What is API 5L Line Pipe?

What is API 5L Line Pipe?

API 5L Line Pipe is one of the transportation method used for transporting oil, natural gas and water through pipeline to the oil and gas industry company. 

Types Specification
Ends Types Standard
Connection Types Test Methods
Steel Grade Benefit

Types of API 5L Line Pipe:

API 5L Welded Line Pipe

API early in 1926 released by the American Petroleum Institute (API) API-5L standard, initially including three steel grade A25, A, B, and later released several times. API 5L welded steel pipe is mainly used for the delivery of the onshore and offshore oil and gas, coal slurry, the slurry media and offshore platforms, power plants, chemical industry and urban construction, structural tubes.

API 5L seamless steel line pipe - What is API 5L Line Pipe?
China is currently used in the Petroleum Pipeline tube spiral welded pipe (SSAW steel pipe), LSAW steel pipe, electric resistance welded pipe (ERW steel pipe). Diameter less than 152mm selection of seamless steel tubes. Of the late 1960s to the 1970s, spiral pipe plant rapid development of crude oil pipelines almost all spiral welded steel pipe. The spiral welded steel pipe of the disadvantage is the internal stress is large, the dimensional accuracy is poor, the probability of generation of defects. According to expert analysis, should adopt the policy of “walking on two legs”, and actively carry out technological transformation now spiral welded pipe plant, also in promising; vigorously develop straight seam submerged arc control tube industry in China. ERW steel pipe with a smooth appearance, high dimensional accuracy, lower prices, and has been widely used at home and abroad.
Straight seam high frequency welded steel molding process that used in the production of LSAW steel pipe by Yaang Steel Pipe is with advanced, reliable quality, welding position, stable welding parameters, welding speed, high yield, and the entire production line equipment and technology are world-class level.

  • (1) straight seam high frequency welded steel pipe forming process spring back small residual stress.
  • (2) the strain hardening effect is small, precise geometric dimensions full circle, will help ensure the quality of construction and welding.
  • (3) straight seam high frequency welded steel bead shape is good, not prone to biting edge, inside and outside the weld misalignment defects.
  • (4) straight-seam pipe weld distributed in a point on the circumference and, therefore, according to the demand to weld on a favorable position.

API 5L Seamless Line Pipe

API 5L Seamless Line Pipe will often be categorized based upon the way in which it was manufactured. Two manin methods of manufacturing API 5L Seamless Line Pipe exist, cold drawing and finishing, cold drawing refers to a tube-building method in which the tubing is drawn, or shaped at room temperature. this method is good for creating a bettersurface finish, closer tolerances,lighter walls or smaller diameters of tubing. hot finished API 5L Seamless Line Pipe is made without the use of any cold finishing, meaning that the seamless pipe is built while the material is extremely hot. Both of these processes are commonly used.

Ends Types of API 5L Line Pipe:

  • Plain Ends
  • Threaded Ends
  • Socket Ends

Line Pipe with Plain End and Beveled - What is API 5L Line Pipe?

Connection Types of API 5L Line Pipe

  • Welding Connection
  • Coupling Connection
  • Socket Connection

Steel Grade of API 5L Line Pipe:

GR.B, X42, X52, X60, X65, X70, L245, L290, L320, L360, L450, L485

API 5L steel line pipe adopts different steel grades, generally are Gr.B, X42, X46, X52, X60, X70, X80. Some manufacturers are capable of manufacturing steel grade up to X100 and X120. As the steel line pipe grades higher, more strictly control on the carbon equivalent control, and higher mechanical strength performances.
More over, for the same grade API 5L pipe, seamless and welded chemical elements content is different, which welded pipe is required more strictly and lower on Carbon and Sulfur.
By different delivery condition, there are also As-rolled, normalizing rolled, thermomechanical rolled, normalizing formed, normalized, normalized and tempered, quenched and tempered.

For intermediate grades, API 5L pipe grade shall be in one of following description format:

  1. The letter L followed by the specified minimum yield strength in Mpa. For example, L290 (X42) means the minimum yield strength is 290 Mpa. In case of PSL2 pipe, Suffix letter (R, N, Q or M) shall be added to describe the delivery condition;
  2. The letter X follwed by a two or three digital number equal to the minimum yield strength in 1000 psi rounded down to the nearest integer and, for PSL2 pipe, the letter describing the delivery condition (R, N, Q, or M) consist with the above formats.

Chemical Composition

Grade

Mfg. Process

Chemical composition (%)

C
Si
Mn
P
S
Ni
Cr
Mo
Others
A25C1 Ⅰ
S
0.21Max
0.30~0.60
0.045Max
0.06Max
A25C1 Ⅱ
0.21Max
0.30~0.60
0.045~0.80
0.06Max
A
0.21Ma2
0.90Max
0.04Max
0.05Max
B
0.27Max
1.15Max
0.04Max
0.05Max
X42(Non-expanded)
0.29Max
1.25Max
0.04Max
0.05Max
X42(Cold expanded)
0.29Max
1.25Max
0.04Max
0.05Max
X46(Non expanded)
0.31Max
1.35Max
0.04Max
0.05Max
X46(Cold expanded)
0.29Max
1.25Max
0.04Max
0.05Max
X52(Non expanded)
0.31Max
1.35Max
0.04Max
0.05Max
X52(Cold expanded)
0.29Max
1.25Max
0.04Max
0.05Max
X56
0.26Max
1.35Max
0.05Max
Cb 0.005Max

V 0.005Max

Ti 0.005Max

X60
0.26Max
1.35Max
0.05Max
Cb 0.005Max

V 0.005Max

Ti 0.005Max

X65
X70
0.045Max
X80
0.045~0.080
A25C1 Ⅰ
W
0.21Max
0.04Max
0.06Max
A25C1 Ⅱ
0.21Max
0.04Max
0.06Max
A
0.21Max
0.04Max
0.05Max
B
0.26Max
0.04Max
0.05Max
X42
0.28Max
0.04Max
0.05Max
X46(Non expanded)
0.30Max
0.04Max
0.05Max
X46(Cold expanded)
0.28Max
0.04Max
0.05Max
X52(Non expanded)
0.30Max
0.04Max
0.05Max
X52(Cold expanded)
0.28Max
0.04Max
0.05Max
X56
0.26Max
0.04Max
0.05Max
X60
0.26Max
0.04Max
0.05Max
X65
0.26Max
0.04Max
0.05Max
X70
0.23Max
0.04Max
0.05Max
X80
0.18Max
0.030Max
0.018Max

Mechanical Properties

Grade
Tensile Test MPa or N/mm2

Remaks (Similar to JIS)

Possibility Temperature

Min Yield point

Tensile Strength

A25C1 Ⅰ
172
310Min
A25C1 Ⅱ
1772
310Min
A
207
331Min
(STPG370)
B
241
413Min
(STPG410)
X42(Non-expanded)
289
413Min
X42(Cold expanded)
289
413Min
X46(Non expanded)
317
434Min
X46(Cold expanded)
317
413Min
X52(Non expanded)
358
455Min
X52(Cold expanded)
358
455Min
X56
386
489Min
X60
413
517Min
X65
448
530Min
X70
482
565Min
X80
551
620~827
A25C1 Ⅰ
172
310Min
A25C1 Ⅱ
172
310Min
A
207
331Min
B
241
413Min
X42
289
413Min
X46(Non expanded)
289
413Min
X46(Cold expanded)
317
434Min
X52(Non expanded)
358
455Min
X52(Cold expanded)
358
455Min
X56
386
489Min
X60
413
517Min
X65
448
530Min
X70
482
565Min
X80
551
620Min

Specification of API 5L Line Pipe:

  • Seamless Steel Pipe Specification: Outside Diameter: 10.3mm ~ 1016mm, Wall Thickness: 1.7mm ~ 52mm;
  • ERW Steel Pipe Specification:  Outside Diameter: 21.3mm ~ 660mm, Wall Thickness: 1mm ~ 20mm;
  • LSAW Steel Pipe Specification: Outside Diameter: 406mm ~ 1626mm, Wall Thickness: 6.0mm ~ 75mm;
  • SSAW Steel Pipe Specification: Outside Diameter: 219mm ~ 4060mm, Wall Thickness: 3.2mm ~ 40mm;

Tolerance of Outside Diameter

Standard Out Diameter Tolerance of Pipe End Tolerance of Pipe Body
API 5L

219.1~273.1

+1.6mm, -0.4mm ±0.75%
274.0~320 +2.4mm, -0.8mm ±0.75%
323.9~457 +2.4mm, -0.8mm ±0.75%
508 +2.4mm, -0.8mm ±0.75%
559~610 +2.4mm, -0.8mm ±0.75% 

Tolerance of Wall Thickness

Standard Grade Out Diameter Wall Thickness
API 5L A 219.1~457 +15%, -12.5%
B 508~610 +17.5%, -12.5%
X42-X80 508~610 +19.5%, -8%

Standard of API 5L Line Pipe:

API 5L Line Pipe Standard has put forward specific requirements on the manufacturing of seamless and welded steel pipe including two steel pipe specification level (PSL1 and PSL2). API 5L Line Pipe is widely used for petroleum and natural gas industry pipeline transportation systems, but this API 5L Line Pipe criterion is not suitable for the cast iron pipe. PSL is the abbreviation of Product Specification Level which is the quality level of API 5L Line Pipe. API 5L Line Pipe has two standards which are PSL1 and PSL2. Although these two standard only have one word 
difference, the content is very different. PSL2 is a higher quality level than PSL1. Both standard level have different levels of inspectio requirements, chemical composition requirements, mechanical properties requirements, mechanical properties requirements. When making order follow the API 5L Line Pipe Standard, the purchaser need to indicate the level of standard (PSL1 or PSL2) regard of the basic contract terms such as product specification, steel grades, order quantity etc. In general condition, if the contracts do not mention the standard level, the manufacturer will produce in accordance with the standard of PSL1. To be more specify, the differences are including:

  1. Pipeline Hydro-static Test should be done piece by piece, and the API 5L Line Pipe Standard does not specify to allow non-destructive alternative hydro-static testing. 
  2. Impact performance test is necessary for PSL2 standard, while PSL1 is not necessary for this type of test. 
  3. Non-destructive Test should be applied for PSL 2 standard pipe piece by piece, while for PSL1 standard is not required. 

API 5L Line Pipe Standard is similar to the Chinese Standard GB/T9711. API 5L Line Pipe PSL1 is equivalent to the GB/T9711.1. Compared with API 5L Line Pipe PLS1, API 5L Line Pipe PSL2 standard level requires more impact energy experiments, so the production time and production cost for the manufacturers will increase. Besides, API 5L Line Pipe PSL2 standard requires a higher quality level of raw materials for producing steel pipes, the raw materials ordering time will be longer than the PSL1 standard steel pipe raw materials. Moreover, in order the reach the quality standard of PSL2 and also control the production cost of the factory, the manufacturer will set up a higher level of minimum order quantity for the purchasers. For API 5L Line Pipe PSL2, some time purchasers will request for following NACE standard which means during the production the manufacturers have to add hardness and acid resistance test for the pipes to reach a even higher quality level of steel pipes.

Chemical Properties %

PSL C, a    Mna P        S  Si V Nb

Ti

Other CEIIW CEpcm
1 0.24 1.40 0.025 0.015 0.45 0.10 0.05 0.04 b,c .043 0.025
2 0.28 1.40 0.03 0.03 b b b

Mechanical Properties        

PSL API 5L PSL-1 X52 API 5L PSL-2 X52
Tensile strength, min /max, psi (MPa) 66,700(460)/ n/a 66,700 / 110,200
Yield strength, min /max, psi (MPa) 52,000 (300)/n/a 52,000 / 76,900

  • A. For each reduction of 0.01% below the specified maximum concentration for carbon, an increase of 0.05% above the specified maximum concentration for manganese is permissible, up to a maximum of 1.65% for > grades B, but < X52; up to a maximum of 1.75% for grades >X52, but < X70; and up to a maximum of 2.00% for grade X70
  • B. The sum of the niobium, vanadium, and titanium concentrations shall be < 0.06%.
  • C. Unless otherwise agreed, 0.50% maximum for copper, 0.30% maximum for nickel, 0.30% maximum for chromium, and 0.12% maximum for molybdenum.

API 5L X60 PSL 1 grade designations come from API Spec 5L Specification for Line Pipe. Stronger grades have the designation X followed by the specified minimum yield strength of the pipe steel, measured in kilopounds per square inch (abbreviated ksi). Standard Line Pipe has grade designation A and B.

Select differences between PSL 1 and PSL 2:

 Data

PSL1

PSL2

CVN impact (Charpy) testing

None required

Required for all grades

Nondestructive inspection of seamless

Only when purchaser specifies   SR4

SR4 mandatory

Certification

Certificates when specified per SR15

Certificates (SR 15.1) mandatory

Traceability

Traceable only until all tests are passed, unless SR15 is specified

Traceable after completion of tests (SR 15.2) mandatory

Hydrostatic Test

Required    

Required

Note: 
This is summarized information from API Specification 5L. Please refer to the specific Standard or Specification or contact us for more details.

API 5L PSL1 and PSL2 Differences for API 5L Line Pipe

API 5L line pipe of all grades have PSL1 and PSL2 two product specifications, they are different on chemical composition, manufacturing processes, mechanical strength, heat treatment, test records, traceability etc.

Line pipes in API 5L PSL2 is higher than PSL1

PSL is the short name of product standard level. The product standard level of line pipe have PSL1 and PSL2, also we could say the quality standard divided in PSL1 and PSL2. PSL2 is higher than PSL1, not only the inspection standard is different, also the chemical property, mechanical strength standards are different. So when place the order for the API 5L line pipe, there should be stated clearly for the size, grades these general specification, also have to clarify the production standard leve, PSL1 or PSL2.
PSL2 is more strictly than PSL1 on the chemical properties, tensile strength, non-destructive test, and impact test.

Different impact test methods for PSL1 and PSL2

API 5L PSL1 steel line pipe not required to do the impact test.
For API 5L PSL2 steel line pipe, except Grade X80, all the other grades of API 5L line pipe required the impact test at temperature of 0℃. The average value of Akv: longitudinal direction≥41J, tranverse direction≥27J.
For API 5L Grade X80 PSL2 line pipe, at 0℃ for all the size, impact test the Akv average value: longitudinal direction≥101J, tranverse direction≥68J.

Different hydraulic test for API 5L line pipe in PSL1 and PSL2

For API 5L PSL2 line pipe shall perform the hydraulic test for each single pipe, and in the API standard specification not permit to have Non-destructive test replace the hydraulic test, this also is a big difference between Chinese standard and API 5L standard. For PSL1 not required Non-destructive test, for PSL2 shall do the Non-destructive test for each single pipe.

Different chemical composition for API 5L line pipe in PSL1 and PSL2

Chemical composition and mechanical strength is also different between API 5L PSL1 line pipe and API 5L PSL2 line pipe. For the detailed specification as below. API 5L PSL2 have restrictions with the carbon equivalent content, where for the carbon mass fraction greater than 0.12%, and equal or less than 0.12%. Different CEQ shall be applied. For line pipe in PSL2 tensile strength have maximum limits. More info please review API 5L Specification part 9.2 and 9.3.

Test Methods for API 5L Line Pipe

Below we will introduce the methods for API 5L line pipe.

1). Hydrostatic test

  • A. Jointers need not be hydrostatically level, provided that the portions of pipe used in making the jointers were successfully hydrostatically tested prior to the joining operation.
  • B. Except the previous situation, the pipe shall withstand the hydrostatic test without leakage through the weld seam or the pipe body.

2). Bend test

Cracks should not occur in any part of the sample and opening of weld shall not occur as well.
Please Note: For all bend test, the weld extends to a distance of 6.4 mm (0.25 in) on each side of fusion line.

3). Flattening test

The flattening test method is used to verify the deformation performance of line pipe to the specified size, and display its defects. According to the stress and deformation characteristics of the specimen during the flattening process, the flattening test shall show the resistance to longitudinal cracking and circumferential cracking of the pipe, and display its internal defects and surface defects.

Benefit of API 5L 3LPE Anticorrosion Pipe

3-layer anticorrosion pipe is a multilayer, thermoplastic coating designed to provide maximum long term corrosion resistance and mechanical protection to steel pipe. The system was developed for use in demanding pipeline environments where superior adhesion, cathodic disbondment and impact resistance properties are essential to maintaining pipeline integrity.
It consists of the 3 following components which are simultaneously applied to the pre-heated pipe to form a homogenous barrier against corrosion. The system is typically available in yellow or black:

  • I) A primary layer of thermosetting fusion bonded epoxy (FBE) powder that adheres to the heated steel substrate providing the corrosion protection and
  • II) A secondary layer of adhesive polymer resin that reacts chemically with the previously applied FBE to act as a bonding agent and
  • III) A third layer of high density polyethylene (HDPE) that bonds with the previously applied adhesive resin providing mechanical protection to the system

Benefits:

  1. Service temperature up to 80° C (85° C peaks)
  2. Excellent flexibility and corrosion resistance (impervious to moisture)
  3. Excellent adhesion to steel and extremely resistant to soil stresses
  4. Superb impact/abrasion resistance (minimizes need for finely graded padding for the trench. Also reduces incidents of coating damage during handling, transportation & construction)
  5. Coating thickness can be customer specified dependent on project requirements
  6. Compatible with most known field joint protection systems
  7. Technically superior to 2-layer HDPE systems
  8. Complies with China SY/T0413-2002\Canadian CAN/CSA-Z245.21-2002\GermanyDIN30679

Source: China Steel Pipes Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com

Please notice that you might be interested in the other technical articles we’ve published:

  • What is the difference between a steel pipe and a steel tube

  • Engineering Specification for Pressure Test of Piping System

  • Manufacturing process of cold rolled steel pipe

  • How to get high quality alloy steel pipes

  • HOW TO GET HIGH QUALITY STEEL PIPES

  • How to get high quality carbon steel pipes

  • The standard and application of stainless steel seamless pipe and welded pipe

  • How To Distinguish Inferior Steel Pipe

  • HOW TO GET HIGH QUALITY BOILER TUBES

  • API 5L Specification for Line Pipe

  • What is the Meaning of API 5L Pipe

References:

  • https://www.yaang.com

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