SSC VS HIC Tests

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Sulfide stress cracking (SSC) is a form of hydrogen embrittlement cracking. Sulfide stress cracking occurs in low alloy steel pipeline, high-strength steels, weld joints, and welding heat-affected zones (HAZs) subjected to tensile stress in acidic environments and temperatures below 82°C (180°F), depending on the composition, microstructure, strength, residual stress, and external stress of the steel.

The steel plate samples were immersed in an acidic aqueous solution containing H2S, and the anti-SSCC performance data were obtained by applying an appropriate incremental load. According to the standard NACE TM0177-2016, the specific requirements are as follows: take a group of forged steel plate sample σb or Hb to be the highest, carry out anti-sulfide stress cracking test, and the stress σTh ≥247MPa to be qualified. A group of samples from class A, B and D welded joint samples were taken for sulfide stress cracking test, and the stress σTh ≥247MPa was considered qualified.

Hydrogen induced cracking (HIC) is a kind of internal cracks with stepped characteristics formed by the interconnection of parallel hydrogen layer cracks, which have no obvious interaction with external stress or residual stress. At the bubbling part, hydrogen cracking is aggravated by the stress generated by hydrogen accumulation inside. HIC is closely related to the cleanliness of steel, as well as the manufacturing method of steel, the presence of impurities and their shape.

HIC occurs in thin and heterogeneous sulfide or oxide inclusions occurring parallel to the rolling direction of the steel plate. These inclusions form sites that form microscopic hydrogen bubbles and eventually grow together through step-like fractures. Since HIC is not stress-dependent and does not occur with hardened microstructure, post-weld heat treatment is not meaningful. The resistance to hydrogen cracking can only be achieved by limiting trace element sulfur and controlling the manufacturing variables of steel.

SSC and HIC tests are based on the NACE international test standard recommended by the American Society of Corrosion Engineers. Constant load stress corrosion test and three-point bending test were mainly used for SSC test, mainly according to NACE TM0177, and NACE TM0284 was mainly used for HIC test. The materials used in the design and manufacture of the elastic design criteria may be selected from those already qualified in ISO 15156-2 and ISO15156-3 or NACE_MR0175 standards, which have specified environmental conditions to avoid stress corrosion. The materials should be selected only if they meet this limitation.

Conditions for exemption from SSC and HIC tests for carbon steel, low alloy steel and cast iron

1. Materials shall be delivered in the following conditions:

Hot rolling (carbon steel only)/annealing/normalizing/normalizing + tempering/normalizing, Austenitizing, quenching + tempering/Austenitizing, quenching + tempering

2. Material hardness is not more than 22HRC, and nickel content is less than 1.0%;

S 0.003% or less, P 0.010% or less;

The hardness of weld and heat affected zone shall not exceed 22HRC.

3. The yield strength of the material is less than 355Mpa and the tensile strength is less than 630Mpa

4. Carbon equivalent limit:

Low carbon steel and carbon manganese steel: Ce ≤0.43 Ce =C+Mn/6

Low alloy steel: Ce ≤045 Ce =C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15

Conditions for exemption from SSC and HIC tests for stainless steel

CCrNiPSMnSi
≤0.08≥16.00≥8.00≤0.045≤0.04≤2.0≤2.0
Chemical composition limitation
  1. The content of 321 stainless steel with higher carbon content allowed to contain other elements is acceptable within the corresponding technical range.

2. Should be solution annealing and quenching, or annealing heating stabilized heat treatment conditions;

3. It is not allowed to improve mechanical properties through cold working;

4. The hardness of raw materials, welds and heat affected zone shall not exceed 22HRC.

Alloy UNS.NoTemperature, maxPressure H₂S, kpa(psi)Chloride ion concentration(mg/l)PhSulphate resisting
S3160093(200)10.2(1.5)5000≥5.0No
S31603149(300)10.2(1.5)1000≥4.0No
S2091066(150)100(15)//No

The welding of API J55 casing

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API 5A J55 is a commonly used casing material. The tubing body is threaded to the coupling and must be welded to reinforce the strength of the threaded connection. A harsh working environment requires high quality for the pipe body and welding quality. We analyze its weldability by calculating carbon equivalent. The chemical composition of J55 casing is shown in the following table:

CSiMnPSCrNiCu
0.34～0.390.20～0.351.25～1.50≤0.025≤0.015≤0.15≤0.20≤0.20
J55 Casing tubing chemical composition

CE＝C＋Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15

CE＝0.69＞0.4

The weldability of the material is poor when the carbon equivalent exceeds 0.4, high preheating temperature and strict process are needed to obtain qualified welding quality. The carbon content of 0.34%~0.39% makes the transition curve of supercooled Austenite shift to the right, and the stability of supercooled Austenite increases. The addition of alloying elements, such as Cr, Mn, Ni and Cu, makes the transition curve of supercooled Aaustenite shift to the right, and enhances its stability and MS point (the beginning point of Mmartensite formation). All these effects increase the quenching tendency of J55, and it is easy to crack during welding.

The cold crack tendency of J55 casing is mainly due to the large quenching embrittlement crack. The highest hardness value of welding heat affected zone is high and the rapid cooling is easy to form martensite because of the high strength. In order to reduce the cooling rate, extend the cooling time of the welded joint from 800 ℃ to 500℃, improve the microstructure of the weld metal and reduce the maximum hardness of the heat-affected zone, preheating before welding and tempering after welding is required. J55 casing has a small hot crack tendency because it does not contain strong carbide and has low thermal conductivity, which is difficult to generate low fusion eutectic. The tensile strength of J55 is greater than or equal to 517 MPa, and the yield strength is 379-522MPa. we should use welding wire ER55-G which has similar strength. The welding wire has high welding Ni content, strong cold cracking resistance, and excellent comprehensive mechanical properties of the deposited metal. Our engineers make the following two plans:

Welding method 1: 80%Ar+20%CO2 gas welding. ER55-G welding wire with a diameter of 3.2mm. Welding parameters: current 250~320A, voltage 26 ~30V; Welding speed 35~50cm/min; The preheating temperature is 100℃, and the inter-layer temperature is not lower than the preheating temperature, but it is not allowed to be higher than the preheating temperature of 30℃. Post-welding treatment: air cooling without any heat treatment.

Welding method 2: The same welding materials and welding parameters as method one, only the change of post-welding heat treatment: tempering treatment, temperature 600±20℃, holding time for 4h; Heating rate 50℃/h, cooling rate 50℃/h.

The results of the two welding tests are as follows:

The tensile test of the first scheme is qualified. The impact values of the three samples in the heat-affected zone are 26,47,23, which are unqualified. The four lateral bending samples had cracks of 3.75mm, 4mm, 1.38mm and 0.89mm, respectively, which were unqualified. The test shows that this welding scheme is not reasonable.

The second scheme is qualified by tensile test; The impact values of the three samples in the heat-affected zone are 51,40,40, which are qualified. All the four side bending samples are intact and qualified; The experiment proves that this welding scheme is reasonable. Post-welding heat treatment can improve the welding microstructure and properties, which is one of the important factors for obtaining the welded joints that meet the technical requirements of J55 casing welding.

What’s the steel material for Hydrogen pipeline?

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Hydrogen can be gaseous hydrogen, liquid hydrogen and solid hydrogen according to the state when transportation, among which high-pressure gaseous hydrogen is the most commonly used and environmentally friendly transportation mode at present. Pipeline transportation is the most efficient way for a large throughput and distance occasions can be a long-distance pipeline, also be a short distance distribution pipeline. The long-distance transmission pipeline has high pressure and large diameter, which is mainly used for conveying high-pressure hydrogen between hydrogen production unit and hydrogen station. The latter pipeline is low-pressure and a small diameter is mainly used for the distribution of medium and low-pressure hydrogen between the hydrogen station and end-user. The current cost of long-distance hydrogen pipelines is about $630,000 / km, compared with $250,000 / km for natural gas pipelines, 2.5 times the cost of natural gas pipelines, then comes with the question, how to choose the right material for the transportation of Hydrogen pipeline?

Compared with natural gas, metal materials working in a hydrogen environment for a long time will cause the deterioration of mechanical properties, which is called environmental hydrogen embrittlement. The evaluation of high-pressure hydrogen embrittlement properties of metals is mainly conducted through in-situ hydrogen environment tests, in which materials are directly placed in a hydrogen environment. The types of tests mainly include slow strain rate tensile test, fracture toughness test, crack growth rate test, fatigue life test and disc pressure test. The hydrogen embrittlement can be determined according to No.NASA8-30744 standard and the resistance of materials to hydrogen embrittlement can be evaluated according to ASTM G142-98 comparison of sensitivity test results.

Compared with natural gas pipelines, hydrogen pipelines are different in alloy elements, steel grade, pipe shape and operating pressure due to the limitation of hydrogen embrittlement in the environment. The available materials for natural gas pipelines specified in ASME B31.8-2018 include all the steel pipes in API SPEC 5L. However, in practical engineering, to reduce the wall thickness of pipelines, high-strength steel pipes are generally preferred, and commonly used pipe types include SAWL, SAWH, HFW and SMLS. For hydrogen gas pipeline, a hydrogen environment induced by hydrogen embrittlement occurred, in turn, can lead to pipeline failure, that depends on the steel pipe molding process, weld quality, defect factors such as size, steel strength, so the ASME B31.12-2014 in API SPEC 5 l limited several hydrogens can be used for pipeline steel type, indicating to ban the use of furnace tube welding, pipeline steel specified in the standard can be used in the hydrogen pipe and the maximum allowable pressure as shown in the table below.

API 5LX42X52X56X60X65X70X80
Yield strength /Mpa289.6358.5386.1413.7488.2482.7551.6
Tensile Strength /Mpa413.7455.1489.5517.1530.9565.4620.6
Allowable Pressure, Max 20.6820.6820.6820.6810.3410.3410.34

Alloying elements such as Mn, S, P and Cr can enhance the hydrogen embrittlement sensitivity of low alloy steels. At the same time, the higher the hydrogen pressure and the higher the strength of the material, the more obvious hydrogen embrittlement and hydrogen-induced cracking will be. Therefore, in practical engineering, low steel grade steel tubes are preferred for hydrogen pipelines. ASME B31.12-2014 recommends the use of X42, X52 steel pipes, and stipulates that hydrogen embrittlement, low temperature performance transition, ultra-low temperature performance transition and other issues must be considered.

International standardization organizations include the International Hydrogen Technical Committee (ISO/TC197), the European Industrial Gas Association (EIGA) and the American Society of Mechanical Engineers (ASME) and another organization specifies standards for the production, storage, transportation, testing and use of hydrogen energy, mainly includes ASMEB31.12-2014 “Hydrogen Pipelines”, CGAG-5.6-2005 “Hydrogen Pipeline Systems”, which are suitable for the design of long Hydrogen Pipeline and short distance Hydrogen delivery Pipeline. Hydrogen pipelines are mostly made of seamless steel pipes. The hydrogen pressure is generally 2~10MPa, the diameter of the pipes is 0.3~1.5m, and the pipeline materials are mainly X42, X52, X56, X60, X65, X70, X80 and other low strength pipeline steels. The expected service life is 15~30 years.

Line Pipe for Gas, Oil, and Water Pipelines

Line Pipe for Gas, Oil, and Water Pipelines

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Line pipe is a type of steel pipe that is used for transporting materials through pipelines across the country. Line pipe can be used to transport petroleum, natural gas, oil, and water. It is a durable pipe that must meet certain specifications and regulations. This pipe typically has a high strength and durability in order to withstand high pressures. At Wldsteel, we sell and distribute line pipe in a complete variety of sizes, lengths, diameters, and grades.

Line Pipe for Gas, Oil, and Water Pipelines

To learn more about our line pipe sales and distribution services or to receive a quote for your specific requirements, please

What is Line Pipe
Line pipe is a type of pipe that is manufactured from high strength carbon steel. It is typically made according to metallurgical specifications that were developed by the American Petroleum Institute (API). Line pipe can be used to build pipelines that transport a variety of resources including natural gas, oil, petroleum, and water. This pipe is available in a variety of diameters ranging from 2 inches to 48 inches. Line pipe can include either seamless or welded carbon steel or stainless steel piping. Because line pipe needs to withstand high pressures, there are important tests done on line pipe to ensure it meets all of the requirements of steel chemistry, strength, toughness, and dimensional characteristics. Using line pipe that meets the set criteria will ensure safe and reliable pipeline service.

The size and diameter of line pipe that is required for a pipeline can vary based on the amount of gas or liquid that a pipe is intended to carry as well as the pressures that a line pipe must withstand. For example, in most cases a mainline, the principal pipeline that delivers natural gas, will require line pipe that is around 16 to 48 inches in diameter. Smaller pipelines that deliver gas to the mainline or take gas from a mainline can be constructed of 6 to 16 inch diameter line pipe. One can determine the necessary diameter required for a pipeline by considering the volume of gas or liquid that the line pipe will be carrying as well as the pressure at which this will be transported.

The thickness requirements for line pipe are determined by the maximum operating pressure required for a pipeline. This is based on published standards and federal regulations. Following proper safety regulations when selecting and installing line pipe, will ensure proper pipeline operation and prevent dangerous or hazardous situations.

Buy Line Pipe
At Wldsteel, we sell carbon steel line pipe and  stainless steel pipe in a variety of sizes, diameters, and thicknesses. This line pipe can be used for pipelines that carry oil, petroleum, natural gas, or water. Most sizes of our ERW, DSAW and Seamless Steel pipe are available with mill test reports and full traceability as required. We can supply many grades of line pipe, including API 5L-B, X-42, X-46, X-52, X-60, X-70 and higher.

As a leading pipe distributor, we are not only able to supply new line pipe direct from stock or mill sources, but we can also cut pipe to your required length and add special coatings as needed. We can deliver line pipe and other stainless steel piping to nearly any worksite or location throughout the United States. To learn about our current selection of line pipe for sale or to learn more about our stainless steel pipe distribution services, please feel free to contact us at WLD Steel.

Steel line pipe for oil & gas

Steel line pipe for oil & gas

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What is Line Pipe:

Line pipe is a type of pipe that is manufactured from high strength carbon steel. It is typically made according to metallurgical specifications that were developed by the American Petroleum Institute (API). Line pipe can be used to build pipelines that transport a variety of resources including natural gas, oil, petroleum, and water. This pipe is available in a variety of diameters ranging from 2 inches to 48 inches. Line pipe can include either seamless or welded carbon steel or stainless steel piping. Because line pipe needs to withstand high pressures, there are important tests done on line pipe to ensure it meets all of the requirements of steel chemistry, strength, toughness, and dimensional characteristics. Using line pipe that meets the set criteria will ensure safe and reliable pipeline service.The size and diameter of line pipe that is required for a pipeline can vary based on the amount of gas or liquid that a pipe is intended to carry as well as the pressures that a line pipe must withstand. For example, in most cases a mainline, the principal pipeline that delivers natural gas, will require line pipe that is around 16 to 48 inches in diameter. Smaller pipelines that deliver gas to the mainline or take gas from a mainline can be constructed of 6 to 16 inch diameter line pipe. One can determine the necessary diameter required for a pipeline by considering the volume of gas or liquid that the line pipe will be carrying as well as the pressure at which this will be transported.The thickness requirements for line pipe are determined by the maximum operating pressure required for a pipeline. This is based on published standards and federal regulations. Following proper safety regulations when selecting and installing line pipe, will ensure proper pipeline operation and prevent dangerous or hazardous situations.

Steel line pipe for oil & gas

TYPES OF OIL & GAS PIPES
Steel pipes can be classified according to multiple criteria, such as:

Manufacturing process: seamless, erw, LSAW, DSAW, HSAW pipes
Finishing: cold rolled, hot rolled, cold finished
Materials: metal, plastic, cement, glass, fiberglass, etc and material grades (carbon steel, stainless steel, nickel alloy steel pipes)
Manufacturing norms

Line pipe sizes, grades and dimensions
Nominal pipe sizes (NPS) and diameters differ on the transported amount of gas or other flammable liquid as well as the pressures it has to withstand. The outside diameter (OD) of line tubes ranges from 1/8″ to 80″ in accordance with API 5L and other international standards (DIN, ASTM/ASME, NFA, EN) and grades (A / B / X-42 / X-46 / X-52 / X-56 / X-60 / X-65 / X-70 / X-80). Industry standards and federal regulations also specify wall thickness that is determined by the maximum operating pressure (MAOP). Further detailed information is displayed in our line pipe product chart.

standard of Steel line pipe for oil & gas

  • API 5L/ISO 3183 Gr. A, B, X42, X46, X52, X56, X60, X65, X70, X80
  • ASTM A134 and ASTM A135
  • CSA Z245.1 Gr. 241, 290, 359, 386, 414, 448, 483, 550

Dimensional Tolerances for Line Pipes to API Specification 5L / ISO 3183

Pipe SizeDiameter Tolerances
Pipe oxeept the endPipe end 1)
Mrtmir,ai Specified Outside Nominal Pipe Size Djam〇terseamless weldedseamless welded
Up to 2″ Up to 60.3 mm-0.8 mm / + 0.4 mm-0.4 mm / + 1.6 mm
, c. . . 60.3 mm up to 2 t〇6.._nd. 168.3mmjncl.± 0.0075 D
6*to24*,incl. 168.3 mm up to 610 mm. incl.+/- 0.0075 D±0.0075 D butmaximum of *3.2+/- 0.005 D. but maximum of +/-1.6 mm
26′ up to 56″, incl. 660 up to 1422 mm incl.+/- 0.01 D± 0.005 D but maximum of ±4.0+/- 2.0 mm+/-1.6 mm
Over 56* Over 1 422.0 mmas agreed

Pipeline System Supply delivers line pipe for onshore and offshore applications in the oil and gas industry used to convey natural gas, oil and other flammable fluids. Due to extreme conditions such as low and high temperature, high pressure and corrosive environments in the transportation of flammable media, line tubes are made from carbon, alloy or stainless steel in accordance with API 5L, EN and ISO 9001 standards. International standards determine metallurgical specifications to guarantee safe, reliable and long lasting pipelines. Therefore important tests are performed on line pipe to ensure it meets all of the determined requirements of steel chemistry, strength, toughness, and dimensional characteristics. Steel pipes can be manufactured seamless and in different welded varieties ranging from Fusion Welded (EFW), Electric Resistance Welded (ERW), High Frequency Induction (HFI) to Double Submerged Arc Welded (DSAW).

API 5L Seamless Line Pipe Specifications

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The American Petroleum Institute specification API 5L covers seamless and welded steel line pipe.  This is steel pipe for pipeline transportation systems in the petroleum and natural gas industries.  API 5L is suitable for conveying gas, water, and oil.  Size range is limited only by manufacturer’s capabilities.

Specifications for API 5L adhere to the International Organization for Standardization ISO 3183, which standardizes pipeline transportation systems within the materials, equipment and offshore structures for petroleum, petrochemical, and natural gas industries.  The technical committee authoring the standards recognized that there are two basic Product Specifications Levels (PSL) of technical requirements and therefore developed PSL 1 and PSL 2.  PSL 1 is a standard quality for line pipe where PSL 2 contains additional chemical, mechanical properties, and testing requirements.

Grades covered by this specification are A25 ,A ,B (and the following “X” Grades), X42, X46, X52, X56, X60, X65, X70, X80.  The two digit number following the “X” indicates the Minimum Yield Strength (in 000’s psi) of pipe produced to this grade.

Federal Steel Supply stocks a full range of API 5L X52 PSL-1 & PSL-2 line pipe in seamless.

Sizes
Nominal Pipe Size 2″ to 24″ O.D.
Wall Thickness – Schedule 10 through 160, STD, XS, XXS.


Standard                                            API 5L

Product Specification Level             PSL-2

Steel grade                                         X52

Chemical Properties %

PSLC, a   Mn aP       S SiVNbTiOtherCEIIWCEpcm
10.241.400.0250.0150.450.100.050.04b,c.0430.025
20.281.400.030.03–bbb–––

 Mechanical Properties        

                                                                        API 5L PSL-1 X52                API 5L PSL-2 X52

Tensile strength, min /max, psi (MPa)         66,700(460)/ n/a66,700 / 110,200

Yield strength, min /max, psi (MPa)            52,000 (300)/n/a          52,000 / 76,900

  1. 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
  2. b.      The sum of the niobium, vanadium, and titanium concentrations shall be < 0.06%.
  3. 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.

Select differences between PSL 1 and PSL 2:

PSL1PSL2
CVN impact (Charpy) testingNone requiredRequired for all grades
Nondestructive inspection of seamlessOnly when purchaser specifies   SR4SR4 mandatory
CertificationCertificates when specified per SR15Certificates (SR 15.1) mandatory
TraceabilityTraceable only until all tests are passed, unless SR15 is specifiedTraceable after completion of tests (SR 15.2) mandatory
Hydrostatic TestRequiredRequired

What’s Underground Coated Steel Pipe

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Many individuals usually confused about concerning the plastic-coated pipes and 3PE anti-corrosive pipes because they are extremely comparable to their look. The covered plastic pipeline, also known as underground covered steel pipe or steel-plastic composite steel pipeline, is the steel pipeline which is melted a natural layer with a thickness of 0.5 ~ 1.0 mm on the inner and also external walls such as customized polyethylene (PE), ethylene-acrylic copolymer (EAA), epoxy (EP) powder, non-toxic polypropylene (PP) or non-toxic polyvinyl chloride (PVC). This below-ground covered steel pipe incorporates the advantages of steel and plastics. It not only has the advantages of high strength, very easy link, water effect resistance and so forth however likewise terminates the downsides such as easy rust, pollution, scaling, reduced toughness of the plastic pipe as well as inadequate fire-fighting efficiency of steel pipe in water. It offers a lengthy life expectancy and more financially with layout life can get to 50 years.

What's Underground Coated Steel Pipe

Coted pipe
Firefighting covered steel pipeline is the most generally utilized plastic layered steel pipeline, with a steel pipeline as the base pipe, the outer wall surface finishing high adhesion, effect resistance, deterioration resistance weather resistance kind of thermosetting powder finish and also the inner wall surface coating food grade sanitary polycarbonate powder finishing, and after that made by sandblasting and chemical therapy, preheating, inner paint, external painting, curing and also various other post-treatment.

The functions of below ground covered steel pipeline
The pipeline wall is smooth as well as burr-free, suitable for the underground or one more humid environment, can hold up against very high or reduced temperatures.
It have a solid capacity to stand up to stress, also can withstand the stress of 6Mpa.
With superb anti-interference ability, it can successfully evaluate the signal interference from the outside.
The covering itself additionally has good electric insulation and does not create corrosion.

The Specification of underground coated steel pipe
Color: black, gray, blue, red, white, eco-friendly;
Layer thickness: PE( customized polyethylene) coating density is 400um– 1000um, EP( epoxy material) is 100um– 400um;
Layer method: Hot-dip EP, epoxy internal/external spraying;
Specification: DN15– DN1660;
Ambient temperature: -30 ℃ to 120 ℃;.
Link: cord clasp (DN15-DN100), groove (DN65-DN400), flange (ideal for any size), welding type, bimetal link, outlet, pipeline joint, securing connection, and so on

Applications of underground layered steel pipeline.

  1. The plastic-coated pipeline can be utilized in all kinds of flowing water system (civil flowing water as well as industrial circulating water), fire water system, structure water system and also water drainage transportation, city sewage pipeline;.
  2. Gas discharge, mud sharing, drainage as well as air flow system in the coal mine;.
  3. The chemical anticorrosive pipeline transportations various chemical fluids, such as acid, antacid and other harsh media.
  4. Utilized for the security of hidden pipelines as well as interaction wires of electric cords as well as cables.
  5. It can ensure the normal operation of the water blood circulation system of central air conditioning in the HVAC circulation system of air conditioning.