Astm a53 standard specification covers seamless and welded, black and hot-dipped galvanized nominal (average) wall pipe for coiling, bending, flanging and other special purposes and is suitable for welding. The steel for both seamless and welded pipe shall be made by one or more of the following processes: open-hearth, electric furnace, or basic-oxygen. The weld seam of electric-resistance welded pipe in grade b shall be heat treated after welding. A53 pipe comes in three types and two grades Weight of any length shall not vary more than 10% over and 3.5% under that specified. Note-nps 4 and smaller-weighed in lots. Larger sizes shall be weighed separately by length.