Companion piping

SRVs are extremely sensitive to the effects of improper companion piping both on inlet and outlet sides. In this section, we consider some basic reasons for this. 

Pressure surges occur in liquid service as the violent, multiple closing cycles cause water hammer and place undue stress on companion piping, piping supports, connections, internal components in pressure vessels, instrumentation, and so on. 

Damaged companion piping SRV stress and inertia reversals caused by violent opening/closing cycles. 

Process flowsheets do not normally show companion flanges for valves unless these serve as blinds or for orifice plates. This detail is sometimes shown on the piping flow-... 

As a direct companion of the completed flowsheet, the line schedule sheet transmits the process and mechanically necessary details for proper interpretation of the piping aspects of the flowsheet (see Figures 1-24A, B, C, D). These schedules are initiated by the process engineer to further explain the requirements of the process as shown on the flowsheets. They are often and perhaps usually cooperatively completed by other engineers, particularly the piping, mechanical and instrumentation groups. 

Figure 2-6. Continued. Forged steei companion flanges to attach to steel pipe by the methods indicated. By permission. Tube Turn Technologies, Inc.

Fig. 5. Mixing in the partitioned pipe mixer, (a) Schematic view of the mixer geometry one element of the mixer is shown, and the mixer comprises several such elements joined together, (b) KAM surfaces in flow bounding regions of regular flow, (c) A and B show examples of experimentally obtained streaklines undeformed streaklines pass through KAM tubes, whereas streaklines in the chaotic region are well mixed. The white arrows indicate the location of a companion streak-tube. (Khakhar, Franjione, and Ottino, 1987 Kusch and Ottino, 1992).

Methods for the calculation of pressure drop through pipes and fittings are given in Section 5.4.2. It is important that a proper analysis is made of the system, and the use of a calculation form (worksheet) to standardize pump-head calculations is recommended. A standard calculation form ensures that a systematic method of calculation is used, and provides a checklist to ensure that all the usual factors have been considered. It is also a permanent record of the calculation. A template for a standard pump and line calculation is given in Appendix G and can be downloaded in MS Excel format from http //books.elsevier.com/companions. Example 5.8 has been set out using this calculation form. The calculation should include a check on the net positive suction head (NPSH) available see Section 5.4.3. 

Pipes, S.C. Price controls dry up drug discovery. San Francisco Chronicle, August 24, 2006, p. B7. See also its companion article in favor of this plan, Clayton, E., Alonzo-Diaz, L. Make affordable medicine the law , ibid. 

This suggests further iteration or the installation of a companion flange to 900 mm for European sizes of pipes or 36" suction pipes for U.S. sizes of pipes. 

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