Fluid Services

Heat for soldering is usually obtained from torches. The high conductivity of copper makes it necessary to use large flames for the larger sizes, and for this reason the location in which the joint will be made must be carefully considered. Soldered joints are most widely used in sizes 2 in and smaller for which heat requirements are less burdensome. Soldered joints should not be used in areas where plant fires are hkely because exposure to fires resiilts in rapid and complete failure of the joints. Properly made, the joints are completely impervious. The code permits the use of soldered joints only for Category D fluid service and then only if the system is not subject to severe cychc condions. 

The use of high-silicon iron in flammable-fluid service or in Cate-goiy M fluid seivdce is prohibited by the code. 

Classification of Fluid Services The code apphes to piping systems as illustrated in Fig. 10-124, but two categories of fluia services are segregated for specif consideration as follows ... 

Category M fluid service is defined as a fluid service in which a single exposure to a veiy small quantity of atoxic fluid, caused by leakage, can produce serious irreversible harm to persons on breathing or bodily coutacl , even when prompt restorative measures are taken. ... 

Examination Normally Required Fiping not covered by Category D fluid service or severe cyclic conditions shall be examined as follows or to any greater extent specified in the engineering design. 

Pressure Testing Prior to initial operation, installed piping shall be pressure-tested to assure tightness except as permitted for Category D fluid service described later. The pressure test shall be maintained for a sufficient time to determine the presence of any leaks but not less than 10 min. 

Popping Pressure the pressure at which the internal pressure in a vessel rises to a value that causes the inlet valve seat to begin to open and to continue in the opening direction to begin to relieve the internal overpressure greater than the set pressure of the device. For compressible fluid service. 

Simmer the audible or visible escape of fluid between the seat/disk of a pressure-relieving valve at an inlet static pressure below the popping pressure, but at no measurable capacity of flow. For compressible fluid service. 

Holes for drainage must be adequate to drain the column in a reasonable time, yet not too large to interfere with tray action. Draining of the column through the trays is necessary before any internal maintenance can be started or before fluid services can be changed, when mixing is not desirable. The majority of holes are placed adjacent to the outlet or downcomer weir of the tray. However, some holes are placed in the downcomer inlet area or any suspected low point in the mechanical layout of the column. 

Except for components designed in accordance with provisions of (c)(1) above, fluid service requirements for materials stated in this Code shall not restrict their use as cladding or lining in pipe or other components. Fluid service requirements for the outer material (including those for components and joints) shall govern, except that temperature limitations of both inner and... 

Selection of material to resist deterioration in service is not completely addressed in this Code. It is the designer s responsibility to select materials suitable for the fluid service. Recommendations based on experience are presented for guidance in para. GR-2.1 and Nonmandatory Appendix A. 

A-9.1.3 Slip-On Flanges. The need for venting the space between the welds in double-welded, slip-on flanges should be considered for fluid services (including vacuum) that require leak testing of the inner fillet weld, or when fluid handled can diffuse into the enclosed space, resulting in possible failure. 

The compatibility of lubricants or sealants used on threads with the fluid service. 

The compatibility of packing, seals, and O-rings with the fluid service. 

The compatibility of materials, such as cements, solvents, solders, and brazing materials, with the fluid service. 

The compatibility of materials, including sealants, gaskets, lubricants, and insulation, used in strong oxidizer fluid service (e.g., oxygen or fluorine). 

NOTE These temperature limits are based on material tests and do not necessarily reflect evidence of successful use as piping component linings in specific fluid services at these temperatures. The designer should consult the manufacturer for specific applications, particularly as temperature limits are approached. 

Category D Category D fluid service is defined as a fluid service to which all the following apply (1) the fluid handled is nonflammable and nontoxic (2) the design gage pressure does not exceed 150 psi (1.0 MPa) and (3) the design temperature is between -20°F (-29°C) and 366°F (186°C). ... 

The code assigns to the owner the responsibility for identifying those fluid services which are in Categories D and M. The design and fabrication requirements for Class M toxic-service piping are beyond the scope o this Handbook, See ASME B31.3—2004, chap. VIII. 

Brazing procedures, brazers, and brazing operators must be qualified in accordance with the requirements of Part QB, Sec. IX, ASME Code. At the owner s option, qualification is not required for Category D fluid service not exceeding 93°C (200°F). The clearance between... 

Any carbon steel material may be used to a minimum temperature of —29°C (—20°F) for Category D Fluid Service. 

Normal and Category M fluid service Severe cyclic conditions Category D fluid service ... 

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