Threaded valve connections,

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).

B. Valves. Table 9.21 summarizes the application of various types of valve, according to the same four classes used for piping services in Fig. 9.60. The table has the status of a recommendation rather than a hard specification. Exceptions exist, but they should be made only after thorough testing and documentation. All practical combinations are listed, but threaded valves usually should be considered only for connection to transportation equipment, instruments, and special process equipment. Flanged valves generally are preferred. 

Container valve connections that do not fit must not be forced. Threads on regulator connections or other auxiliary requirements must match those on the container valve outlet. The valve outlet connection should conform to recognized standards such as ANSI/CGA V-1, American National, Compressed Gas Association Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections [14]. However, it must be acknowledged that connections other than those found in ANSI/CGA V-1 may exist. If a user chooses such a connection, extreme care must be taken to ensure that such connections do not cross-connect with existing connections in ANSI/CGA V-1, and that they have been properly engineered for the intended gas service and pressure. The threads on a cylinder valve outlet, as well as on regulators and other ancillary equipment, should be examined at frequent intervals to ensure they are clean and undamaged. 

Table 9-1, which appears at the end of this chapter, lists nearly 200 different pure chemicals and gases in alphabetical order that are commonly shipped in compressed gas cylinders. Listed to the right of each gas in Table 9-1 are the cylinder volumes and fill pressures for each gas when it is pertinent to the selection of the valve connection. Information concerning whether the connection is for liquid withdrawal of product from the cylinder and whether the connection is threaded or of the yoke type is also provided. 

Fig. 9-7. Typical straight thread valve inlet connection. Oversize threads...

Make sure that the threads on regula-tor-to-cylinder valve connections or the pin-indexing devices on yoke-to-cylinder valve connections are properly mated. Never force connections that do not fit. 

A simple manifold is illustrated in Figure 40.41. This manifold contains one pressure inlet port and several pressure outlet ports that can be blocked off with threaded plugs. This type of manifold can be adapted to systems containing various numbers of subsystems. A thermal relief valve may be incorporated in this manifold. In this case, the port labeled T is connected to the return line to provide a passage for the relieved fluid to flow to the reservoir. 

Packing glands or seals on pumps and compressors Pipe flanges, fittings and valve stems Threaded fittings that are not seal-welded Sample stations with an air break Manways and piping connections to vessels Piping to equipment connections... 

Unless valves are specified, threaded vent and drain connections shall be plugged. Carbon steel plugs shall be used with cast iron casings. 

CC1-11, CC14-15, CC18-19 74514 1 connection parts for pipes with threads (R 1 1/2") Constant pressure valve with... 

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