General knowledge of pressure vessel classification and safety accessories

General knowledge of pressure vessel classification and safety accessories

There are many ways to classify pressure vessels, from the point of view of use, manufacture and supervision and inspection, there are the following:

Classification by design pressure

• ① low pressure (L) 0.1MPa ≤ P < 1.6MPa；
• ② medium pressure (M) 1.6MPa ≤ P < 10MPa；
• ③ high pressure (H) 10MPa ≤ P < 100MPa；
• ④ ultra-high pressure (U) P ≥ 100MPa.

Classification by the role of the process

Reaction pressure vessel (R)
Mainly used to complete the physical and chemical reaction of the medium pressure vessel. Such as reactor, reactor kettle, decomposition pot, vulcanization tank, decomposition tower, polymerization tower, autoclave, ultra-high pressure kettle, synthesis tower, transformation furnace, cooking pot, steam ball, autoclave, gas generating furnace, etc.
Heat exchange pressure vessel (E)
Mainly pressure vessels used to complete the heat exchange of media. Such as shell and tube waste heat boiler, heat exchanger, cooler, condenser, evaporator, heater, disinfection pot, dyer, drying cylinder, steam frying pan, preheating pot, solvent preheater, steam pot, steam off machine, electric steam generator, gas generator water jacket, etc.
Separation pressure vessel (S)
Mainly used to complete the medium of fluid pressure balance buffer and gas purification and separation of pressure vessels. Such as separators, filters, oil collectors, buffers, scrubbers, absorption towers, copper wash towers, drying towers, steam towers, sub-vapor cylinders, deaerators, etc.
Storage pressure vessel (C, where the spherical tank for B)
Mainly used for storage, holding gas, liquid, liquefied gas and other media pressure vessels, such as various types of storage tanks.

Comprehensive classification

Fixed pressure vessel
The use of fixed environment, can not be moved. A wide variety of working media, mostly toxic, flammable and explosive and corrosive types of chemical hazards. Such as spherical storage tanks, horizontal storage tanks, various heat exchangers, synthesis towers, reactors, dryers, separators, shell and tube waste heat boilers, manned containers (such as medical oxygen chambers), etc.
Mobile pressure vessel
Mainly used in the mobile, as a certain medium packaging piggybacked on the means of transport. Many of the working media are flammable, explosive or toxic. Such as cars and railroad tank cars tank.
Gas cylinder type pressure vessel
As a kind of pressure vessel, the society has a very large number of high-pressure gas cylinders (such as hydrogen, oxygen, nitrogen cylinders) and low-pressure gas cylinders (such as civilian LPG cylinders), many of the working medium is also flammable, explosive or toxic substances. There is also a strong mobility, both in the transport process of long-distance movement, but also in the specific use of short-distance movement. Such as liquefied petroleum gas cylinders, oxygen cylinders, hydrogen cylinders, nitrogen cylinders, carbon dioxide cylinders, liquid chlorine cylinders, liquid ammonia cylinders and dissolved acetylene cylinders, etc.

Safety accessories for pressure vessels

Safety valve

The role of the safety valve is to automatically open when the pressure in the equipment exceeds the specified requirements, releasing the excess pressure, so that the equipment back to the normal working pressure state. After the pressure is normal, the safety valve automatically closes.

After the safety valve is calibrated, it is strictly forbidden to add weight, move the weight, jam the valve flap and other means to arbitrarily increase the safety valve setting pressure or make the safety valve fail.
Pressure gauge

The range of the pressure gauge should be adapted to the working pressure of the equipment, usually 1.5-3 times the working pressure, preferably 2 times. The pressure gauge dial should be red line, pointing out the highest allowable working pressure. The connection pipe of the pressure gauge should not have water leakage or steam leakage, otherwise it will reduce the indication value of the pressure gauge.

Rupture disc
The rupture disc device consists of a rupture disc and a corresponding holder. The rupture disc is generally divided into shear type, bending type, positive arch ordinary tension type, positive arch open seam type, anti-arch type and other types.
Temperature measuring instrument
Need to control the wall temperature of the pressure vessel, should be installed to test the wall temperature of the temperature measuring instrument (or thermometer).
Liquid level meter
Pressure vessel level gauge should be selected according to the medium, maximum allowable working pressure and temperature of the pressure vessel.
Pressure reducing valve
Pressure vessel working pressure is lower than the pressure source pressure, the pressure reducing valve should be installed on the pipeline leading to the pressure vessel inlet, such as pressure reducing valve due to media conditions can not ensure reliable work, the regulating valve can be used instead of pressure reducing valve.
Emergency cut-off device
Its role is when the pipeline and its accessories rupture and misoperation or fire accident near the tanker, the valve can be urgently closed to quickly cut off the gas source to prevent the spread of the accident.
Safety interlocking device for quick-opening pressure vessels

Quick-opening safety interlock alarm device is to prevent the quick-opening pressure vessel operation accident effective measures. Its role is to:

• a. When the quick opening of the door to reach the intended closing part of the interlock control function before the pressure can be raised to run.
• b. When the internal pressure of the pressure vessel is completely released, the safety interlock device is disconnected, before opening the interlock linkage function of the fast opening door.
• c. Alarm function synchronized with the above actions.

Source: China Pressure Vessels Manufacturer – www.secmachinery.com