Full Description

The Advanced 347 AP alloy (UNS S34752) is an austenitic stainless steel which combines the advantageous polythionic acid stress corrosion cracking resistance of Type 347LN with elevated temperature strength and creep properties superior to that of traditional Type 347H. This combination of features is obtained through alloying additions of copper and other elements, to impart creep strength, as well as niobium and extra-low carbon to reduce the propensity for sensitization at elevated temperature. These qualities were sought for applications in the petroleum refining industry, primarily in fired heaters, but also for other applications at temperatures up to and exceeding 1250F (675C). The original developer and a supplier of Advanced 347 AP, Nippon Steel and Sumitomo Metal Corporation, provided the Materials Properties Council (MPC) of WRC with available creep and rupture data for analysis. E2G | The Equity Engineering Group, Inc. analyzed the results on behalf of WRC and developed high temperature material properties based on the methodology outlined in WRC Bulletin 546. The results of this work, as documented in the current Bulletin, are provided to API and ASME to obtain recognition by those organizations for applications of Advanced 347 AP material in refinery service. It is the intention of WRC that the properties and data included in this Bulletin will be referenced by WRC Bulletin 541 and subsequently, API Std 530, as well as by API 579-1/ASME FFS-1. This WRC Bulletin records the data provided in both US customary and metric units. It is anticipated that additional test results will be reported in the future to enable allowable stresses to be assigned to higher temperatures.