The selection and installation of Boiler and pressure vessel
selection requirements
1、 Safety valve models, specifications, setting parameters, material should meet the design requirements.
2、 with certification, quality certificates, and exhaust volume calculations or summary sheet.
3、 complete factory nameplate, spring type safety valve has the screw device that prevents the random dynamic adjustment screws, lever type safety valve has the limit device that prevents heavy hammer movement and leverage offside, the upper and lower adjust ring adjustment bolt should be lead sealing.
4、 purchase to gain quality system qualification or large enterprise products.
5、 high, medium pressure safety valve should be asked manufacturer for equipment drawing, easy to repair and maintenance.
installation requirements
1、 Number of installations, models, specifications and location should be consistent with design requirements.
2、 safety valve in the check passing period, the test exhaust steam (gas) or hydraulic pressure set normally.
3、 steam rigorous checking should be no leakage.
4、 impulse safety valve connects impulse pipes with insulation, and pipe internal diameter is greater than or equal to 15mm, air chamber safety valve is equipped with a reliable gas source.
5、 safety valve and the drum, joint boxes, pressure vessel connecting pipe seat should not be generally equipped with valve and gain media extraction pipe. Dangerous medium can be equipped with valves, but the valve must be always open, and hang warning signs.
6、 the safety valve exhaust steam pipe settings are correct, and have a reliable hangers, the bottom of exhaust pipe drain pipe should be installed valve, should ensure smooth hydrophobic routed to a safe place. Strictly forbidden a few safety valve to share one drain pipe, easy to block drainage pipes.
7、 Safety valve exhaust pipe outlet is equipped with environmental protection requirements muffler, muffler should have sufficient space for the emission area and the expansion space, and fixed fastness. Exhaust pipe and muffler have enough strength, their butt welding meets the requirements.
8、 When out of factory, the safety valve should have a metal plate. Metal plate at least contain the following items: safety valve models, specifications; factory name, and manufacturing license number; product number; out factory date; Nominal pressure (MPa); medium temperature (℃); valve throat diameter (mm); disc opening height (mm); test passing mark, supervisory inspection mark; emission factor (the actual exhaust volume / theory exhaust volume), determined by safety valve manufacturer testing.
9、 safety valve installation of quality testing requirements. The test item are as follows: alloy steel components, spectral analysis materials without error use; between disc and seat joints is non-pitting, grooves, using red ink check and 100% good connection; parts machining accuracy, comply with documentation requirements for equipment and technology ; alloy steel bolt hardness test, meet the material performance requirements; body appearance is without trachoma, crack defects; valve spring appearance is free of cracks, delamination, surface and spring at both ends of the vertical center line, its material and dimensions meet the technical documentation requirements; high, medium pressure and large-scale manufacturers should provide a safety valve of its spring characteristic curve; stem curvature should be ≤ 0.1/1000mm of stem length. Safety valve components with the gap, in line with equipment technical documentation requirements; safety valve piston chamber appearance is crack-free groove defects; valve opening trip to meet the requirements; safety valve flange connection meets the requirements; welding safety valve welded joint metal testing meets the requirements; impulsed electromagnetic devices and transmission lever valve position is correct, fixed strongly; lever-type impulse valve lever should be level, power point and the pivot assembly should be non-distorted cross-eyes, heavy hammer fixed solid; impulse pipe should be clean, pulse valves and piping supports should be arranged reasonably, fixed strongly, craft beautifully.
Commissioning requirements
1、 The check department should have engineers and technicians that adapt to the safety valve check work, calibration equipment, installations and sites, and establish the necessary rules and regulations. The check valve personnel should have safety valve basic knowledge, familiar with it and able to perform safety valve verification aspects of the relevant standards, procedures, check work should have detailed records, after passing the check, the deparment issues the verification report and is responsible for check results. safety valve passed the check should be installed lead sealing.
2、 When using pressure vessel safety valve to on-site check and adjust pressure, the using department in charge of Pressure Vessel Safety Authority engineering and technical personnel should recognize on site. Debugging qualified safety valve should be adjusted back tight cap, recovering the back cap cover. Adjustment and calibration devices pressure gauge precision should not less than one level. For the high, middle pressure safety valve should be installed in the 0.25 to 0.4 level precision pressure gauge (pressure gauge in the verification qualified effective cycle). When debugging the safety valve, there should be a reliable debugging measure for safety valve.
3、 Boiler Pressure Vessel Safety Valve is usually checked at least once a year. Before installing the new valve, it should be debugged based on the using condition, and then to install.
4、 Starting seat pressure of the boiler safety valve is according to manufacturer regulations. No provisions of the factory calibration can according to Table 1. The back seat pressure differential normally is the 4% ~ 7% of starting seat pressure, the biggest pressure is not more than 10% of the starting seat pressure. The safety valve should have good sealing performance under running pressure.
5、 When fixed type pressure vessel installs one safety valve, the opening pressure P开 should not greater than the pressure vessel design pressure P设, and the sealing pressure P密 should larger than the maximum working pressure P工 .
6、 Fixed pressure vessels are equipped with multiple safety valves, one opening pressure should not be greater than the pressure vessel design pressure, the other safety valves opening pressure can be properly increased to 1.1 times of the working pressure, but shall not exceed the 1.05 times of design pressure.
7、 Mobile type pressure vessels opening pressure should be 1.05 ~ 1.10 times of the tank design pressure, the rated discharge pressure of safety valve shall not exceed 1.2 times of the tank design pressure, the back seat pressure should not be less than 0.8 times of the opening pressure.
8、 Deaerator safety valve starting seat pressure: constant pressure running is 1.25-1.3 times of the rated working pressure, sliding pressure operation is 1.20 ~ 1.25 times of rated working pressure (typically 1.10 ~ 1.15 times of rated working pressure).
9、 Thermal systems other pressure vessel safety valve starting seat pressure should less than or equal to the containers design pressure. Checking according to fixed pressure vessel safety valve starting seat pressure.
