QUESTION: What is the significance of P. No. and group No. in ASME section II D materials ? ANS. ASME P-Numbers To reduce the number of welding and brazing procedure qualifications required base metals have been assigned P-Numbers by the ASME BPVC. Ferrous metals which have specified impact test requirements have been assigned Group Numbers within P-Numbers. These assignments have been based on comparable base metal characteristics, such as: Composition Weldability Brazeability Mechanical Properties Indiscriminant substitution of materials in a set of P-Numbers or Group Numbers may lead to problems or potentially failures. Engineering assessment is necessary prior to a change in materials. When a base metal with a UNS number Designation is assigned a P-Number, then a base metal listed in a different ASME material specification with the same UNS number shall be considered that P-Number. The table below is a guide and is for instructive purposes only. Anyone specifying materials or requirements should refer directly to the ASME Boiler and Pressure Vessel Code to specify materials, P-Numbers, procedures, or other requirements and not rely on the table below. The table below is only a rather incomplete and approximate summary of ASME data. P-Numbers Base Metal (Typical or Example) 1 Carbon Manganese Steels (four Group Numbers) 2 Not Used 3 Half Molybdenum or half Chromium, half Molybdenum (three Group Numbers) 4 One and a quarter Chromium, half Molybdenum (two Group Numbers) 5A Two and a quarter Chromium, one Molybdenum 5B Five Chromium, half Molybdenum or nine Chromium, one Molybdenum (two Group Numbers) 5C Chromium, Molybdenum, Vanadium (five Group Numbers) 6 Martensitic Stainless Steels (Grade 410, 415, 429) (six Group Numbers) 7 Ferritic Stainless Steels (Grade 409, 430) 8 Austenitic Stainless Steels Group 1 - Grades 304, 316, 317, 347 Group 2 - Grades 309, 310 Group 3 - High Manganese Grades Group 4 - High Molybdenum Grades 9A, B, C Two to four Nickel Steels 10A, B, C, F Various low alloy steels 10H Duplex and Super Duplex Stainless Steel (Grades 31803, 32750) 10I High Chromium Stainless Steel 10J High Chromium, Molybdenum Stainless Steel 10K High Chromium, Molybdenum, Nickel Stainless Steel 11A Various high strength low alloy steels (six Group Numbers) 11B Various high strength low alloy steels (ten Group Numbers) 12 to 20 Not Used 21 High Aluminum content (1000 and 3000 series) 22 Aluminum (5000 series - 5052, 5454) 23 Aluminum (6000 series – 6061, 6063) 24 Not Used 25 Aluminum (5000 series - 5083, 5086, 5456) 26 to 30 Not used 31 High Copper content 32 Brass 33 Copper Silicone 34 Copper Nickel 35 Copper Aluminum 36 to 40 Not Used 41 High Nickel content 42 Nickel, Copper - (Monel 500) 43 Nickel, Chromium, Iron - (Inconel) 44 Nickel, Molybdenum – (Hastelloy B2, C22, C276, X) 45 Nickel, Chromium 46 Nickel, Chromium, Silicone 47 Nickel, Chromium, Tungsten 47 to 50 Not Used 51, 52, 53 Titanium Alloys 61, 62 Zirconium Alloys
Posted on: Tue, 09 Sep 2014 08:50:47 +0000
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