GB/T 15560-1995 Hydraulic instantaneous burst and pressure resistance test methods for plastic pipes for fluid transportation
Some standard content:
National Standard of the People's Republic of China
Test method for short-time hydraulic failure and resistance to constant internal pressure of theplastics pipes for the transport of fluids
Standard test method for short-time hydraulic failure and resistance to constant internal pressure of theplastics pipes for the transport of fluids 1 Subject content and scope of application
This standard specifies the test method for short-time hydraulic failure and resistance to constant internal pressure of theplastics pipes for the transport of fluids. GB/T 15560-1995
This standard applies to various types of thermoplastics pipes and thermosetting reinforced plastics pipes for the transport of fluids. 2 Reference standards
GB 8806
Method for measuring dimensions of plastic pipes
3 Terminology
3.1 Failure: refers to the continuous loss of pressure of the liquid passing through the specimen. Failure can be one of the following forms or a combination of the following forms.
a. Ductile failure: refers to the occurrence of plastic deformation or local spherical expansion when the specimen breaks. Note: The slight expansion of the sample due to creep caused by long-term stress does not belong to ductile failure. b. Brittle failure: refers to the absence of obvious material deformation in the rupture area of the sample, such as extension, necking, etc. At this time, the test pressure does not show yielding phenomenon, the sample ruptures instantly, and the pressure drops rapidly to zero. C. Leakage and seepage: refers to the seepage of liquid in the sample through the tiny rupture of the pipe wall under pressure. At this time, if the test pressure is reduced, the pipe sample will usually not lose liquid. 4 Test principle
This test method is divided into two test types: instantaneous burst test and pressure resistance test: Instantaneous burst test refers to the rapid and continuous application of liquid pressure to a given section of plastic pipe sample, so that the sample ruptures in a short time. Read the pressure value when the sample ruptures and calculate its hoop stress. Pressure resistance test refers to subjecting a given section of plastic pipe sample to a specified constant internal pressure for a given time to observe whether the sample is damaged. The test pressure value and test time are determined by the product standard of the pipe. 5 Sealing joints
Sealing joints are installed at both ends of the specimen. Reasonable joint design makes it sealed with the specimen and the pressure device. The joints installed on the specimen cannot cause the specimen to bear axial force. It is also not allowed to damage the specimen. It is recommended to use the sealing joints in Appendix A (reference). Approved by the State Administration of Technical Supervision on May 2, 1995 and implemented on December 1, 1995
6 Test device
6.1 Constant temperature control system
GB/T 15560—1995
The constant temperature system consists of a constant temperature bath, a fluid circulation or stirring device, a heating and temperature control device, etc. Regardless of whether the heating medium in the constant temperature bath is water, air or other fluid, the temperature is maintained within a deviation of 2'℃. 6.2 Pressure system
6.2.1 The pressure device is required to gradually and steadily increase the pressure to the specified pressure value. Then keep the pressure within a deviation of ±2% during the entire test process.
6.2.2 For the instantaneous burst test, the pressure device is required to have sufficient pressure capacity to complete the sample burst within 60~~70s. It is recommended to use the gas pressurization system shown in Appendix B (reference). 6.2.3 The pressure system can apply pressure to each sample individually, or it can apply pressure to multiple samples simultaneously through the system branch. In the case of a system branch, each pressure branch is required to have a controllable shut-off valve, and each sample branch has its own measuring pressure gauge. When a sample ruptures, the pressure control system can close the branch to prevent the pressure of the samples on other branches from dropping (it is recommended to use an electric contact pressure gauge control method or a similar pressure control system). 6.3 Pressure gauge
6.3.1 The accuracy of the test measuring pressure gauge shall not be less than Class 1.0. 6.3.2 Select the range scale of the pressure gauge so that the pressure value reading is around 60% of the pressure gauge scale. Each sample is required to have a measuring pressure gauge, and the pressure gauge should be equipped with a pressure buffer protection device. 6.4 Timing device
The accuracy of the timer shall be within ±2%.
7 Test specimen
7.1 The test specimen surface shall not have visible cracks, scratches or other defects that may affect the test results. Both ends of the specimen shall be flat and perpendicular to the axis of the pipe.
7.2 Length of specimen: Unless otherwise specified in the product standard, the effective length L of the specimen between two sealing joints shall comply with the provisions of the following table. L
Nominal outer diameter D<160mm
Nominal outer diameter D≥160mm
7.3 Number of specimens
L=5D, but not less than 300 mm
L=3D, but not less than 760mmbzxz.net
Under the same test conditions, the number of specimens shall not be less than 5. Or determine the number of specimens according to the provisions of the product standard. 8 Test conditions and pretreatment
8.1 The test temperature shall be carried out according to the test conditions specified in the product standard. 8.2 Liquid pressure must be applied inside the specimen. For example, water. If other liquids are used, it must be ensured that the liquid does not corrode the specimen. 8.3 The outside of the specimen can be a liquid environment or a gas environment. The temperature of the external environment is required to be the same as the temperature of the liquid inside the specimen. 8.4 The specimen should be pretreated before pressure is applied. The pretreatment temperature is the same as the test temperature. The pretreatment time should be until the specimen reaches the test temperature. For tests under 23C conditions, when the specimen is immersed in liquid, the pretreatment time is not less than 1h. When the specimen is placed in a gas medium, the pretreatment time is not less than 16h.
9 Test steps
9.1 Install the sealing joint on the specimen, fill each specimen with liquid at the test temperature, remove the air in the specimen, and then pretreat according to 350
8.4.
GB/T 15560 -- 1995
9.2 Connect the sample to the pressure device and support the sample to prevent bending and deflection of the sample due to the weight of the pipe and the joint (the support should not cause the sample to be restrained in the longitudinal and radial directions). 9.3 Apply test pressure to the sample
9.3.1 During the instantaneous burst test, apply pressure to the sample continuously, evenly and quickly, and start timing at the same time until the sample ruptures. If the sample ruptures in less than 60s, reduce the pressure application speed and repeat the test until the sample ruptures in 60-70s. Record the pressure and time when the sample ruptures and the rupture state of the sample. 9.3.2 During the pressure test, continuously and evenly apply pressure to the sample to a given value, and then start timing. During the entire test process. Keep the pressure constant and meet the requirements of Article 6.2.1. After reaching the specified time, record the test results and the rupture state of the sample. 9.4 When the failure occurs within one diameter of the joint, if there is reason to confirm that the failure is caused by some defect in the sample itself, the sample is valid. Otherwise, take another sample and retest. 10 Calculation
10.1 If it is necessary to calculate the hoop stress of the pipe, it should be calculated according to the following formula: - P(D- t)/2t
Where - hoop stress, MPa
P test pressure, MPa;
D-. Average outer diameter, mm (for thermosetting reinforced pipes, the outer diameter does not include the non-reinforced layer); minimum wall thickness, mm (for thermosetting reinforced pipes, the minimum reinforcement layer wall thickness is used). 10.2 When the test pressure value is given as hoop stress value, unless otherwise specified, the test pressure P is calculated according to formula (1). 10.3 The measurement of pipe sample dimensions shall be carried out in accordance with GB8806. 11 Test report
The test report should include the following contents:
11.1 Description of the test sample: including manufacturer, material type, product code, product specifications, etc. 11.2 Nominal diameter, flat outer diameter, minimum thickness, and effective length L of the sample between two joints. 11.3 Test temperature, test environment medium and sealing joint type. 11.4 Test results of each sample
For instantaneous burst test, the burst pressure, burst time and sample rupture state should be written. For pressure resistance test, the test pressure, test time and test results (whether the sample is ruptured or the rupture state) should be written. 11.5 Any operation that does not meet the standard and any abnormal phenomenon exposed during and after the test. 351
GB/T15560--1995
Appendix A
Sealed joint
(reference)
A1Figure A1The joint is rigidly connected to the specimen, and the weight of the lower joint is carried by the specimen and bears the back pressure. This type of joint is suitable for rigid pipes with good diameter roundness. For example, PVC, PP and other pipes. A2Figure A2The sealed joint with an annular seal is installed on the outer surface of the specimen. It is connected to the sealed joint at the other end through a metal rod inside the specimen. The specimen can make a certain amount of longitudinal movement between the two joints, and the pressure is applied to the specimen through the hollow end of the metal rod.
This type of joint is suitable for rigid pipes with good diameter roundness. For example, PVC, PP and double-wall corrugated pipes. For the assembly form of the corrugated pipe seal, metal joint and specimen, see Figure A7. A3Figure A3Install the sealing joint with an annular seal ring on the inner surface of the sample and connect it to the sealing joint at the other end through a metal rod. The sample can move longitudinally to a certain extent between the two joints. This type of joint is suitable for hard pipes with good roundness of the pipe diameter. For example, PVC, PP and other pipes. A4Figure A4Immerse both ends of the sample in an oil bath at 120-130℃ and heat until soft, then put on the inner flange with an inclined plug and the outer flange with the same inclination. Bolt and tighten evenly. Install another sealing joint in turn. The test pressure is applied to the sample through the sealing joint.
This type of joint is suitable for hard pipes and hoses with thick walls and large non-roundness of the pipe diameter. For example, thermoplastic plastic pipes such as PE and PVCA5Figure A5Insert the sample into the tapered pipe plug. And put a tapered pipe sleeve on the outside of the pipe. Then put on the nut and tighten it with the thread of the plug. The test pressure is applied to the sample from the other joint. This type of joint is suitable for various plastic hoses. For example, soft PVC pipe, PE pipe, nylon pipe, soft PVC mesh pipe, etc. A6 Figure A6 Put the sample tightly on the pipe joint and put on the pipe clamp. Then use an electric hair dryer to evenly heat and blow air on its surface. Make it soft, and tighten the pipe clamp at the same time. The test pressure is applied to the sample from another joint. This type of joint is suitable for thin-walled PE pipes, soft PVC pipes, soft PVC mesh pipes, etc. 352
Connecting press
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GB/T15560--1995
1-connecting bolt; 2-sample; 3-inner flange; 4-sealing joint Figure A3
GB/T 15560
1-connector; 2-pressing nut; 3-pressing ring; 4-sample; 5-exhaust cap 2
1-connector: 2-sample, 3-adjustable pipe clamp: 4-exhaust cap Figure A7
1-metal connecting rod; 2-bellows sample: 3-sealing ring; 4-metal joint Appendix B
Gas pressurization system
(reference)
B1 As shown in Figure B1, compressed air, such as nitrogen, is used to apply pressure to the liquid pressure buffer, and then the sample is pressurized by the pressure liquid in the buffer.
Additional Notes:
GB/T 15560—1995
1 Nitrogen cylinder; 2 Liquid pressure buffer; 3- Test specimen, 4- Measuring pressure gauge This standard is proposed by China Light Industry General Association.
This standard is under the jurisdiction of the National Technical Committee for Standardization of Plastic Products. This standard was drafted by Dalian Plastics Research Institute. The main drafters of this standard are Sun Junhua, Wang Yuhuan, Huang Dan, Li Yumin, and Xue Ping. 3.
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