Q: What Are The Manufacturing Methods For Line Pipe?

Line pipe can be manufactured in two main ways: seamless steel pipe (SMLS) and welded steel pipe (Welded). Welded steel pipes are divided into resistance welding (ERW/HFW) and submerged arc welding (SAW), and the latter is further divided into longitudinal submerged arc welding (LSAW) and spiral submerged arc welding (SSAW).

Q: What Is The Difference Between The Properties Of The X70 And X80 Steel Grades?

The yield strength of X80 pipeline steel is equivalent to X70, but the tensile strength is higher than X70. X80 offers higher strength levels, reduced wall thickness, reduced engineering costs, but higher weld process and toughness control requirements. At present, X80 has been widely used in major projects such as West-East Natural Gas Transmission Project in China.

Question 1

Pipelines must have sufficient impact toughness at low temperature to prevent brittle fracture. Charpy V-notch impact tests are normally required to achieve the specified absorbed energy value at the specified temperature. For example, GB/T 9711 requires the average value of transverse impact energy ≥ 27J (0 ℃ test temperature), and X80 steel grade has higher requirements. Impact test shall be carried out for low temperature materials used at - 20 ℃ and below, welds and heat affected zones.

Accepted Answer

Pipelines must have sufficient impact toughness at low temperature to prevent brittle fracture. Charpy V-notch impact tests are normally required to achieve the specified absorbed energy value at the specified temperature. For example, GB/T 9711 requires the average value of transverse impact energy ≥ 27J (0 ℃ test temperature), and X80 steel grade has higher requirements. Impact test shall be carried out for low temperature materials used at - 20 ℃ and below, welds and heat affected zones.

Question 2

In accordance with API 5L and GB/T 9711, pipeline pipes shall be subject to hydrostatic test one by one, and the standard does not specify that non-destructive testing is allowed to replace hydrostatic test, which is significantly different from some Chinese steel pipe standards (such as SY/T 5037). The test pressure and pressure holding time shall be calculated and determined according to the standard formula.

Accepted Answer

In accordance with API 5L and GB/T 9711, pipeline pipes shall be subject to hydrostatic test one by one, and the standard does not specify that non-destructive testing is allowed to replace hydrostatic test, which is significantly different from some Chinese steel pipe standards (such as SY/T 5037). The test pressure and pressure holding time shall be calculated and determined according to the standard formula.

Question 3

① PSL1 is not required to be subject to impact performance test, and PSL2 must be subject to and specifies the minimum absorbed energy (e.g. transverse ≥ 27J); ② PSL1 does not require NDT, and PSL2 requires NDT one by one; ③ PSL1 only specifies the minimum value of yield strength, PSL2 specifies the minimum value and the maximum value at the same time, and control the yield ratio ≤ 0.93;

Accepted Answer

① PSL1 is not required to be subject to impact performance test, and PSL2 must be subject to and specifies the minimum absorbed energy (e.g. transverse ≥ 27J); ② PSL1 does not require NDT, and PSL2 requires NDT one by one; ③ PSL1 only specifies the minimum value of yield strength, PSL2 specifies the minimum value and the maximum value at the same time, and control the yield ratio ≤ 0.93; ④ PSL2 has more strict restrictions on the content of sulfur, phosphorus and other impurities (S ≤ 0.015%, P ≤ 0.025%); ⑤ PSL2 requires an upper limit of carbon equivalent to ensure weldability.

Question 4

General principle: LSAW or SSAW shall be selected for large-diameter trunk line (above Φ 508mm); ERW is selected for small and medium-sized branch pipelines; LSAW is preferred for high steel grade, large wall thickness and severe working conditions; LSAW or seamless pipes are preferred for submarine pipelines and crossing sections; SSAW can be selected for large-diameter water transmission pipeline with low pressure rating.

Accepted Answer

General principle: LSAW or SSAW shall be selected for large-diameter trunk line (above Φ 508mm); ERW is selected for small and medium-sized branch pipelines; LSAW is preferred for high steel grade, large wall thickness and severe working conditions; LSAW or seamless pipes are preferred for submarine pipelines and crossing sections; SSAW can be selected for large-diameter water transmission pipeline with low pressure rating.

Question 5

The seamless steel pipe has no longitudinal weld and uniform overall performance. It is mainly used in the crossing section, complex terrain area and high pressure, high temperature and other harsh working conditions. However, the large-diameter seamless pipe is difficult to manufacture and the cost is high, so it is less used in the large-diameter trunk line.

Accepted Answer

The seamless steel pipe has no longitudinal weld and uniform overall performance. It is mainly used in the crossing section, complex terrain area and high pressure, high temperature and other harsh working conditions. However, the large-diameter seamless pipe is difficult to manufacture and the cost is high, so it is less used in the large-diameter trunk line.

Question 6

ERW is applicable to medium and small-sized pipelines (Φ 168~660mm, wall thickness of 8~25mm), with steel grade of X56~X80. It is commonly used for branch pipelines and urban natural gas pipelines, submarine transmission pipelines and pipelines in high and cold areas. Its welding speed is high and it can be continuously produced, but it cannot be used as the main natural gas pipeline.

Accepted Answer

ERW is applicable to medium and small-sized pipelines (Φ 168~660mm, wall thickness of 8~25mm), with steel grade of X56~X80. It is commonly used for branch pipelines and urban natural gas pipelines, submarine transmission pipelines and pipelines in high and cold areas. Its welding speed is high and it can be continuously produced, but it cannot be used as the main natural gas pipeline.

Question 7

Advantages: narrow-band steel can be used to produce large-diameter steel pipes, with a maximum diameter of more than 2500mm; Less equipment investment. Limitation: complex residual stress distribution; Weak resistance to large deformation; The wall thickness is generally ≤ 25mm; the development of high steel grade (above X90) is limited.

Accepted Answer

Advantages: narrow-band steel can be used to produce large-diameter steel pipes, with a maximum diameter of more than 2500mm; Less equipment investment. Limitation: complex residual stress distribution; Weak resistance to large deformation; The wall thickness is generally ≤ 25mm; the development of high steel grade (above X90) is limited.

Question 8

Advantages: Mature forming process, easy to ensure welding quality; The residual stress is small after the pipe is expanded; Good geometric accuracy and mechanical property; It can reach high steel grade (≥ X120) and large wall thickness (≥ 40mm). Limitation: the diameter is limited by the plate width (generally ≤ 1422mm); Expensive investment in UOE molding; Less economical with diameter<406mm.

Accepted Answer

Advantages: Mature forming process, easy to ensure welding quality; The residual stress is small after the pipe is expanded; Good geometric accuracy and mechanical property; It can reach high steel grade (≥ X120) and large wall thickness (≥ 40mm). Limitation: the diameter is limited by the plate width (generally ≤ 1422mm); Expensive investment in UOE molding; Less economical with diameter

Question 9

Line pipe can be manufactured in two main ways: seamless steel pipe (SMLS) and welded steel pipe (Welded). Welded steel pipes are divided into resistance welding (ERW/HFW) and submerged arc welding (SAW), and the latter is further divided into longitudinal submerged arc welding (LSAW) and spiral submerged arc welding (SSAW).

Accepted Answer

Line pipe can be manufactured in two main ways: seamless steel pipe (SMLS) and welded steel pipe (Welded). Welded steel pipes are divided into resistance welding (ERW/HFW) and submerged arc welding (SAW), and the latter is further divided into longitudinal submerged arc welding (LSAW) and spiral submerged arc welding (SSAW).

Question 10

The yield strength of X80 pipeline steel is equivalent to X70, but the tensile strength is higher than X70. X80 offers higher strength levels, reduced wall thickness, reduced engineering costs, but higher weld process and toughness control requirements. At present, X80 has been widely used in major projects such as West-East Natural Gas Transmission Project in China.

Accepted Answer

The yield strength of X80 pipeline steel is equivalent to X70, but the tensile strength is higher than X70. X80 offers higher strength levels, reduced wall thickness, reduced engineering costs, but higher weld process and toughness control requirements. At present, X80 has been widely used in major projects such as West-East Natural Gas Transmission Project in China.

Question 11

PSL2 has strict limits on chemical composition. With X46 PSL2 as an example, carbon equivalent (CE) is subject to mandatory upper limit requirements. Impurities such as phosphorus and sulfur are strictly controlled to improve toughness and HIC/SSC resistance. Microalloy elements such as niobium, vanadium and titanium are added to refine grains. Different steel grades and wall thicknesses have different carbon equivalent limits, and the larger the wall thickness, the more strict the requirement.

Accepted Answer

PSL2 has strict limits on chemical composition. With X46 PSL2 as an example, carbon equivalent (CE) is subject to mandatory upper limit requirements. Impurities such as phosphorus and sulfur are strictly controlled to improve toughness and HIC/SSC resistance. Microalloy elements such as niobium, vanadium and titanium are added to refine grains. Different steel grades and wall thicknesses have different carbon equivalent limits, and the larger the wall thickness, the more strict the requirement.

Question 12

In the process of using pipeline steel, in addition to high compressive strength, it is also required to have high low temperature toughness and excellent welding performance. Specific indicators include yield strength, tensile strength, yield strength ratio (PSL2 ≤ 0.93), Charpy impact energy, carbon equivalent (CE), hardness, etc

Accepted Answer

In the process of using pipeline steel, in addition to high compressive strength, it is also required to have high low temperature toughness and excellent welding performance. Specific indicators include yield strength, tensile strength, yield strength ratio (PSL2 ≤ 0.93), Charpy impact energy, carbon equivalent (CE), hardness, etc

Question 13

The "L" series of GB/T 9711 corresponds to the "X" series of API 5L one by one, but the unit is different - the L series is in MPa (MPa) and the X series is in ksi (ksi). For example, L360 corresponds to X52 (360MPa ≈ 52ksi), L415 corresponds to X60, L485 corresponds to X70 and L555 corresponds to X80. The number of the steel grade number represents the minimum yield strength: X52 minimum yield strength is 52ksi, L360 minimum yield strength is 360MPa.

Accepted Answer

The "L" series of GB/T 9711 corresponds to the "X" series of API 5L one by one, but the unit is different - the L series is in MPa (MPa) and the X series is in ksi (ksi). For example, L360 corresponds to X52 (360MPa ≈ 52ksi), L415 corresponds to X60, L485 corresponds to X70 and L555 corresponds to X80. The number of the steel grade number represents the minimum yield strength: X52 minimum yield strength is 52ksi, L360 minimum yield strength is 360MPa.

Question 14

The steel grades specified in GB/T 9711 and API 5L cover a wide range, from low steel grade to ultra-high steel grade: L175/A25、L210/A、L245/B、L290/X42、L320/X46、L360/X52、L390/X56、L415/X60、L450/X65、L485/X70、L555/X80、L625/X90、L690/X100、L830/X120  Etc. At present, the commonly used steel grades in the project are L245/X42 to L555/X80.

Accepted Answer

The steel grades specified in GB/T 9711 and API 5L cover a wide range, from low steel grade to ultra-high steel grade: L175/A25、L210/A、L245/B、L290/X42、L320/X46、L360/X52、L390/X56、L415/X60、L450/X65、L485/X70、L555/X80、L625/X90、L690/X100、L830/X120 Etc. At present, the commonly used steel grades in the project are L245/X42 to L555/X80.

Question 15

Applicable.

Accepted Answer

Applicable. GB/T 9711-2023 added technical requirements for pure hydrogen transmission pipeline (Appendix A), and put forward stricter requirements for carbon control and hydrogen embrittlement control for materials, such as carbon content ≤ 0.07%, Pcm carbon equivalent ≤ 0.15. In addition, the standard provides supplementary requirements for special environment pipes such as acid service (Appendix H) and marine service (Appendix J).

Question 16

General principle: PSL1 can be selected for low-pressure gathering and transmission pipeline, non-critical water transmission pipeline and temporary works; PSL2 must be selected for long-distance high-pressure oil and gas transmission pipelines, submarine pipelines, sour service environment and pipelines crossing sensitive areas.

Accepted Answer

General principle: PSL1 can be selected for low-pressure gathering and transmission pipeline, non-critical water transmission pipeline and temporary works; PSL2 must be selected for long-distance high-pressure oil and gas transmission pipelines, submarine pipelines, sour service environment and pipelines crossing sensitive areas.

Question 17

PSL (Product Specification Level) is the product specification level specified in API 5L and GB/T 9711. PSL1 provides pipeline steel pipes with ordinary quality level, while PSL2 provides a higher quality level, which increases mandatory requirements for chemical composition, hardness, notch toughness, strength performance and supplementary non-destructive testing.

Accepted Answer

PSL (Product Specification Level) is the product specification level specified in API 5L and GB/T 9711. PSL1 provides pipeline steel pipes with ordinary quality level, while PSL2 provides a higher quality level, which increases mandatory requirements for chemical composition, hardness, notch toughness, strength performance and supplementary non-destructive testing. PSL1 only specifies the lower limit of yield and tensile strength, while PSL2 specifies the lower limit and upper limit, and makes mandatory requirements for Charpy impact test, carbon equivalent and other indicators. PSL2 pipe prices are typically 5% - 15% higher than PSL1.

Question 18

GB/T 9711-2023 is consistent with ISO 3183:2019, and the parts with the same requirements as API Spec 5L: 2018 are no longer repeated. The technical contents of the two are highly coordinated. Applicable standards can be selected according to the project location and the Owner's requirements during procurement.

Accepted Answer

GB/T 9711-2023 is consistent with ISO 3183:2019, and the parts with the same requirements as API Spec 5L: 2018 are no longer repeated. The technical contents of the two are highly coordinated. Applicable standards can be selected according to the project location and the Owner's requirements during procurement.

Question 19

The latest version is GB/T 9711-2023, which will be issued in November 2023 and implemented in March 2024, completely replacing the 2017 version. The new standard docking API Spec 5L-2018, core changes include: new technical requirements for pure hydrogen transmission pipeline; Strengthening material control (e.g. carbon content ≤ 0.07%, carbon equivalent ≤ 0.15); Improved mechanical property requirements (Charpy impact work increased to 94J);

Accepted Answer

The latest version is GB/T 9711-2023, which will be issued in November 2023 and implemented in March 2024, completely replacing the 2017 version. The new standard docking API Spec 5L-2018, core changes include: new technical requirements for pure hydrogen transmission pipeline; Strengthening material control (e.g. carbon content ≤ 0.07%, carbon equivalent ≤ 0.15); Improved mechanical property requirements (Charpy impact work increased to 94J); Introduction of hardness full domain control, digital radiographic inspection, etc.

Question 20

The most authoritative international standard is API Spec 5L (American Petroleum Institute Pipeline Steel Pipe Specification), and the corresponding domestic standard is GB/T 9711 "Steel Pipes for Pipeline Transportation Systems in the Petroleum and Natural Gas Industry". In addition, there are also standards such as ISO 3183. The technical requirements of GB/T 9711 and API Spec 5L are basically coordinated and consistent.

Accepted Answer

The most authoritative international standard is API Spec 5L (American Petroleum Institute Pipeline Steel Pipe Specification), and the corresponding domestic standard is GB/T 9711 "Steel Pipes for Pipeline Transportation Systems in the Petroleum and Natural Gas Industry". In addition, there are also standards such as ISO 3183. The technical requirements of GB/T 9711 and API Spec 5L are basically coordinated and consistent.

Question 21

Divided by manufacturing process into seamless steel pipe (SMLS) and welded steel pipe (Welded); Welded steel pipes are divided into spiral submerged arc welded pipes (SSAW), straight seam submerged arc welded pipes (LSAW), and high-frequency straight seam welded pipes (ERW). The main types of oil and gas steel pipes are these four, each with a suitable diameter and pressure range.

Accepted Answer

Divided by manufacturing process into seamless steel pipe (SMLS) and welded steel pipe (Welded); Welded steel pipes are divided into spiral submerged arc welded pipes (SSAW), straight seam submerged arc welded pipes (LSAW), and high-frequency straight seam welded pipes (ERW). The main types of oil and gas steel pipes are these four, each with a suitable diameter and pressure range.

Question 22

Mainly used for: ① long-distance oil and gas pipelines (onshore and subsea); ② Urban high-pressure gas pipeline network; ③ Internal gathering and transportation pipelines in oil and gas fields; ④ Slurry conveying pipeline; ⑤ Carbon dioxide and hydrogen transportation pipelines, etc.

Accepted Answer

Mainly used for: ① long-distance oil and gas pipelines (onshore and subsea); ② Urban high-pressure gas pipeline network; ③ Internal gathering and transportation pipelines in oil and gas fields; ④ Slurry conveying pipeline; ⑤ Carbon dioxide and hydrogen transportation pipelines, etc.

Question 23

Pipeline pipes are steel pipes manufactured in accordance with API 5L, GB/T 9711 and other special standards. They are specially used for long-distance transmission of oil, natural gas, water and other fluids, and have special requirements on strength, toughness, weldability and corrosion resistance.

Accepted Answer

Pipeline pipes are steel pipes manufactured in accordance with API 5L, GB/T 9711 and other special standards. They are specially used for long-distance transmission of oil, natural gas, water and other fluids, and have special requirements on strength, toughness, weldability and corrosion resistance. Ordinary steel pipes are subject to general structural or low-pressure fluid transmission standards, with low technical requirements, and cannot directly replace pipeline pipes for high-pressure oil and gas transmission.

Question 24

ASTM-A252 is a steel pipe foundation standard for pipe piles developed by the American Society for Testing and Materials, applicable to seamless and welded steel pipes. This type of steel pipe is mainly used as a protective sleeve for load-bearing piles or concrete piles. ​
The standard includes three strength levels:
Grade 1: Minimum yield strength 207 MPa (30 ksi)
Grade 2: Minimum yield strength 241 MPa (35 ksi)
Grade 3: Minimum yield strength 310 MPa (45 ksi)

Accepted Answer

ASTM-A252 is a steel pipe foundation standard for pipe piles developed by the American Society for Testing and Materials, applicable to seamless and welded steel pipes. This type of steel pipe is mainly used as a protective sleeve for load-bearing piles or concrete piles. ​The standard includes three strength levels:Grade 1: Minimum yield strength 207 MPa (30 ksi)Grade 2: Minimum yield strength 241 MPa (35 ksi)Grade 3: Minimum yield strength 310 MPa (45 ksi)

Question 25

3 Types: SSAW Pipe,LSAW Pipe,ERW Pipe.

Accepted Answer

3 Types: SSAW Pipe,LSAW Pipe,ERW Pipe.

Question 26

Absolutely. We specialize in custom fabrication. Send us your drawings or specifications, and our engineering team will provide DFM suggestions and quotes.

Accepted Answer

Absolutely. We specialize in custom fabrication. Send us your drawings or specifications, and our engineering team will provide suggestions and quotes.

Question 27

Yes! Each shipment includes: Mill Test Certificate (EN 10204 3.1), chemical composition report, mechanical test reports, coating inspection report, and material traceability documents.

Accepted Answer

Yes! Each shipment includes: Mill Test Certificate (EN 10204 3.1), chemical composition report, mechanical test reports, coating inspection report, and material traceability documents.

Question 28

Standard products: 15-25 days. Custom sizes: 25-40 days. We provide real-time production updates.

Accepted Answer

Standard products: 15-25 days. Custom sizes: 25-40 days. We provide real-time production updates.

Question 29

Spiral steel pipe uses hot-rolled strip steel as raw material, and the steel strip is welded into a spiral shape by automatic submerged arc welding. Its main process steps include forming, welding, sizing, straightening, trimming and quality inspection.

Accepted Answer

Spiral steel pipe uses hot-rolled strip steel as raw material, and the steel strip is welded into a spiral shape by automatic submerged arc welding. Its main process steps include forming, welding, sizing, straightening, trimming and quality inspection.

Question 30

Spiral steel pipe is a welded pipe, which is usually used in oil and gas, water supply and drainage projects. It is made by rolling the steel strip into a spiral shape and welding it with internal and external welds, hence the name "spiral steel pipe".

Accepted Answer

Spiral steel pipe is a welded pipe, which is usually used in oil and gas, water supply and drainage projects. It is made by rolling the steel strip into a spiral shape and welding it with internal and external welds, hence the name "spiral steel pipe".

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