GB/T 16508.5-2022 PDF in English
GB/T 16508.5-2022 (GB/T16508.5-2022, GBT 16508.5-2022, GBT16508.5-2022)
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Shell boilers - Part 5: Safety appurtenances and instruments
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| GB/T 16508.5-2013 | English | 140 |
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Standards related to (historical): GB/T 16508.5-2022
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GB/T 16508.5-2022: PDF in English (GBT 16508.5-2022) GB/T 16508.5-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 27.060.30
CCS J 98
Replacing GB/T 16508.5-2013
Shell boilers - Part 5: Safety appurtenances and instruments
ISSUED ON: MARCH 09, 2022
IMPLEMENTED ON: OCTOBER 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 6
1 Scope ... 8
2 Normative references ... 8
3 Terms, definitions and symbols ... 8
4 Basic requirements ... 9
5 Safety valve ... 9
6 Pressure measuring device ... 15
7 Water level measuring device ... 16
8 Temperature measuring device ... 18
9 Sewage and water discharge device ... 19
10 Safeguards and other devices ... 20
Bibliography ... 24
Shell boilers - Part 5: Safety appurtenances and instruments
1 Scope
This document specifies the requirements for safety appurtenances and instruments of
shell boilers, including safety valves, pressure measuring devices, water level
measuring devices, temperature measuring devices, sewage and water discharge
devices, safety protection and other devices.
This document applies to the safety appurtenances and instruments selected for shell
boilers defined in GB/T 16508.1.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 2900.48, Electrotechnical terminology of boilers
GB/T 12241, Safety valves - General requirements
GB/T 16508.1, Shell boilers - Part 1: General requirements
GB/T 16508.3, Shell boilers - Part 3: Design and strength calculation
GB/T 36699, Specification for liquid fuels and gaseous fuels burners of boilers
NB/T 47063, Safety valves for power station
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions defined in GB/T 2900.48
and GB/T 16508.1 as well as the followings apply.
3.1 set pressure of safety valve
The set pressure at which a safety valve begins to open under operating conditions.
3.2 ignition safety time
The safety time for burner ignition flame to ignite. That is, when no ignition flame is
formed, the time interval between the ignition fuel control valve getting the opening
signal and the closing signal.
3.3 extinction safety time
When the burner is running, the time interval from when the flame detection device
sends out the signal of flame extinguishment to when the safety shut-off valve starts to
close.
4 Basic requirements
4.1 The safety appurtenances and instruments configured by the boiler shall meet the
requirements for safe and reliable operation of the boiler.
4.2 The safety appurtenances and instruments configured by the boiler shall meet the
requirements of relevant product standards.
4.3 All necessary parts required by boiler drawings and technical documents shall be
equipped with measuring devices such as pressure, water level and temperature. The
measuring device shall have an appropriate range and be safe and reliable. The
measured values shall be accurate enough. Configure local and remote pressure, water
level and temperature measuring devices according to the requirements of this
document.
4.4 The calibration and maintenance of measuring instruments shall comply with the
regulations of the national metrology management department.
5 Safety valve
5.1 Quantity and type
5.1.1 Each boiler shall be equipped with at least two safety valves (including drum and
superheater safety valves). Only one safety valve may be installed if one of the
following requirements is met:
a) Steam boilers with rated evaporation not greater than 0.5 t/h;
b) Steam boilers with rated evaporation less than 2 t/h and equipped with reliable
overpressure interlock protection device;
c) Hot water boilers with a rated heating power no greater than 2.8 MW.
5.1.2 Steam boilers shall adopt full-open spring safety valves, lever safety valves or
control safety valves (including pulse type, pneumatic type, hydraulic type and
electromagnetic type, etc.). The hot water boiler can use a micro-opening safety valve.
The selected safety valve shall meet the requirements of the corresponding technical
transmission system.
5.4.7 The safety valve exhaust pipe of the steam boiler meets the following
requirements.
a) Steam boiler safety valve shall be equipped with exhaust pipe. The exhaust pipe
shall lead directly to a safe place. There shall be enough flow cross-sectional area.
Ensure smooth exhaust. At the same time, the exhaust pipe shall be fixed. Avoid
affecting the correct action of the safety valve due to thermal expansion or exhaust
steam reaction. There shall not be any external force from the exhaust pipe
applied to the safety valve.
b) The exhaust pipes of two independent safety valves shall not be connected.
c) The exhaust pipe arranged in the open air shall be equipped with a protective cover.
The installation of the protective cover shall not hinder the normal operation and
maintenance of the safety valve.
d) When the exhaust pipe of the safety valve is equipped with a muffler, its structure
shall have a sufficient flow cross-sectional area. There must be a suitable bracket
and a reliable hydrophobic device.
e) The bottom of the exhaust pipe of the safety valve shall be equipped with a
drainpipe connected to a safe place. Valves shall not be installed on discharge
pipes and drainpipes.
5.4.8 The safety valve of the hot water boiler shall be equipped with a discharge pipe.
The discharge pipe shall lead directly to a safe place. There is enough discharge flow
area to ensure smooth discharge. Valves shall not be installed on the discharge pipe.
Antifreeze measures shall be taken.
5.5 Use and verification
5.5.1 After the safety valve is installed (including maintenance and replacement), its set
pressure and tightness shall be verified. For the control type safety valve, the reliability
test of the control circuit and the opening performance test shall be carried out,
respectively.
5.5.2 After the safety valve is verified, it shall be locked or sealed. The inspection results
of the set pressure and tightness shall be recorded in the boiler safety technical file.
5.5.3 During the operation of the boiler, the safety valve shall not be disconnected
arbitrarily; the set pressure of the safety valve shall not be increased arbitrarily, or the
safety valve shall not be invalidated.
5.5.4 During the operation of the boiler, the discharge test of the safety valve shall be
carried out regularly. For control type safety valves, the control system shall be tested
regularly.
5.5.5 In-use boiler safety valves are verified at least once a year. Verification is generally
carried out when the boiler is running. If the on-site verification is difficult or after the
safety valve is repaired, it can be carried out on the safety valve verification platform.
The verified safety valve shall not be dropped, smashed or collided during
transportation or installation.
6 Pressure measuring device
6.1 Each boiler shall be equipped with pressure gauges at the following locations:
a) in the steam space of the steam boiler shell (drum);
b) before the feed water regulating valve;
c) at the outlet of the economizer;
d) between superheater outlet and main steam valve;
e) on the shell (drum) of the hot water boiler;
f) at the outlet of water inlet valve and inlet of water outlet valve of hot water boiler;
g) at the outlet and inlet of the circulating water pump of the hot water boiler;
h) at the oil pump inlet (oil return) and outlet of the ignition oil system of oil-fired
boilers and coal-fired boilers;
i) behind the gas source inlet of the ignition gas system of gas-fired boilers and coal-
fired boilers and the pressure-regulating valve (regulator valve) of the gas valve
group.
6.2 The selected pressure gauge meets the following requirements.
a) The pressure gauge accuracy shall not be lower than level 2.5. For boilers with a
rated working pressure of not less than 3.8 MPa, the accuracy of the pressure
gauge shall not be lower than level 1.6.
b) The range of the pressure gauge shall be selected according to the working
pressure. Generally, it is 1.5~3.0 times the working pressure. It shall select 2.0
times.
c) The size of the pressure gauge dial shall ensure that the boiler operator can clearly
see the pressure indication value. The dial diameter shall not be less than 100 mm.
d) The pressure gauge shall be calibrated regularly. A red line indicating the working
pressure shall be drawn on the dial. Indicate the date of the next verification. After
the pressure gauge is verified, it shall be sealed with lead.
direct-reading water level gauge:
a) Boilers whose rated evaporation is not more than 2 t/h.
b) Boilers with two independent remote water level measurement devices.
c) Electric heating boilers.
d) Through-flow boilers with a reliable wall temperature interlock protection device.
7.2 Structure, device
7.2.1 The water level gauge shall have obvious signs indicating the highest, lowest safe
water level and normal water level. The upper visible edge of the water gauge shall be
at least 25 mm above the highest safe water level. The lower visible edge shall be at
least 50 mm higher than the highest fire circle. It shall be at least 25 mm lower than the
minimum safe water level.
7.2.2 The inner diameter of the glass tube of the glass tube water level gauge shall be
greater than or equal to 8 mm. The width of the visible water level shall be greater than
8 mm. To prevent safety accidents caused by damage to the glass tube, the water level
gauge shall have protective devices (protective cover, quick-closing valve, automatic
locking bead, etc.). However, any protective device shall not hinder the observation of
the real water level.
7.2.3 A set of water level gauges consisting of two or more glass plates or mica sheets
shall be able to continuously indicate the water level. The glass tube and mica sheet
shall be able to be purged and replaced during boiler operation.
7.2.4 The water level gauge shall have a drain valve for flushing and a drain pipe
connected to a safe discharge location.
7.2.5 The flow path diameter of the valve between the water level gauge (or water meter
column) and the boiler shell (drum) shall be greater than or equal to 8 mm. The inner
diameter of the steam-water connecting pipe shall be greater than or equal to 18 mm.
When the length of the connecting pipe is greater than 500 mm or there is a bend, the
inner diameter shall be appropriately enlarged to ensure the sensitivity and accuracy of
the water level gauge.
7.2.6 The length of the connecting pipe of the water level gauge shall be as short as
possible to ensure that the water level of the water level gauge is clearly visible and
easy to flush. When the connecting pipe is not horizontally arranged, the condensed
water in the connecting pipe on the steam side shall be able to flow to the water level
gauge by itself. Ensure that condensed water does not accumulate in the pipe. The water
in the water side connecting pipe shall be able to flow to the boiler shell (drum) by itself.
7.2.7 A valve shall be installed on the steam-water connecting pipe between the water
level gauge (or water meter column) and the boiler shell (drum). The valve shall be in
the fully open position when the boiler is running. For boilers with rated evaporation
less than 0.5 t/h, valves may not be installed on the steam-water connecting pipe
between the water level gauge and the boiler shell (drum).
7.3 Installation
7.3.1 The water level gauge shall be installed in a place that is easy to observe and
operate and can accurately reflect the real water level of the drum. When the distance
between the water level gauge and the operating ground is higher than 6000 mm, a
remote water level measuring device or a water level video monitoring system shall be
installed.
7.3.2 When multiple remote water level measuring devices monitor the boiler water
level, their signals shall be taken out independently. There shall be two reliable remote
water level measuring devices in the boiler control room. At the same time, a direct-
reading water level gauge shall be guaranteed to work normally during operation.
7.3.3 The steam-water connecting pipe and other related components of the water level
meter shall have good insulation.
8 Temperature measuring device
8.1 Temperature measuring points shall be installed at the corresponding parts of the
boiler. The following temperatures shall be measured:
a) Steam boiler feed water temperature (except normal temperature feed water);
b) Water temperature at the inlet and outlet of the hot water boiler;
c) Water temperature at the outlet of cast iron economizers and steam boiler
economizers with a rated working pressure greater than 3.8 MPa;
d) Steam temperature at the superheater outlet and each stage outlet of the multi-
stage superheater;
e) Steam temperature before and after the desuperheater;
f) Air preheater inlet and outlet air temperature and inlet smoke temperature;
g) Smoke exhaust temperature.
8.2 For boilers with a rated evaporation capacity (or rated thermal power) not less than
20 t/h (or 14 MW), a furnace flue gas temperature measuring device shall be installed
at the furnace outlet (internal combustion oil-fired gas boilers can be exempted).
8.3 The steam outlet of the steam boiler superheater and the hot water outlet of the hot
water boiler with a rated thermal power not less than 7 MW shall be installed with a
recording temperature measuring instrument.
8.4 For boilers with a rated evaporation capacity (or rated thermal power) not less than
20 t/h (or 14 MW), a recording type exhaust gas temperature measuring instrument shall
be installed.
8.5 The range of the dial temperature measuring instrument shall be selected according
to the working temperature. Generally, it is 1.5~2.0 times the working temperature.
9 Sewage and water discharge device
9.1 Drainage valves shall be installed at the bottom of steam boiler shell (drum), vertical
boiler foot ring and water circulation system. Boilers with rated working pressure less
than 3.8 MPa shall use quick-opening blowdown valves. The nominal diameter of the
blowdown valve is generally 20 mm ~ 65 mm. The nominal diameter of the drain valve
on the shell of the horizontal shell boiler shall be greater than or equal to 40 mm.
9.2 For steam boilers with a rated evaporation greater than 1 t/h and hot water boilers
with a rated working pressure of less than 3.8 MPa and a rated outlet water temperature
of not less than 120°C (except tubular boilers), two valves in series shall be installed on
the sewage pipe. At least one of them is a blowdown valve, which is installed on the
side close to the outlet of the blowdown pipeline.
9.3 The steam boiler shell (drum) with a superheater shall be equipped with a
continuous sewage discharge device. A water discharge valve shall be installed at the
lowest header (or pipeline) of the superheater system and economizer system.
9.4 Each boiler shall be equipped with an independent sewage pipe. The sewage pipe
shall minimize the number of elbows to ensure smooth sewage discharge. Connect it to
a safe place or sewage expansion tank (expansion vessel). When multiple boilers share
one discharge header, more than 2 boilers shall be prevented from discharging sewage
at the same time.
9.5 The outlet pipe of the hot water boiler is generally located at the highest point of the
boiler. An air collecting device, or an automatic exhaust valve shall be installed at the
highest point of the outlet pipe before the outlet valve. An exhaust valve with a nominal
diameter of not less than 20 mm shall be installed at the highest point of each circuit
and the highest point of the pot shell (drum) or on the outlet pipe. The exhaust pipes at
the highest point of each circuit shall be arranged in a centralized manner.
9.6 A relief pipe shall be installed at the highest point of the shell (drum) of the hot
water boiler or on the outlet pipe. Its inner diameter shall be determined according to
the rated thermal power of the boiler, which shall not be less than 25 mm. A relief valve
shall be installed on the relief pipe. When the boiler is in normal operation, the relief
valve is closed. For boilers equipped with relief valves, exhaust valves may not be
installed on the boiler shell (drum) or outlet pipe.
power is not less than 7 MW. The rated outlet water temperature is greater than
95°C and less than 120°C.
10.1.5 The interlock protection device shall not be out of operation at will during the
operation of the boiler. The backup power supply or air source of the interlock
protection device shall be reliable. The standby shall not be withdrawn arbitrarily. The
standby power supply or self-injection test of gas shall be carried out regularly.
10.1.6 When two or more boilers share one main flue, a reliable flue baffle with a limit
device shall be installed in the branch flue of each boiler.
10.1.7 The valves on the boiler pipes and the baffles of the smoke and air system shall
have obvious signs to indicate the name, number, switch direction and medium flow
direction of valves and baffles. The main regulating valve shall also have an opening
indication.
10.1.8 The operating mechanisms of valves and baffles shall be installed in places that
are convenient for operation.
10.2 Layer fired boiler
10.2.1 The mechanical layer fired boiler shall be equipped with an interlock protection
device for failure of the combustion system. When any of the following situations
occurs during operation, the air supply and fuel delivery shall be stopped urgently:
a) Safety protection device fails;
b) Combustion equipment or slag removal equipment fails;
c) Blower or induced draft fan is not working properly;
d) Backfire occurs in the feeding device of the biomass layer combustion system;
e) Control parameters related to boiler safety (such as water level, temperature,
pressure, etc.) exceed the limit.
10.2.2 Effective measures to prevent backfire shall be taken in the biomass fuel
combustion system and feeding system. The feeding device between the fuel bunker
and the combustion chamber shall be interlocked with the boiler fan. A steam boiler
with a rated evaporation greater than 4 t/h or a hot water boiler with a rated thermal
power greater than 2.8 MW shall be equipped with a furnace negative pressure alarm
device. The upper part of the combustion chamber shall be provided with a release
device with an interlock function.
10.2.3 The layer fired hot water boiler shall be equipped with a device that can
automatically cut off the air supply or induction when the pressure drops to the point
where vaporization occurs or the water temperature exceeds the specified value, and
the circulating water pump suddenly stops running, and the backup pump fails to start
normally.
10.3 Chamber fired boiler
10.3.1 Chamber fired boilers shall be equipped with ignition program control devices
and flameout protection devices. They shall meet the following requirements:
a) In the ignition program control, the total ventilation volume before ignition shall
be greater than or equal to 3 times the total volume of the flue from the furnace
to the chimney inlet. The ventilation time of liquid fuel boilers below 0.5 t/h (350
kW) lasts at least 10 s. The ventilation time of shell boilers and through-flow
boilers lasts at least 20 s. When it is difficult to fully purify due to structural
reasons, the ventilation time shall be extended appropriately.
b) When the flameout protection device operates, it shall ensure that the fuel supply
is automatically cut off. Perform an adequate post-purge.
10.3.2 Chamber fired boilers shall be equipped with interlocking devices with the
following functions:
a) When all induced draft fans trip, automatically cut off all air supply and fuel
supply.
b) When all blowers trip, all fuel supply will be cut off automatically.
c) When the pressure of fuel oil and its atomized substance and gas pressure are
lower than the specified value, the fuel or gas supply will be cut off automatically.
d) When the pressure of the hot water boiler is reduced to the point where
vaporization occurs or the water temperature exceeds the specified value, when
the circulating water pump stops running suddenly, when the backup pump cannot
start normally, the fuel supply will be cut off automatically.
10.3.3 The main gas control valve system of the gas fuel burner with a rated output
thermal power greater than 1200 kW shall be equipped with a valve leak detection
device.
10.3.4 For boilers using liquid or gas as fuel, the ignition safety time, extinction safety
time and starting thermal power of the burner shall meet the requirements of GB/T
36699.
10.3.5 Natural gas-fired condensing steam boilers shall adopt continuous water supply
automatic adjustment devices.
10.4 Electric heating boiler
10.4.1 Electric heating boilers shall be equipped with overcurrent protection, short
circuit protection, leakage protection, overvoltage protection and phase loss protection.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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