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

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GB/T 38008-2019: Gate valves of thermoplastics materials
GB/T 38008-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.140.30
G 33
Gate Valves of Thermoplastics Materials
热塑性塑料闸阀
(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’s 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