Large-caliber coated steel pipe is made by coating plastic on the basis of large-caliber spiral welded pipe and high-frequency welded pipe. The maximum pipe diameter is 1200mm. It can be coated with polyvinyl chloride (PVC), polyethylene (PE), etc. according to different needs. Epoxy resin (EPOZY) and other plastic coatings with different properties, good adhesion, strong corrosion resistance, resistant to strong acids, alkalis and other chemical corrosion, non-toxic, non-corrosive, wear-resistant, impact-resistant, and resistant to penetration It has strong performance, smooth surface of the pipeline, and does not adhere to any material, which can reduce the resistance during transportation, increase the flow rate and transportation efficiency, and reduce the pressure loss of transportation. There is no solvent and no exudable substances in the coating, so it will not pollute the conveyed medium, so as to ensure the purity and sanitation of the fluid. It can be used alternately with cold and hot cycles in the range of -40℃ to +80℃, without aging, It does not crack, so it can be used in harsh environments such as cold regions.

Large-caliber coated steel pipes are widely used in engineering fields such as tap water, natural gas, petroleum, chemicals, medicine, communications, electric power, and oceans.

[(Outer diameter-wall thickness)*wall thickness]*0.02466=kg/m (weight per meter)

Pipe diameter expression

The expression of large-diameter steel pipe diameter should meet the following requirements:

1 For water gas transportation steel pipes (galvanized or non-galvanized), cast iron pipes and other pipes, the pipe diameter should be expressed by the nominal diameter DN;

2 For seamless steel pipes, welded steel pipes (straight seam or spiral seam), copper pipes, stainless steel pipes and other pipes, the pipe diameter should be expressed in terms of outer diameter × wall thickness;

3 For pipes such as reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes, cylinder tile pipes, etc., the pipe diameter should be expressed as the inner diameter d;

4 For plastic pipes, the pipe diameter should be expressed in accordance with the product standard method;

5 When the design uses the nominal diameter DN to indicate the pipe diameter, there should be a comparison table between the nominal diameter DN and the corresponding product specifications.

The specifications of rigid PVC pipes for building drainage are expressed by de (nominal outer diameter) × e (nominal wall thickness) (GB 5836.1-92)

The specifications of polypropylene (PP) pipes for water supply are expressed by de×e (nominal outer diameter×wall thickness)

1. Normal length (also called non-fixed-length length): Any length within the standard specified length and no fixed length requirement is called normal length. For example, the structural pipe standard stipulates: hot rolled (extruded, expanded) steel pipe 3000mm ~ 12000mm; cold drawn (rolled) steel pipe 2000mm ~ 10500mm.

2. Fixed-length length: The fixed-length length should be within the usual length range, which is a certain fixed-length dimension required in the contract. However, it is impossible to cut out the absolute fixed-length length in actual operation, so the standard stipulates the allowable positive deviation value for the fixed-length length.

3. Length of multiple ruler: The length of the multiple ruler should be within the range of normal length. The contract should indicate the length of the single ruler and the multiples of the total length (for example, 3000mm×3, which is 3 multiples of 3000mm, and the total length is 9000mm). In actual operation, the allowable positive deviation of 20mm should be added to the total length, plus a margin for the incision of each single ruler length. If there is no double-length deviation and cutting allowance in the standard, it should be negotiated by the supplier and the buyer and indicated in the contract. The double-length scale is the same as the fixed-length length, which will bring about a substantial reduction in the yield rate of the manufacturer. Therefore, it is reasonable for the manufacturer to raise the price, and the price increase is basically the same as the fixed-length length.

4. Range length: The range length is within the usual length range. When the user requires a fixed range length, it must be indicated in the contract.

Round tube billet → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → stripping → sizing (or reducing diameter) → cooling → straightening → hydraulic test (or flaw detection) → marking → warehousing

One: In order to know the calculation method of seamless pipe outer diameter specification and wall thickness of

Pressure = (wall thickness * 2 * steel pipe material tensile strength) / (outer diameter * coefficient)

Two: Know the calculation method of seamless steel pipe outer diameter and pressure-bearing wall thickness:

Wall thickness=(pressure*outer diameter*factor)/(2*tensile strength of steel pipe material)

Three: Expression method of steel pipe pressure coefficient:

Pressure P<7Mpa coefficient S=8

7<steel pressure P<17.5 coefficient S=6

Pressure P>17.5 coefficient S=4 [2]

The mechanical properties of large-diameter steel pipes are an important index to ensure the final use performance (mechanical properties) of large-diameter steel pipes, and it depends on the chemical composition and heat treatment system of the steel pipe. Therefore, according to different application requirements, the mechanical properties of large-diameter spiral steel pipes are specifically introduced from the aspects of tensile strength, yield point, and elongation.

1 Tensile strength

In the tensile process, the maximum force (Fb) that the sample bears when it breaks is the stress (σ) obtained from the original cross-sectional area (So) of the sample, which is called the tensile strength (σb), and the unit is N/mm2 (MPa). It represents the maximum ability of a metal material to resist damage under tensile force.

2 Yield point

For a metal material with a yield phenomenon, the stress at which the sample can continue to elong without an increase in the force during the stretching process (remains constant) is called the yield point. If the force drops, the upper and lower yield points should be distinguished. The unit of yield point is N/mm2 (MPa).

3 Elongation after breaking

In the tensile test, the percentage of the length of the gauge length increased after the sample is broken to the original gauge length is called the elongation. Expressed by σ, the unit is %.

Large-caliber coated steel pipes are widely used in engineering fields such as tap water, natural gas, petroleum, chemicals, medicine, communications, electric power, and oceans.

**weight formula**[(Outer diameter-wall thickness)*wall thickness]*0.02466=kg/m (weight per meter)

Pipe diameter expression

The expression of large-diameter steel pipe diameter should meet the following requirements:

1 For water gas transportation steel pipes (galvanized or non-galvanized), cast iron pipes and other pipes, the pipe diameter should be expressed by the nominal diameter DN;

2 For seamless steel pipes, welded steel pipes (straight seam or spiral seam), copper pipes, stainless steel pipes and other pipes, the pipe diameter should be expressed in terms of outer diameter × wall thickness;

3 For pipes such as reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes, cylinder tile pipes, etc., the pipe diameter should be expressed as the inner diameter d;

4 For plastic pipes, the pipe diameter should be expressed in accordance with the product standard method;

5 When the design uses the nominal diameter DN to indicate the pipe diameter, there should be a comparison table between the nominal diameter DN and the corresponding product specifications.

The specifications of rigid PVC pipes for building drainage are expressed by de (nominal outer diameter) × e (nominal wall thickness) (GB 5836.1-92)

The specifications of polypropylene (PP) pipes for water supply are expressed by de×e (nominal outer diameter×wall thickness)

**Delivery length regulations**1. Normal length (also called non-fixed-length length): Any length within the standard specified length and no fixed length requirement is called normal length. For example, the structural pipe standard stipulates: hot rolled (extruded, expanded) steel pipe 3000mm ~ 12000mm; cold drawn (rolled) steel pipe 2000mm ~ 10500mm.

2. Fixed-length length: The fixed-length length should be within the usual length range, which is a certain fixed-length dimension required in the contract. However, it is impossible to cut out the absolute fixed-length length in actual operation, so the standard stipulates the allowable positive deviation value for the fixed-length length.

3. Length of multiple ruler: The length of the multiple ruler should be within the range of normal length. The contract should indicate the length of the single ruler and the multiples of the total length (for example, 3000mm×3, which is 3 multiples of 3000mm, and the total length is 9000mm). In actual operation, the allowable positive deviation of 20mm should be added to the total length, plus a margin for the incision of each single ruler length. If there is no double-length deviation and cutting allowance in the standard, it should be negotiated by the supplier and the buyer and indicated in the contract. The double-length scale is the same as the fixed-length length, which will bring about a substantial reduction in the yield rate of the manufacturer. Therefore, it is reasonable for the manufacturer to raise the price, and the price increase is basically the same as the fixed-length length.

4. Range length: The range length is within the usual length range. When the user requires a fixed range length, it must be indicated in the contract.

**Production process**Round tube billet → heating → piercing → three-roll cross rolling, continuous rolling or extrusion → stripping → sizing (or reducing diameter) → cooling → straightening → hydraulic test (or flaw detection) → marking → warehousing

**Pipe compression algorithm**One: In order to know the calculation method of seamless pipe outer diameter specification and wall thickness of

**seamless steel pipe**to withstand pressure (the tensile strength of different steel pipes is different)Pressure = (wall thickness * 2 * steel pipe material tensile strength) / (outer diameter * coefficient)

Two: Know the calculation method of seamless steel pipe outer diameter and pressure-bearing wall thickness:

Wall thickness=(pressure*outer diameter*factor)/(2*tensile strength of steel pipe material)

Three: Expression method of steel pipe pressure coefficient:

Pressure P<7Mpa coefficient S=8

7<steel pressure P<17.5 coefficient S=6

Pressure P>17.5 coefficient S=4 [2]

**Mechanical properties**The mechanical properties of large-diameter steel pipes are an important index to ensure the final use performance (mechanical properties) of large-diameter steel pipes, and it depends on the chemical composition and heat treatment system of the steel pipe. Therefore, according to different application requirements, the mechanical properties of large-diameter spiral steel pipes are specifically introduced from the aspects of tensile strength, yield point, and elongation.

1 Tensile strength

In the tensile process, the maximum force (Fb) that the sample bears when it breaks is the stress (σ) obtained from the original cross-sectional area (So) of the sample, which is called the tensile strength (σb), and the unit is N/mm2 (MPa). It represents the maximum ability of a metal material to resist damage under tensile force.

2 Yield point

For a metal material with a yield phenomenon, the stress at which the sample can continue to elong without an increase in the force during the stretching process (remains constant) is called the yield point. If the force drops, the upper and lower yield points should be distinguished. The unit of yield point is N/mm2 (MPa).

3 Elongation after breaking

In the tensile test, the percentage of the length of the gauge length increased after the sample is broken to the original gauge length is called the elongation. Expressed by σ, the unit is %.

Large-diameter steel pipe specification table | |||||

406*16 | 457*32 | 508*80 | 530*22 | 660*80 | 820*55 |

406*17 | 457*35 | 508*90 | 530*25 | 660*90 | 820*60 |

406*18 | 457*40 | 508*100 | 530*28 | 660*100 | 820*70 |

406*19 | 457*45 | 530*16 | 610*30 | 660*150 | 820*80 |

406*20 | 457*50 | 530*17 | 610*32 | 710*20 | 820*90 |

406*22 | 457*55 | 530*18 | 610*35 | 710*22 | 820*100 |

406*25 | 457*60 | 530*19 | 610*40 | 710*25 | 820*150 |

406*28 | 457*65 | 530*20 | 610*45 | 710*28 | 820*200 |

406*30 | 457*70 | 530*22 | 610*50 | 710*30 | 864*40 |

406*32 | 457*80 | 530*25 | 610*55 | 710*32 | 864*55 |

406*35 | 457*90 | 530*28 | 610*60 | 710*35 | 864*60 |

406*40 | 457*100 | 530*30 | 610*65 | 710*40 | 864*70 |

406*45 | 480*16 | 530*32 | 610*70 | 710*45 | 864*80 |

406*50 | 480*17 | 530*35 | 610*80 | 710*50 | 864*90 |

406*55 | 480*18 | 530*40 | 610*90 | 710*55 | 864*100 |

406*60 | 480*19 | 530*45 | 610*100 | 710*60 | 864*150 |

406*65 | 480*20 | 530*50 | 610*150 | 710*65 | 864*200 |

406*70 | 480*22 | 530*55 | 630*18 | 710*70 | 900*60 |

406*80 | 480*25 | 530*60 | 630*19 | 710*80 | 900*70 |

406*90 | 480*28 | 530*65 | 630*20 | 710*90 | 900*80 |

426*16 | 480*30 | 530*70 | 630*22 | 710*100 | 900*90 |

426*17 | 480*32 | 530*80 | 630*25 | 710*150 | 900*100 |

426*18 | 480*35 | 530*90 | 630*28 | 720*25 | 900*150 |

426*19 | 480*40 | 530*100 | 630*30 | 720*28 | 900*200 |

426*20 | 480*50 | 559*16 | 630*32 | 720*30 | 950*60 |

426*22 | 480*55 | 559*17 | 630*35 | 720*32 | 950*70 |

426*25 | 480*60 | 559*18 | 630*40 | 720*35 | 950*80 |

426*28 | 480*65 | 559*19 | 630*50 | 720*40 | 950*90 |

426*30 | 480*70 | 559*20 | 630*55 | 720*50 | 950*100 |

426*32 | 480*80 | 559*22 | 630*60 | 720*55 | 950*150 |

426*35 | 480*90 | 559*25 | 630*65 | 720*60 | 950*200 |

426*40 | 480*100 | 559*28 | 630*70 | 720*65 | 1000*80 |

426*45 | 508*16 | 559*30 | 630*80 | 720*70 | 1000*90 |

426*50 | 508*17 | 559*32 | 630*90 | 720*80 | 1000*100 |

426*55 | 508*18 | 559*35 | 630*100 | 720*90 | 1000*150 |

426*60 | 508*19 | 559*40 | 630*150 | 720*100 | 1000*200 |

426*70 | 508*20 | 559*50 | 660*20 | 720*150 | 1050*80 |

426*80 | 508*22 | 559*55 | 660*22 | 812.8*40 | 1050*90 |

426*90 | 508*25 | 559*60 | 660*25 | 812.8*45 | 1050*100 |

426*100 | 508*28 | 559*65 | 660*28 | 812.8*50 | 1050*150 |

457*16 | 508*30 | 559*70 | 660*30 | 812.8*55 | 1050*200 |

457*17 | 508*32 | 559*80 | 660*32 | 812.8*60 | 1100*80 |

457*18 | 508*35 | 559*90 | 660*35 | 812.8*70 | 1100*90 |

457*19 | 508*40 | 559*100 | 660*40 | 812.8*80 | 1100*100 |

457*20 | 508*50 | 610*16 | 660*50 | 812.8*90 | 1100*150 |

457*22 | 508*55 | 610*17 | 660*55 | 812.8*100 | 1100*200 |

457*25 | 508*60 | 610*18 | 660*60 | 812.8*150 | 1200*80 |

457*28 | 508*65 | 610*19 | 660*65 | 812.8*200 | 1200*90 |

457*30 | 508*70 | 610*20 | 660*70 | 820*50 | 1200*200 |