The High Pressure Institute of Japan published the first edition of Fitness for Service assessment procedure, HPIS Z101, in 2001. The current assessment procedure contained only Level 1 version, in which the structural integrity of flawed pressure vessels and piping systems is evaluated using Charpy absorbed energy and allowable flaw size. Z101 is currently revised and updated including the addition of Level 2 version. In the Level 2 assessment procedure, the structural integrity of flawed pressure vessels and piping systems is going to be evaluated by means of a two parameter method. The two parameter method requires evaluation of fracture ratio K_r and a ratio of applied load and yield load L_r, respectively. K_r is calculated as a ratio of stress intensity factor to fracture toughness and L_r is calculated as a ratio of reference stress to yield stress. Z101 Level 2 assessment procedure, therefore, should provide stress intensity factor (SIF) solutions and reference stress solutions.
This paper describes SIF solutions that are going to be adopted in Z101 Level 2 assessment procedure. SIF values of semi-elliptical cracks in a cylinder were calculated using existing FFS codes such as API579 and R6, and these values were compared. It was found by the comparison that the two codes gave almost the same SIF when the ratio of crack depth and thickness a⁄t is equal to or greater than 0. 2 but gave different SIF when a⁄t is equal to 0. Since SIF values at a⁄t=0 calculated by R6 showed good agreement with those by Z101 Level 1 solutions, R6 solutions for semi-elliptical cracks in a cylinder were adopted as the SIF solutions in Z101 Level2. For extended axial cracks and fully circumferential cracks in cylinder, API579 and R6 gave almost the same SIF values. Since API579 provides SIF solutions for broad range of inner radius to thickness ratio, API579 solutions for extended axial cracks and fully circumferential cracks in cylinder were adopted as the SIF solutions in Z101 Level2.

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Joint performance was examined by tensile tests in respect of the friction welded joint of tough pitch copper and aluminum alloy using braking method. The materials of this experiment were C1100 (tough pitch copper) and aluminum alloys A1050, A5052, A6061, and A6063. Conditions of friction pressure welding for rotational frequency and upset time were constant (N_s=3000min^-1, T₂=10 s) . Conditions for friction pressure P₁, friction time T₁ and upset pressure P₂ change in every classification of the sample material. Those conditions for which the sample material joints seemed to be optimal in the preliminary experiment were selected. Using them, the experiment was carried out.
Results showed 96% joint efficiency in the C1100⁄A1050 joint. Other joints showed joint strengths that were greatly inferior to the base metal strength. Performance in joints produced with A6061 with artificial aging hardening was examined for joint strength improvement, as well as in joints that underwent solution heat treatment before the junction, and in joints that underwent solution heat treatment after they were produced. Results showed slight improvement in joint efficiency. Furthermore, intermetallic compounds were not observed in joints that had undergone solution heat treatment.

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Fitness-for-Service (FFS) assessments are quantitative engineering evaluations that are performed to demonstrate the structural integrity of an in-service component that may contain a flaw or damage. It can be used to make run-repair-replace decisions to help determine if pressurized equipment containing flaws that have been identified by inspection can continue to operate safely for some period of time.
This report provides an interpretation of general and local metal loss assessment procedures which are specified in FFS assessment procedure developed by PAJ⁄JPCA FFS task group based on API RP579 with following three parts
Part 1 Overview of FFS assessments and fundamental technology of metal loss assessment
Part 2 Study on various assessment procedures and margin for failure
Part 3 Comparison of metal loss assessment procedures based on FEM analysis

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American Petroleum Institute (API) proposed the first Risk Based Inspection (RBI) method for petroleum refinery industries in 1996. Since that time, the interest in RBI was growing also in Japan resulted that “RBM Specialty Study Committee” was built in High Pressure Institute of Japan (HPI) as the first Japanese study organization of Risk Based Maintenance (RBM) in 2001. Following the issue of preliminary version of RBI standard in 1996, API issued the first edition of “API Publication 581 (API581) ”in 2000 as the first practical RBI standard in the world. API also issued“API RP580 (API580) ”as the recommended practice of general procedure for RBI application. On the other hand, new RBI project named “Risk Based Inspection and Maintenance Procedures (RIMAP) ”was established in 2001 in Europe and started to make the original procedure of RBM or RBI. The results of RIMAP are supposed to be released to public in 2006 as CEN Workshop Agreement. These works in USA and Europe are targeted to produce the suitable standard of RBM to their countries and improve the international competitiveness of their industries. Such kind of work is also important to Japanese industries to keep safety and compete with them. We, as the members of RBM Specialty Study Committee, studied API 581, API580 and RIMAP and are trying to make the Japanese version of RBM standard. In this paper, we introduce API 581 and RIMAP comparing their characteristic points of procedures.

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