Safety relieve valve -steam safety valve
Safety valve is open-close part under the action of external force in a normally closed state, when a device orThe pipeWithin themediumPressure than specified value, through a discharge medium system to prevent the pipeline or equipment within the medium pressure in excess of the prescribed special valves.The relief valve belongs toAutomatic valveClass, it is mainly used forThe boiler,pressureContainers andThe pipeOn the control pressure shall not exceed the specified value, play an important protective effect on personal safety and equipment operation.Note the relief valve must pass through pressure test to use.
Usage
Reflux valves install at the liquid reflux pipe of LPG tank pump outlet. When the front pump pressure greater than rated value, safety reflux valve reduce pressure & back flow.
Structure
Safety reflux valve include flange parallel type (picture 4) and right-angle type (picture 2). Disc sealing material is PTFE (picture 5), good sealability. Valve open and close function is realized by the inlet and outlet different pressure.
Working principle
When inlet pressure is greater than outlet pressure of 0.5MPa, spring is compressed, and valve open automatically. When inlet pressure is less than outlet pressure of 0.5MPa, the valve get closed automatically by spring moving.
Selection principle
1, steamThe boilerThe relief valve, generally the selecting open typeThe relief valve springThe 0490 series;
2, liquid medium with safety valve, generally choose tiny qi spring 0485 series;
3, air or other gas medium with relief valve, generally choose the rev type spring safety valve;
4,Liquefied petroleum gas (LPG)Rail tanker car tank lorry or liquefied petroleum gas (LPG) with safety valve, generally choose the typeBuilt-in relief valve;
5, production export with safety valve, general selectionPilot operated relief valve;
6 high pressure bypass valve, steam power generation equipment, has a dual function of safety and control is generally selected pilot operated relief valve
7, if you want to do when you start the test on a regular basis, you should be chosen with wrench increased safety valve.When the medium pressure reaches more than 75% of the opening pressure, can use spanner to ascend will disc slightly, from the seat to check for the flexibility of the relief valve opens;
8, if the medium temperature is higher, in order to lower the temperature of the spring chamber, generally when the temperature of the safety valve in closed more than 300 ºC, and open the relief valve using the temperature over 350 ºC, the relief valve should be chosen with the radiator;
9 back pressure is changing, if the valve outlet, and its variation by more than 10% of the opening pressure, should be chosenCorrugated pipeThe relief valve.
10, if the medium iscorrosiveWhen, should choose bellows valve, prevent important parts failure due to corrosion by the medium.
11, the relief valve installation construction, installation and maintenance should be paid attention to the following points 1), the installation location, altitude, direction of import and export must comply with the design requirements, pay attention to the medium flow direction should be withThe valve bodyThe arrows in the same direction, connection should be firmly connected.2), a visual inspection must be conducted before installation of valve, the valve nameplate should be consistent with existing national standards "universal signal valve" GB 12220.For the working pressure is greater than 1.0 MPa and valve with the function of cutting off on ZhuGanGuan, strength and strict performance test should be done before the installation, qualified rear must use.Strength test, the test pressure is 1.5 times the nominal pressure, duration of not less than 5 min, valve shell,packingShould be no leakage as qualified.Leak test, the test pressure is 1.1 times the nominal pressure;The duration of the test in line with the requirements of GB 50243. 1. All kinds of safety valve should be installed vertically.
12, the relief valve outlet should be without resistance, avoid to produce compression phenomenon.
13, the relief valve should be specially test before installation, and check its seal.
14 and the relief valve should be of use in regular inspection.
Closed spring loaded low lift type high pressure safety valve
| NO. |
Name of part |
A41Y-160
A41Y-320 Materials |
A41Y-160P A41Y-320P Materials |
A41Y-160R A41Y-320R Materials |
| 1 |
Flange |
35/35CrMoA |
2Cr13 |
1Cr18Ni9Ti |
| 2 |
Nozzle |
2Cr13 |
1Cr18Ni9Ti |
1Cr18Ni12Mo2Ti |
| 3 |
Body |
35/40 |
1Cr18Ni9Ti |
1Cr18Ni12Mo2Ti |
| 4 |
Disc |
2Cr13 |
1Cr18Ni9Ti |
1Cr18Ni12Mo2Ti |
| 5 |
Guide sleeve |
2Cr13 |
1Cr18Ni9Ti |
1Cr18Ni12Mo2Ti |
| 6 |
Spring |
50CrVA |
50CrVA Coated Teflon |
50CrVA Coated Teflon |
| 7 |
Stem |
2Cr13 |
1Cr18Ni9Ti |
1Cr18Ni12Mo2Ti |
| 8 |
Bonnet |
ZG230-450 |
1Cr18Ni9Ti |
1Cr18Ni9Ti |
| 9 |
Adjusting bolt |
45 |
2Cr13 |
2Cr13 |
| 10 |
Cap |
ZG200-400 |
1Cr18Ni9Ti |
1Cr18Ni9Ti |
maintenance
1, the relief valve to prevent heavy hammer to mobile devices and limiting leverage deviant guide frame, the spring safety valve to have raise a hand and prevent twisted casually adjusting screw of the device.
2, it should be installed vertically in the pot, the top of the header.Between the relief valve and the drum or header, shall not be equipped with access steam outlet pipe and valve.
3, safety valve and connecting pipe of boiler, its cross-sectional area should not be less than import cross-sectional area of the relief valve.If several common relief valve installed in a short tube attached directly to the drum, the access of the short tube cross-sectional area should not step in all safety valve's steam discharge area is 1.25 times.
4, for the rated steam boiler pressure is less than or equal to 3.82 MPa, the relief valve throat diameter should not less than 25 mm;Rated for boiler steam pressure is greater than 3.82 MPa, the relief valve throat diameter should not less than 20 mm.
5, the relief valve should be installed commonly exhaust tube, exhaust steam pipe should be direct safety, and have enough area, ensure the exhaust steam flow.At the bottom of the relief valve exhaust pipe shall be fitted with drain pipe from safety, on the exhaust pipe and drain pipe, are not allowed to furnish the valve.
6, pressure vessel safety valve best directly on the top of the pressure vessel ontology.Liquefied gas storage tank safety valve must be installed in the gas phase.Generally available short tube connected to the container, the diameter of this relief valve spool valve diameter should not be less than the relief valve.
7, between the relief valve and container generally shall not be installed valves, containers of flammable and explosive or viscous medium, convenient to the clean or replace the relief valve, valve can be installed, the cut-off valve must be fully open during normal operation and sealing, avoid touch.
8, the rated capacity is greater than 0.5 t/h boiler, installed at least two relief valve;The rated capacity is less than or equal to 0.5 t/h boiler, install a relief valve at least.Split the economizer exit, steam superheater outlet must furnish the relief valve.
9, of flammable or toxic medium pressure vessel, the relief valve discharge medium must have a security device and recovery system.Lever of the relief valve installation must keep the vertical position, the spring safety valve is installed vertically, best so as not to affect its action.When installation, also should pay attention to, and the alignment of the parts and should make the bolts evenly stress.
10, exports of the relief valve should be without resistance, avoiding the phenomenon of back pressure, if installed drainage tube, its export of inner diameter should be greater than the relief valve size, safety valve mouth should pay attention to prevent frostbite, for holding containers of flammable or toxic, highly toxic medium, a discharge line should be straight outdoor safety facilities or have to properly handle, any valve discharge line are not allowed to be installed.
11, the new relief valve shall be accompanied by product certificate, after school, before installation to seal and issue a safety valve calibration.
12, any valve between the relief valve shall not be equipped with pressure equipment, to fill inflammable, explosive, toxic or container of viscous medium, for ease of replacement, cleaning, can be cut-off valve, the structure and size size should not interfere with the normal operation of the relief valve.During normal operation, the valve must be fully open and seal.
Relief valve belong to automatic valve class, mainly for the boiler, pressure vessel and piping, control pressure shall not exceed the specified value, to protect personal safety and equipment operation plays an important role.
Technical term
The relief valve
Nominal pressure: it means under the state of the maximum allowable pressure relief valve,High temperature equipmentUse of the relief valve should not be considered under the high temperature material allowable stress reduce.The relief valve is according to the nominal pressure standard design and manufacture.
Opening pressure: also calledThe rated pressureOr setting pressure, it is to point to the relief valve disc under operating conditions arise when the inlet pressure, under the pressure, began to have a measurable open height, medium show by visual or auditory perception of continuous discharge state.
Discharge pressure: disc reach regulation when you start the height of inlet pressure.The cap on the discharge pressure to conform to the demands of the relevant national standards or specifications.
More than pressure, discharge pressure and opening pressure difference, usually expressed in the percentage of opening pressure.
Emissions back pressure: disc and seat again after contact, the opening into the inlet pressure to the zero.
Pressure difference for opening and closing, opening pressure and back pressure difference, usually expressed in back pressure and the percentage of opening pressure, only using both when opening pressure is very lowThe pressure differenceTo represent.
Back pressure: pressure relief valve outlet.
The rated discharge pressure: the upper limit of discharge pressure prescribed standards.
Sealing test pressure: the inlet pressure to the sealing experiment was carried out, under the pressure measured by closing a sealing surface leakage rate.
Opening: disc leave the actual lift in the closed position.
Port area: refers to the inlet valve is to shut down the smallest cross-sectional area of flow channel between a sealing surface, used to calculate without the theoretical displacement of impact resistance.
The runner diameter: corresponding to the diameter of the port area.
Shade area: when the disc in the seat above, in the form of formed between the sealing surface of a cylinder or cone surface shape channel area.
Discharge area: valve discharge fluid channel, the minimum cross-sectional area.For full enlightenment, relief valve discharge area is equal to the port area;To raise safety valve, discharge area is equal to the shade area.
Theory of displacement: it is with flow cross-sectionThe relief valve flow areaThe ideal of equal nozzle displacement calculation.
Discharge coefficient, the ratio of actual displacement and displacement theory.
Rated capacity coefficient, displacement coefficient and reduce the product of the coefficient (0.9).
Is allowed in the rated capacity: refers to the actual delivery as that part of the relief valve applicable benchmark.
Equivalent calculation of displacement: refers to the condition such as pressure, temperature, characteristic of medium and the application of the rated discharge conditions at the same time, the calculation of the relief valve discharge.
Frequency jump: unusually rapid movement back and forth the relief valve disc and disc contact seat in the movement.
Chatter: unusually rapid movement back and forth the relief valve disc and the disc does not contact the seat in the movement.
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