Pressure vessels supports

ORNL/TM-10966, "Impact of Radiation Embrittlement on the Integrity of Pressure Vessel Supports for Two PWR Plants", Oak Ridge National Laboratory, 1988. 

Reactor pressure vessel supports are subject to neutron irradiation at low temperature during plant operation. The neutron flux is lower than that at RPV, but the low irradiation temperature could result in higher embrittlement rate. Some reactor pressure vessel supports were fabricated without special requirements on fracture and radiation resistance. Steel surveillance specimens that had been irradiated in an environment believed to be similar to that in operating reactor cavities exhibited a greater than expected shift (increase) in the nil-ductility-transition temperature. This indicated that there was a potential for excessive embrittlement of reactor vessel supports. Moreover, the RPV supports are in many cases difficult to access or inaccessible for in-service inspection. 

NUREG/CR-5644, Consequence evaluation of radiation embrittlement of Trojan reactor pressure vessel supports, Oak Ridge National Laboratory, October, 1990. 

NUREG/CR-5320, Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants. Oak Ridge National Laboratory, January, 1989. 

NUREG-1509, Radiation effects on reactor pressure vessel supports, US Nuclear Regulatory Commission, to be issued. 

Another possibiUty is to enclose only the working, top part of the horizontal belt in a pressure vessel and pass the belt through the sides of the vessel. The operation must be intermittent because the belt cannot be dragged over the support surface with the pressure on, and the entrance and exit ports for the belt must be sealed during operation to prevent excessive losses of air. The movement of the belt is intermittent and is synchronized with decompression in the vessel therefore, the entire vessel volume must be depressurized in every cycle and this is wasteful. There is also an inevitable downtime. There are no problems with discharging the cake because this is done at atmospheric pressure. 

Reductive alkylations and aminations requite pressure-rated reaction vessels and hiUy contained and blanketed support equipment. Nitrile hydrogenations are similar in thein requirements. Arylamine hydrogenations have historically required very high pressure vessel materials of constmction. A nominal breakpoint of 8 MPa (- 1200 psi) requites yet heavier wall constmction and correspondingly more expensive hydrogen pressurization. Heat transfer must be adequate, for the heat of reaction in arylamine ring reduction is - 50 kJ/mol (12 kcal/mol) (59). Solvents employed to maintain catalyst activity and improve heat-transfer efficiency reduce effective hydrogen partial pressures and requite fractionation from product and recycle to prove cost-effective. 

Internal Cake Tube Filters or Liquid Bag Filters This type of filter, such as manufactured by Industrial Filter and Pump Mfg. Co., Rosedale, Illinois, and many others, utihzes one or more perforated tubes supported by a tube sheet or by the hp of the pressure vessel. A cyhndrical filter bag sealed at one end is inserted into the perforated... 

Tubular Tubular membranes (Fig. 22-51) are supported by a pressure vessel, iisiiallv perForated or porous. It can be as simple as a wrapped nonw oven Fabric, or as robust as a stainless-steel tube. All rim with tube-side Feed. Thev are rnainlv used For UF, with some RO applications, particularly For Food and daiiw. The primary diameters available are 12 and 25 mm. Tubes are oFten connected in series parallel bundles, gasketed or potted, are also common. 

Figure 15.19 Examples of crack patterns due to stress-corrosion cracking and corrosion fatigue in branch connections and vessel or pipe support attachment welds. (Reprinted with permission from Helmut Thielsch, Defects and Failures in Pressure Vessels and Piping, New York, Van Nostrand Reinhold, 1965.)...

Pressure storage tanks should be coirelated using /lb vs. w eight, much the same as other pressure vessels. Materials of construction, of course, would be another variable. Special internals, insulation, and internal heat exchangers should again be separated from the base cost of the tank. The w eight of supports, ladders, and platforms should be estimated and added to the weight of the... 

Zick, L. P., Stresses in Large Horizontal Cylindrical Pressure Vessels on Two Saddle Supports, Welding Journal Research Supplement, 1951. 

The hollow fine fiber configuration (refer to Figure 51) consists of a bundle of porous hollow fine fibers. These fibers are externally coated with the actual membrane and form the support structure for it. Both ends of each fiber are set in a single epoxy tube sheet, which includes an 0-ring seal to match the inside diameter of the pressure vessel. 

Normally the filter strueture consists of a stack of plates attached to a hollow shaft which are mounted inside a pressure vessel with eaeh plate eovered with a suitable filter medium. The slurry is fed under pressure into the vessel and the eake, which is retained by the filter medium, forms on the top of eaeh plate whilst the filtrate passes through the hollow shaft further to the proeess. Filter sizes may vary but generally the maximum is 60 m area and designed for a 6 bar operating pressure. Each circular plate in the staek is eonstructed with radial ribs that are welded to the bottom and support a horizontal eoarse mesh screen whieh is eovered with a fmer woven metal screen or filter cloth to retain the cake. The bottom of the plate slopes towards the hollow eentral shaft whieh lets the filtrate flow freely through circumferential holes and further down the shaft to the filtrate outlet. The elearanee between the plates is maintained by speeial spacers... 

A vertical cylindrical, and mechanical agitated pressure vessel, equipped with baffles to prevent vortex formation is the most widely used fermenter configuration. The baffles are typically one-tenth of the fermenter diameter in widtli, and are welded to supports tliat extend from the sidewall. A small space between the sidewall and the baffle enables cleaning. Internal heat transfer tube bundles can also be used as baffles. The vessels must withstand a 45 psig internal pressure and full vacuum of -14.7 psig, and comply with the ASME code. 

Standards and codes have very speeific safety requirements for Uie design of tanks for flaimiiable liquids or gases and pressurized chemicals such as aimnonia. Overpressure devices and vents are included in Uie design. Tank and vessel supports should be built for the ma.ximum intended load. 

Try 1/ -inch (i.d. = 1.61), since 114-inch (i.d. = 1.38) is not stocked in every plant. If it is an acceptable plant pipe size, then it should be considered and checked, as it would probably be as good pressure drop-wise as the 114-inch. The support of 114-inch pipe may require shorter support spans than the 114-inch. Most plants prefer a minimum of 114-inch valves on pressure vessels, tanks, etc. The valves at the vessels should be 114 inch even though the pipe might be VA inch The control valve system of gate and globe valves could very well be lA inch. For this example, use 114-inch pipe, Schedule 40 ... 

In 1854, the Manchester Steam Users Association was formed to help with the prevention of explosions in steam boilers and to find efficient methods in their use. To achieve this, the Association employed the first boiler inspectors, whose services were then made available to the Association s members. Within a short space of time, the members became convinced that insurance to cover the high cost of repair or replacement of damaged boilers was desirable, and this resulted in the first boiler insurance company (The Steam Boiler Assurance Company) being formed in 1858. The scope of the services for inspection and insurance later extended to include pressure vessels, steam engines, cranes, lifts and electrical plant, the insurance protection in each case being supported by an inspection service carried out by qualified engineer surveyors. 

Zick, L. P. (1951) Welding J. Research Supplement 30, 435. Stresses in large horizontal cylindrical pressure vessels on two saddle supports. 

The load from piping and pipe-supporting elements (including restraints and braces) shall be suitably transmitted to a pressure vessel, building, platform, support structure, foundation, or to other piping capable of bearing the load without deleterious effects. 

Each type of pressure leaf filter features a pressure vessel in which are located one or more filter elements or leaves of circular or rectangular construction. The filter media may be in the form of a synthetic fibre or other fabrics, or metallic mesh. Supports and intermediate drainage members are in coarse mesh with all components held together by edge binding. Leaf outlets are connected individually to an outlet manifold which passes through the wall of the pressure vessel. 

---