1. **What is ASTM A928?**
* ASTM A928/A928M is the Standard Specification for Ferritic/Austenitic (Duplex) Stainless Steel Pipe Electric Fusion Welded with Addition of Filler Metal. It covers duplex stainless steel pipe made via specific electric fusion welding processes that use filler metal, ensuring enhanced weld integrity for corrosive service applications.
2. **What is the difference between ASTM A790 and ASTM A928?**
* Both ASTM A790/A790M and ASTM A928/A928M cover seamless and welded ferritic/austenitic (duplex) stainless steel pipe.
* The key difference is the welding process:
* **ASTM A790:** Primarily covers pipes made by *autogenous* welding processes (like continuous welding without filler metal, such as laser or electron beam) or seamless processes. Welded pipe under A790 may or may not use filler metal.
* **ASTM A928:** Specifically mandates the use of electric fusion welding processes *with the addition of filler metal*. This requirement ensures a controlled weld chemistry and microstructure, making it particularly suitable for highly corrosive environments where weld integrity is critical.
3. **What is the preferred ASTM designated steel type for use in steel pipe?**
* There is no single "preferred" ASTM steel type for all pipe applications; the choice depends entirely on the service requirements (pressure, temperature, fluid, corrosion).
* However, the **most commonly specified standards for general service carbon steel pipe** are:
* **ASTM A53/A53M:** Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless. Widely used for mechanical and pressure applications, conveying fluids, and structural purposes.
* **ASTM A106/A106M:** Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service. Primarily used for seamless pipe in power plants, refineries, and high-temperature/pressure applications.
* Other important standards include ASTM A333 for low-temperature service, ASTM A335 for high-temperature alloy steel pipe, and the duplex standards (A790/A928) mentioned earlier.
4. **What is the ASTM standard for stainless steel pipe fittings?**
* The primary ASTM standard for stainless steel pipe fittings (such as elbows, tees, reducers, caps) is **ASTM A403/A403M** - Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings.
* This standard covers fittings made from austenitic stainless steel grades (like 304, 316) and also duplex stainless steel grades (like S31803, S32205). It defines different "WP" (Wrought Product) and "WX" (Wrought Product Extra Low Carbon) classes corresponding to material grades and requirements. The standard references dimensional standards like ASME B16.9 and B16.11.
5. **What is the ASTM for 304 stainless steel pipe?**
* The primary ASTM standard for both seamless and welded 304 stainless steel pipe is **ASTM A312/A312M** - Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes.
* Within ASTM A312, Grade 304 stainless steel pipe is designated as **TP304** (for seamless and welded pipe). For welded pipe specifically made by certain automated welding processes without filler metal, ASTM A312 references supplementary specifications like ASTM A358 (for electric-fusion-welded pipe) or ASTM A409 (for large diameter welded pipe).
