Some standard content:
National Standard of the People's Republic of China
Buried polyethylene (PE) pipes for the supply of gaseous fuels
1 Subject content and scope of application
GB15558 .1-1995
This standard specifies the technical requirements, test methods, inspection rules, signs, and Packaging, transportation and storage. In addition, the main performance requirements of raw materials are also specified. This standard is applicable to pipes with an operating temperature of between 20 and 40°C and a maximum working pressure of no more than 0.4MPa. When pipes transport artificial gas and liquefied petroleum gas, SDR11 series pipes should be selected. At the same time, the adverse effects of other components (such as aromatic hydrocarbons, condensates, etc.) present in the gas on the performance of the pipes at a certain concentration must be considered. Note: SDR standard size ratio, that is, the ratio of nominal outer diameter to wall thickness. 2 Reference Standards
3 Plastic Density and Relative Density Test Methods
GB1033
GB1842
Polyethylene Environmental Stress Cracking Test Methods
GB2828 Batch-by-Batch Inspection Count Sampling procedures and sampling tables (applicable to inspection of continuous batches) Standard environment for condition adjustment and testing of plastic samples GB2918
GB3681
Natural climate exposure test method for plastics
Thermoplastic melt Flow rate test method GB3682
GB6111 Method for determination of damage resistance time of thermoplastic pipes under long-term constant internal pressure Determination of moisture content in chemical products Karl Fischer method (general method) GB6283
GB6671.2 Determination of the longitudinal retraction rate of polyethylene (PE) pipes GB8804.2 Test methods for tensile properties of thermoplastic pipes Polyethylene pipes
GB8806 Dimensional measurement methods for plastic pipes
GB13021 Carbon black for polyethylene pipes and fittings Content determination (thermal weight loss method) 3 Raw materials
3.1 Basic raw materials and additives
The basic raw material is polyethylene resin. Necessary additives can be added, such as antioxidants, UV stabilizers and colorants. Additives added should be dispersed evenly.
3.2 Recycled materials
The clean residual materials produced when producing pipes according to this standard can be mixed with new materials for reuse as long as pipes that meet the requirements of this standard can be produced.
3.3 Basic properties
The basic properties of raw materials should meet the requirements of Table 1.
State Bureau of Technical Supervision approved on 1995-05-02 for implementation on 1995-12-01
Density, kg/m2
Item
Moisture content, mg/kg|| tt||Volatile content, mg/kg
Carbon black content\, %
Thermal stability (200℃), min
Environmental stress cracking resistance, h||tt| |(100C,100%,F)
Gas-resistant component, h
(80C, 2MPa)
Long-term hydrostatic strength, MP:
(20℃ , 50 years, 95%)
item
Note: 1) Carbon black content only applies to black tubes. 4Technical requirements
4.1 Color
GB15558.1—1995
Table 1
Performance requirements
≥930
<300|| tt||<350
2.0~2.6
>20
≥1 000
≥30
≥8.0
Pipe color It is yellow or black, and the black tube must have an eye-catching yellow color strip. 4.2 Appearance
Test method
See 5.5
See 5.6
See 5.7
See 5.8
See 5.9
See 5.10
See 5.11
See Appendix A
The internal and external surfaces of the pipe should be clean and smooth, and no bubbles, obvious scratches, dents, impurities, uneven colors and other defects are allowed. The pipe ends should be cut flat and perpendicular to the pipe axis. 4.3 Specifications and dimensions
4.3.1 Outer diameter, wall thickness and allowable deviation
The outer diameter and allowable deviation and wall thickness and allowable deviation of the pipe shall comply with the provisions of Table 2. 4.3.2 Pipe length
The length of straight pipe is generally 6, 9, or 12m, or it can be agreed upon by both parties. The allowable length deviation is 20mm. The unfolded length of the coil is agreed upon by both parties. The outer diameter of the coiled pipe should not be larger than 110mm. The diameter of the coil rack or the minimum inner diameter of the reel should not be less than 24 times the outer diameter of the pipe, and the minimum should not be less than 0.6m. 4.3.3 Out-of-roundness
Test according to 5.4, the out-of-roundness should not be greater than 5%. Table 2
nominal outer diameter d.
SDRu
Basic size
20
Allowable deviation
+0.3
0
Working pressure ≤0.4MPa| |tt||Basic size
3.0
Allow deviation
+0.4
0
Wall
Thickness e
SDR
Working pressure ≤0.2MPa
Basic size
2.3
mm
Permissible deviation
+0.4
0
Nominal outer diameter d.
Basic size
25
32
40
50
63
75
90| |tt||110
125
140
160
180
allowable deviation
+0.3
0| |tt||+0.3
0
+0. 4
0
+0. 4
0
+0.4| |tt||0
+0.5
0
+0.6
0
+0.6
0
+ 0.6
0
+0.9
0
+1.0
0
+1.0
0||tt| |GB15558.1-1995
Continued Table 2
Wall
SDR1
Working pressure ≤0.4MPa
Basic size
3.0| |tt||3.0
3.7
4. 6
5.8
6.8
8.2
10.0
11.4| |tt||12.7
14.6
16.4
Allowable deviation
+0. 4
0
+0.4||tt| |0
+0.5
0
+0.6
0
+0.7
0
+0.8|| tt||.
+1.0
0
+1.1
0
+1.3
0
+1.4||tt| |0
+1.6
0
+1.8
0
Thick e
SDR116
Working pressure ≤0.2 MPa
Basic size
2.3
2.3
2.3
2.9
3.6
4.3
5.2
6.3
7.1
8.0
9.1
10.3
mm
allowable deviation
+0.4
0
+0.4
0
+0. 4
0
+0.4
0||tt ||+0.5
0
+0.6
0
+0.7
0
+0.8
0| |tt||+0.9
0
+0.9
0
+1.1
0
+1.2
o||tt| |Nominal outer diameter d.
Basic size
200
225
250
Allowable deviation
+1.2
0
+1.4
0
+1.5
0
4.4 Performance requirements
GB15558.1—1995
Continued Table 2||tt ||Wall
SDRu
Working pressure ≤0.4MPa
Basic size
18.2
20.5
22.7
Pipe Performance requirements should comply with the requirements in Table 3
serial number
1
2
3
4
5
6| |tt||7
8
item
item
Long-term hydrostatic strength, MPa (20℃, 50 years, 95%) 20℃||tt| |Short-term hydrostatic strength
MPa
80℃
Thermal stability (200℃), min
Stress cracking resistance, h
(80℃ C,4.0MPa)
Compression recovery (80℃, 4MPa),h
Longitudinal shrinkage rate, (110℃), %
Elongation at break, %||tt ||Allowable deviation
+2.0
0
+2.2
0
+2.4
0
Table 3
Weather resistance (after the pipe has accumulated ≥3.5kMJ/m2 aging energy)
Thicke
SDRm
Working pressure ≤0.2MPa
Basic size
11.4
12.8
14.2
Sex
Can
To
>8. 0
9.0
Find
ductile failure time (h)>100
4. 61)
brittle failure time (h)>165
4.0|| tt||Destruction time (h)>10002)
>20
≥10002)
≥170
>170
≤3||tt ||>350
mm
allowable deviation
+1.3
0
+1.4
0
+1.6
0
Test method
See Appendix A
See 5.13
See 5.9
See 5.12
See 5.14| |tt||See 5.15
See 5.16
It can still meet the performance requirements of items 2, 3 and 7 of this table and maintain good welding performance
See 5.17||tt| |Note: 1) Only suitable for brittle failure. If ductile failure occurs within the above required time (165h), select a lower failure stress and corresponding minimum failure time according to the table below.
2) Type inspection requirements.
3) Factory inspection requirements.
5 Test methods
5.1 Test environment
Failure stress, MPa
4.6
4.5
4.4
GB15558. 1—1995
Minimum failure time, h
165
219
293
Failure stress, MPa
4.3||tt| |4.2
4.1
Minimum destruction time, h
394
533
727
The test environment is in accordance with GB2918, the temperature is 23 ±2℃. The specimen must be conditioned according to the test environment for more than 24 hours before testing.
5.2 Appearance and color inspection
Observe directly with the naked eye, and the inner wall can be illuminated with a light source. 5.3 Dimensional measurement
The outer diameter and wall thickness of the pipe are measured according to the regulations of GB8806. The length of the pipe and the diameter of the coil rack or the minimum inner diameter of the reel should be measured with a ruler with an accuracy of not less than 10mm. 5.4 Out-of-roundness measurement
5.4.1 Instrument: micrometer or vernier caliper, accuracy is 0.02mm. 5.4.2 Measurement method: Measure the maximum outer diameter and minimum outer diameter of the pipe along the same section of the pipe. 5.4.3 Calculation and result expression: Out-of-roundness (%) is calculated according to formula (1). dmax-dmin
Take the arithmetic mean of the test results of three samples as the out-of-roundness. 5.5 Density measurement
shall be measured according to the provisions of GB1033.
5.6 Moisture content determination
Measurement shall be carried out in accordance with the provisions of GB6283, and the sample shall not be conditioned. 5.7 Determination of volatile content
5.7.1 Test instrument
5.7.1.1 Oven: 105±0.5℃, no air blast. 5.7.1.2 Weighing bottle: 935mm×70mm glass weighing bottle. 5.7.1.3 Analytical balance: sensitivity 0.0001g. 5.7.1.4 Desiccant: glass desiccator containing color-changing silica gel. 5.7.2 Test steps
(1)
5.7.2.1 Heat the clean weighing bottle with a lid in an oven at 105 ± 0.5°C for 1 hour, take it out, and place it in a desiccator to cool to room temperature. , its weight is m (accurate to 0.001g).
5.7.2.2 Spread about 25g of resin evenly on the bottom of the weighing bottle, cover the bottle cap, and call the weight m (accurate to 0.001g). 5.7.2.3 Place the weighing bottle containing the resin in an oven at 105 ± 0.5°C, remove the lid and leave it in the oven. Close the oven door and dry for 1 hour, take it out, cool it to room temperature in a desiccator, and weigh it accurately. Heating for another 0.5h, the operation is the same as above until the weight is constant (that is, the difference between continuous weighing is not more than 0.001g), and the weight is called m2. The lid must be closed at all times during transfer and weighing. 5.7.3 Calculation and result expression
Volatile content (mg/kg) is calculated according to formula (2): where: m. Weight of dry weighing bottle, g; GB15558.1—1995
m - m2 × 106
m,-m.
m1——The weight of the resin before heating plus the weighing bottle, g:m2——The weight of the resin after heating to constant weight plus the weight of the weighing bottle, g. Take the arithmetic mean of the test results of the three samples as the volatile content. 5.8 Carbon black content determination
shall be determined in accordance with GB13021.
5.9 Thermal Stability Test
5.9.1 Test Instrument
5.9.1.1 A differential scanning calorimeter (DSC) or thermal analyzer that can continuously record the sample temperature, with an accuracy of 0.1℃. 5.9.1.2 Temperature measuring instrument with an accuracy of 0.1°C. 5.9.1.3 Analytical balance, sensitivity: 0.1 mg. 5.9.1.4 Oxygen and high-purity nitrogen supplies with switch. 5.9.1.5 Gas flow meter.
5.9.2 Sample
5.9.2.1 Pipe sample preparation:
(2)
Saw a 2~3cm wide ring from the pipe, use Clamp the ring in a vise, cut a cylinder on the surface of the ring in the radial direction with a diameter slightly smaller than the inner diameter of the thermal analyzer sample plate, and use a sharp blade to cut a disc weighing 15±0.5 mg from the cylinder as a test Sample. 5.9.2.2 Raw material sample preparation:
Place the raw material in a cylindrical mold plate, heat it at 150 ± 3°C for 2 minutes, and cut a cylinder with a diameter slightly smaller than the inner diameter of the thermal analyzer sample plate. Use a sharp blade to cut a disc weighing 15 ± 0.5 mg from the cylinder as a sample. 5.9.3 Test steps
5.9.3.1 Calibrate the thermal analyzer.
5.9.3.2 Adjust the nitrogen flow to allow 50±5cm/min of nitrogen to flow through the thermal analyzer, then connect the switch to oxygen and adjust the oxygen flow to allow 50±5cm*/min of oxygen to flow through the thermal analyzer. , and then switch to nitrogen. 5.9.3.3. Place an open aluminum plate containing 15 ± 0.5 mg of the sample into the thermal analyzer, raise the temperature at a rate of 20°C/min to keep the temperature constant at 200 ± 0.1°C, and start recording the temperature changes with time. 5.9.3.4 After the nitrogen flow passes through the thermal analyzer for 5 minutes, switch to oxygen until the temperature rise of oxidation reaches the maximum value. 5.9.4 Test results
On the graph of temperature changing with time, as shown in Figure 1, mark the point A1 after switching from nitrogen to oxygen for 1 minute, and draw the tangent line with the largest slope when the temperature rises. Mark Find the intersection point A2 between this tangent line and the baseline, and the time between these two points is the oxidation induction period (min) of the thermal stability of the sample.
The test results are the arithmetic mean of five tests. 5.10 Environmental stress cracking resistance test
GB15558.1—1995
Oxidation induction period
Figure 1
Time, min
Test according to the regulations of GB1842, The test temperature is 100±2℃. The test results are expressed as the time (F.) when the sample damage probability reaches 0. 5.11 Gas resistance component test
Test medium: 50% (weight ratio) n-propane (99%) and 50% (weight ratio) trimethylbenzene mixture. The test medium temperature is 80℃. The test hoop stress is 2.0MPa. Before the test, the mixture of n-alkane and trimethylbenzene should be injected into a 32mm × 3.0mm tubular sample with a free length of not less than 250mm. After being placed in an environment of 23±2℃ for 1500h, the test should be carried out according to the regulations of GB6111. 5.12 Stress cracking resistance test
5.12.1 Test instrument
5.12.1.1 Cutting equipment: 76.2mm×12.5mm×25.4mm double equiangular milling cutter with 60° angle, and rigid base and cutter shelf. Note: The milling cutter should be replaced after 500m of use. 5.12.1.2 Test equipment such as constant temperature system, pressurization system, timer and sealing joints required in GB6111. 5.12.2 Sample
5.12.2.1 The sample should be made of pipe with a nominal outer diameter of not less than 63mm, and the free length of the sample should not be less than 6 times the outer diameter of the pipe. 5.12.2.2 Sample incision: The milling cutter speed is 700r/min, and the reciprocating speed is 150mm/min. 5.12.2.3 The sample shall comply with the requirements of Figure 2; a cutout shall be made every 90° along the circumference of the pipe, with a total of four cuts. The cutout shall be in the middle of the length of the specimen. The depth of the cutout shall be 19% of the wall thickness of the pipe. The length of the cutout shall not exceed 19% of the pipe wall thickness. Less than the outer diameter of the sample, the minimum shall not be less than 125mm. 5.12.2.4 The number of specimens is 10.
5.12.3 Test steps
5.12.3.1 Before the test, the sample should be pretreated in a constant temperature water bath of 80±1℃ for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the sample is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to the regulations of GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage and elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
4 Test results
On the graph of temperature changing with time, as shown in Figure 1, mark the point A1 after switching from nitrogen to oxygen for 1 minute. Draw the tangent line with the largest slope when the temperature rises. Mark this point. The intersection point A2 of the tangent line and the baseline, and the time between these two points is the oxidation induction period (min) of the thermal stability of the sample.
The test results are the arithmetic mean of five tests. 5.10 Environmental stress cracking resistance test
GB15558.1—1995
Oxidation induction period
Figure 1
Time, min
Test according to the regulations of GB1842, The test temperature is 100±2℃. The test results are expressed as the time (F.) when the sample damage probability reaches 0. 5.11 Gas resistance component test
Test medium: 50% (weight ratio) n-propane (99%) and 50% (weight ratio) trimethylbenzene mixture. The test medium temperature is 80℃. The test hoop stress is 2.0MPa. Before the test, the mixture of n-alkane and trimethylbenzene should be injected into a 32mm × 3.0mm tubular sample with a free length of not less than 250mm. After being placed in an environment of 23±2℃ for 1500h, the test should be carried out according to the regulations of GB6111. 5.12 Stress cracking resistance test
5.12.1 Test instrument
5.12.1.1 Cutting equipment: 76.2mm×12.5mm×25.4mm double equiangular milling cutter with 60° angle, and rigid base and cutter shelf. Note: The milling cutter should be replaced after 500m of use. 5.12.1.2 Test equipment such as constant temperature system, pressurization system, timer and sealing joints required in GB6111. 5.12.2 Sample
5.12.2.1 The sample should be made of pipe with a nominal outer diameter of not less than 63mm, and the free length of the sample should not be less than 6 times the outer diameter of the pipe. 5.12.2.2 Sample incision: The milling cutter speed is 700r/min, and the reciprocating speed is 150mm/min. 5.12.2.3 The sample shall comply with the requirements of Figure 2; a cutout shall be made every 90° along the circumference of the pipe, with a total of four cuts. The cutout shall be in the middle of the length of the specimen. The depth of the cutout shall be 19% of the wall thickness of the pipe. The length of the cutout shall not exceed 19% of the pipe wall thickness. Less than the outer diameter of the sample, the minimum shall not be less than 125mm. 5.12.2.4 The number of specimens is 10.
5.12.3 Test steps
5.12.3.1 Before the test, the sample should be pretreated in a constant temperature water bath of 80±1°C for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the sample is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to the regulations of GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage, elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;bzxZ.net
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
4 Test results
On the graph of temperature changing with time, as shown in Figure 1, mark the point A1 after switching from nitrogen to oxygen for 1 minute. Draw the tangent line with the largest slope when the temperature rises. Mark this point. The intersection point A2 of the tangent line and the baseline, and the time between these two points is the oxidation induction period (min) of the thermal stability of the sample.
The test results are the arithmetic mean of five tests. 5.10 Environmental stress cracking resistance test
GB15558.1—1995
Oxidation induction period
Figure 1
Time, min
Test according to the regulations of GB1842, The test temperature is 100±2℃. The test results are expressed as the time (F.) when the sample damage probability reaches 0. 5.11 Gas resistance component test
Test medium: 50% (weight ratio) n-propane (99%) and 50% (weight ratio) trimethylbenzene mixture. The test medium temperature is 80℃. The test hoop stress is 2.0MPa. Before the test, the mixture of n-alkane and trimethylbenzene should be injected into a 32mm × 3.0mm tubular sample with a free length of not less than 250mm. After being placed in an environment of 23±2℃ for 1500h, the test should be carried out according to the regulations of GB6111. 5.12 Stress cracking resistance test
5.12.1 Test instrument
5.12.1.1 Cutting equipment: 76.2mm×12.5mm×25.4mm double equiangular milling cutter with 60° angle, and rigid base and cutter shelf. Note: The milling cutter should be replaced after 500m of use. 5.12.1.2 Test equipment such as constant temperature system, pressurization system, timer and sealing joints required in GB6111. 5.12.2 Sample
5.12.2.1 The sample should be made of pipe with a nominal outer diameter of not less than 63mm, and the free length of the sample should not be less than 6 times the outer diameter of the pipe. 5.12.2.2 Sample incision: The milling cutter speed is 700r/min, and the reciprocating speed is 150mm/min. 5.12.2.3 The sample shall comply with the requirements of Figure 2; a cutout shall be made every 90° along the circumference of the pipe, with a total of four cuts. The cutout shall be in the middle of the length of the specimen. The depth of the cutout shall be 19% of the wall thickness of the pipe. The length of the cutout shall not exceed 19% of the pipe wall thickness. Less than the outer diameter of the sample, the minimum shall not be less than 125mm. 5.12.2.4 The number of specimens is 10.
5.12.3 Test steps
5.12.3.1 Before the test, the sample should be pretreated in a constant temperature water bath of 80±1°C for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the sample is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to the regulations of GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage, elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
11 Gas component test
Test medium: 50% (weight ratio) n-propane (99%) and 50% (weight ratio) trimethylbenzene mixture. The test medium temperature is 80℃. The test hoop stress is 2.0MPa. Before the test, the mixture of n-alkane and trimethylbenzene should be injected into a 32mm × 3.0mm tubular sample with a free length of not less than 250mm. After being placed in an environment of 23±2℃ for 1500h, the test should be carried out according to the regulations of GB6111. 5.12 Stress cracking resistance test
5.12.1 Test instrument
5.12.1.1 Cutting equipment: 76.2mm×12.5mm×25.4mm double equiangular milling cutter with 60° angle, and rigid base and cutter shelf. Note: The milling cutter should be replaced after 500m of use. 5.12.1.2 Test equipment such as constant temperature system, pressurization system, timer and sealing joints required in GB6111. 5.12.2 Sample
5.12.2.1 The sample should be made of pipe with a nominal outer diameter of not less than 63mm, and the free length of the sample should not be less than 6 times the outer diameter of the pipe. 5.12.2.2 Sample incision: The milling cutter speed is 700r/min, and the reciprocating speed is 150mm/min. 5.12.2.3 The sample shall comply with the requirements of Figure 2; a cutout shall be made every 90° along the circumference of the pipe, with a total of four cuts. The cutout shall be in the middle of the length of the specimen. The depth of the cutout shall be 19% of the wall thickness of the pipe. The length of the cutout shall not exceed 19% of the pipe wall thickness. Less than the outer diameter of the sample, the minimum shall not be less than 125mm. 5.12.2.4 The number of specimens is 10.
5.12.3 Test steps
5.12.3.1 Before the test, the sample should be pretreated in a constant temperature water bath of 80±1°C for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the sample is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage, elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
11 Gas component test
Test medium: 50% (weight ratio) n-propane (99%) and 50% (weight ratio) trimethylbenzene mixture. The test medium temperature is 80℃. The test hoop stress is 2.0MPa. Before the test, the mixture of n-alkane and trimethylbenzene should be injected into a 32mm × 3.0mm tubular sample with a free length of not less than 250mm. After being placed in an environment of 23±2℃ for 1500h, the test should be carried out according to the regulations of GB6111. 5.12 Stress cracking resistance test
5.12.1 Test instrument
5.12.1.1 Cutting equipment: 76.2mm×12.5mm×25.4mm double equiangular milling cutter with 60° angle, and rigid base and cutter shelf. Note: The milling cutter should be replaced after 500m of use. 5.12.1.2 Test equipment such as constant temperature system, pressurization system, timer and sealing joints required in GB6111. 5.12.2 Sample
5.12.2.1 The sample should be made of pipe with a nominal outer diameter of not less than 63mm, and the free length of the sample should not be less than 6 times the outer diameter of the pipe. 5.12.2.2 Sample incision: The milling cutter speed is 700r/min, and the reciprocating speed is 150mm/min. 5.12.2.3 The sample shall comply with the requirements of Figure 2; a cutout shall be made every 90° along the circumference of the pipe, with a total of four cuts. The cutout shall be in the middle of the length of the specimen. The depth of the cutout shall be 19% of the wall thickness of the pipe. The length of the cutout shall not exceed 19% of the pipe wall thickness. Less than the outer diameter of the sample, the minimum shall not be less than 125mm. 5.12.2.4 The number of specimens is 10.
5.12.3 Test steps
5.12.3.1 Before the test, the sample should be pretreated in a constant temperature water bath of 80±1°C for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the specimen is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage and elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
1 Before the test, the sample should be pretreated in a constant temperature water bath at 80 ± 1°C for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the sample is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to the regulations of GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage, elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type inspection
Inspection of 4.1, 4.2, and 4.3 shall be carried out in accordance with the technical requirements of this standard and the provisions of Article 6.3.2. Sufficient samples shall be randomly selected from the samples that have passed the inspection to carry out the inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
1 Before the test, the sample should be pretreated in a constant temperature water bath at 80 ± 1°C for at least 1 hour. 5.12.3.2 Carry out hydrostatic strength test according to GB6111, and the test temperature is 80±1℃. 5.13 Short-term hydrostatic strength test
GB15558.1—1995
Special 700/mlm
Workbench feed speed
150mm/mlm
According to GB6111 Testing is required.
5.14 Compression recovery test
5.14.1 Sample
Incision length
Mouth length
Figure 2
5.14.1.1 The free length of the sample should not be less than 8 times the outer diameter of the pipe, and the minimum should not be less than 250mm. 5.14.1.2 The number of specimens is 10.
5.14.2 Test steps
5.14.2.1 First place the sample in a 0℃ (-5~0℃) environment for more than 10h. 5.14.2.2 Use special pipe pressing equipment to slowly press the sample within 10 minutes until the distance is twice the wall thickness of the original sample, and maintain it for at least 60 minutes.
5.14.2.3 Loosen the pressure tube equipment and allow the sample to recover naturally. 5.14.2.4 After the sample is restored, test it according to the GB6111 method. The test temperature is 80°C and the test hoop stress is 4MPa. 5.15 Longitudinal shrinkage measurement
is measured according to GB6671.2.
5.16 Determination of elongation at break
Measured according to the regulations of GB8804.2.
5.17 Weather resistance test
Conduct the test according to the regulations of GB3681.
6 Inspection Rules
6.1 Pipes must be inspected by the quality inspection department of the manufacturer and must be accompanied by a certificate of conformity before leaving the factory. 6.2 Group batches
Pipes of the same specification produced continuously with the same raw materials, formulas and processes shall be regarded as one batch, and the quantity of each batch shall not exceed 30t. If the production period of 6 days is less than 30t, the 6-day output will be considered as one batch.
6.3 Factory inspection
6.3.1 The factory inspection items are 4.1, 4.24.3, and short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, and longitudinal rebound in 4.4. Shrinkage, elongation at break. The inspection of items 6.3.24.1, 4.2, and 4.3 adopts a normal inspection one-time sampling plan according to GB2828, taking general inspection level I and qualified quality level 6.5, see Table 4.
Batch range
N
≤150
151~280
281~500
501~1200
1201 ~3200
3201~10000
GB15558.1-1995
Table 4
Sample size
n
8||tt| |13
20
32
50
80
Pass judgment number
A
1||tt| |2
3
5
7
10
Sample unit: meter (root)
Number of unqualified judgments||tt ||R
2
3
4
6
8
11
6.3.3 In counting sampling Among the qualified products, sufficient samples are randomly selected to test the short-term hydrostatic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal shrinkage rate, and elongation at break specified in Article 4.4. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transportation and storage
7.1 Marking
When the pipe leaves the factory, it should have the following water-resistant markings, and the distance between the marks shall not exceed 2m. "Gas" or \Gas" words;
b.
c.
d.
e.
f.
g .
Raw material grade;
Standard size ratio or "SDR";
Specification size;
Standard code and serial number;
Manufacturer name or Trademark;
Date of production.
7.2 Packaging
The pipe ends should be blocked, and the pipes should be tied firmly with non-metallic ropes. Straight pipes can also be tied at both ends with wooden frames. The certificate of conformity should be attached, and the outer packaging of the pipe should contain the factory name, factory address and production date. 7.3 Transportation
During transportation, pipes shall not be subject to scratches, throws, violent impacts, exposure to the sun, rain, oil and dirt. Chemical contamination. 7.4 Storage
1-1995
Table 4
Sample size
n
8
13
20
32||tt ||50
80
Pass judgment number
A
1
2
3
5||tt ||7
10
Sample unit: meter (root)
Number of unqualified judgments
R
2
3|| tt | | 4 | | tt | | 6 | | tt | Hydraulic strength, thermal stability, stress cracking resistance, compression recovery, longitudinal retraction, and elongation at break. 6.4 Type Inspection
According to the technical requirements of this standard, and in accordance with the provisions of Article 6.3.2, 4.1, 4.2, and 4.3 shall be inspected. Sufficient samples shall be randomly selected from the samples that have passed the inspection to conduct various inspections in Article 4.4. If any of the following conditions occurs, type inspection should be carried out. a.
b.
c.
d.
e.
f.
New products or old products are transferred to the factory for production Trial prototype identification; after formal production, if there are major changes in equipment, raw materials, and processes, which may affect product performance; during normal production, a periodic inspection should be carried out regularly or after accumulating a certain amount of output; after the product has been discontinued for a long time, When production is resumed; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision agency proposes a request for type inspection. 6.5 Judgment Rules
Items 4.1, 4.2, and 4.3 shall be judged according to Table 5. If one item in Article 4.4 fails to meet the requirements, double samples may be randomly selected for retesting. If there is still one unqualified item, the batch will be deemed unqualified. 7 Marking, packaging, transporta
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