Bolted closures

After the initial hydrogenation studies were completed with WVGS 13407, all other liquefaction experiments were conducted in a larger, 3.8-liter bolted-closure autoclave fitted with an electrically driven magnetic stirrer arbitrarily set to provide mixmg at 1000 rpm. A temperature controller and power supply were connected to a three-zone furnace to control reaction temperature... 

The heart of the system is the oxidation vessel depicted in Figure 1. This vessel is a high pressure, 1000 cc, Hastelloy C-276, bolted closure reactor manufactured by Autoclave Engineers Inc. Hastelloy C-276 was chosen as the material of construction due to its excellent corrosion resistance to a wide variety of chemical process environments, which include processes utilizing strong oxidizers (5,6,7). The unit is fitted with 1/8" and 1/4" Hastelloy C-276 feed delivery and product outlet lines... 

Flat gasket seals must be preloaded with a force equivalent to the force that will be exerted by the pressure within the vessel. A flanged bolt closure or split ring bolt closure design can be used to achieve this preload. Closure bolts should be evenly tightened to a specified torque that will provide the proper closing force. 

Fig. 3-5 Conventional flange-and-bolt closure for batch reactor...

In some cases, bolted closure vessels that are being used to conduct tests which involve very high temperatiujes (>250°C) may experience thermal expansion of the bolts in the closure. This situation can result in a relaxation of the... 

Yokes. The need to couple the end cover to the body of the vessel may be avoided if yokes, external to the vessel, are used to resist the load arising from the internal pressure acting on the closures. However the necessity to move the vessel out of the yoke and remove one of the closures to gain access to the inside of the vessel limits its use for chemical process equipment. Yokes may be pinned, welded, bolted, or wire wound. Both the vessel and yoke maybe wire wound (136). 

Unstayed flat heads and covers can be designed by very specific rules and formulas given in this subsection. The stresses caused by pressure on these members are bending stresses, and the formulas include an allowance for additional edge moments induced when the head, cover, or blind flange is attached By bolts. Rules are provided for quick-opening closures because of the risk of incomplete attachment or opening while the vessel is pressurized. Rules for braced and stayed surfaces are also provided. 

The rest of the rules in Part AD for flat heads, bolted and studded connections, quick-actuating closures, and layered vessels essentially duphcate Division 1. The rules for support skirts are more definitive in Division 2. 

Figure 2. Diagram of laboratory reactor (1) glass reactor vessel (2) inlet port (3) outlet port (4) thermocouple port (5) propeller impeller (6) turbine impeller (7) impeller shaft (8) stainless steel center plug (9) Teflon center plug (10) center bolt (11) interface plate (12) flange assembly (13) Chemco reactor support (14) Chemco reactor top closure plate (15) Chemco reactor impeller shaft bearing housing (16) reactor blead port...

Figure 13.9. Flat-end closures (a) Flanged plate (b) Welded plate (c) Welded plate (d) Bolted cover...

Flanged openings shall be provided with metal closures at least 5 mm (0.19 in.) thick, with elastomer gaskets and at least four full diameter bolts. For studded openings, all nuts needed for the intended service shall be used to secure closures. 

The most commonly used types of closures are shown in Fig. 4.3-18 [14], The cover seals (Fig. 4.3-18 A - E) are attached by means of threaded bolts and are used for all diameters and pressure ranges. The bolts are generally tightened hydraulically or pneumatically. It is, however, also possible to pre-stress the bolts longitudinally and then to tighten the nuts. 

Fig. 10.11. Metal gasket sealed bolted flange closures. A soft metal gasket, generally made of aluminum or copper, is clamped between knife edges (ci) or stepped flanges (b).

Fig. 10.10. O-Ring sealed bolted flange closure. This type of joint is used for large diameter openings. The groove to receive an O-ring seal is machined so that the depth E is 0% of the O-ring width and Fis 135% of the O-ring width. The extra clearance is on the inside of the groove for applications in which the apparatus is to be pressurized and on the outside of the groove when the apparatus is to be evacuated.

Tinkering with Pressured Vessel-Closure Bolts Ends with a Harmless Bang... 

Figure 8-5 A close-up look at the quick closure bolts that failed on the sand pot.

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