Manhole Covers

Chlorine is stored and transported as a Hquefied gas in cylinders of 45.4-kg or 68-kg capacity that are under pressure and equipped with fusible-plug rehef devices. Quantities in the range of 15 to 90 t are transported in tank cars having special angle valves on the manhole cover on top of the vessel. Tank barges of the open-hopper type having several cylindrical uninsulated pressure vessels are used for amounts ranging from 600 to 1200 t. Road tankers are used for capacities of 15 to 20 t. 

Fig. UW-13.2. UA-4S to 52. UA-SS. Fig. UA 48. Appendix S Bolted flange. Spherical cover UA-6 Manhole cover plate. UG-11. UG-46 Flued openings. UG-32. UG-38. Fig. UG-38 Yoke. UG-11...

An operator had tested dryer samples on a number of occasions. After the last sampling, he closed the manhole cover, put the dryer under vacuum, and started rotation of the dryer. A few minutes later an explosion and flash fire occurred, which self-extinguished. No one was injured. Investigations revealed that after... 

As an example. Fig. 20-7 shows potential and protection currents of two parallel-connected 750-liter tanks as a function of service life. The protection equipment consists of a potential-controlled protection current rectifier, a 0.4-m long impressed current anode built into the manhole cover, and an Ag-AgCl electrode built into the same manhole [10,11]. A second reference electrode serves to control the tank potential this is attached separately to the opposite wall of the tank. During the whole of the control period, cathodic protection is ensured on the basis of the potential measurement. The sharp decrease in protection current in the first few months is due to the formation of calcareous deposits. 

Vacuum Pressure-V acuum Relief Manhole Cover Pressure Safety Valve ... 

If the tank vent is not large enough to pass the liquid inlet rate, then the tank should be fitted with a hinged manhole cover or similar overflow device. Proprietary devices are available. 

A similar incident occurred in a tank truck used to cany waste liquids. While it was being filled with a nonflammable liquid and the driver was standing on the top, smoking, an explosion occurred, and the manhole cover was thrown 60 m. On its previous Journey the tank truck had carried a waste liquid containing dissolved flammable gas. Some of the gas was left in the tank and was pushed out when it was filled with the next load. For other examples see Reference lO. 

Either the driver forgot to vent the tank or thought it would be safe to let the pressure (a gauge pressure of 10 psi or 0.7 bar) blow off through the manhole. After the accident the manhole covers were replaced by a... 

The manhole covers on tank cars are sometimes sealed with wires. Loose ends of wires protruding above the manhole cover have come into contact with the overhead electric wire, which supplies power to the train, and caused a short circuit. 

The manhole-cover assembly on the tank struck a rock the resulting rupture of the tank head caused propane to escape. There were woods on one side of the road on the other side a steeply rising embankment and trees and bushes, and then a steep dropoff to a creek. 

Figure 7-39B. Hinged emergency pressure manhole cover vent. By permission, The Protectoseal Co.

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. 

The traditional unpredictably violent nature of the Skraup reaction (preparation of quinoline and derivatives by treating anilines with glycerol, sulfuric acid and an oxidant, usually nitrobenzene) is attributed to lack of stirring and adequate temperature control in many published descriptions [1], A reaction on 450 1 scale, in which sulfuric acid was added to a stirred mixture of aniline, glycerol, nitrobenzene, ferrous sulfate and water, went out of control soon after the addition. A 150 mm rupture disk blew out first, followed by the manhole cover of the vessel. The violent reaction was attributed to doubling the scale of the reaction, an unusually high ambient temperature (reaction contents at 32°C) and the accidental addition of excess acid. Experiment showed that a critical temperature of 120°C was attained immediately on addition of excess acid under these conditions [2],... 

The more obvious forms of public art include monuments, sculptures, fountains, murals, and gardens. But public art also takes the form of ornamental benches or street lights, decorative manhole covers, and mosaics on trash bins. Many city dwellers would be surprised (10) to discover just how much public art is really around them and how... 

Move as quickly as possible with the most obvious and cost-effective physical improvements, such as perimeter fences, security lighting, tamper-proof manhole covers and valve boxes, etc. 

Cleveland, USA 1944 LNG 136 killed, surrounding streets swept with burning gas. Windows broken, pavements raised up and manhole covers blown over buildings. Fire engine blown into the air FB CVE... 

This idea of the conservation of energy is at the heart of any process plant. In the case of the Chicago Water Treatment Plant, the reduced velocity of the water was converted into feet of head. That is, the elevation of the water in the sump suddenly increased, and blew the manhole covers off the top of the sump. 

The mass of water in our pipeline weighed 160 X106 lb. This much water, moving at 8 ft/s, represents a tremendous amount of energy (about 500 million Btu per hour). If the flow of water is cut in half, then the momentum of the water flowing in the pipeline is also cut in half. This energy cannot simply disappear. It has to go somewhere. The energy is converted to an increase of feet of head in the sump that is, the water level in the sump jumps up, and blows the manhole covers off the top of the sump. 

Manhole covers Consumer products Tool boxes... 

Cost of kettles. Purchased cost includes kettle, jacket, agitator, thermometer well, drive and support, manhole cover, stuffing box, and clamps where necessary. Installed cost includes above plus installation costs (labor, material, and overhead), design, and expense. (No piping, structural changes, instrumentation. or electrical charges are included.)... 

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... 

A stirred tank containing liquid CS2 solvent had to be cleaned because of solid residue that had accumulated in the stirrer. To avoid a possible fire and explosion, the CS2 was pumped out and the tank blanketed with nitrogen. Then the manhole cover was removed from the top of the tank, and a worker started to remove the solid from the stirrer rod with a scraper. At this point the maintenance worker left for lunch. When he returned to complete the job, a spark caused by the scraper striking the stirrer rod started a flash fire. 

Manhole cover with large light and sight glasses... 

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