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API RP 574-2009 pdf free download

API RP 574-2009 pdf free download.Inspection Practices for Piping System Components.
4.5.2 FRP Flanges FRP flanges are manufactured using the same methods as the fittings. Contact molded flanges should be inspected for dimensions, drawback and face flatness. The layers of reinforcement should extend onto the pipe in order to create the proper bond and hub reinforcement. More information on FRP flanges can be found in MTI Project 160-04. FRP flanges should have the proper torques and gaskets. 4.6 Expansion Joints Expansion joints are devices used to absorb dimensional changes in piping systems, such as those caused by thermal expansion, to prevent excessive stresses/strains being transmitted to other piping components, and connections to pressure vessels and rotating equipment. While there are several designs, those commonly found in a plant are metallic bellows and fabric joint designs. Metallic bellows can be single wall or multilayered, containing convolutions to provide flexibility. Often, these joints will have other design features, such as guides, to limit the motion of the joint or type of loading applied to the joint. Metallic bellows are often found in high-temperature services and are designed for the pressure and temperature of the piping system. Fabric joints are often used in flue gas services at low pressure and where temperatures do not exceed the rating of the fabric material. 5 Pipe-joining Methods 5.1 General The common joining methods used to assemble piping components are welding, threading, and flanging. Piping should be fabricated in accordance with ASME B31.3. Additionally, cast iron piping and thin wall tubing require special connections/joining methods due to inherent design characteristics. 5.2 Threaded Joints Threaded joints are generally limited to auxiliary piping in noncritical service (minor consequence should a leak occur) that has a nominal size of 2 in. (51 mm) or smaller. Threaded joints for NPSs of 24 in. (610 mm) and smaller are standardized (see ASME B1.20.1).
Lengths of pipe can be joined by any of several types of threaded fittings (see 4.4). Couplings, which are sleeves tapped at both ends for receiving a pipe, are normally used to connect lengths of threaded pipe. When it is necessary to remove or disconnect the piping, threaded unions or mating flanges are required (see 5.4). Threaded joints that are located adjacent to rotating equipment or other specific sources of high vibration can be especially susceptible to failure due to fatigue. Special consideration should be given to these situations. 5.3 Welded Joints 5.3.1 General Welded joints have for the most part replaced threaded and flanged joints except in SBP where some users still rely on threaded joints and in cases where piping is connected to equipment which requires periodic maintenance. Joints are either butt-welded (in various sizes of pipe) or socket welded (typically NPS 2 and smaller).
5.3.2 Butt-welded Joints Butt-welded connections are the most commonly found in the petrochemical industry. The ends of the pipe, fitting, or valve are prepared and aligned with adequate root opening in accordance with ASME B16.25, permitting the ends to be joined by fusion welding. 5.3.3 Socket-welded Joints Socket-welded joints are made by inserting the end of the pipe into a recess in a fitting or valve and then fillet welding the joint. Space should be provided between the end of the pipe and the bottom of the socket to allow for pipe expansion and weld shrinkage. Two lengths of pipe or tubing can be connected by this method using a socket-weld coupling. Figure 11 illustrates a cross section of a socket-welded joint. 5.3.4 Welded Branch Connections A large number of piping failures occur at pipe-to-pipe welded branch connections. The reason for the failures is that branch connections are often subject to higher-than-normal stresses caused by excessive structural loadings from unsupported valves or piping, vibration, thermal expansion or other configurations. The result is concentrated stresses that can cause fatigue cracking or other failures. 5.4 Flanged Joints Flanged joints are made by bolting two flanges together with some form of gasket between the seating surfaces. The gasket surfaces can be flat and range from serrated (concentric or spiral) to smooth (depending on the type of gasket, gasket material, and service conditions), or grooves can be cut for seating metal-ring gaskets. Figure 12 illustrates common flange facings for various gaskets. The common types of flanges are welding neck, slip-on welding, threaded, blind, lap joint, and socket welded. Each type is illustrated in Figure 13.

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