ASME PCC

ASME PCC-1 may be used as a guide for assembling flanged joints. 

FIGURE 22.5 Relationship between component, equipment item, system, nnit, and facility. (From ASME, Inspection Planning Using Risk-Based Methods, ASME PCC-3-2007, August 2008. With permission.)... 

ASME, Inspection Planning Using Risk-Based Methods, ASME PCC-3-2007, August 2008. 

ASME PCC-2-2008 Repair of Pressure Equipment and Piping, Issued by the American Society of Mechanical Engineers... 

According to ASME PCC-2 (2006), the main purpose of FRP wrap repair is to strengthen an undamaged section of the pipe to carry the additional loads caused by the damaged or weakened section. Assuming that the repair is applied at zero internal pressure and the pipe material behaves elastic-perfectly plastic (i.e. no strain hardening), the minimum composite repair thickuess. 

ASME PCC-2 Article 4.1, Non-metaUic Composite Repair System for Pipehnes and Pipework High Risk Applications, 2006. 

The composite repair laminate must be thick enough to sustain the load transferred from defective pipelines. Otherwise, transverse cracking of the matrix due to high stresses can cause the laminate repair to fail. The minimum required laminate thickness can be determined through ASME PCC-2 (2008). 

In 2006, the first revision of two international codes, one by the International Organization for Standardization (ISO), ISO/TS-24817 (ISO, 2006) and the other the ASME PCC-2 (ASME, 2006), were published to assist engineers in designing a reliable composite overwrap repair. The former is recognised as a general code that covers pipes with different materials from steel to FRP while the latter is specifically focused on steel pipes. 

In order to use composites for the repair of damaged pipelines, it is crucially important that they be designed based on a valid code to ensure that sufficient reinforcement has been provided. ASME PCC-2 and ISO/TS 24817 provide required parameters to design a repair system with sufficient stiffness, strength and thickness. The design revolves around the determination of a minimum thickness for the FRP wrap that reinstates the design pressure in the pipe in the presence of other probable loads. 

The ASME PCC-2 approach is similar to ISO 24815 with only minor differences that... 

ASME PCC-2 doesn t define any repair class but has two different articles about nonmetallic composite repairs. Article 4.1 talks about high-risk applications and Article 4.2 talks about low-risk applications. 

For the case in which the pipe contribution in canying the load is considered, ASME PCC-2 suggests an equation similar to that of ISO 24817 (Eqn (10.4)) with two differences the substitution of the term pipe allowable stress by Specific Minimum Yield Stress , which... 

ASME PCC-2 does not offer any solutions for the circumferential through-wall defect. 

ASME PCC-2 and ISO 24,817 pipes/pipehnes composite repair codes were developed in order to provide the rules for designing a reliable and robust repair. Equation (11.1) has been proposed by ASME PCC-2 and ISO 24,817 for the design of composite repair when the defected pipe contributes to the load carrying capacity ... 

In Eqn (11.1), Puve is the internal pressure in the pipe at the time of the repair application, Ec and Eg are the composite and the steel module of elasticity, is the remaining pipe wall thickness, tmin is the minimum required thickness of the composite layer, D is the pipe diameter, P is the design pressure and finally is the composite allowable strain. The only difference between the two codes is the definition of s—ASME PCC-2 identifies it as the specific minimum yield stress while ISO 24,817 recognizes it as the pipe allowable stress. 

The repair laminate was assumed to be reinforced with a bidirectional carbon fibre woven fabric with equal number of tows by weight in the weft and warp direction. The matrix was assumed to be epoxy. The laminate properties used for the FEA simulation were calculated using mle-of-mixtures (Daniel and Ishai, 1995), assuming a fibre volume fraction of 40%. The laminate elastic properties are given in Table 11.2. To calculate the repair thickness, the composite allowable strain (sc) was limited to 0.3%, selected as a number in between the two extremes (0.25% and 0.40%) proposed by ASME PCC-2 and also equal to the allowable strain for a class 2 repair with a 10 year lifetime. 

Different design scenarios that were considered in this smdy are presented in Table 11.3. The erosion/defect was assumed to be circumferential with a constant circumferential depth and the wall thinning was considered in the range of 30—80% in increments of 10%. The maximum allowable internal pressure for the corroded pipe was calculated based on ASME B31.4 considering the remaining wall thickness of the pipe. In the study, the live pressure varied from 0 to 100% of the maximum allowable live pressure in steps of 25%. The minimum laminate thickness for each repair situation was calculated using Eqn (11.1) (based on ISO 24,817 and ASME PCC-2) and Eqn (11.10), as given in Table 11.3. 

This test condition was held for the 1000-h duration specified in ASME PCC-2 (2011) and witnessed by a third party certification body, Lloyd s Register. 

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