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Help CenterSteel Pipe & Tube & Upset Tubing，J55/K55、N80、L80、P110
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Steel Pipe & Tube & Upset Tubing，J55/K55、N80、L80、P110NegotiableMOQ: 5 Metric Tons -
Steel Pipe & Tube & Upset Tubing，J55/K55、N80、L80、P110NegotiableMOQ: 5 Metric Tons
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Steel Pipe & Tube & Upset Tubing，J55/K55、N80、L80、P110NegotiableMOQ: 5 Metric Tons
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Steel Pipe & Tube & Upset Tubing，J55/K55、N80、L80、P110NegotiableMOQ: 5 Metric Tons
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Steel Pipe & Tube & Upset Tubing，J55/K55、N80、L80、P110NegotiableMOQ: 5 Metric Tons
Detailed Description of Petroleum Pipes
Petroleum pipes (OCTG, Oil Country Tubular Goods) are core special pipes applied in the exploration, drilling, oil production, gathering, transportation and refining of oil and natural gas. They are designed to withstand harsh working conditions including high temperature, high pressure, severe corrosion (H₂S/CO₂/Cl⁻) and complex geological stress, complying with both API and national standards. The main categories include Casing, Tubing, Drill Pipe and Line Pipe & Refinery Pipe.
1. Product Classification & Main Applications
1.1 Casing
Application: To support well walls, isolate formations and prevent well collapse and interlayer channeling, serving as the permanent framework of oil wells. It is divided into surface casing, intermediate casing and production casing.
Specifications: Outer diameter 114.3～508mm (4.5"～20"), wall thickness 6.35～16mm, standard length 8.53～9.75m (R2 as the mainstream).
Steel Grades: J55/K55 (shallow wells), N80/L80 (medium-deep wells), P110 (deep wells / high-pressure wells), Q125 (ultra-deep wells).
1.2 Tubing
Application: Suspended inside casing, acting as the flow channel for oil and gas lifting, water injection, polymer injection, acidizing and fracturing. It is recyclable and reusable.
Specifications: Outer diameter 60.3～114.3mm (2.375"～4.5"), wall thickness 4.83～9.52mm, length 6～12.5m.
Steel Grades: Same as casing. N80, L80 and P110 are commonly used; L80-13Cr and Super 13Cr are adopted for sulfur-containing wells.
1.3 Drill Pipe
Application: Connect drill bits and surface equipment to transmit torque and drilling pressure, and circulate drilling fluid. It works as the power transmission channel during drilling operations.
Specifications: Outer diameter 60.3～168.3mm, wall thickness 8.56～12.7mm, length 8.5～9.5m, equipped with upset tool joints.
Steel Grades: E75, X95, G105, S135 (high strength and high toughness).
1.4 Line Pipe
Application: For long-distance transportation of crude oil, natural gas and refined oil products, including main pipelines, gathering pipelines and subsea pipelines.
Specifications: Outer diameter 21.3～1067mm (1/8"～42"), wall thickness 2～50mm. Available in seamless and welded types (ERW/LSAW).
Steel Grades: API 5L Grade B, X42, X52, X65, X70, X80 (high strength and deformation resistance).
1.5 Refinery Pipe
Application: Used as furnace tubes, heat exchanger tubes and high-pressure pipelines in refineries, resistant to high temperature (450～600℃) and hydrogen corrosion.
Specifications: Outer diameter 10～426mm, wall thickness 1.5～20mm. Seamless pipe is the primary type.
Steel Grades: 20#, 12CrMo, 15CrMo, 304/316 Stainless Steel.
2. Material & Chemical Composition (Main Steel Grades)
2.1 Carbon Steel / Low Alloy Steel (Mainstream)
| Steel Grade | C (%) | Mn (%) | Cr (%) | Mo (%) | Ni (%) | Application |
|---|---|---|---|---|---|---|
| J55/K55 | 0.30～0.38 | 0.60～0.90 | — | — | — | Shallow well casing & tubing |
| N80 | 0.35～0.45 | 0.70～1.00 | — | — | — | Medium-deep wells; N80-1 (Normalized & Tempered) / N80Q (Quenched & Tempered) |
| L80 | 0.25～0.35 | 0.50～0.80 | 0.40～0.60 | — | — | Sulfur-containing wells, dedicated for H₂S environment |
| P110 | 0.30～0.40 | 0.80～1.20 | 0.40～0.60 | 0.15～0.25 | — | Deep wells & high-pressure wells, high collapse resistance |
2.2 Corrosion Resistant Alloys (Special Working Conditions)
13Cr (L80-13Cr): Chromium content 12～14%, resistant to CO₂ corrosion, applicable to medium-temperature CO₂-bearing oil and gas wells.
Super 13Cr: 14～16% Cr + 2% Mo, resistant to combined corrosion of CO₂, H₂S and Cl⁻, for high-temperature, high-pressure and sulfur-rich wells.
Nickel-based Alloy (Inconel 825/718): High content of Ni, Cr and Mo, used for extreme corrosion environments with high sulfur, high temperature and high chloride ion content.
3. Execution Standards (International & Domestic)
3.1 API Standards (International Authoritative Standards)
API 5CT: Specification for Casing and Tubing (dimensions, steel grades, mechanical properties, threads and inspection).
API 5D: Specification for Drill Pipe (joints, torque, fatigue resistance and nondestructive testing).
API 5L: Specification for Line Pipe (PSL1/PSL2, pressure resistance, toughness and weldability).
API 5B: Threading, Gauging and Thread Inspection for Casing, Tubing and Line Pipe.
3.2 Chinese National & Industrial Standards
GB/T 9711: Line Pipe (equivalent to API 5L, PSL1/PSL2).
GB 9948: Seamless Steel Pipes for Petroleum Cracking Service.
SY/T 6194: Casing and Tubing (equivalent to API 5CT).
4. Mechanical Property Requirements (Key Indicators)
4.1 Casing & Tubing
Yield Strength: J55 ≥ 379MPa, N80 ≥ 552MPa, P110 ≥ 758MPa.
Tensile Strength: N80 ≥ 655MPa, P110 ≥ 862MPa.
Impact Energy: ≥ 27J (0℃, V-notch).
Collapse Resistance: N80 ≥ 276MPa, P110 ≥ 483MPa (critical for deep wells).
4.2 Drill Pipe
Yield Strength: S135 ≥ 931MPa, G105 ≥ 724MPa.
Tensile Strength: S135 ≥ 1034MPa.
Torsional Strength: Φ127mm drill pipe ≥ 38kN·m.
5. Thread Types & Connection Modes
5.1 Standard API Threads
Buttress Thread (BTC): 60° thread angle, ordinary sealing performance, easy to assemble and disassemble, suitable for shallow wells.
Butress Coupling Thread (BC): 3° thread angle, excellent sealing performance and high torque resistance, widely used for medium-deep wells.
5.2 Premium Connection Threads (High-end)
Air-tight Thread (e.g. VAM TOP, BGT1): Metal-to-metal sealing, no leakage, specially used for high-pressure and gas-bearing wells.
Flush Joint (XC): Without coupling, small outer diameter, ideal for slim-hole wells and cluster wells.
6. Manufacturing Process
Seamless Pipe (Mainstream): Billet heating → Piercing → Hot rolling → Sizing → Straightening → Heat treatment (Normalizing / Quenching & Tempering) → Thread machining → Nondestructive testing → Anti-corrosion treatment.
Welded Pipe (Line Pipe): Steel plate rolling → Welding (LSAW / ERW) → Heat treatment → Nondestructive testing → Anti-corrosion treatment.
7. Surface Treatment & Anti-corrosion
Outer Surface: Zinc-rich epoxy primer, asphalt paint, 3PE (Three-layer Polyethylene) coating to prevent soil corrosion.
Inner Surface: Epoxy anti-corrosion coating, copper plating and chromium plating for drag reduction and scale inhibition; Stainless steel coating is applied inside pipes for sulfur-containing wells.
Coupling: Phosphating treatment and copper plating to prevent thread galling; Special sealing grease is used for thread lubrication.
8. Packaging, Marking & Delivery
Packaging: Plastic thread protectors are installed at both ends of pipes. Pipes are bundled (10～20 pieces per bundle) with moisture-proof and rainproof measures.
Marking: API logo, steel grade, specifications, heat number, batch number, manufacturer and production date are marked on each pipe.
Delivery Condition: Casing and tubing are generally supplied in quenched & tempered condition (N80Q/P110) or normalized & tempered condition (N80-1); Drill pipes are quenched & tempered with friction welded joints.
9. Quality Inspection
Chemical Composition: Spectroscopic analysis, tested per heat. Impurity control: S ≤ 0.03%, P ≤ 0.03%.
Mechanical Properties: Tensile test, impact test, hardness test and collapse test, sampled per batch.
Nondestructive Testing: 100% inspection by Ultrasonic Testing (UT), Eddy Current Testing (ET) and Magnetic Particle Testing (MT) to detect cracks and laminations.
Thread Inspection: Check thread profile, pitch and taper with thread gauges and projectors to ensure interchangeability.
10. Application & Selection Recommendation
Shallow Wells (Depth ＜ 2000m): J55/K55 casing + N80 tubing, cost-effective solution.
Medium-deep Wells (Depth 2000～4000m): N80 casing + L80 tubing (for sulfur-containing wells), balanced performance and cost.
Deep & High-pressure Wells (Depth ＞ 4000m): P110 casing + Super 13Cr tubing, featuring high collapse resistance and corrosion resistance.
Long-distance Transmission Pipelines: X70/X80 line pipe with 3PE anti-corrosion coating, connected by welding.
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