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GB 27790-2020: City gas pressure regulators
GB 27790-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 91.140
P 47
Replacing GB 27790-2011
City gas pressure regulator
城镇燃气调压器
ISSUED ON: NOVEMBER 17, 2020
IMPLEMENTED ON: DECEMBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 4
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions, symbols ... 9
3.1 Terms and definitions ... 9
3.2 Symbols ... 16
4 Classification and models ... 19
4.1 Classification ... 19
4.2 Models ... 19
5 Structure and materials ... 21
5.1 General requirements ... 21
5.2 Structure ... 22
5.3 Materials ... 25
6 Requirements ... 31
6.1 Appearance ... 31
6.2 Strength of pressure-bearing parts ... 31
6.3 Inspection of finished diaphragm products ... 31
6.4 External seal ... 32
6.5 Performance ... 32
6.6 Flow coefficient Cg ... 35
6.7 Adaptability at extreme temperatures ... 35
6.8 Durability ... 36
6.9 Failure state ... 36
6.10 Performance of integrated shut-off device ... 36
6.11 Performance of integrated monitor ... 37
6.12 Performance of integrated release device ... 38
6.13 Torsion and bending resistance of meter pressure regulator ... 38
7 Test methods ... 38
7.1 General requirements ... 38
7.2 Appearance ... 41
7.3 Strength of pressure-bearing parts ... 42
7.4 Inspection of finished diaphragm products ... 42
7.5 External seal ... 43
7.6 Performance ... 44
7.7 Flow coefficient Cg ... 50
7.8 Adaptability at extreme temperatures ... 53
7.9 Durability ... 53
7.10 Failure state ... 54
7.11 Integrated shut-off device ... 54
City gas pressure regulator
1 Scope
This Standard specifies the terms and definitions, symbols, classification and marking,
structure and materials, requirements, test methods, inspection rules, marking, labeling,
instruction manual, packaging, transportation and storage of gas pressure regulators for
city gas (hereinafter referred to as pressure regulators).
This Standard applies to pressure regulators for regulating outlet pressure with an inlet
pressure not exceeding 10.0 MPa, an operating temperature range not exceeding -
20℃~60℃ and a lower limit not lower than the gas dew point temperature, and a
nominal size not exceeding 400 mm.
This Standard does not apply to pressure regulators for bottled liquefied petroleum gas
and dimethyl ether.
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 150 (all parts), Pressure vessels
GB/T 191, Packaging -- Pictorial marking for handling of goods
GB/T 229, Metallic materials -- Charpy pendulum impact test method
GB/T 528, Rubber, vulcanized or thermoplastic -- Determination of tensile stress-
strain properties
GB/T 531.1, Rubber, vulcanized or thermoplastic -- Determination of indentation
hardness -- Part 1: Durometer method (Shore hardness)
GB/T 699, Quality carbon structure steels
GB/T 1047, Pipework components -- Definition and selection of nominal size
GB/T 1173, Casting aluminium alloy
GB/T 1220, Stainless steel rod
GB/T 1239.2, Cold coiled helical springs technical specifications -- Part 2:
and custom number of A;
b) RTZB-15/0.01L indicates a meter pressure regulator with a nominal size of DN15,
a maximum inlet pressure of 0.01 MPa, in threaded connection.
5 Structure and materials
5.1 General requirements
5.1.1 Design pressure
5.1.1.1 Metal pressure-bearing parts
The design pressure of metal pressure-bearing parts (including metal parts that bear
pressure during normal operation and metal parts that bear pressure after the failure of
diaphragms or differential pressure seals) shall meet the following requirements:
a) When the metal pressure-bearing parts are subjected to the inlet pressure p1, their
design pressure shall not be less than the maximum inlet pressure and not less
than 0.4 MPa;
b) When metal pressure-bearing parts are protected by safety protection devices, if
the pressure they withstand after the failure of the diaphragm or differential
pressure seal is less than the inlet pressure and not less than the normal working
pressure, the design pressure of the metal pressure-bearing parts shall not be less
than 1.1 times the pressure they withstand after the failure of the diaphragm or
differential pressure seal, or the design pressure specified in a) shall be adopted;
c) For metal pressure-bearing parts whose pressure after failure of diaphragm or
differential pressure seal is less than the normal working pressure, the design
pressure shall not be less than 1.1 times of the maximum normal working pressure,
or the design pressure specified in a) shall be adopted.
5.1.1.2 Metal partition
The design pressure of the metal diaphragm shall not be less than 1.1 times the
difference between the maximum pressure on the high-pressure side and the minimum
pressure on the low-pressure side. However, the design pressure of the metal diaphragm
in the valve body shall comply with the requirements of 5.1.1.1 a).
5.1.1.3 Diaphragm
The diaphragm design pressure shall meet the following requirements:
a) When the maximum pressure difference Δpmax that the diaphragm withstands is <
0.015 MPa, the diaphragm design pressure shall not be less than 0.02 MPa;
b) When 0.015 MPa ≤ Δpmax < 0.5 MPa, the diaphragm design pressure shall not be
less than 1.33Δpmax;
c) When Δpmax ≥ 0.5 MPa, the diaphragm design pressure shall not be less than
1.1Δpmax and shall not be less than 0.665 MPa.
5.1.2 Operating temperature range
The operating temperature range of the voltage regulator shall be -10℃~60℃ or -
20℃~60℃.
5.2 Structure
5.2.1 Inlet and outlet connection types
5.2.1.1 The connection between the pressure regulator and the upstream and
downstream pipelines shall meet the following requirements:
a) The connection dimensions and sealing surface type of the flange shall comply
with the requirements of GB/T 9124.1, GB/T 9124.2, HG/T 20592 or HG/T
20615;
b) Pipe threads shall only be used for pressure regulators with a nominal size not
greater than DN50 and shall comply with the requirements of GB/T 7306.1, GB/T
7306.2 or GB/T 12716.
5.2.1.2 The nominal pressure of the flange shall not be less than the design pressure of
the regulator housing and shall be selected from the series of 0.6 MPa, 1.0 MPa, 1.6
MPa, 2.0 MPa, 2.5 MPa, 4.0 MPa, 5.0 MPa, 6.3 MPa, 10.0 MPa and 11.0 MPa.
5.2.1.3 The nominal pressures of the inlet and outlet flanges of the pressure regulator
shall be the same.
5.2.2 Other configurations
5.2.2.1 The driving pressure of the indirect acting pressure regulator shall be provided
by the inlet gas of the pressure regulator.
5.2.2.2 The pressure signal sampling position of the voltage regulator and the size of
the signal tube shall be able to provide a stable pressure signal.
5.2.2.3 The breathing tube or breathing apparatus shall have measures to prevent the
entry of foreign matter.
5.2.2.4 Integrated safety units such as integrated shut-off device, integrated monitor,
integrated release device, etc. shall be independent of the operation of the voltage
regulator.
b) Austenitic stainless steel is not subjected to impact test;
c) When the tensile strength of forged and cast aluminum alloys is not higher than
350 MPa, impact test is not performed.
5.3.2.3 The materials of pressure-bearing parts shall meet the following requirements:
a) The material of steel pressure-bearing parts shall comply with the requirements of
GB/T 12224 and GB/T 12229;
b) The material of iron pressure-bearing parts shall comply with the requirements of
GB/T 12227 or GB/T 9440;
c) The material of aluminum pressure-bearing parts shall comply with the
requirements of GB/T 15115, GB/T 1173 or GB/T 32249.
5.3.2.4 When the pressure-bearing parts of the voltage regulator are made of carbon
steel, high-quality carbon structural steel shall be selected. The chemical composition
of carbon steel and low-alloy steel used for welding shall meet the following
requirements:
a) Carbon mass fraction: shall not exceed 0.23% when using pre-furnace analysis,
and shall not exceed 0.25% when using finished product analysis;
b) Sulfur mass fraction shall not exceed 0.020%. Phosphorus mass fraction shall not
exceed 0.025%;
c) Carbon equivalent: shall not exceed 0.43% when using pre-furnace analysis, and
shall not exceed 0.45% when using finished product analysis.
NOTE: The carbon equivalent (CE) calculation formula is: CE= wC (%) +wMn/6 (%)
+ [wCr (%) +wMo (%) +wV (%)]/5+ [wNi (%) + wCu(%)]/15.
5.3.2.5 Nondestructive testing of steel pressure-bearing parts shall comply with the
following requirements:
a) Steel pressure-bearing parts shall be subjected to nondestructive testing according
to the requirements of Tables 8 and 9.
b) Nondestructive testing shall be carried out after the material heat treatment is
completed or after the welding heat treatment is completed, or before or after
machining. Surface nondestructive testing shall include internal and external
surfaces, except for external threads, holes and internal threads.
c) During random inspection, if the pressure-bearing parts are unqualified, two or
more samples shall be taken from the production batch for re-inspection. If there
are still unqualified ones, the inspection scope shall be expanded to all similar
pressure-bearing parts in the production batch.
6 Requirements
6.1 Appearance
6.1.1 The surface of the voltage regulator shall be treated with anti-corrosion. The anti-
corrosion layer shall be uniform and have a uniform color without any defects such as
peeling, cracking, or bubbles.
6.1.2 The connecting pipes between the pressure regulator and the auxiliary devices and
the pilot shall be smooth and free of damage such as dents and bumps.
6.1.3 The surface of the pressure regulator valve body shall be marked with a permanent
arrow according to the medium flow direction.
6.2 Strength of pressure-bearing parts
6.2.1 Pressure-bearing parts shall be subjected to strength tests at 1.5 times the design
pressure p and not less than p + 0.2 MPa. The test results shall meet the following
requirements:
a) There is no leakage during the test;
b) After unloading, the residual deformation between any two points on the test piece
shall not be greater than the larger of the following values:
- 0.2% multiplied by the distance between the two points;
- 0.1 mm.
6.2.2 Metal diaphragms shall be subjected to hydraulic pressure tests. The test pressure
shall meet the requirements of 6.2.1 and there shall be no leakage or abnormal
deformation.
6.3 Inspection of finished diaphragm products
6.3.1 The test pressure of the diaphragm pressure test shall be 1.5 times the design
pressure specified in 5.1.1.3. There shall be no leakage during the pressure maintenance
period.
6.3.2 The gas resistance of the diaphragm shall comply with the requirements of Annex
A.
6.3.3 The finished diaphragm shall not be damaged after being kept at -20℃ for 1 h.
p2s and SG are the values obtained from the test at room temperature.
6.7.3 Opening and closing flexibility
Under extreme temperatures, the voltage regulator shall be opened and closed flexibly
within the full stroke range.
6.8 Durability
After the regulator has been opened and closed for 30,000 times at room temperature
with a stroke greater than 50% of the full stroke (excluding the closed and fully open
positions), the external seal of the regulator shall meet the requirements of 6.4. The
accuracy shall meet the requirements of 6.5.2. The lock-up performance shall meet the
requirements of 6.5.4.
6.9 Failure state
The control member of a fail-open regulator shall tend to open or open. The control
member of a fail-closed regulator shall tend to close or close under any of the following
conditions:
a) The main diaphragm of the pressure regulator or pilot fails (such as rupture);
b) The pressure regulator driver loses continuous energy supply (such as gas outage,
signal pipe blockage or leakage, etc.).
NOTE: The same voltage regulator has only one post-failure state.
6.10 Performance of integrated shut-off device
6.10.1 Valve seat tightness
When the pressure regulator has an integrated shut-off device, the valve seat sealing
shall comply with the requirements of 6.1.5 in CJ/T 335-2010.
6.10.2 Shut-off pressure accuracy class
When the pressure regulator has an integrated shut-off device, the shut-off pressure
accuracy class shall meet the following requirements in addition to the requirements of
6.1.6 of CJ/T 335-2010:
a) At laboratory temperature, it shall comply with the requirements of 6.1.6.2 of CJ/T
335-2010, and the shut-off pressure pta shall comply with the requirements of
formula (5):
the requirements of 6.5.
6.11.2 Adaptability at extreme temperatures
The adaptability of the integrated monitor of the voltage regulator under extreme
temperature shall comply with the requirements of 6.7.
6.11.3 Durability
The durability of the integrated monitor of the voltage regulator shall comply with the
requirements of 6.8.
6.11.4 Failure state
The failure state of the integrated monitor of the voltage regulator shall comply with
the requirements of 6.9.
6.12 Performance of integrated release device
The integrated release device of the voltage regulator shall meet the following
requirements:
a) The relief pressure setting value of the integrated release device shall be greater
than the lock-up pressure value of the pressure regulator and shall be less than the
shut-off pressure value. The relief pressure setting error shall not be greater than
±5% of the setting value.
b) The return pressure shall not be less than th...