Risers design standards

There are essentially two main standards that are commonly used in design and operation of flexible risers ISO 13628-2 and API 17J. These standards offer valuable information regarding the design, test and inspection of risers. As an example, ISO 13628-2 illustrates the riser design criteria. Table 5 of the same publication outlines the load combination to be used for riser design. 

ASME B31.4 (2006) Pipeline Transportation for Hydrocarbon Liquid and Other Liquids and ASME B31.8 (2003) Gas Transmission and Distribution Piping System are standards related to the design of pipelines which provide information on the stress and strain limits of industrial oil and gas pipelines. Although not specihcally intended for offshore risers, these standards provide a good foundation for pipeline design that in turn defines the requirements on the repair using FRPC materials. 

Flame arresters cannot be designed from first principles and can only be proven by tests simnlating the conditions of nse. The riser should ensure that a flame arrester has been properly tested to meet the intended purpose, and should be prepared to stipulate the required performance standard or test protocol to be followed. 

In which the vapour passes up through short pipes, called risers, covered by a cap with a serrated edge, or slots. The bubble-cap plate is the traditional, oldest, type of cross-flow plate, and many different designs have been developed. Standard cap designs would now be specified for most applications. 

Several types of FCC testing equipment are described in literature, varying from the more traditional standardized micro activity test (MAT) and fluidised bed reactors to complete riser-regenerator combinations. Also other designs such as a pulse reactor, or a very short contact time reactor have been reported in literature (7-9). 

Sinee the early 1970 s bed crackers have been steadily updated to achieve residence times in the 2 second range by revamping to riser cracking. In riser cracking, contact time is kept to a minimum by forcing the oil vapors to flow cocurrently with catalyst at high velocity in a riser pipe. New FCC designs have incorporated riser reactors as standard for nearly 20 years. 

A number of standard riser separator designs are available. Simple separators are very suitable for VGO cracking at moderate severity. They typically allow only 20% to 10% (or less) of the catalyst circulation up the riser to be entrained to the cyclones. More efficient and intricate devices are required for high temperature operation as the thermal cracking after the riser is exacerbated under these circumstances. This will be discussed later under reformulated gasoline. 

This chapter will first outline the conventional offshore riser repair techniques and their limitations which, in turn, provide the motivation for adoption of composite repair. A brief discussion about the application of FRPC in pipeline repair, its limitations, current practices, and material types will be given. A subsequent section provides information on the industrial design and safety standards used in designing and assessing the performance of offshore risers, corroded pipelines, and pipelines repaired with FRPC. The typical loading conditions of an offshore riser are also discussed so that the requirements of CRS can be understood. 

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