Joints flanged

Flanged Joints For sizes larger than 2 in when disassembly is contemplated, the flanged joint (Fig. 10-132) is the most widely used. 

Figures 10-133 and 10-134 illustrate the wide variety of types and facings available. Though flanged joints consume a large volume of metal, precise machining is required only on the facing. Flanged joints do not impose severe diametral tolerances on the pipe. Careful alignment prior to assembly of flat-face and raised-face flanges is not required, and the necessary wrenches are far smaller than those for screwed assembly for the same size of pipe.

Bolting Bolting requirements for ANSI flanged joints are pre-... 

Pressure-seal joints (Fig. 10-142) are used for pressures of 4.4 MPa (600 Ibf/in") and higher. They use less metal than flanged joints but require much more machining of surfaces. There are several designs, in all of which increasing fluid pressure increases the... 

TABLE 10-42 Glass Pipe and Tubing Conical Flanged Joint ... 

Temperature shoeks may eause horizontal flange joints to open, allowing nitrie aeid to enter... 

Feakage of liquids transferred under pressure, e.g. from flange joints, pump glands... 

Structural baghouses are limited to very large baghouses. All structural components are fabricated as separate panels with formed flanges. The panels are bolted or welded in the field. These flanged joints serve as stiffeners to the hoppers, plenum, tube sheets, and baghouse enclosures. 

In another incident, on a new plant, two flanged joints leaked an hour after chlorine was introduced. The gaskets were removed and analyzed and were found to be made from titanium although they were stamped Hastelloy, the material specified [5]. 

The problem manifested itself as an equipment problem, namely a leaking flange joint. The department broadly responsible for this area (but not for implementing, monitoring, and subsequent recommendations) is the engineering department, as the specialist contractors work for them. The critical event took place during a corrective maintenance operation. From here, two separate root causes were identified, based on the data from the investigation. 

The molded liners for the inlet head, cylinder section, and conical sections have Integral molded gaskets for sealing at the flanged joints. Molded liners and vulcanized linings are offered in gum rubber, polyurethane, nitrile rubber, butyl. Neoprene , Viton , Hypalon , and other liner materials can be supplied. 

Figure 14-16F. Cutaway of large steam turbine, multistaged, multivalve, for driving mechanical rotating equipment. Connection to mechanical driven equipment shaft shown as a flange joint on right end of turbine shaft. Exhaust steam is at lower right, inlet steam is at bottom center near smaller wheels. (Used by permission Bui. 8908-E0MD. Dresser-Rand Company.)...

Where pipework is welded, the number of flanged joints should be kept to a minimum and such flanges shall be welded to the pipe. 

The amount of movement to be taken up by the piping and any device incorporated into it can be reduced by the use of cold draw . The total amount of expansion is first calculated for each section between fixed anchor points. The pipes are left short by half this amount, and stretched cold, as by pulling up bolts at a flanged joint, so that at ambient temperature the system is stressed in one... 

Pipe runs are normally made up from lengths of pipe, incorporating standard fittings for joints, bends and tees. Joints are usually welded but small sizes may be screwed. Flanged joints are used where this is a more convenient method of assembly, or if the joint will have to be frequently broken for maintenance. Flanged joints are normally used for the final connection to the process equipment, valves and ancillary equipment. 

Containment sound design of equipment and piping, to avoid leaks. For example, specifying welded joints in preference to gasketed flanged joints (liable to leak). 

Flanged joints are used for connecting pipes and instruments to vessels, for manhole covers, and for removable vessel heads when ease of access is required. Flanges may also be used on the vessel body, when it is necessary to divide the vessel into sections for transport or maintenance. Flanged joints are also used to connect pipes to other equipment, such as pumps and valves. Screwed joints are often used for small-diameter pipe connections, below 40 mm. Flanged joints are also used for connecting pipe sections where ease of assembly and dismantling is required for maintenance, but pipework will normally be welded to reduce costs. 

Processes and equipment should be designed to reduce the chances of mis-operation by providing tight control systems, alarms and interlocks. Sample points, process equipment drains, and pumps should be sited so that any leaks flow into the plant effluent collection system, not directly to sewers. Hold-up systems, tanks and ponds, should be provided to retain spills for treatment. Flanged joints should be kept to the minimum needed for the assembly and maintenance of equipment. 

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