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GB/T 34527-2017 English PDF (GBT34527-2017)

GB/T 34527-2017 English PDF (GBT34527-2017)

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GB/T 34527-2017: Specification of gas cylinder valve for air rebreather

This Standard specifies the terms and definitions, basic structural style and model, technical requirements, test methods, inspection rules, marking, packaging, transportation, and storage of gas cylinder valve for air rebreather.
GB/T 34527-2017
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 23.020.30
J 74
Specification of gas cylinder valve for air rebreather
ISSUED ON: OCTOBER 14, 2017
IMPLEMENTED ON: MAY 01, 2018
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 structural style and model ... 5
5 Technical requirements ... 7
6 Test methods ... 10
7 Inspection rules ... 14
8 Marking, packaging, storage and transportation ... 17
Appendix A (Informative) Connection type and dimension of valve inlet and outlet ... 20
Appendix B (Normative) Mechanical impact resistance test device ... 22 Specification of gas cylinder valve for air rebreather
1 Scope
This Standard specifies the terms and definitions, basic structural style and model, technical requirements, test methods, inspection rules, marking, packaging, transportation, and storage of gas cylinder valve for air rebreather (hereinafter referred to as "valve").
This Standard applies to cylinder valves used on air rebreathers with an ambient temperature of -40 ??C~+ 60 ??C and a nominal working pressure of not greater than 30 MPa.
This Standard does not apply to cylinder valves for rebreathers for medical and diving use.
2 Normative references
The following documents are indispensable for the application of this document. For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.
GB/T 196 General purpose metric screw threads - Basic dimensions
GB/T 197 General purpose metric screw threads - Tolerances
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 1804 General tolerances - Tolerances for linear and angular
dimensions without individual tolerance indications
GB/T 3934 Specification of gauges for general purpose screw threads
GB/T 4423 Copper and copper-alloy cold-drawn rod and bar
GB/T 5121.1 Methods for chemical analysis of copper and copper alloys - Part 1: Determination of copper content
GB/T 5121.3 Methods for chemical analysis of copper and copper alloys - Part 3: Determination of lead content
b) The rubber seals shall be placed in oxygen at a pressure of 2.3 MPa??0.2 MPa, a temperature of 70 ??C??5 ??C, and a purity of ???99.5% for 96 h for hot air accelerated aging and heat resistance test. After the test, there shall be no cracking.
c) The rubber seals shall be placed in the air at a temperature of -40 ??C??2 ??C for 24 h for low-temperature test. After the test, there shall be no cracks or other damage.
5.2 Process requirements
5.2.1 The valve body shall be forged and formed. On the surface of the valve body, there shall be no defects such as cracks, wrinkles, inclusions, looseness, shrinkage, underfill which would impair the performance of the valve.
5.2.2 The valve body and components without individual tolerance indications are processed according to level M in GB/T 1804 standard.
5.2.3 Before leaving the factory, the valve shall be kept clean; there shall be no oil stains and visible foreign particles.
5.3 Performance requirements
5.3.1 Opening and closing
The opening and closing of the valve shall meet the following requirements: a) Under the nominal working pressure, if the handwheel diameter is ???65 mm, the opening and closing torque of the valve shall not be greater than 7 N ?€? m. If the handwheel diameter D is < 65 mm, the opening and closing torque shall not be greater than 7D/65 N ?€? m;
b) The valve shall be subjected to a resistance torque test of the operating mechanism. USE a torque of 25 N ?€? m to close the valve. The operating
mechanism shall be free of breakage; and, it is able to open the valve. Then, continue to increase the torque, until the valve's operating
mechanism fails. The pressure holding element shall not be damaged.
5.3.2 Air tightness
The air tightness of the valve shall meet the following requirements:
a) At 1.2 times the nominal working pressure, the valve is closed and open arbitrarily. There shall be no leakage for at least 1 min of pressure holding; b) Under the pressure of 0.05 MPa, the valve is closed and opened arbitrarily. There shall be no leakage for at least 1 min of pressure holding.
The operating mechanism of the valve shall generally be equipped with a locking device in the open state. If the valve cannot be locked after the valve is opened, the handwheel in the full-open state shall be rotated at least two turns to close the valve.
5.3.10 Unscrewing torque of pressure cap
The unscrewing torque of the pressure cap of the valve shall not be less than 50 N ?€? m.
5.3.11 Stress corrosion resistance of valve body
After 4 h of ammonia test in an ammonia water container with a temperature of 25 ??C??1 ??C, the valve body shall have no visible cracks.
6 Test methods
6.1 General test rules
6.1.1 Test environment
Except for special requirements, the tests of this Standard are carried out at room temperature 15 ??C~30 ??C. The test room shall be kept shockproof,
dampproof, corrosion proof, and ventilated.
6.1.2 Test medium
Except that the pressure resistance test medium is clean tap water, the medium for other tests is pure dry air or nitrogen.
6.1.3 Pressure gauge for tests
The accuracy of the pressure gauge for tests shall not be lower than level 1.6. The range of the pressure gauge shall be 1.5~2 times the test pressure. 6.2 Material inspection
6.2.1 Mechanical properties test and chemical composition analysis
method of valve body metal materials
The tensile test samples and test methods of the valve body metal materials shall be implemented in accordance with GB/T 228.1. The chemical
composition analysis methods shall be implemented in accordance with the standards such as GB/T 5121.1, GB/T 5121.3, GB/T 5121.9, YS/T 482. If other materials are used, the chemical composition analysis method shall be in accordance with the corresponding standard.
close the valve. From the air inlet of the valve, fill nitrogen or air to 1.2 times the nominal working pressure. Immerse the test device in water to hold pressure at least 1 min. The result shall meet the requirements of 5.3.2 a).
6.6.2 Opening air tightness test
Install the valve on the test device. BLOCK the air outlet. According to the torque specified in 5.3.1 a), open the valve to any open state. From the air inlet of the valve, fill nitrogen or air to 1.2 times the nominal working pressure. Immerse the test device in water to hold pressure at least 1 min. REPEAT opening and closing valve. The result shall meet the requirements of 5.3.2 a).
6.6.3 Low-pressure air tightness test
Install the valve on the test device. From the air inlet of the valve, fill nitrogen or air at a pressure of 0.05 MPa; TEST according to the methods of 6.6.1 and 6.6.2. The result shall meet the requirements of 5.3.2 b).
6.7 Vibration resistance test
Install the valve on the test device. According to the torque specified in 5.3.1 a), close the valve. From the air inlet of the valve, fill nitrogen or air to the nominal working pressure. Then, install the test device on the vibration test bench. According to the amplitude of 2 mm (P-P), the frequency of 33.3 Hz,
respectively in the three mutually perpendicular directions of X, Y, and Z, vibrate for 30 min. Then according to the provisions of 6.6, conduct the air tightness test. The result shall meet the requirements of 5.3.3.
6.8 Temperature resistance test
The temperature resistance test of the valve shall be carried out according to the following procedure:
a) Install the valve on the test device; BLOCK the air outlet; MAKE the valve in any open state. From the air inlet of the valve, fill nitrogen or air to the nominal working pressure. Then, put it in the test box at 60 ??C??2 ??C for 2 h. After taking it out, within 30 s, start the full stroke manual opening and closing of the valve. After 25 times, put it in the test box at 60 ??C??2 ??C again for 1 h. After taking it out, within 10 min, according to the provisions of 6.6 of this Standard, conduct the air tightness test. The result shall meet the requirements of 5.3.4.
b) Install the valve on the test device; BLOCK the air outlet; MAKE the valve in any open state. From the air inlet of the valve, fill nitrogen or air to the nominal working pressure. Then, put it in the test box at -40 ??C??2 ??C for 2 h. After taking it out, within 30 s, start the full stroke manual opening and 6.13.1 Handwheel with self-locking function: ROTATE the handwheel
counterclockwise to any open position. Without releasing the handwheel self- locking function, check the handwheel self-locking function. It shall meet the requirements of 5.3.9.
6.13.2 Handwheel without self-locking function: ROTATE the handwheel
counterclockwise to the fully open state; then, rotate the handwheel clockwise until the valve closes. The number of turns measured from opening to closing of the handwheel shall meet the requirements of 5.3.9.
6.14 Test for unscrewing torque of pressure cap
USE a torque wrench or a torque meter of no more than 100 N ?€? m to press the cap unscrewing direction to turn the valve's pressure cap. At 50 N ?€? m, the pressure cap shall not be loose. The test result shall meet the requirements of 5.3.10.
6.15 Test for stress corrosion resistance of valve body
The test method is in accordance with GB/T 10567.2. The result shall meet the requirements of 5.3.11.
7 Inspection rules
7.1 Material inspection
7.1.1 Materials and parts, when entering the factory, shall have quality certificates.
7.1.2 The mechanical properties (Rm, A) and chemical composition of valve body materials and the dimensions of non-metallic seals shall be re-inspected according to the lot number of entering the factory.
7.2 Exit-factory inspection
7.2.1 One-by-one inspection
The one-by-one inspection items of valve shall include:
a) Visual inspection;
b) Thread check of air inlet and outlet;
c) Air tightness test.
7.2.2 Sampling inspection of lot size
8 Marking, packaging, storage and transportation
8.1 Marking
8.1.1 The valve shall have the following permanent and clear marks:
a) The model of the valve;
b) The nominal working pressure of the valve;
c) Manufacturer or trademark;
d) Lot and serial number (shall include the year and month of manufacture); e) Manufacturing license number and sign;
f) Inspection conformity mark;
g) Design bursting pressure of safety pressure relief device.
8.1.2 The handwheel of the valve shall be permanently marked with the
direction of opening or closing.
8.2 Packaging
8.2.1 Before packaging, the water remaining in the valve shall be removed. When packaging, the valve shall be kept clean; the screw threads of the air inlet and outlet shall not be damaged. The product certification, packing list, instruction manual, and product lot size inspection quality certificate shall be attached to the packaging box.
8.2.2 There shall be the following marks on the packaging box:
a) Name and address of manufacturer;
b) Name and model of the valve;
c) Symbols of necessary operation requirements;
d) Quantity and gross weight;
e) Volume (length??width??height);
f) Production date or lot number;
g) Code of standard that the product implements;

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