Piping classes

Maximum allowable working pressure MAWP) Highest pressure to which the system can be subjected during operation. Thus, pressure is established by a relief device set pressure and must be less than or equal to the material strength limitations of equipment. This pressure e.stabli.sh-es piping class for fittings and pipe wall thickness requirements, both of which are discussed in Volume 1. 

Skelton, D., Clements, B., McCandless, T.E., Hood, C. Aulbach, S., Daview, R,. Boyer, L.P. 2003. The Buffalo Head Hills kimberlite province, Alberta. In Kjarsgaard, B.A. (ed.). Slave Province and Northern Alberta Field Trip Guidebook. Geological Survey of Canada, Miscellaneous Publication G-293. Skinner, E.M.W. Marsh, J.S. 2004. Distinct kimberlite pipe classes with contrasting eruption processes. Lithos, 76, 183-200. Sweet, A.R., Boyce, K,. Eccles, D.R. In prep. Palynological constraints on kimberlite emplacement models chronostratigraphy of host rock and clastic xenoliths, Buffalo Head Hills, Alberta. 

LineList A list of all the pipes shown on the PID. Each pipe will be identified with a unique number, which is printed on the PID as well. Different projects have different requirements to the actual content of the information in a hne list. As a minimum, the operating and design pressure and temperature, the nominal diameter and the pipe class have to be listed. In some projects a pressure-drop budget figure will also appear [851]. 

Tables 9.9((a) through (c)), which follow, sununarize Chlorine Institute recommendations. They are taken from Tables 4-1 through 4—7 of Pamphlet 6. Certain threaded valves are permitted in small sizes. Except for connections to transport equipment, instruments, and special process equipment, flanged valves are preferred in piping classes II, III, V, and VI. In the tables, S denotes satisfactory service, NR denotes not recommended, and a dash denotes the lack of sufficient experience to support classification (as of December 1998).

FIGURE 9.60. Piping class service limits— NaOH. 

Pipe Nominal Width DN Nominal Pressure PN Piping Class PC Medium... 

Determination of piping classes The determination of the piping classes basically depends on the media to be pumped (see Chapter 2, section 2.2.2.4, Materials concept ). From the piping classes the exact dimensions (internal diameter) and wall roughness (k-values) will result however, possible incrustahons or other deposits that may lead to an increased wall roughness compared to newly installed pipes have to be considered. 

Indication of nominal widths, nominal pressures and piping class... 

The import of the piping classes into the database is the task of the so-called system administrator of the CAD-system. Professional CAD-systems for process plant engineering are highly complex. Frequently, they are based on the operating system Windows, which has replaced UNIX during the last couple of years, with an Oracle database being lodged, for example. The system maintenance then... 

Figure 4.31 Part of a piping class from Auto-trol Technology.

Following the generation of the isometric drawings and bills of material, aU components required for the individual piping classes have to be compiled separately. The bills of material will be derived from this. Of course the generation of the bills of material is easier with the aid of CAD systems. The same apphes to the pipe lists (see Figure 4.35). The results can be stored on a data carrier and enclosed to the pipe inquiries. 

The manufacturing and assembly of the pipes may be assigned to several subcontractors. This depends decisively on the number and kind of piping classes used. Thus a separation into metal pipes and plastic pipes is thinkable. If several pipe suppliers are commissioned, the clarification of the numerous interfaces and the avoidance of mutual hindrances at the buildtng site may turn out to be difficult. 

Pipe No. Rev. Pipe Class Pipe Route from to Medium Denominatio Medium No.. ON PN Material Insulation [ mm ]... 

Pipe class transition Hydraulic hammer Pig launcher and receivers Pressure in relief headers Overload of vacuum lines Underground piping Vents and bleeders... 

When a pipe class changes, it is important to make sure that the lower grade of steel is not located too near the more severe service. For example, the transition from high temperature-to low temperature-rated pipe should not be so close to the higher temperature service such that the lower temperature line could be affected. 

Similarly, it is important to ensure that hazardous chemicals cannot flow back into a lower pipe class zone. 

ASTM Type 1 PVC pressure pipe (Class 12454)— NSF Single-Screw Twin-Screw... 

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