This standard is not equivalent to the international standard ISO4427:1996 "Specifications for polyethylene pipes for water supply"
The main differences between this standard and ISO4427:1996 are:
1. This standard only contains pipes made of PE63, PE80 and PE100 materials, and does not contain pipes made of PE32 and PE42 materials;
2. This standard adds a definition chapter;
3. For the performance requirements of the pipe, the "elongation at break" project has been added;
4. Added the chapter "Inspection Rules";
The difference between this standard and GB/T13663-1992 is:
GB/T13663-1992 "High-density polyethylene for water supply (HDPE) pipe" has not been developed using international standards.
From the date of implementation of this standard, at the same time replace GB/T13663-1992
Appendix A of this standard is an appendix to the tip.
This standard was proposed by the National Light Industry Bureau.
This standard is under the jurisdiction of the National Plastics Standardization Technical Committee.
This standard was drafted: Shandong Shengli Co., Ltd. Plastics Division; participated in the drafting unit: Qilu Petrochemical Co., Ltd. Resin Research Institute, Beijing Snow Electric Group Corporation Beijing Plastic Products Factory, Beijing Municipal Engineering Design and Research Institute.
The main drafters of this standard: Sun Xun, Xie Jianling, Feng Xinshu, Li Yangli, Liu Yusheng.
1 Scope
The product specifications, technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of polyethylene pipes (hereinafter referred to as "pipes") for extrusion of water-based polyethylene materials are specified. . This standard also specifies the basic performance requirements of raw materials, including classification systems.
This standard applies to water supply pipes made of PE63, PE80 and PE100 materials (see 4.1). The nominal pressure of the pipe is 0.32 MPa to 1.6 MPa, and the nominal outer diameter is 16 mm to 1000 mm.
The pipes specified in this standard are suitable for pressure water delivery of 40 ° C, general purpose, and drinking water.
2, reference standards
The provisions contained in the following standards constitute provisions of this standard by reference in this standard. At the time of publication, the editions indicated were valid. All standards will be revised and parties using this standard should explore the possibility of using the latest version of the following standards.
GB/T2918-1998 Standard environment for conditioning and testing of plastic samples (idtISO291:1997)
GB/T3681-1983 plastic natural weather exposure test method
GB/T3682-1983 thermoplastic melt flow rate test method
GB/T6ill-1985 Method for determination of damage resistance time of thermoplastic pipes under constant internal pressure (eqvISO/DP1167:1978)
Determination of longitudinal retraction rate of GB/T6671.2-1986 polyethylene (PE) pipe (idtISO2506: 1981)
GB/T8804.2-1988 Test method for tensile properties of thermoplastic pipes - Polyethylene pipes (eqv ISO/DIS3504-2)
GB/T8806-1988 Plastic pipe size measurement method (eqvISO3126: 1974)
GB/T13021-1991 Determination of carbon black content of polyethylene pipes and tubes - Thermometric weight loss method (neqISO6964:1986
GB/T17219-1998 Safety evaluation criteria for drinking water distribution equipment and protective materials
GB/T17391-1998 Test method for thermal stability of polyethylene pipes and fittings (eqvISO/TR10837:1991)
GB/T18251-2000 Method for determination of pigment and carbon black dispersion in polyolefin pipes, fittings and compounds
Determination of long-term hydrostatic strength of thermoplastic pipes by extrapolation method of GB/T18252-2000 plastic piping system
3. Definitions, symbols and abbreviations
This standard uses the following definitions, symbols and abbreviations.
3.1 Definition
3.1.1 Geometric definition
3.1.1.1 Nominal outer diameter dn: specified outer diameter in millimeters.
3.1.1.2 Average outer diameter dem: The measured value of the outer circumference of the pipe is divided by the value obtained by 3.142 (pi), accurate to 0.1 mm, and the second non-zero digit carry after the decimal point.
3.1.1.3 Minimum average outer diameter dem, min: The minimum value of the average outer diameter specified in this standard, which is equal to the nominal outer diameter dn, in millimeters.
3.1.1.4 Maximum average outer diameter dem, max: The maximum value of the average outer diameter specified in this standard.
3.1.1.5 Outer diameter dey: The outer diameter measured by the cross section of any point of the pipe is accurate to 0.1mm, and the second non-zero digit after the decimal point is carried.
3.1.1.6 Out-of-roundness: The difference between the maximum outer diameter and the minimum outer diameter measured at the same cross-section of the pipe.
3.1.1.7 Nominal wall thickness en: The specified value of the wall thickness of the pipe, in millimeters, equivalent to the minimum wall thickness ey, min at any point.
3.1.1.8 Wall thickness at any point ey: The measured value of the wall thickness of the pipe at any point, accurate to 0.lmm, the second non-zero digit carry after the decimal point.
3.1.1.9 Minimum wall thickness ey, min: The minimum value of the wall thickness at any point on the circumference of the pipe specified in this standard.
3.1.1.10 Maximum wall thickness ey, max: The maximum wall thickness at any point on the circumference of the pipe determined by the tolerance of the minimum wall thickness (ey, min).
3.1.1.11 Standard Size Ratio (SDR): The ratio of the nominal outside diameter of the pipe to the nominal wall thickness. SDR=dn/en
3.1.2 Material-related definitions
3.1.2.1 Mixed ingredients: pellets made from polyethylene base resin by adding the necessary antioxidants, UV stabilizers and pigments.
3.1.2.2 σlpl1): Hydrostatic strength corresponding to 20°C, 50 years, probability prediction of 97.5%, in megapascals.
3.1.2.3 Minimum required strength (MRS): σlpl rounded to the next smaller value in the priority number R10 or R20 series.
3.1.2.4 Design stress σs: The allowable stress under the specified application conditions, MRS divided by the factor C, rounded to the next smaller value in the priority number R20 series, ie:
Σs=[MRS]/C....................................(1)
3.1.2.5 Total Use (Design) Coefficient C: A total factor greater than 1 that takes into account the conditions of use that are not reflected in the lower prediction limit and the nature of the components such as fittings in the piping system.
3.1.3 Definitions related to the conditions of use
3.1.3.1 Nominal pressure (PN): The nominal pressure PN in this standard corresponds to the maximum working pressure of the pipe at 20 ° C, in megapascals.
3.1.3.2 Maximum Working Pressure (MOP): The maximum effective pressure of a fluid in a piping system that allows continuous use, in megapascals.
3.2 symbol
C: total use (design) coefficient;
Dem: average outer diameter;
Dem,max: the maximum average outer diameter;
Dem, mix: minimum average outer diameter;
Dn: nominal outer diameter;
Ey: wall thickness at any point;
Ey,min: minimum wall thickness;
Ey,max: maximum wall thickness;
Ft: the coefficient of reduction of temperature versus pressure;
Ty: wall thickness tolerance at any point of the pipe;
Σlpl: hydrostatic strength corresponding to 20°C, 50 years, probability prediction of 97.5%;
Σs: design stress;
3.3 Abbreviations
MFR: melt flow rate;
MOP: maximum working pressure;
MRS: minimum required strength;
PE: polyethylene;
PN: nominal pressure;
SDR: Standard size ratio.
4, materials
4.1 naming
The polyethylene pipe material in this standard is named as follows:
4.1.1 According to GB/T18252, determine the hydrostatic strength σlpl of the material corresponding to 20 ° C, 50 years, and the predicted probability of 97.5%.
4.1.2 According to Table 1, the minimum required intensity (MRS) is converted according to σlpl, and the MRS is multiplied by 10 to obtain the grade number of the material.
4.1.3 According to Table 1, the materials are named according to the type of material (PE) and the number of grades.
Table 1 Name of the material
Σlpl, MpaMRS, Mpa material grading number material naming
6.30～7.996.363PE63
8.00～9.998.080PE80
10.00～11.1910.0100PE100
4.2 Polyethylene pipe is produced by mixing ingredients, the mixture is blue or black, and the basic performance should meet the requirements of Table 2. The blue pipe material shall ensure that the weatherability of the pipe made of the material meets the requirements of Table 12. For PE63 grade materials, polyethylene pipe can also be produced by pipe-grade base resin plus masterbatch. The material performance requirements are sampled from the pipe for testing.
The clean recycled materials produced when the pipes are produced according to this standard can be recycled into new materials as long as they can produce pipes complying with this standard.
Table 2 Basic performance requirements for materials
Serial number project requirements
1 carbon black content 1), (mass)% 2.5 ± 0.5
2 carbon black dispersion 1) ≤ level 3
3 color dispersion 2) ≤ level 3
4 oxidation induction time (200), ≥ 20
5 melt flow speed 3) (5,190), the deviation from the product nominal value should not exceed ± 25%
Note
1 Only for black tube materials
2 Only for blue tube materials
3 Only for compounding
5, product specifications
5.1 The pipe of this standard is designed according to the expected service life of 50 years.
5.2 transport water at 20 ° C, C minimum can use Cmin = 1.25. The maximum allowable value of design stress of different grades of materials obtained by formula (1), see Table 3.
Table 3 Maximum allowable values ​​of design stress for different grades of materials
The maximum allowable value of the grade design stress of the material σ, Mpa
PE635
PE806.3
PE1008
5.3 The relationship between the nominal pressure (PN) of the pipe and the design stress σs and the standard size ratio (SDR) is:
PN=2σs/(SDR-1)........................(2)
Where: PN and σs are in megapascals.
5.4 For pipes made of PE63 and PE100 grade materials, the nominal outer diameter and wall thickness determined by the design stress in Table 3 shall be in accordance with Table 4, Table 5 and Table 6 respectively according to the selected nominal pressure.
Pipeline systems can be designed and used with a larger total use (design) factor of C, in which case pipes of higher nominal pressure ratings can be used.
Table 4 Nominal pressure and size of PE63 grade polyethylene pipe
Nominal outer diameter nominal wall thickness
Standard size
3.32617.613.611
Nominal pressure
0.320.40.60.81.0
16 2.3
20 2.32.3
25 2.32.32.3
32 2.32.42.9
40 2.32.33.03.7
50 2.32.93.74.6
632.32.53.64.75.8
752.32.94.35.66.8
902.83.55.16.78.2
1103.44.26.38.110.0
1253.94.87.19.211.4
1404.35.48.010.312.7
1604.96.29.111.814.6
1805.56.910.213.316.4
2006.27.711.414.718.2
2256.98.612.816.620.5
2507.79.614.218.422.7
2808.610.715.920.625.4
3159.712.117.923.228.6
35510.913.620.126.132.2
40012.315.322.729.436.3
45013.817.225.533.140.9
50015.319.128.336.845.4
56017.221.431.741.250.8
63019.324.135.746.357.2
71021.827.240.252.2
80024.530.645.358.8
90027.634.451.0
100030.638.256.6
Table 5 PE80 grade polyethylene pipe nominal pressure and size
Nominal outer diameter nominal wall thickness
Standard size ratio
33211713.611
Nominal pressure
0.40.60.81.01.25
16
20
25 2.3
32 3.0
40 3.7
50 4.6
63 4.75.8
75 4.55.66.8
90 4.35.46.78.2
110 5.36.68.110.0
125 6.07.49.211.4
1404.36.78.310.312.7
1604.97.79.511.814.6
1805.58.610.713.316.4
2006.29.611.914.718.2
2256.910.813.416.620.5
2507.711.914.818.422.7
2808.613.416.620.625.4
3159.715.018.723.228.6
35510.916.921.126.132.2
40012.319.123.729.436.3
45013.821.526.733.140.9
50015.323.929.736.845.4
56017.226.733.241.250.8
63019.330.037.446.357.2
71021.833.942.152.2
80024.538.147.458.8
90027.642.953.3
100030.647.759.3
Table 6 PE100 grade polyethylene pipe nominal pressure and size
Nominal outer diameter nominal wall thickness
Standard size ratio
26211713.611
Nominal pressure
0.60.81.01.251.6
32 3.0
40 3.7
50 4.6
63 4.75.8
75 4.55.66.8
90 4.35.46.78.2
1104.25.36.68.110.0
1254.86.07.49.211.4
1405.46.78.310.312.7
1606.27.79.511.814.6
1806.98.610.713.316.4
2007.79.611.914.718.2
2258.610.813.416.620.5
2509.611.914.818.422.7
28010.713.416.620.625.4
31512.115.018.723.228.6
35513.616.921.126.132.2
40015.319.123.729.436.3
45017.221.526.733.140.9
50019.123.929.736.845.4
56021.426.733.241.250.8
63024.130.037.446.357.2
71027.233.942.152.2
80030.638.147.458.8
90034.442.953.3
100038.247.759.3
5.5 Polyethylene pipe system pressure reduction of temperature
When the polyethylene piping system is continuously used at temperatures above 20 °C, the maximum working pressure (MOP) shall be calculated according to formula (3):
MOP=PN×f1....................................(3)
Where: f1------ reduction factor, found in Table 7.
For a material, as long as it is considered feasible according to the analysis of GB/T18252, a reduction factor higher than the value in Table 7 can be used.
Table 7 50-year life expectancy, pressure reduction factor below 40 °C
Temperature, 203040
Pressure reduction factor 1.00.870.74
6, technical requirements
6.1 color
The color of the municipal drinking water pipe is blue or black, and the black tube should have a coextruded blue color strip. The color strips have at least three strips along the longitudinal direction of the tube.
Other uses of water pipes can be blue and black.
Laying pipes exposed to the sun (such as above-ground pipes) must be black.
6.2 Appearance
The inner and outer surfaces of the pipe should be clean and smooth, and no defects such as bubbles, obvious scratches, dents, impurities, and uneven color are allowed. The tube end should be cut flat and perpendicular to the tube axis.
6.3 pipe size
6.3.1 Pipe length
6.3.1.1 The length of the straight pipe is generally 6m, 9m, 12m, which can also be agreed by both the supplier and the buyer. The limit deviation of the length is +0.4% of the length, -0.2%.
6.3.1.2 The diameter of the coil tray shall not be less than 18 times the outer diameter of the pipe. The coil expansion length is agreed upon by the supplier and the buyer.
6.3.2 Average outer diameter
The average outer diameter of the pipe shall comply with the requirements of Table 8. Grade B is used for fine tolerance pipes and Class A is used for standard tolerance pipes. The use of grade B or grade A is agreed between the supplier and the buyer. Level A shall be considered if there is no express requirement.
Table 8 Average outer diameter
Nominal outer diameter minimum average outer diameter maximum average outer diameter
Level A Level B
1616.016.316.3
2020.020.320.3
2525.025.325.3
3232.032.332.3
4040.040.040.3
5050.050.550.3
6363.063.663.4
7575.075.775.5
9090.090.990.6
110110.0111.0110.7
125125.0126.2125.8
140140.0141.3140.9
160160.0161.5161.0
180180.0181.7181.1
200200.0201.8201.2
225225.0227.1226.4
250250.0252.3251.5
280280.0282.6281.7
315315.0317.9316.9
355355.0358.2357.2
400400.0403.6402.4
450450.0454.1452.7
500500.0504.5503.0
560560.0565.0563.4
630630.0635.7633.8
710710.0716.4714.0
800800.0807.2804.2
900900.0908.1904.0
10001000.01009.01004.0
6.3.3 Wall thickness and deviation
The minimum wall thickness of the pipe, ey, min, etc., is nominally the wall thickness en. The wall thickness tolerance at any point of the pipe shall comply with the requirements of Table 9.
Table 9 wall thickness tolerance at any point
Minimum wall thickness
Minimum tolerance wall thickness
tolerance
Minimum wall thickness
tolerance
>
≤
>
≤
>
≤
25.025.55.045.045.59.0
25.526.05.145.546.09.1
2.03.00.526.026.55.246.046.59.2
3.04.00.626.527.05.346.547.09.3
4.04.60.727.027.55.447.047.59.4
4.65.30.827.528.05.547.548.09.5
5.36.00.928.028.55.648.048.59.6
6.06.61.028.529.05.748.549.09.7
6.67.31.129.029.55.849.049.59.8
7.38.01.229.530.05.949.550.09.9
8.08.61.330.030.56.050.050.510.0
8.69.31.430.531.06.150.551.010.1
9.310.01.531.031.56.251.051.510.2
10.010.61.631.532.06.351.552.010.3
10.611.31.732.032.56.452.052.510.4
11.312.01.832.533.06.552.553.010.5
12.012.61.933.033.56.653.053.510.6
12.613.32.033.534.06.753.554.010.7
13.314.02.134.034.56.854.054.510.8
14.014.62.234.535.06.954.555.010.9
14.615.32.335.035.57.055.055.511.0
15.316.02.435.536.07.155.556.011.1
16.016.53.236.036.57.256.056.511.2
16.517.03.336.537.07.356.557.011.3
17.017.53.437.037.57.457.057.511.4
17.518.03.537.538.07.557.558.011.5
18.018.53.638.038.57.658.058.511.6
18.519.03.738.539.07.758.559.011.7
19.019.53.839.039.57.859.059.511.8
19.520.03.939.540.07.959.560.011.9
20.020.54.040.040.58.060.060.512.0
20.521.04.140.541.08.160.561.012.1
21.021.54.241.041.58.261.061.512.2
21.522.04.341.542.08.3
22.022.54.442.042.58.4
22.523.04.542.543.08.5
23.023.54.643.043.58.6
23.524.04.743.544.08.7
24.024.54.844.044.58.8
24.525.04.944.545.08.9
6.4 Hydrostatic strength
The hydrostatic strength of the pipe shall comply with the requirements of Table 10.
Table 10 Hydrostatic strength of pipes
Serial number project hoop stress requirements
PE63PE80PE100
120 ° C hydrostatic strength () 8.09.012.4 does not break, no leakage
280 ° C hydrostatic strength () 3.54.65.5 does not break, no leakage
380 ° C hydrostatic strength () 3.24.05.0 does not break, no leakage
The 80 ° C hydrostatic strength (165 h) test only considered brittle failure. If toughness failure occurs within the required time (165 h), retest the lower failure stress and the corresponding minimum failure time according to Table 11.
Table 11 Re-experimental requirements for hydrostatic strength (165h) at 80 °C
PE63PE80PE100
Stress minimum failure time stress minimum failure time stress minimum failure time
3.42854.52195.4233
3.35384.42835.3332
3.210004.33945.2476
4.25335.1688
4.17275.01000
4.01000
6.5 physical properties
The physical properties of the pipe should meet the requirements of Table 12. When the recycled material is added to the compound, the difference between the melt flow rate (MFR) (5 kg, 190 ° C) and the measured value of the mixture measured for the pipe should not exceed 25%.
Table 12 Pipe physical properties requirements
Serial number project requirements
1 short crack elongation, % ≥350
2 longitudinal retraction rate (110 ° C), % ≤ 3
3 oxidation induction time (220 ° C), ≥ 20
4 Thickness resistance 1) (After cumulative acceptance of ≥ aging energy) 80 °C hydrostatic strength (), the experimental conditions are the same as 10 without cracking, no leakage
Short split elongation, % ≥ 350
Oxidation induction time (200 ° C), ≥ 10
1) Only for blue pipes.
6.6 Hygienic performance
The sanitary performance of pipes used for drinking water distribution shall comply with the provisions of GB/T17219.
7, experimental methods
7.1 Standard conditions for condition adjustment and testing of samples
According to the provisions of GB/T2918, the temperature is 23 °C ± 2 °C, the state adjustment time is 24h. The test method standards are specified in the test method standards.
7.2 color and appearance
Observed with the naked eye.
7.3 Size measurement
7.3.1 length
The straight tube was measured with a steel tape measure of exactly 1 mm.
7.3.2 Average outer diameter
Measuring the average outer diameter according to GB/T8806
7.3.3 Wall thickness and deviation
The wall thickness and deviation of the pipe are measured according to the provisions of GB/T8806.
7.4 carbon black content
According to GB/T13021 regulations.
7.5 Pigment and carbon black dispersion
According to the provisions of GB/T18251. A tableting method is used.
7.6 oxidation induction time
According to the provisions of GB/T17391. The specimen shall be taken from the inner surface of the pipe. After aging, the sample shall be taken from the surface after the aging surface of the exposed pipe sample is scraped 0.4 mm.
7.7 melt flow rate
According to the provisions of GB/T3682.
7.8 Hydrostatic strength
According to the provisions of GB/T6111. The medium inside and outside the tube is water. A type joint or b type joint can be used, and a type joint is used for arbitration.
7.9 elongation at break
According to the provisions of GB/T8804.2. The elongation at break test is applicable when the wall thickness of the pipe is not more than 12 mm. After aging, the sample should be taken from the exposed side of the pipe.
7.10 longitudinal retraction rate
According to the provisions of GB/T6671.2. Pipes with an outer diameter greater than 200 mm can be tested using longitudinally cut pipe splines. The test temperature was 110 °C ± 2 °C.
7.11 Weather resistance
Pipes with a nominal outer diameter of 82 mm and SDR11 shall be used. When the pipe size of the production plant is larger than the nominal outer diameter of 32 mm, the pipe with the smallest nominal outer diameter and the largest SDR should be used. Exposure according to GB/T3681. Then, the hydrostatic strength test was carried out in accordance with 7.8, the elongation at break was measured in accordance with 7.9, and the oxidation induction time was measured in accordance with 7.6.
7.12 Hygienic performance
The pipe with the smallest outer diameter of the manufacturer shall be used. According to the provisions of GB/T17219.
8, inspection rules
Inspection is divided into factory inspection and type inspection.
8.1 Factory inspection
The factory inspection items are the 80 °C hydrostatic strength (165h) test in 6.1, 6.2, 6.3, and 6.4, and the elongation at break and oxidation induction time test in 6.5.
8.1.1 Group Approval
The same specification pipe produced continuously by the same raw materials, formula and process is taken as a batch, and the quantity of each batch does not exceed 100t. The production period is less than 100t in 7 days, and the production volume is 7 days.
8.1.2 Sampling
6.1, 6.2, 6.3 Inspection According to the provisions of Table 13, the normal inspection once sampling plan is adopted, and the general inspection level is 1 and the qualified quality level is 6.5.
Table 13 sampling plan
Batch range sample size qualified judgment number unqualified judgment number
≤150812
151～2801323
281～5002034
501~12003256
1201～32005078
3201～10000801011
In the products with acceptable sampling, the 80 ° C hydrostatic strength () test in 6.4, the elongation at break in 6.5, and the oxidation induction time were performed. The number of test samples for hydrostatic strength and oxidation induction time was one.
The pipe must be inspected by the quality inspection department of the manufacturer and accompanied by a certificate to be shipped.
8.2 type test
The type inspection items are all technical requirements except the 80 °C hydrostatic strength (165h) in Chapter 6 of this standard.
8.2.1 Grouping and sampling
According to the nominal outer diameter of the pipe, the pipes are grouped according to Table 14.
Table 14 Dimensional grouping of pipes
Size group 1234
Nominal outer diameter ≤ 6363 < ≤ 225225 < ≤ 630630 < ≤ 1000
According to the technical requirements of this standard, the largest diameter pipe and the smallest diameter pipe with the smallest SDR produced by the production plants in each group are selected, and 6.1, 6.2, and 6.3 are tested according to the provisions of 8.1.2. Samples were taken from the samples that passed the test, and the hydrostatic strength (100 h) test at 20 ° C, the hydrostatic strength (1000 h) test at 80 ° C, and the performance test of 6.5 and 6.6 were performed.
8.2.2 Type inspection shall be carried out if one of the following conditions exists.
a) Trial-type identification of new products or old products to factory production;
b) When there are large changes in structure, materials and processes that may affect product performance;
c) when the product resumes production after a long-term shutdown;
d) When the factory inspection result is significantly different from the previous type inspection result;
e) when the national quality supervision agency requests the type inspection;
8.3 Decision Rules
6.1, 6.2, and 6.3 are judged according to Table 13. If one of the other indicators fails to meet the requirements, a double sample is randomly sampled for re-inspection. If it is still unqualified, the batch of products is judged to be unqualified.
9. Marking, packaging, transportation and storage
9.1 mark
The pipe shall have a permanent mark when it leaves the factory, and the spacing shall not exceed 2m.
The logo should at least include the following:
-- the name and/or trademark of the manufacturer;
-- nominal outer diameter;
-- "Standard size ratio" or "SDR";
-- material grade (PE100, PE80 or PE63);
-- nominal pressure (or PN);
--Production Date;
-- using the standard number;
-- "Water" or "water" (for drinking water only).
9.2 packaging
According to the agreement between the supplier and the buyer.
9.3 Transportation
Pipes shall not be subject to scratches, throws, severe impacts, oil and chemical contamination.
9.4 Storage
The pipe is stored in a warehouse that is far away from heat sources and oil and chemical pollution, and has a well-ventilated and well-ventilated floor; if it is stacked outdoors, it should be covered.
The pipes should be stacked neatly and the stacking height should not exceed 1.5m.
Appendix A
(Appendix to the tip)
Tube roundness
The maximum outer diameter and the minimum outer diameter of the same section are measured according to the provisions of GB/T8806, and the maximum outer diameter minus the minimum outer diameter is the roundness. The degree of unwinding of the pipe is measured at the time of extrusion.
See Table B1 for recommended requirements for the roundness of straight pipes with a nominal diameter of 630 mm or less. The degree of non-circularity of the coil and the pipe with a nominal outer diameter greater than 630 mm may be agreed between the supplier and the buyer.
Table A1 Tube roundness
Nominal outer diameter maximum roundness
161.2
201.2
251.2
321.3
401.4
501.4
631.5
751.6
901.8
1102.2
1252.5
1402.8
1603.2
1803.6
2004.0
2254.5
2505.0
2809.8
31511.1
35512.5
40014.0
45015.6
50017.5
56019.6
63022.1
710
800
900
1000
It can be equipped with a scrolling display that displays 300-500 words of display content. It can also be equipped with intelligent infrared probe anti-collision device, which can automatically return to work when people or foreign objects are 20-30CM, thus ensuring the safety of vehicles and pedestrians.It can automatically open and close when automatic clutch is cut off. Manually open and close when manual clutch is cut off. The control system has control panel, push button switch, and other requirements. Equipped with wireless remote control.The door body is made of high-quality stainless steel and aluminum alloy profiles, and is hinged by the parallelogram principle. The drive is driven by special motor, worm and worm gear deceleration, and has automatic clutch or manual clutch.
Factory Sliding Retractable Gate,Aluminum Alloy School Sliding Gate,Automatic Electric Single Double Gate,Store Retractable Gate
Shenzhen Hongfa Automatic Door Co., Ltd. , https://www.hfautodoors.com