific applications.
AW (As Welded) refers to pipes that are welded without any subsequent heat treatment or cold working. These pipes are typically produced using ERW (Electric Resistance Welding). The mechanical properties and corrosion resistance in the weld zone are generally lower compared to other methods, and the weld seam is usually visible. AW pipes are cost-effective and suitable for non-critical, general-purpose applications.
WM (Welded and Machined) refers to pipes that are welded and then further processed—either by mechanical finishing or additional treatments. These are commonly produced using TIG (Tungsten Inert Gas) welding, which results in cleaner welds with more stable mechanical and corrosion-resistant properties. WM pipes are widely used in industries where weld quality and surface finish are essential, such as food processing, pharmaceutical, and chemical sectors.
For high-temperature or high-pressure applications, or where weld integrity is critical, seamless pipes are generally recommended. ASTM A213
In practice, for standard applications, AW pipes offer a cost-effective solution. For hygiene-critical environments or where superior corrosion resistance is required, WM or seamless pipes are preferred—especially for European clients in the food and pharmaceutical industries. For more information about our stainless steel pipe solutions, feel free to contact us. mail： zhangying@kasugai-group.co.jp
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