Assembly of the piping

Since multiple bellows have more flexibility than conventional ones, they require shorter pipe lengths to accommodate a given movement. This makes the assembly of the piping system more compact and economical. 

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. 

Insulation work can start only after the assembly of the piping. Even electric trace heatings-if available-have to be installed, since they run inside the insulation. 

The code prescribes minimum requirements for the materials, design, fabrication, assembly, support, erection, examination, inspection, and testing of piping systems subject to pressure or vacuum. The scope of the piping covered by B31.3 is illustrated in Fig. 10-124. It applies to all fluids including fluidized sohds and to all seivdces except as noted in the figure. 

For flanges of nonstandard dimensions or for sizes beyond the scope of the approved standards, design shall be in accordance with the requirements of the ASME Boiler and Pressure Vessel Code, Sec. T11, except that requirements for fabrication, assembly, inspection testing, and the pressure and temperature hmits for materials of the Piping Code are to prevail. Countermoment flanges of flat face or otherwise providing a reaction outside the bolt circle are permitted if... 

In joining reinforced thermosetting pipe it is particularly important that the pipe be cut without chipping or cracking it. It is also important to sand, file, or grind any mold-release agent from the surfaces to be cemented. Joints are built up layer by layer of adhesive-saturated reinforcement by following the manufacturer s recommended procedure. Application of adhesive to the surfaces to be joined and assembly of these surfaces shall produce a continuous bond and provide an adhesive seal to protect the reinforcement from attack by the contents of the pipe. Unfilled or unbonded areas of the joint are considered defects and must be repaired. 

For conducting tests in pipe lines of 75-mm (3-in) diameter or larger, a spool holder as shown in Fig. 28-21, which employs the same disk-type specimens used on the standard spool holder, has been used. This frame is so designed that it may be placed in a pipe line in any position without permitting the disk specimens to touch the wall of the pipe. As with the strip-type holder, this assembly does not materially interfere with the fluid through the pipe and permits the study of corrosion effects prevailing in the pipe line. 

Crimped metal ribbon arresting elements can be made circnlar, rect-angnlar, or sqnare depending on the shape of the pipe or honsing in which they are to be installed. The element is often reinforced by inserting metal rods radially throngh the assembly. 

Duct flows can be converted into efficient mixing flows (i.e., flows with an exponential stretch of material lines with time) by time- modulation or by spatial changes along the duct axis. One example of the spatially periodic class is the partitioned-pipe mixer (PPM). This flow consists of a pipe partitioned with a sequence of orthogonally placed rectangular plates (Fig. 5a). The cross-sectional motion is induced through rotation of the pipe with respect to the assembly of plates, whereas the axial flow is caused by... 

During assembly of the system before testing, each component (including cast-in passages of these components) and all piping and appurtenances shall be cleaned chemically or by another appropriate method to remove foreign materials, corrosion products, and mill scale. 

Packed-Cland Joints These joints (Fig. 10-138) require no special end preparation of pipe but do require careful control of the diameter of the pipe. Thus the supplier of the pipe should be notified when packed-gland joints are to be used. Cast- and ductile-iron pipe, fittings, and valves are available with the bell cast on one or more ends. Glands, bolts, and gaskets are shipped with the pipe. Couplings equipped with packed j ands at each end, known as Dresser couplings, are available in several metals. The joints can be assembled with small wrenches and unskilled labor, in limited space, and if necessary, under water. 

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