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GB/T 38008-2019 English PDF (GBT38008-2019)

GB/T 38008-2019 English PDF (GBT38008-2019)

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GB/T 38008-2019: Gate valves of thermoplastics materials

This Standard specifies the terms, definitions and symbols, materials, design, requirements, test methods, inspection rules, markings, packaging, transportation and storage of gate valves of thermoplastics materials.
GB/T 38008-2019
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 83.140.30
G 33
Gate Valves of Thermoplastics Materials
???????€????????????€
(ISO 16139:2006, Industrial Valves - Gate Valves of Thermoplastics
Materials, MOD)
ISSUED ON: AUGUST 30, 2019
IMPLEMENTED ON: MARCH 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Terms, Definitions and Symbols ... 7
4 Materials ... 11
5 Design ... 13
6 Requirements ... 15
7 Test Methods ... 20
8 Inspection Rules ... 22
9 Markings, Packaging, Transportation and Storage ... 24
Appendix A (informative) Comparison between Nominal Outer Diameter dn and Nominal Size DN ... 26
Appendix B (informative) Purchasing Information ... 27
Bibliography ... 28
Foreword
This Standard was drafted in accordance with the rules in GB/T 1.1-2009. This Standard adopts the re-drafting method in the modification and adoption of ISO 16139:2006 Industrial Valves - Gate Valves of Thermoplastics Materials. In comparison with ISO 16139:2006, this Standard has the following structural changes: ---?€?Symbols?€? is added to ?€?Terms and Definitions?€? (see 3.4);
---Chapter 4 ?€?Requirements?€? of ISO 16139:2006 are divided into ?€?Materials?€?, ?€?Design?€? and ?€?Requirements?€? (see Chapter 4 ~ Chapter 6);
---The contents of 4.7.2 and 4.8 in ISO 16139:2006 are deleted;
---Chapter 5 ?€?Inspection Procedures?€? of ISO 16139:2006 is divided into ?€?Test Methods?€? and ?€?Inspection Rules?€? (see Chapter 7 and Chapter 8);
---Chapter 6 of ISO 16139:2006 is deleted;
---Chapter 7 ?€?Markings?€? and Chapter 8 ?€?Transportation and Storage?€? of ISO 16139:2006 are combined into ?€?Markings, Packaging, Transportation and
Storage?€? (see Chapter 9);
---The comparison between nominal outer diameter dn and nominal size DN is added (see Appendix A);
---Appendix A of ISO 16139:2006 is adjusted to Appendix B.
In comparison with ISO 16139:2006, the main technical differences and the causes for these differences are as follows:
---The pressure class is deleted (see Chapter 1), and uniform use of metric units is adopted;
---In terms of Normative References, this Standard makes specific adjustments with technical differences, so as to adapt to the technical conditions of China. The condition of the adjustments is intensively reflected in Chapter 2
?€?Normative References?€?. See the specific adjustments below:
??? GB/T 7306.1-2000 and GB/T 7306.2-2000, which equivalently adopt
international standard, are used to replace ISO 7-1:1994 (see 6.3.1.3); ??? GB/T 12222-2005, which modifies and adopts international standard, is used to replace ISO 5210:2001 (see 5.3.2);
Gate Valves of Thermoplastics Materials
1 Scope
This Standard specifies the terms, definitions and symbols, materials, design, requirements, test methods, inspection rules, markings, packaging, transportation and storage of gate valves of thermoplastics materials (hereinafter referred to as gate valves).
In accordance with different materials of gate valves, this Standard has a range of operating temperature of -40 ??C ~ + 120 ??C.
The range of nominal outer diameter is dn 16 mm ~ dn 355 mm.
The range of nominal pressure is PN 0.6 MPa ~ PN 2.0 MPa.
The range of pipe series is S 2 ~ S 12.5.
NOTE: it is the responsibility of the purchaser to appropriately select this product in accordance with its specific application demands, and in combination with the requirements of relevant laws, regulations, standards or specifications. 2 Normative References
The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 2828.1-2012 Sampling Procedures for Inspection by Attribute - Part 1: Sampling Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-lot Inspection (ISO 2859-1:1999, IDT)
GB/T 2918-2018 Plastics - Standard Atmospheres for Conditioning and Testing (ISO 291:2008, MOD)
GB/T 7306.1-2000 Pipe Treads with 55 Degree Thread Angle where Pressure-tight Joints are Made on the Threads - Part 1: Parallel Internal and Taper External Threads (eqv ISO 7-1:1994)
GB/T 7306.2-2000 Pipe Treads with 55 Degree Thread Angle where Pressure-tight Joints are Made on the Threads - Part 2: Taper Internal and External Threads (eqv ISO 7-1:1994)
3.2.5 Opening torque
Opening torque refers to the maximum torque required when the valve reaches a fully opening state under the nominal pressure.
[GB/T 19278-2018, Definition 2.4.9]
3.3 Terms and Definitions Related to Structure
3.3.1 Gate valves of thermoplastic materials
Gate valves of thermoplastic materials refer to valves whose shell is made of thermoplastic materials, and the opening and closing parts (wedge) are driven by the stem, and linearly move upwards and downwards along the axis of the seat (sealing surface).
3.3.2 Valve body
Valve body is a main component of the valve that provides ports for the connection between fluid channels and pipes (or equipment).
[GB/T 19278-2018, Definition 2.2.22]
3.3.3 Shell
Shell is a component that constitutes the valve pressure chamber. It usually includes valve body and bonnet.
[GB/T 19278-2018, Definition 2.2.23]
3.3.4 Bonnet
Bonnet is a main component connected with the valve body and constitutes the pressure chamber with the valve body (or through other components, for example, diaphragm).
3.3.5 Packing; packing rings
Packing refers to a filler that is put into the packing gland (packing box) to prevent the medium from leaking along the stem.
3.3.6 Trim
Trim refers to other functional parts that are in direct contact with the fluid inside the valve, except for the shell.
[GB/T 19278-2018, Definition 2.2.24]
3.3.7 Seat
en: nominal wall thickness
F: manual forces
Fs: instantaneous manual forces
fr: derating factor
MOP: maximum operating pressure
PN: nominal pressure
S: pipe series
4 Materials
4.1 Shell Materials
4.1.1 PVDF, ABS, PVC-U, PVC-C, PB, PE, PE-RT, PE-X and PP used for the
production of valve body and bonnet shall comply with the requirements of ISO 10931:2005, ISO 15493:2003 and ISO 15494:2015.
4.1.2 In terms of the materials selected for the production of valve body and bonnet, the raw material supplier shall provide a raw material creep failure curve report that complies with the requirements of the predicted strength reference curve. 4.1.3 When PPO / PPE, PPSU and PA or other materials are selected, the supplier shall provide a raw material creep failure curve report and a temperature derating factor fr.
4.2 Materials of Other Components of Gate Valve
The selection of materials for other various components, such as: sealing element, stem and wedge, shall ensure that the performance of the gate valve complies with the requirements specified in Chapter 6. These materials shall not adversely affect the performance of the gate valve.
4.3 Pressure - Temperature Derating
4.3.1 The maximum operating pressure (MOP) of the gate valve is related to the operating temperature, the characteristics of the valve body material and the structural design. The maximum operating pressure (MOP) of the gate valve shall be determined by the derating factor fr and may be calculated in accordance with Formula (2): Where,
of Table 3, Table 4 and Table 5 in 6.3.2.
5.2 Connection
5.2.1 The connection between the gate valve and the pipeline has the following modes: a) Adhesive connection;
b) Electrofusion connection;
c) Hot-melting connection;
d) Socket elastic sealing ring connection;
e) Flange connection;
f) Threaded connection;
g) Articulated connection.
5.2.2 The connecting end and the gate valve shall be integrated. Different connection modes are allowed on the same gate valve.
5.2.3 When the gate valve is connected to the pipe through adhesive connection, electrofusion connection or hot-melting connection, the material of the connecting end shall be the same as that of the pipe.
5.3 Operation
5.3.1 The design shall adopt manually operated device and (or) power-driven device. 5.3.2 The operating device shall have a direction mark or a display of the handwheel position.
5.3.3 The manual gate valve and motorized gate valve shall have the following characteristics:
a) Manual gate valve:
---Looking from the upward side of the handwheel, turning the handwheel clockwise is closing;
---After operation, the position of the handwheel relative to the stem cannot be changed;
---There should be a stem position or stroke indicator.
b) Motorized gate valve:
---The ?€?ON?€? and ?€?OFF?€? end positions have a stop device limit;
A of GB/T 27726-2011.
6.6 Flow Capacity
The manufacturer shall provide the nominal value of the flow coefficient and flow resistance coefficient of the gate valve. The actually measured value of the flow coefficient cannot be less than 90% of the provided value; the actually measured value of the flow resistance coefficient cannot be greater than 110% of the provided value. 6.7 Air-tightness of Seat and Valve Body
The air-tightness of seat and valve body shall comply with the requirements of A.4 in Appendix A of GB/T 27726-2011.
6.8 Operating Torque
When the pressure difference is equal to the nominal pressure PN, the torque value, at which, the gate valve is fully opened or fully closed, shall be not greater than the nominal value provided by the manufacturer.
6.9 Fatigue Strength
6.9.1 During the test, the gate valve shall not manifest any leakage.
6.9.2 After the test, the sealing performance of the gate valve shall comply with the requirements of A.4 in Appendix A of GB/T 27726-2011.
6.9.3 After the test, all functions of the gate valve shall still be normally used. 6.9.4 The number of cycles of gate valves with dn < 63 mm shall be not less than 15,000 times; the number of cycles of gate valves with dn ??? 63 mm shall be not less than 5,000 times.
6.10 Light Transmittance
The light transmittance of gate valve shall be ??? 0.2%.
6.11 Hygiene Requirements
The gate valve used to convey drinking water shall comply with the stipulations of GB/T 17219.
7 Test Methods
7.1 Adjustment of Test Conditions
Sampling shall be taken 48 h after the gate valve is assembled.

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