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GB/T 16508.5-2013 English PDF (GBT16508.5-2013)

GB/T 16508.5-2013 English PDF (GBT16508.5-2013)

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GB/T 16508.5-2013: Shell boilers ?€? Part 5: Safety appurtenances and instruments

This Part of GB/T 16508 specifies the requirements of setting and selecting etc. for safety appurtenances and instruments of shell boilers, including safety valve, pressure measuring device, water level measuring device, temperature measuring device, blowdown and drainage device and safety protection system. This Part is applicable to the shell boilers defined within the scope of GB/T 16508.1.
GB/T 16508.5-2013
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.060.30
J 98
Shell Boilers -- Part 5: Safety Appurtenances and
Instruments
ISSUED ON: DECEMBER 31, 2013
IMPLEMENTED ON: JULY 1, 2014
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the PRC;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 5
4 Basic Requirements ... 5
5 Safety Valves ... 6
6 Pressure Measuring Device ... 12
7 Water Level Measuring Device ... 14
8 Temperature Measuring Device ... 16
9 Blowdown and Drainage Device ... 17
10 Safety Protection Devices ... 18
11 Monitoring and Metering Instrument ... 22
12 Other Requirements ... 23
Shell Boilers -- Part 5: Safety Appurtenances and
Instruments
1 Scope
This Part of GB/T 16508 specifies the requirements of setting and selecting etc. for safety appurtenances and instruments of shell boilers, including safety valve, pressure measuring device, water level measuring device, temperature measuring device, blowdown and drainage device and safety protection system.
This Part is applicable to the shell boilers defined within the scope of GB/T 16508.1. 2 Normative References
The following documents are essential for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 1576 Water Quality for Industrial Boilers
GB/T 12145 Quality Criterion of Water and Steam for Generating Unit and Steam Power Equipment
GB/T 12241 Safety Valves - General Requirements
GB 13271 Emission Standard of Air Pollutants for Coal-burning Boilers
GB 50041 Code for Design of Boiler Plant
TSG G0001 Boiler Safety Technical Supervision Administration Regulation TSG G0002 Supervision Administration Regulation on Energy Conservation
Technology for Boiler
TSG ZF 001 Safety Valve - Safety Technical Supervision Administration
Regulation
operation of boilers.
4.2 All necessary parts as required in drawings and technical documents of boilers shall be equipped with measuring devices for pressure, water level and temperature. All those devices shall be safe, reliable and accurate and be provided with proper measuring range and local and remote transmission measuring devices for pressure, water level and temperature as required in regulations.
5 Safety Valves
5.1 Basic requirements
5.1.1 Technical requirements for the manufacturing license of safety valves, product type test, nameplate and quality certificate shall be in accordance with those specified in TSG ZF 001 Safety Technical Supervision Regulation for Safety Valve. 5.1.2 Each boiler shall be installed with at least two safety valves (including boiler drum and superheater safety valve). In case of any of the following conditions, only one safety valve may be installed:
a) The steam boiler whose rated evaporation is less than or equal to 0.5t/h; b) The steam boiler with a reliable overpressure interlock protection device and rated evaporation less than 4t/h;
c) Hot water boiler with a rated thermal power less than or equal to 2.8MW. 5.2 Selection of safety valve
5.2.1 For safety valve of steam boilers, fall-lift spring safety valve, lever safety valve or controlled safety valves (pulsed safety valve, pneumatic safety valve, hydraulic safety valve and electromagnetic safety valve etc.) shall be adopted and all these valves selected shall meet those specified in TSG ZF 001 Safety Technical Supervision Regulation for Safety Valve and the requirements of corresponding technical standards. 5.2.2 For steam boilers whose rated operating pressure is less than or equal to 0.1MPa, dead weight safety valve or water-sealed safety equipment may be adopted. In case that hot water boiler is equipped with water-sealed safety equipment, safety valve may not be installed. The inner diameter of sealing water tube for water-sealed safety equipment shall be determined in accordance with the rated evaporation (rated thermal power) and rated operating pressure of boilers and no less than 25mm. The sealing water tubes of water-sealed safety equipment shall not be provided with valves, but anti-freezing measures.
less than 0.3MPa, the maximum opening/closing pressure difference is 0.03MPa. 5.6 Installation of safety valve
5.6.1 The safety valve shall be installed vertically at the highest position of the shell and header; pipelines and valves for taking steams or hot water shall not be installed between the safety valve and the shell or between the safety valve and the header. 5.6.2 If several safety valves are installed together at a short tube that is directly connected with the shell, the flow sectional area of the tube shall be no less than the sum of the flow sectional areas of all safety valves.
5.6.3 Where the threaded spring safety valve is adopted, the requirements specified in GB/T 12241 shall be met. The safety valve shall be connected with the short tube with threads while the welded structure shall be adopted to connect the short tube with the shell or the header drum.
5.7 Devices on the safety valve
5.7.1 The basic requirements are as follows:
a) The dead weight safety valve shall be provided with devices to prevent the weight piece from flying off;
b) The spring safety valve shall be provided with a lifting handle and a device to prevent the screw from adjustment by random twisting;
c) The lever safety valve shall be provided with a device to prevent the heavy punch from moving automatically and a guide bracket to prevent the lever moving out.
5.7.2 The controlled safety valve shall be provided with reliable power source and power supply, and meet the following requirements:
a) Impulse of the impulse safety valve is connected to the valve on the duct and it shall be kept fully open and sealed with lead;
b) The safety valve controlled by compressed air is provided with reliable air supply and power supply;
c) The hydraulic safety valve is provided with reliable hydraulic transfer system and power supply;
d) The electromagnetic safety valve is provided with reliable power supply. 5.10.5 The inspection results such as the set pressure and airtightness of the safety valve shall be recorded into the boiler safety technology file.
5.11 Application of the safety valve during the operation of boiler
5.11.1 During the operation of boiler, the discharge test shall be carried out periodically. For controlled safety valve, the users shall carry out periodical test for the control system.
5.11.2 During the operation of boiler, it is forbidden that the safety valve be disconnected and set pressure increased randomly or the valve invalid.
6 Pressure Measuring Device
6.1 Setting
6.1.1 Pressure gauges shall be installed:
a) At the steam space of the steam boiler shell (drum);
b) In front of the feedwater control valve;
c) At the economizer outlet;
d) Between the superheater outlet and the main steam valve;
e) On the shell (drum) of hot water boiler;
f) At the outlet of the inflow valve and at the inlet of the outflow valve for the hot- water boiler;
g) At the circulating water pump outlet/ inlet of the hot-water boiler; h) At the oil pump inlet (return oil) and outlet of the ignition oil system for the oil- fired boiler and coal-fired boiler;
i) At the air supply inlet of the ignition gas system and at the back of the pressure maintaining valve (pressure control valve) of the gas valve set for the gas-fired boiler and coal-fired boiler.
6.1.2 Other requirements for the installation of pressure measuring device: a) In addition to meeting the requirements of 6.1.1, boiler furnace outlet whose c) A three-way valve shall be installed between the pressure gauge and the bent tube so as to purge the tube, change and calibrate the pressure gauge;
d) The connection pipeline of pressure gauge shall match with its maximum permissible operating pressure and temperature; where the temperature is larger than 208??C, the copper tube shall not be adopted;
e) The effect of liquid column static pressure shall be taken into consideration where the vertical distance between lead-out position of pressure gauge and monitoring position is larger than 10m.
6.5 Disuse conditions of the pressure gauge
In case of any of the following conditions, the pressure gauge shall be disused: a) As for the pressure gauge with limiting nail under no pressure condition, the hand fails to return to the limiting nail after rotation; as for the pressure gauge without limiting nail under no pressure condition, the value that the hand is away from the zero position exceeds the permissible deviation specified in the pressure gauge;
b) The glass on the surface is broken or the dial scale is blurry;
c) The seal is damaged or beyond the calibration period;
d) The gauge inside has leak or the hand is not stable;
e) The pressure gauge is subject to other defects that affect its accurate indication. 7 Water Level Measuring Device
7.1 Arrangement
At least two separate direct-reading water gauges shall be installed for each steam boiler shell (drum). For the boiler meeting one of the following conditions, one direct- reading water gauge may be installed:
a) With rated evaporation less than or equal to 0.5t/h;
b) Provided with the rated evaporation less than or equal to 2t/h and equipped with a set of reliable water level control device;
c) Installed with two sets of separate remote water level measuring devices; The installation of water gauge shall meet the following requirements:
a) The water gauge shall be installed at the position convenient for observing. Where the distance between the water gauge and the operation ground is
greater than 6m, the remote water level measuring device or water level video monitoring system shall be installed;
b) Where a single or several remote water level measuring devices are applied to monitor the boiler water level, the signal(s) shall be taken out separately. Two reliable remote water level measuring devices shall be installed in the boiler control room and during the operation of the boiler, one direct-reading water gauge shall be guaranteed to work normally.
8 Temperature Measuring Device
8.1 Arrangement
The temperature measuring device shall be arranged at the corresponding positions of the boiler to measure the following temperatures:
a) Feedwater temperature of steam boiler (except feedwater under normal temperature);
b) Outlet water temperature of cast-iron economizer;
c) Steam temperature of the superheater outlet as well as the sectionalized superheater outlet at each grade;
d) Front/rear steam temperature of desuperheater;
e) Fuel oil (light oil excluded) inlet oil temperature of the oil burner; f) Air preheater inlet/outlet air temperature;
g) Inlet gas temperature of the boiler air heater;
h) Discharge gas temperature: discharge gas temperature measuring instruments installed at steam boilers with rated evaporation larger than or equal to 20t/h or hot-water boiler with rated thermal power larger than or equal to 14MW shall be provided with recording function;
i) Inlet/outlet water temperature of the hot-water boiler;
on it;
f) Where one main blowdown tube is jointly used for several boilers, simultaneous blowdown from over two boilers shall be avoided;
g) Threaded connection should not be adopted for the boiler blowdown valve and blowdown tube.
9.2 Outlet tube of hot-water boiler is generally arranged at the topmost of boiler; and gas extractor shall be arranged at the topmost of outlet tube in front of outlet valve. Exhaust valve with nominal diameter greater than or equal to 20mm shall be arranged at the topmost of each loop and boiler shell (drum) or outlet tube. Exhaust tube at the topmost of each boiler loop should be centrally arranged.
9.3 Drain tube shall be arranged on the topmost of the boiler shell (drum) or outlet tube, its inner diameter shall be determined according to the rated thermal power of the boiler, and it shall be no less than 25mm. Relief valve shall be arranged on the drain tube and where the boiler is under normal operation, the relief valve is closed. For boiler arranged with relief valve, its boiler shell (drum) or outlet tube may not be arranged with exhaust valve.
9.4 Blowdown valve or drain valve shall be arranged in boiler shell (drum) as well as the lowest position of header under each circulation loop.
10 Safety Protection Devices
10.1 Basic requirements
10.1.1 Steam boiler shall be installed with high/low water level alarm and low water level interlock protection device (higher/low water level alarm signal shall be discriminated) and protection device shall operate at lowest safe water level at latest. 10.1.2 As for the boiler with rated evaporation larger than or equal to 6t/h, the steam overpressure alarm device and interlock protection device shall be installed; and the operation set value of the overpressure interlock protection device shall be less than the lower set pressure of the safety valve.
10.1.3 Boiler installed in the multistory or high-rise building shall be equipped with overpressure (overheat) interlock protection device.
10.1.4 Gas-fired boiler shall be provided with gas leakage monitoring and alarm device.
10.1.5 Superheat alarm device and interlock protection device shall be installed for hot-water boiler within the following range:
a) Rated operating pressure less than 3.8MPa, nominal outlet temperature less than 120??C and rated thermal power larger than or equal to 7MW;
b) Rated operating pressure less than 3.8MPa and nominal outlet temperature larger than or equal to 120??C.
10.1.6 For grate firing hot-water boiler, devices which can automatically stop air blast and induction shall be arranged where pressure of the boiler reduces to the degree that vaporization happens, or the water temperature exceeds the specified value and the circulating water pump stops working.
10.1.7 The suspension firing boiler shall be installed with the interlock device which has the following functions:
a) It will cut off all the air supply and fuel supply automatically where all draught fans are subject to tripping;
b) It will cut off all the fuel supply automatically where all draught fans are subject to tripping;
c) It will automatically cut off the fuel oil or gas supply where the pressure and gas pressure of the fuel oil and other atomized working medium are less than the specified value;
d) It will cut off the fuel supply automatically where the hot-water boiler pressure drops to the point where vaporization takes place or where the water
temperature rises higher than the specified value;
e) It will cut off the fuel supply automatically where the circulating water pump of the hot-water boiler suddenly stops operating and the standby pump fails to start normally.
10.1.8 Appropriate protection measures shall be adopted for superheater of boiler according to its operating mode, automatic control conditions and design structure of superheater to prevent the overtemperature of metal wall.
10.2 Ignition control program and flameout protection
The ignition control program and flameout protection device shall be installed in the suspension firing boiler and meet the following requirements:
also be provided with opening indication.
10.4.6 All valves and dampers operating mechanisms shall be installed at the position convenient for operation.
11 Monitoring and Metering Instrument
11.1 Flow
11.1.1 Steam flow metering device
Main steam valve outlet of steam boiler with rated evaporation greater than 4t/h shall be arranged with steam flow metering instrument which shall be provided with indication, integrating and recording functions.
11.1.2 Feedwater flow metering device
Feedwater tube at boiler inlet shall be arranged with feedwater flow metering instrument which shall be provided with indication, integrating and recording functions. 11.1.3 Circulating water flow metering device of hot-water boiler
Backwater inlet of hot-water boiler shall be arranged with circulating water flow metering instrument which shall be provided with indication, integrating and recording functions.
11.1.4 Water supplement volume metering device of hot-water boiler
Water supplement inlet of hot-water boiler with rated thermal power greater than 2.8MW shall be arranged with water supplement volume metering instrument which shall be provided with indication, integrating and recording functions. 11.2 Online oxygen content of flue gas
Online oxygen content of flue gas measuring instruments shall be arranged following final stage heating surface of steam boiler with rated evaporation greater than 10t/h and hot-water boiler with rated thermal power greater than 7MW. Flue gas oxygen content measuring instruments installed at steam boilers with rated evaporation larger than or equal to 20t/h or hot-water boiler with rated thermal power larger than or equal to 14MW shall be provided with recording function.
11.3 Fuel consumption of boiler

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