Comprehensive understanding of PE water supply pipe
Comprehensive understanding of PE water supply pipePE (polyethylene) material is widely used in the field of water supply pipe manufacturing due to its high strength, corrosion resistance, and non-toxic characteristics. Because it does not rust, it is an ideal pipe material to replace ordinary iron water supply pipes. PE water supply pipes implement national product standards: GB / T 13663.1-2017, GB / T 13663.2-2018 "Polyethylene (PE) piping system for water supply part 2: pipes"
Chinese name PE water supply pipe Foreign name feeder Features high strength, corrosion resistance, non-toxicity, etc. Suitable for tap water pipes, pressure water supply pipes, irrigation pipes and other materials High-strength polyethylene (HDPE), color masterbatch, etc.
table of Contents
1 Pipeline development
2 Characteristic benefits
▪ Corrosion resistance
▪ Flexibility
▪ Low temperature resistance
▪ Fracture toughness
3 Rules of use
▪ General regulations
▪ Material acceptance
▪ storage
▪ handling
▪ Transportation
4 Connection technology
5 Hot melt docking installation
6 Technical requirements
7 Materials used
8 Installation process
9 Construction steps
10 National Standard
▪ Scope of application
▪ Reference standards
▪ Definition
▪ Symbol
▪ Acronyms
▪ Material naming
▪ Product specifications
▪ Management
▪ Safekeeping
11 Pipe connection
Pipeline development
China's plastic pipes are developing rapidly, and the quality is constantly improving. Among them, polyethylene PE pipes are widely used in building water supply, building drainage, buried drainage pipes, building heating, gas pipes, electrical and telecommunication protection sleeves, industrial pipes, agricultural pipes, etc. due to their unique advantages. It is mainly used in urban water supply, urban gas supply and farmland irrigation.
Characteristic benefit
Corrosion resistance
(1) Polyethylene has excellent corrosion resistance, better hygienic performance and longer service life
Polyethylene is a non-inert material. Except for a small amount of strong oxidant, it is resistant to the erosion of various chemicals, and it is not easy to breed bacteria. It is well known that the reason why steel pipes and cast iron pipes are replaced by plastic pipes is not only because plastic pipes have lower energy consumption for water transportation, lower energy consumption for living, light weight, small water flow resistance, simple and rapid installation, low cost, long life, and thermal insulation. Etc., also because plastic pipes are better than steel pipes and cast iron pipes in terms of corrosion resistance and resistance to microorganism growth.
The service life of polyethylene pipes is more than 50 years, which has not only been confirmed by international standards and some advanced standards abroad, but has also been proved by practice.
Another reason why polyethylene can be popularized is that polyvinyl chloride is increasingly under pressure from environmental protection. The first is the hygienic performance of polyvinyl chloride itself: it is well known that the production of polyvinyl chloride pipes under regular production and strict control can ensure hygienic performance and are allowed to be used in the field of drinking water. However, there are still concerns that problems may occur in places where the control is not strict: for example, the excess of the vinyl chloride monomer in the polyvinyl chloride resin, and the use of toxic additives in the formulation of polyvinyl chloride pipes for water supply. The PVC pipes and fittings for drainage that do not guarantee non-toxicity are misused to the water supply pipes and fittings. Secondly, the problem of recycling of PVC pipes: PVC and polyethylene are thermoplastics, which can be used in theory, but countries have proved that the proportion of old plastic products that can be recycled is limited, and the main treatment method It is energy recovery by incineration. Polyvinyl chloride contains chlorine, which may produce harmful substances when it is not well controlled during incineration. Polyethylene contains only hydrocarbons, and water and carbon dioxide are generated after incineration.
Flexibility
Polyethylene has unique flexibility and excellent scratch resistance
The flexibility of the polyethylene piping system has great technical and economic value. The flexibility of polyethylene is an important property, which greatly increases the value of the material for pipeline engineering. Good flexibility allows polyethylene pipes to be coiled and supplied in a longer length, avoiding a large number of joints and fittings. At the same time, the flexibility and light weight and excellent scratch resistance make it possible to use a variety of cost-effective installation methods that can reduce the impact on the environment and social life, such as no-excavation construction technology. The excavation-free construction technology refers to the construction technology of laying, replacing or repairing various underground pipelines without using trenches (troughs) on the ground surface by using various geotechnical drilling techniques. A variety of no-excavation construction techniques are very suitable for the use of polyethylene pipes, such as horizontal directional drilling and directional drilling methods for laying new pipelines, the expansion method of replacing old pipelines in situ, the replacement of old pipelines and the replacement of lining method and various An improved lining method (folding deformation method, hot drawing method and cold rolling method).
PE's unique flexibility also enables it to effectively resist underground movements and end loads. Seen from the surface, in terms of strength and rigidity, plastic buried pipes are inferior to cement pipes and metal pipes, but from the practical application, plastic buried pipes are "flexible pipes". Under proper design and construction, plastic buried pipes are It bears the load with the surrounding soil. Therefore, the plastic buried pipe does not need to achieve the same strength and rigidity as the "steel pipe" to meet the requirements of the mechanical properties in the buried use. At the same time, the pressure relaxation characteristics of polyethylene can effectively consume stress through deformation. Its actual axial stress level is much lower than the theoretical calculation value, and its elongation at break is generally greater than 500%. The bending radius can be as small as the pipe diameter. 20 to 25 times, it is a kind of high toughness material, and it has a strong adaptability to uneven settlement of foundations. These characteristics make it the most excellent pipeline to resist earthquakes, settlement of foundations and expansion and contraction of temperature difference. For example, in the 1995 Kobe earthquake in Japan, PE water pipes and gas pipes were among the pipeline systems that were spared.
Low temperature resistance
Polyethylene has very outstanding low temperature resistance
The low temperature embrittlement point of PE pipe is -70 ℃, which is better than other pipes. Polyvinyl chloride (PVC-U) pipes are prone to brittleness during winter field construction. An experience summarized in the pilot project of laying polyvinyl chloride (PVC-U) buried water supply pipes in the Beijing area of China is not suitable for temperatures below zero The laying of polyvinyl chloride (PVC-U) pipes is under construction. There is also a clear evidence that in order to improve the toughness and low temperature impact resistance of PP, ethylene and propylene monomers can be copolymerized to make random copolymer polypropylene (PP-R), which generally uses the iPP process route and method to make The mixed gas of propylene and ethylene is copolymerized to obtain a copolymer in which propylene and ethylene segments are randomly distributed in the main chain (that is, PP-R tube material). The ethylene content in PP-R tube material is mostly around 3%. But the improved PP-R low temperature resistance is still not satisfactory, its embrittlement point is about -15 ℃, much higher than the embrittlement point temperature of polyethylene pipes -70 ℃.
Fracture toughness
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Polyethylene has good fast crack growth and fracture toughness
When rapid crack growth and damage occurs, the crack can rapidly expand from hundreds of meters to dozens of kilometers at a speed of 100-45m / s, causing long-distance pipeline damage, a large-scale leakage accident, and subsequent combustion explosion (natural gas transmission) or flood ( Water delivery) accident. The probability of such an accident is not large, and once it occurs, the harm is great. For the continuous development of plastic pressure pipes, the importance of preventing rapid crack growth and destruction has exceeded the requirements of long-term life strength performance. The reason is: at the same SDR (the ratio of pipe diameter to its thickness), the calculated long-term life-long-term strength has nothing to do with increasing the pipe diameter (in fact, large-diameter pipes may be safer than small-diameter pipes), but the risk of rapid crack growth increases with The pipe diameter increases. In the existing large variety of plastic test method materials, such as polyethylene, polypropylene, polyvinyl chloride pipes, etc., when a certain pipe diameter is reached, the allowable pressure determined by preventing rapid crack growth and destruction is always better than the long-term strength The allowable pressure determined by the problem is low. That is to say, after the allowable pressure is determined according to the requirements to prevent rapid crack growth damage, the long-term life (such as 20 ℃, 50 years) requirements can be met by themselves; materials with fast crack growth and poor fracture toughness will be eliminated, regardless of it The long-term strength performance is good or bad. For example, polyvinyl chloride (PVC-U) gas pipes have been basically completely replaced by polyethylene (PE) gas pipes. The trend of European polyvinyl chloride (PVC-U) water supply pipes being replaced by polyethylene (PE) pipes is clear.
China has not established a test device to monitor rapid crack growth and destruction. China's plastic pressure tube standards do not address this issue, which indicates that China's plastic pressure tube level is at least one stage behind the world's general level.
Terms of useedit
General provisions
①Pipes and fittings should have the product quality inspection report of the quality inspection department and the manufacturer's qualification certificate.
② When storing, transporting and transporting the pipe, it should be tied with non-metallic rope, and the end of the pipe should be blocked.
③During storage, transportation and transportation of pipes and fittings, they shall not be thrown or hit with a sharp crack.
④ When storing, transporting and transporting pipes and fittings, do not expose to sunlight and rain; do not contact with oil, acid, salt and other chemical substances.
⑤ The storage period of pipes and fittings from production to use should not exceed one year.
Material acceptance
① Accept the acceptance of the pipes and fittings. First check and accept relevant information such as product manual, product certificate, quality assurance certificate and various performance inspection and acceptance reports.
② When accepting the pipes and fittings, they should be sampled in the same batch, and the specifications, dimensions and appearance performance should be checked in accordance with the current national standard "Water Supply (PE) Polyethylene", and a full test should be conducted if necessary.
Store
① Pipes and fittings should be stored in a well-ventilated warehouse or simple shed with a temperature not exceeding 40 ° C.
② Pipes should be stacked horizontally on a flat support or on the ground. The stacking height should not exceed 1.5 meters. When the pipes are bundled into 1mx1m square bundles, and the supports are protected on both sides, the stacking height can be appropriately increased, but should not exceed 3m. Take and manage.
③ When the pipes and fittings are temporarily stacked outdoors, they should be covered.
④ When storing pipes, pipes with different diameters and different wall thicknesses should be stacked separately.
Carry
① When transporting pipes, they must be hoisted with non-metallic ropes.
② When handling pipes and fittings, they should be handled with care and arranged neatly. Do not throw or drag along the ground.
③ When transporting pipes and fittings in cold weather, violent impact is strictly prohibited.
transport
① When transporting pipes by vehicle, they should be placed on the bottom of the flat car, and when shipping, they should be placed in a flat cabin. During transportation, the full length of the straight pipe should be provided with support, and the coiled pipes should be stacked neatly. Straight pipes and coiled pipes should be bundled and fixed to avoid collision with each other. Stacking and touching should not damage the sharp and protruding objects of the pipe.
②When transporting the pipe fittings, they should be neatly stacked one by one and fixed firmly.
③The pipes and fittings should be covered during transportation to avoid exposure and rain.
Connection technology
PE water supply pipe connection method
There are many connection methods between polyethylene pipes and pipes, pipes and PE pipes, pipes and accessories, and polyethylene pipes and metal pipes. Different connection methods have their own advantages and limitations. Users can choose according to the pipe diameter and working pressure , Use places and other environments, select the appropriate connection method. The most commonly used connection methods for urban water supply polyethylene pipes are: hot melt connection, electric fusion connection, socket type flexible connection, flange connection, steel-plastic transition joint connection, etc.
1. Hot melt connection
Hot melt connection is to use a special heating tool to heat the polyethylene pipe or pipe to be connected under pressure to make it melt, remove the heating tool, apply pressure to connect the two melting surfaces together, and maintain it under a stable pressure For a period of time, until the joint cools. The hot melt connection includes a hot melt butt connection, a hot melt socket connection, and a hot melt saddle connection.
2. Electrofusion connection
The electric fusion connection is to use a special electric fusion tube with embedded resistance wire and a PE tube or a connection part of the tube to contact and energize closely. The PE tube heats the connection part through the embedded resistance wire to melt and connect it until the joint cools. The electrofusion connection can be used to connect with polyethylene pipes or socket fittings of different types and different melt flow rates. The electrofusion connection is divided into electrofusion socket connection and electrofusion saddle connection.
3. Socket flexible connection
The polyethylene pipe socket flexible connection is a new type of connection developed based on the socket flexible connection principle of cast iron pipes and polyvinyl chloride pipes (PVC-U). The PE pipe is welded at one end of the polyethylene pipe to a reinforced Polyethylene socket. The socket type flexible connection is to insert one end of the polyethylene pipe directly into the special socket of the pipe or pipe fitting, and the anti-pulling and rubber sealing ring are pressed and sealed by the locking ring in the socket to achieve the purpose of connecting the PE pipe and pipe .
4. Flange connection
Flange connection is mainly used to connect polyethylene pipes with metal pipes or valves, flow meters, pressure gauges and other auxiliary equipment. The flange connection is mainly composed of polyethylene flange connectors, steel or aluminum back pressure loop flanges, steel or aluminum flanges, gaskets or sealing rings, bolts, nuts, etc. Flange connection is to tighten the bolts and nuts so that the flange connection piece and the flange piece are in close contact to achieve the purpose of connection.
5. Steel-plastic transition joint connection
Steel-plastic transition joint connection is to use a steel-plastic transition joint prefabricated by cold pressing or other methods to connect polyethylene pipes and metal pipes. The steel-plastic transition joint has a pull-resistant locking ring and a sealing ring, which usually require it to have good sealing performance, pull-out resistance, and pressure resistance than the polyethylene pipe in the system.
The above is the connection method of PE pipes. It should be noted that it is strictly prohibited to directly thread the pipe threads on the polyethylene pipes and fittings in any form and use threaded connections; it is strictly prohibited to use open flame baking polyethylene pipes and fittings for direct connection.
The connection technology of polyethylene is very mature and reliable. Statistics show that the leakage rate of polyethylene pipes is less than two hundred thousandths, which is much lower than 2-3% of ductile iron pipes, which greatly improves the safety and economic benefits of pipelines. The very important reason for using polyethylene pipes.
Bonding method
1. Before bonding pipes and fittings, wipe the socket side and the outside of the socket with a dry cloth. When the surface is stained with oil, it must be cleaned with acetone.
2. The cross section of the pipe should be flat, perpendicular to the axis of the pipe and chamfered; before the bonding, the insertion line should be drawn and trial insertion should be done. The trial insertion depth can only be inserted to 1/3 to 1/2 of the original depth. It is strictly prohibited to use bonding method when the gap is too large.
3. When applying the adhesive, apply the inside of the socket first, then the outside of the socket to apply the socket.
Appropriately apply an appropriate amount from the inside to the outside along the axial direction without omission or excessive application (200g / m2).
4. After the adhesive is applied, it is advisable to keep the applied external force unchanged within 1 minute and keep the straightness and position of the interface correct.
5. After the bonding is completed, the excess adhesive that is extruded should be wiped off in time, and it should not be stressed or forced during the curing time.
6. The adhesive joints shall not be constructed in rain or water, and shall not be operated below 5 ℃.
7. Connection procedure: preparation → cleaning work surface → trial insertion → brushing adhesive → bonding → maintenance.
Welding procedure of PE water supply pipe
PE water supply pipes are made of special polyethylene as raw materials and are extruded at one time by a plastic extruder. They are used in urban water supply pipe networks, irrigation and diversion projects and agricultural sprinkler irrigation projects, and are especially suitable for plastic pipes that are resistant to acid and alkali and corrosion. PE pipes are connected by hot melt and electrothermal fusion, which realizes the integration of the interface and the pipe, and can effectively resist the hoop stress and axial impact stress generated by the pressure, and the PE pipe does not add heavy metal salt stabilizer, and the material is non-toxic , No scaling, no breeding bacteria, avoid secondary pollution of drinking water. Welding of PE water supply pipe can be divided into the following steps, these steps are very important. Everyone must pay attention.
(1) When welding the PE water supply pipe, center the axis of the two pipes and first spot weld the ends of the two pipes.
(2) When welding the PE water supply pipe to the flange, the water supply pipe should be inserted into the flange first.
Align the ruler and level it before welding. The flange should be welded on both sides, and the inner side of the flange should not protrude from the sealing surface of the flange.
(3) When the wall thickness of the PE water supply pipe is more than 5mm, the groove should be cut to ensure full penetration. The groove formation can be processed by gas welding or groove machining, but the slag and iron oxide should be removed and polished with a file until Metal light
(4) When cutting the steel pipe, the cut surface should be perpendicular to the center line of the pipe to ensure the concentricity of the pipe after welding.
(5) The flange should be perpendicular to the center line of the pipe, and the surfaces should be parallel to each other. The flange gasket should not protrude into the pipe. The bolt size of the connecting flange should match the flange. 2.
(6) When welding the water supply pipe, the pipe joint should be cleaned of floating rust, dirt and grease.
(7) The flange gasket should be selected according to the drawings and specifications. The cold water system uses rubber pads, and the hot water system uses asbestos rubber pads.
Hot melt docking installation
Hot-melt butt welding uses a hot-melt butt welding machine to heat the pipe end (the temperature of the hot-melt butt joint is 210 + 10 ° C). After the pipe end is melted, it is quickly bonded to maintain a certain pressure, and the purpose of welding is achieved after cooling. Applicable pipe diameter range: dn≥90mm
Steps:
1. Place the two PE pipes to be installed and connected on the hot melt fixture at the same time (the fixture can change the clamp block according to the pipe diameter to be installed), and the other end of each pipe is held up to the same level with a pipe bracket.
2. Cut the ends of the pipes with an electric rotary knife to ensure that the contact surfaces of the two pipes can be fully matched.
3. Warm the electric heating plate to 210 ° C, place the middle of the end faces of the two pipes, and operate the electro-hydraulic device to make the end faces of the two pipes completely contact the heating plate and heat at the same time.
4. Pull out the heating plate and operate the hydraulic device again to fully butt the end faces of the two pipes that have melted and lock the hydraulic device (to prevent rebound).
5. Keep a certain cooling time to release, the operation is completed.
6. After the construction is completed, it must pass the pressure test and acceptance before it can be buried and put into use.
skills requirement
Although HDPE pipeline has been successfully applied in many fields, but still need to pay attention to the following matters during use:
1. Welding: When hot-melting, the temperature must reach 210 ± 10 ℃, and care should be taken to avoid over-scorching.
2. Buried: When working in the trench, the necessary safety measures must be considered.
3. Test: It is recommended to use water as the pressure test medium. During the test, measures should be taken to prevent pipeline movement or damage.
4. Positioning: Polyethylene materials cannot be controlled by magnetic positioning equipment. Other methods can be used to detect polyethylene pipelines, including tracer lines, labeling tapes, detection tapes, line markings, electronic labeling systems, and sound-controlled pipeline tracking methods .
5. Air pressure: HDPE pipeline cannot be used in the field of high-pressure gas transportation.
6. Scope of application: HDPE pipes are not recommended for some occasions, please consult the supplier for their chemical resistance.
7. Static electricity: HDPE pipes are mixed with high static electricity. In the case of flammable and explosive gases, corresponding measures to eliminate static electricity should be taken.
8. Impact performance: HDPE pipeline has good impact resistance. Use a hammer to hit the pipeline. It should be noted that the pipeline will produce a certain resilience.
9. Coil: The small-diameter HDPE pipeline of the coil stores energy like a spring. If the packaging tape is cut, a large rebound force will be generated.
10. Storage: If the pipes must be stacked and stored, then excessive stacking should be avoided, and they should be stacked in a row. If the pipes are not stacked properly, the pipes may be deformed.
11. Weight: Although HDPE pipes are lighter than other traditional pipes, they still have a certain weight, so care should be taken during handling and construction.
12. Unloading: The correct unloading facilities must be used, and all tools used for handling should be checked for compliance.
Use materials
ABS (acrylonitrile-butadiene-styrene copolymer)
Unplasticized polyvinyl chloride (UPVC)
CPVC (post-chlorinated polyvinyl chloride)
PP (polypropylene)
PE (polyethylene), also known as LDPE, MDPE and HDPE (low, medium, and high density)
Installation process
(1) Heat the pipes and fittings at the same time, and then socket (after the socket is in place, let go for a while, and it is forbidden to twist during the heating, socket and cooling process;
(2) Heat the die head of the hot melt machine to about 20;
(3) Use pipe shears to cut the pipe according to the installation needs;
(4) Natural cooling;
(5) Mark the number at the depth of the pipe to be socketed;
(6) Put it into use after the completion of the construction and passing the pressure acceptance test.
Construction steps
1. Material preparation: Put the pipe or fittings in a flat position on the butt joint machine, leaving a 10-20mm cutting allowance.
2. Cutting: cutting impurities and oxide layer on the end face of the welded pipe section and pipe fittings to ensure that the two butt end faces are flat, smooth and free of impurities.
3. Alignment: The end faces of the two welded pipe sections should be completely aligned. The smaller the wrong edge, the better. The wrong edge should not exceed 10% of the wall thickness. Otherwise, the docking quality will be affected.
4. Heating: the jointing temperature is generally between 210-230 ℃, the heating time of the heating plate is different in winter and summer, and the melting length of both ends is preferably 1-2mm.
5. Melt butt joint: It is the key to welding. The butt joint process should always be carried out under melting pressure, and the crimping width is preferably 2-4mm.
6. Cooling: Keep the butt pressure unchanged, let the interface cool slowly, and the cooling time depends on the curly edge of the hand, and you ca n’t feel the heat.
7. The docking is completed: after cooling, release the slips, remove the docking machine, and prepare for the next interface connection.
National standard
The main differences between this standard and ISO 4427: 1996 are: 1. This standard only includes pipes made of PE 63, PE 80, and PE 100 materials, excluding pipes made of PE 32, PE 42 materials; 2. This standard adds a definition chapter; The performance requirements for pipes have been increased
The main differences between this standard and ISO 4427: 1996 are:
1. This standard only covers pipes made of PE 63, PE 80, and PE 100, but not pipes made of PE 32, PE 42;
2. This standard adds a definition chapter;
3. For the performance requirements of pipes, the "elongation at break" item has been added;
4. Added the "Inspection Rules" chapter;
The differences between this standard and GB / T 13663-1992 are:
GB / T 13663-1992 "High-density polyethylene (HDPE) pipes for water supply" has not been formulated using international standards.
Since the implementation of this standard, it also replaces GB / T 13663－1992
Appendix A of this standard is a reminder appendix.
This standard was proposed by the State Administration of Light Industry.
This standard is under the jurisdiction of the National Technical Committee for Standardization of Plastic Products.
Scope of application
The standard stipulates the product specifications, technical requirements, test methods, inspection rules, signs, packaging, transportation, and storage of polyethylene resin as the main raw material and the polyethylene pipe for water supply (hereinafter referred to as "pipe") that is extruded . This standard also specifies the basic performance requirements of raw materials, including classification system.
This standard applies to water supply pipes made of PE63, PE 80 and PE 100 materials (see 4.1). The nominal pressure of the pipe is 0.32MPa ～ 1.6MPa, and the nominal outer diameter is 16 mm ～ 1000 mm.
The pipes specified in this standard are suitable for pressure water delivery at temperatures not exceeding 40 ° C, for general use, and for the delivery of drinking water.
Reference Standard
The provisions contained in the following standards constitute the provisions of this standard by quotation in this standard. At the time of publication, the editions indicated were valid. All standards will be revised, all parties using this standard should explore the possibility of using the latest version of the following standards.
GB / T 2918-1998 Standard environment for plastic sample condition adjustment and testing (idt ISO 291: 1997)
GB / T 3681-1983 Test method for natural weather exposure of plastics
GB / T 3682-1983 Thermoplastic melt flow rate test method
GB / T 6ill－1985 Long-term constant internal pressure measurement method for the failure time of thermoplastic pipes (eqv ISO / DP 1167: 1978)
GB / T 66712.2-1986 Determination of longitudinal shrinkage of polyethylene (PE) pipes (idt ISO 2506: 1981)
GB / T 8804.2-11988 Test method for tensile properties of thermoplastic pipes Polyethylene pipes (eqv ISO / DIS 3504-2)
GB / T 8806-1988 Measuring method of plastic pipe size (eqv 1974)
GB / T 13021 ～ 199 1 Determination of carbon black content of polyethylene pipes and fittings by thermal weight loss method (neq 1986
GB / T 17219－1998 Safety evaluation standard for domestic drinking water transmission and distribution equipment and protective materials
GB / T 17391－1998 Test method for thermal stability of polyethylene pipes and fittings (eqv 1991)
GB / T 18251－2000 Determination method of pigment and carbon black dispersion in polyolefin pipes, fittings and compounding materials
GB / T 18252-2000 Plastic piping system Determination of long-term hydrostatic strength of thermoplastic pipes by extrapolation
definition
3.1 Definition
3.1.1 Geometry definition
3.1.1.1 Nominal outer diameter dn: The specified outer diameter in mm.
3.1.1.2 Average outer diameter dem: The value obtained by dividing the measured value of the outer circumference of the pipe by 3.142 (circumference ratio), accurate to 0.1mm, and the second digit after the decimal point is rounded.
3.1.1.3 The 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 mm.
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 at any point: the outer diameter measured through the cross section of any point of the pipe is accurate to 0.1mm, and the second digit after the decimal point is rounded.
3.1.1.6 Out-of-roundness: the difference between the maximum and minimum outer diameters measured at the same cross-section of the pipe.
3.1.1.7 Nominal wall thickness en: the specified value of the pipe wall thickness in mm, which is equivalent to the minimum wall thickness ey, min at any point.
3.1.1.8 Wall thickness ey at any point: the measured value of the pipe wall thickness 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 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 value of the wall thickness at any point on the circumference of the pipe determined according to the tolerance of the minimum wall thickness (ey, min).
3.1.1.11 Standard size ratio (SDR): the ratio of the nominal outer diameter of the pipe to the nominal wall thickness. SDR = dn / en
3.1.2 Definitions related to materials
3.1.2.1 Mixture: pellets made of polyethylene base resin with necessary antioxidants, UV stabilizers and pigments.
3.1.2.2 σlpl1): hydrostatic strength corresponding to 20 ° C, 50 years, probability prediction 97.5%, unit is MPa.
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: allowable stress under the specified application conditions, MRS divided by the coefficient C, rounded to the next smaller value in the priority number R20 series, namely: σs = [MRS] / C ………… ……(1)
3.1.2.5 Total use (design) factor C: A total factor greater than 1, which takes into account the conditions of use that are not reflected in the lower prediction limit and the nature of components such as fittings in the piping system.
3.1.3 Definitions related to conditions of use
3.1.3.1 Nominal pressure (PN): In this standard, the nominal pressure PN is equivalent to the maximum working pressure of the pipe at 20 ° C in MPa.
3.1.3.2 Maximum working pressure (MOP): the maximum effective pressure of the fluid in the pipeline system that is allowed to be used continuously, in megapascals.
symbol
3.2 Symbol
C: Total use (design) coefficient;
dem: average outer diameter;
dem, max: 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: temperature to pressure reduction factor;
ty: wall thickness tolerance at any point of the pipe;
σlpl: hydrostatic strength corresponding to 20 ° C, 50 years, probability prediction 97.5%;
σs: design stress;
Acronyms
3.3 Acronyms
MFR: melt flow rate;
MOP: Maximum working pressure;
MRS: minimum required strength;
PE: polyethylene;
PN: nominal pressure;
SDR: standard size ratio.
Material naming
4.1 Naming
The polyethylene pipe materials in this standard are named as follows:
4.1.1 According to GB / T18252, determine the hydrostatic strength σlpl of the material corresponding to 20 ℃, 50 years, and the predicted probability of 97.5%.
4.1.2 According to Table 1, convert the minimum required strength (MRS) according to σlpl, and multiply the MRS by 10 to obtain the material classification number.
4.1.3 According to Table 1, name the materials according to the material type (PE) and the number of classifications.
Table 1 Name of materials
Table 1 Naming of materials
σlpl, Mpa
MRS, Mpa
Material classification number
Material naming
6.30 ～ 7.99
6.3
63
PE63
8.00 ～ 9.99
8.0
80
PE80
10.00 ～ 11.19
10.0
100
PE100
Use mixed materials to produce polyethylene pipes. The mixed materials are blue or black. The basic performance should meet the requirements of Table 2 The blue pipe material should be able to ensure that the weather resistance of the pipe made of this material meets the requirements of Table 12. For PE63 grade materials, polyethylene pipes can also be produced by using pipe-level base resin plus masterbatch, and the performance requirements of the materials are sampled from the pipes for testing.
The clean recycled materials produced in the production of pipes according to this standard can be mixed with new materials and recycled as long as the pipes meeting this standard can be produced.
Table 2 Basic performance requirements of materials
Serial number
project
Claim
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 rate 3) (5,190),
The deviation from the nominal value of the product should not exceed ± 25%
Note:
1 Only for black tube materials
2 Only for blue tube material
3 Only suitable for compounding
Product specification
5.1 The pipes of this standard are designed according to the expected service life of 50 years.
5.2 For the transportation of water at 20 ° C, the minimum value of C can be Cmin = 1.25. The maximum allowable value of the design stress of different grades of materials obtained from equation (1) is shown in Table 3.
Table 3 Maximum allowable value of design stress for different grades of materials
Material grade
Maximum allowable value of design stress σ, M
pa
PE63
5
PE80
6.3
PE100
8
The relationship between the nominal pressure (PN) of the pipe and the design stress σs and standard size ratio (SDR) is: PN = 2σs / (SDR-1) …………………… .. (2)
In the formula: The units of PN and σs are megapascals.
For pipes manufactured with PE63 and PE100 grade materials, the nominal outer diameter and wall thickness determined according to the selected nominal pressure and using the design stress in Table 3 shall comply with the requirements in Table 4, Table 5 and Table 6, respectively. The design and user of the piping system can adopt a larger total use (design) coefficient C, in which case pipes with a higher nominal pressure rating can be used.
PEM pipe has the characteristics of light weight and rigidity, which is easy to transport and store. The transportation is mainly truck transportation, and the standard loading is as follows.
Name
specification
Loading
8TON 11TON
water
Tao
tube
D50 (ROLL)
42R / L
50R / L
D75 (ROLL)
22R / L
27R / L
D75 (6M)
500 books
D100
350 books
D125
130 books
D150
175 books
D200
110 books
D250
66 books
D300
52 books
D350
37 books
D400
27 books
D450
20 books
D500
16 books
D600
12 books
D700
8 books
D800
6 books
Pipeline loading
8TON = 2.3m × 7m
11Ton = 2.3m × 9m
(Note: What exactly is the quantifier "本" on the chart? The translator is not clear and is for reference only).
PE water supply pipe construction and installation: management / storage
management
A, often pile the largest pipe diameter on the bottom.
B. The inside and outside of the PEM pipe is very smooth. In order to prevent it from slipping down, it must be securely fixed during loading.
C. Small diameter straight pipe or light pipe can be loaded and unloaded by hand. Construction and installation: management / storage
storage
A. PEM pipes should be kept in a clean place.
B. To prevent direct light during long-term storage, it should be placed indoors or covered with cloth.
C. When stacking the pipes on the ground for storage, remove stones or other sharp objects, arrange the ground evenly and stack them.
D. PEM pipes should be kept away from heat sources.
E. It should be noted that in the case of excessive loading or accumulation, the pipe will deform.
The limit of loading columns is as follows
Diameter
Number of loaded columns
Below SDR18
SDR19—26
SDR26-32.5
D100
45
26
14
D150
31
17
10
D200
twenty four
13
8
D250
17
10
6
D300
13
8
5
D350
12
7
4
D400
11
6
4
D450
10
6
4
D500
9
6
3
D600
7
4
3
6. Technical requirements
6.1 Color
The color of municipal drinking water pipes is blue or black, and there should be co-extruded blue color strips on the black pipes. There are at least three color bars along the longitudinal direction of the pipe. Water pipes for other purposes can be blue and black. Laying pipes exposed to sunlight (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, depressions, impurities, uneven color, etc. The pipe end should be cut flat and perpendicular to the pipe axis.
6.3 Pipe size
6.3.1 Pipe length
6.3.1.1 The length of straight pipe is generally 6m, 9m and 12m, which can also be agreed by both parties. The limit deviation of the length is + 0.4%, -0.2% of the length.
6.3.1.2 The diameter of the coil tube rack should not be less than 18 times the outer diameter of the pipe. The unfolding length of the coil tube shall be agreed by both parties.
6.3.2 Average outer diameter
The average outer diameter of the pipe shall meet the requirements of Table 8. Grade B is used for fine tolerance pipes and Grade A is used for standard tolerance pipes. The use of grade B or grade A shall be agreed by both parties. When there is no clear requirement, it shall be regarded as adopting grade A.
Table 8 Average outer diameter
Nominal outer diameter
Minimum average outer diameter
Maximum average outer diameter
Class A
Rank B
16
16.0
16.3
16.3
20
20.0
20.3
20.3
25
25.0
25.3
25.3
32
32.0
32.3
32.3
40
40.0
40.0
40.3
50
50.0
50.5
50.3
63
63.0
63.6
63.4
75
75.0
75.7
75.5
90
90.0
90.9
90.6
110
110.0
111.0
110.7
125
125.0
126.2
125.8
140
140.0
141.3
140.9
160
160.0
161.5
161.0
180
180.0
181.7
181.1
200
200.0
201.8
201.2
225
225.0
227.1
226.4
250
250.0
252.3
251.5
280
280.0
282.6
281.7
315
315.0
317.9
316.9
355
355.0
358.2
357.2
400
400.0
403.6
402.4
450
450.0
454.1
452.7
500
500.0
504.5
503.0
560
560.0
565.0
563.4
630
630.0
635.7
633.8
710
710.0
716.4
714.0
800
800.0
807.2
804.2
900
900.0
908.1
904.0
1000
1000.0
1009.0
1004.0
6.3.3 Wall thickness and deviation
The minimum wall thickness of pipes ey, min and other instruments is nominally wall thickness en. The wall thickness tolerance at any point of the pipe shall comply with the requirements in Table 9.
Table 9 Wall thickness tolerance at any point
Minimum wall thickness
tolerance
Minimum wall thickness
tolerance
Minimum wall thickness
tolerance
>
≤
>
≤
>
≤
25.0
25.5
5.0
45.0
45.5
9.0
25.5
26.0
5.1
45.5
46.0
9.1
2.0
3.0
0.5
26.0
26.5
5.2
46.0
46.5
9.2
3.0
4.0
0.6
26.5
27.0
5.3
46.5
47.0
9.3
4.0
4.6
0.7
27.0
27.5
5.4
47.0
47.5
9.4
4.6
5.3
0.8
27.5
28.0
5.5
47.5
48.0
9.5
5.3
6.0
0.9
28.0
28.5
5.6
48.0
48.5
9.6
6.0
6.6
1.0
28.5
29.0
5.7
48.5
49.0
9.7
6.6
7.3
1.1
29.0
29.5
5.8
49.0
49.5
9.8
7.3
8.0
1.2
29.5
30.0
5.9
49.5
50.0
9.9
8.0
8.6
1.3
30.0
30.5
6.0
50.0
50.5
10.0
8.6
9.3
1.4
30.5
31.0
6.1
50.5
51.0
10.1
9.3
10.0
1.5
31.0
31.5
6.2
51.0
51.5
10.2
10.0
10.6
1.6
31.5
32.0
6.3
51.5
52.0
10.3
10.6
11.3
1.7
32.0
32.5
6.4
52.0
52.5
10.4
11.3
12.0
1.8
32.5
33.0
6.5
52.5
53.0
10.5
12.0
12.6
1.9
33.0
33.5
6.6
53.0
53.5
10.6
12.6
13.3
2.0
33.5
34.0
6.7
53.5
54.0
10.7
13.3
14.0
2.1
34.0
34.5
6.8
54.0
54.5
10.8
14.0
14.6
2.2
34.5
35.0
6.9
54.5
55.0
10.9
14.6
15.3
2.3
35.0
35.5
7.0
55.0
55.5
11.0
15.3
16.0
2.4
35.5
36.0
7.1
55.5
56.0
11.1
16.0
16.5
3.2
36.0
36.5
7.2
56.0
56.5
11.2
16.5
17.0
3.3
36.5
37.0
7.3
56.5
57.0
11.3
17.0
17.5
3.4
37.0
37.5
7.4
57.0
57.5
11.4
17.5
18.0
3.5
37.5
38.0
7.5
57.5
58.0
11.5
18.0
18.5
3.6
38.0
38.5
7.6
58.0
58.5
11.6
18.5
19.0
3.7
38.5
39.0
7.7
58.5
59.0
11.7
19.0
19.5
3.8
39.0
39.5
7.8
59.0
59.5
11.8
19.5
20.0
3.9
39.5
40.0
7.9
59.5
60.0
11.9
20.0
20.5
4.0
40.0
40.5
8.0
60.0
60.5
12.0
20.5
21.0
4.1
40.5
41.0
8.1
60.5
61.0
12.1
21.0
21.5
4.2
41.0
41.5
8.2
61.0
61.5
12.2
21.5
22.0
4.3
41.5
42.0
8.3
22.0
22.5
4.4
42.0
42.5
8.4
22.5
23.0
4.5
42.5
43.0
8.5
23.0
23.5
4.6
43.0
43.5
8.6
23.5
24.0
4.7
43.5
44.0
8.7
24.0
24.5
4.8
44.0
44.5
8.8
24.5
25.0
4.9
44.5
45.0
8.9
6.4 Hydrostatic strength
The hydrostatic strength of the pipe shall meet the requirements of Table 10.
Table 10 Hydrostatic strength of pipes
Serial number
project
Hoop stress
Claim
PE63
PE80
PE100
1
20 ℃ hydrostatic strength ()
8.0
9.0
12.4
No rupture, no leakage
2
Hydrostatic strength at 80 ℃ ()
3.5
4.6
5.5
No rupture, no leakage
3
Hydrostatic strength at 80 ℃ ()
3.2
4.0
5.0
No rupture, no leakage
The 80 ° C hydrostatic strength (165h) test only considers brittle failure. If ductile failure occurs within the required time (165h), select a lower failure stress and the corresponding minimum failure time according to Table 11 to retest.
Table 11 Retest requirements for hydrostatic strength (165h) at 80 ℃
PE63
PE80
PE100
stress
Minimum destruction time
stress
Minimum destruction time
stress
Minimum destruction time
3.4
285
4.5
219
5.4
233
3.3
538
4.4
283
5.3
332
3.2
1000
4.3
394
5.2
476
4.2
533
5.1
688
4.1
727
5.0
1000
4.0
1000
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 to squeeze the pipe, the difference between the measured melt flow rate (MFR) (5kg, 190 ° C) of the pipe and the measured value of the compound should not exceed 25%.
Table 12 Requirements for physical properties of pipes
Serial number
project
Claim
1
Short crack elongation,%
≥350
2
Longitudinal retraction rate (110 ℃),%
≤3
3
Oxidation induction time (220 ℃),
≥20
4
Thickness
(After accumulative acceptance of pipe ≥ aging energy)
80 ℃ hydrostatic strength (), the experimental conditions are the same as 10
No rupture, no leakage
Short crack elongation,%
≥350
Oxidation induction time (200 ℃),
≥10
1) Only applicable to blue tubes.
6.6 Hygienic performance
The sanitary performance of pipes used for drinking water transmission and distribution shall comply with the provisions of GB / T 17219.
Pipeline connection editing
6.1. General provisions:
6.1.1. The connection of pipes, fittings and pipe accessories shall adopt hot melt connection (hot melt butt joint, hot melt socket connection,
Hot melt saddle connection) or electric fusion connection (electric fusion socket connection, electric fusion saddle connection) and mechanical connection (lock
(Tight and non-locking socket connection, flange connection, steel-plastic over-connection). Pipes with a nominal outer diameter greater than or equal to 63mm should not be connected by hand hot-melt sockets. Pipes with a wall thickness of less than 6mm should not be connected by hot-melt butt joints. Polyethylene pipes and fittings must not be screwed and bonded.
6.1.2. Various special connection tools should be used for various connections of pipelines. Open flame heating is strictly prohibited during connection.
6.1.3. The pipeline connection should adopt pipes, fittings and pipeline accessories of the same grade and the same pressure level (the connection between pipes and pipeline accessories of different grades should be tested and the quality of the connection can be guaranteed. Connectable).
6.1.4. For the connection of polyethylene pipes and fittings with metal pipes and pipe accessories, when using steel spray or ductile cast iron excessive fittings, the pressure level of the excessive fittings shall not be lower than the nominal pressure of the pipe.
6.1.5. When performing hot-melt or electric-melt connection operation in cold climate (below -5 ℃) or strong wind environment, protective measures should be taken, or the process parameters of the connection equipment should be adjusted.
6.1.6. When the pipe is connected, the pipe should be cut with a special cutter or pipe cutting tool. The cutting section should be flat, smooth, free of burrs, and should be perpendicular to the pipe axis.
6.1.7. After the pipeline is connected, the appearance quality of the joint should be checked in time, and the unqualified ones must be reworked.
6.2. Hot melt connection:
6.2.1. The temperature control of the hot melt connection tool should be precise, the temperature distribution of the heating surface should be uniform, and the structure of the heating surface should meet the requirements of the welding process. Before and after the hot melt connection, clean the dirt on the heating surface with a clean cotton cloth.
6.2.2. The heating time, heating temperature and applied pressure as well as the holding pressure and cooling time of the hot melt connection shall comply with the hot melt connection tool manufacturer and polyethylene pipes and fittings
As well as the regulations of the manufacturer of pipeline accessories. Do not move the connector or exert any external force on the connector during pressure holding and cooling.
6.2.3. The hot-melt butt connection shall also meet the following requirements:
6.2.3.1. The connecting ends of the two to-be-connected parts should protrude a certain free length from the welding machine fixture, and straighten the two corresponding to-be-connected parts so that they are on the same axis. The wrong side should not be greater than 10% of the wall thickness.
6.2.3.2. Dirt on the connecting surfaces of pipes, fittings and pipe accessories should be cleaned with clean cotton cloth, and the connecting surface should be milled to be perpendicular to the axis.
6.2.3.3. The sections of the parts to be connected should be heated with hot-melt butt connection tools.
6.3.3.4. After the heating is completed, the piece to be connected should be quickly detached from the heating tool, and the uniformity and melting of the heating surface of the piece to be connected should be checked. Then, use uniform external force to make the connection surface fully contact, and flanging to form a uniform flange, the height and width of the flange should meet the relevant regulations.
6.3.3.5. When the pipes and fittings of different SDR series are welded to each other, the wall thickness of the welded joint should be the same by mechanical processing.
6.3.3.6. When welding, each welding port shall have detailed original welding records. The original welding records shall include at least the ambient temperature, welder code, welding port number, pipe specification type, welding pressure, drag pressure, pressurization time, Heating plate temperature, switching time, endothermic time, cooling time, etc.
6.3.3.7. Polyethylene (PE) water supply pipeline hot-melt butt joints should use the same manufacturer, the same material, the same brand of pipe and pipe, pipe and pipe fittings, pipe and pipe fittings; different SDR series of polyethylene pipe is not suitable Use hot-melt butt connection.
6.2.4. Welding quality inspection:
6.2.4.1. Necessity of testing;
6.2.4.2. Test method: The quality inspection of welded joints is destructive test and non-destructive test respectively, and non-destructive test is generally adopted at the construction site. The main means of non-destructive testing is visual inspection, which can also be called visual inspection. The main standards are as follows:
