Jul . 31, 2025 16:40 Back to list

API 5CT K55 Pipe - High-Strength Oil Drill Tubing

Data updated: 2024-05. All technical data and industry trends referenced from API, ISO, and latest petroleum industry reports.

API 5CT K55 Pipe—API 5CT K55 Pipe—is a widely used steel tubing and casing product manufactured according to the latest American Petroleum Institute (API) 5CT specification. As the backbone of petroleum exploration and production, K55 pipes are known for their optimal strength, corrosion resistance, and affordability. This article provides a comprehensive exploration of API 5CT K55 Pipe—covering global supply trends, technical properties, detailed manufacturing processes, industry-leading applications, vendor comparison, real-world usage, FAQ, and much more.

API 5CT K55 Pipe - High-Strength Oil Drill Tubing

Industry Trends & Market Outlook for API 5CT K55 Pipe

Global Demand: In 2023, the worldwide oilfield tubular goods market reached $24.2 billion and is projected to grow at a 6.3% CAGR through 2027 (Source).
Application Growth: Shale exploration and increased EOR (Enhanced Oil Recovery) drive K55 usage, with 40% of Asian oil wells adopting API 5CT K55 Pipe as casing/tubing in 2022-2023.
Cost-Performance: K55 is preferred for middle-depth oil wells due to its balance of mechanical strength and cost-efficiency compared with higher grades like N80 or L80.
Certified Quality: Over 85% of K55 tubing exports in 2023 held dual API 5CT & ISO 9001:2015 certification.

Technical Specifications — Understanding API 5CT K55 Pipe

API 5CT K55 Pipe is specifically designed for casing and tubing in petroleum extraction. The designation “K55” corresponds to the pipe’s minimum yield strength (55,000 psi / 379 MPa), making it ideal for low-medium pressure environments. Let’s break down the major parameters:

Property	API 5CT K55 Pipe Standard	Typical Range
Outer Diameter (in/mm)	1.900–20.000 inch 48.26–508.00 mm	4 1/2” – 9 5/8” (common)
Wall Thickness	3.18–16.13 mm	Average: 6.55mm
Yield Strength	≥ 379 MPa (55,000 psi)	390–520 MPa
Tensile Strength	≥ 655 MPa	660–800 MPa
Length Range	R1: 6.10–7.32m R2: 8.53–9.75m R3: 11.58–13.72m	Majority export: R2
Manufacturing Type	Seamless & Welded	Seamless: 72% in 2023
End Finish	Plain, BTC, LTC, STC	BTC/LTC preferred
Connection Type	API threading, premium	API, proprietary as per app
Certification	API 5CT, ISO 9001, ISO 14001	Optional: PSL1/PSL2, SR15
Corrosion Resistance	Phosphating/Coated/Raw	85% anti-corrosion rate

Yield vs. Tensile Strength (2022–2024 Average, MPa)

Seamless vs. Welded API 5CT K55 Pipe — 2023 Global Output

Corrosion Resistance Over Years (in various saline groundwater environments)

Manufacturing Process of API 5CT K55 Pipe — Flowchart & Key Steps

1. Raw Material Selection → 2. Pipe Forming (Hot Rolling/ERW) → 3. Heat Treatment (Normalization) → 4. CNC Finishing/Threading → 5. Inspection (NDT, Hydro) → 6. Marking, Certification & Packing

Raw Material: Premium alloy steel coil (Typically 20Mn, J55, K55 standard composition, S≤0.03%, P≤0.03%)
Forming: Hot mandrel seamless process or Electric Resistance Welded (ERW)
Heat Treatment: Complete normalization, stress relief to achieve min. 55,000 psi yield
CNC Finishing: High-precision API threading (BTC, LTC, STC) on CNC lathes to guarantee accurate coupling
Inspection: 100% Non-Destructive Testing (UT, MT, Hydrostatic test), dimensional & hardness checks per API 5CT Annex E; ISO/ANSI-compliant
Marking & Packing: Unique heat number, full traceability, water/oil coating, hexagonal bundles per customer/project specs

▶ Watch API 5CT K55 Pipe Production Video

Material, Process & Performance Advantage — Key Points

Material: High-grade carbon manganese steel, low sulfur/phosphorus for maximized toughness and weldability.
Manufacturing: Strict dimensional tolerance (OD deviation ≤ 0.75%), surface free of cracks, laps, seams as per API 5CT & ISO 11960.
Non-Destructive Testing: 100% UT, hydro & magnetic particle inspection guaranteed; typical leakage rate <0.01% in shipment batch.
Corrosion Resistance: Phosphate or non-metallic coated per NACE TM0177/ISO 15156; standard models pass >2000h salt spray test.
Service Life: In oil field tubing (mild sour environments), K55 pipelines report a 12–17 year median service lifespan (China Petroleum Data 2019–2023).
Application Industries: Petroleum, natural gas, shale, geothermal, groundwater, mining, power plant piping, municipal water/sewage (see next case section).

Application Scenarios and Case Studies

1. Onshore Oilfield Casing — PetroChina Daqing Oilfield
Over 73,000 meters of API 5CT K55 Pipe installed between 2020-2023 for medium-depth wells (vertical & horizontal). Pipes showed 99.7% leak-free performance in first 18 months, reducing workover frequency by 16% against previous casing solutions (PetroChina Technical Report, 2023).

2. Geothermal Well Lining — Icelandic Energy Ltd
K55 pipe lining applied at 1,250m below ground. Withstand geothermal brine corrosion, reporting 0.2mm/year corrosion loss rate (vs. 0.7mm on standard carbon steel).

3. Municipal Water Conveyance — Hanoi Waterworks (Vietnam)
27km of K55 pipe for new trunk line, meeting ISO 14001 & API 5CT. Operators praised easy coupling & alignment, accelerated installation time by 23%.

4. Well Servicing (Workover Tubing Re-entry) — Saudi Aramco
Replacing L80 with API 5CT K55 Pipe in multiple wells, service team documented $320,000 annual savings/well (2022–2023).

API 5CT K55 Pipe Vendor Comparison Table (2024)

Supplier	Country	Process Type	Certification	Export Volume (tons/yr)	Lead Time
Tenaris	Italy/Global	Seamless	API 5CT, ISO 9001, ISO 14001	48,000+	4–6 weeks
TMK Group	Russia/Europe	Seamless	API 5CT, ISO 9001	52,500	6–8 weeks
Baosteel	China	Seamless, ERW	API 5CT, ISO 14001	81,500	3–5 weeks
Y&L Steel Fittings	China/Export	Seamless, ERW	API 5CT, ISO 9001, ISO 14001	19,400	2–4 weeks
Vallourec	France/Brazil	Seamless	API 5CT, ISO 9001	46,200	5–7 weeks

Custom Solutions & Technical Service

Custom Lengths & Threading: Pipe cut and threaded to strict dimensions (within ±2 mm length accuracy); connections: BTC, LTC, premium
Surface Treatment: Anti-corrosion phosphate, lacquer, or special coatings for H2S, CO2, saline
Pre-install Inspection: Ultra-sonic, hydrostatic, hardness tests with certificates
Special Packing: Protective end caps, seaworthy bundles, laser tracking code labeling
Project Documentation: Full TPS (Test, Process, Source) traceability; API 5CT mill certificates
Onsite Support: Remote video QA/QC, field technical assistance, coupling torque guidance

Quality Assurance, Certification, and Service Guarantees

Full Compliance: All delivery in accordance with API 5CT:2018, ISO 9001:2015, and local inspection authorities
Testing & Traceability: Each pipe heat-marked and tested (full traceability via ERP system)
Warranty: Standard 24-month quality guarantee; replace/compensate defective pieces promptly
Customer Support: 24/7 engineer hotline, technical FAQ, rapid documentation issuing (SLA: 2h)

API 5CT K55 Pipe — Frequently Asked Technical Questions

FAQ SECTION

1. What does K55 mean in API 5CT K55 Pipe?

"K55" means the pipe’s minimum yield strength is 55,000 psi (≈ 379 MPa). This class is designed for moderate-pressure wells and is an economical choice versus higher grades like N80.

2. What is the typical chemical composition of API 5CT K55 Pipe?

API 5CT K55 Pipe is mainly carbon-manganese alloyed, with max 0.28% C, 1.2% Mn, S ≤ 0.03%, P ≤ 0.03%, and residual Si, Cr within standard. This composition ensures weldability and strength.

3. What standard thread types are available?

Pipes are offered with API standard threads: BTC (Buttress), LTC (Long Thread), STC (Short Thread), and can be customized with premium connections (VAM, Hydril, etc.).

4. How does API 5CT K55 Pipe’s corrosion resistance perform?

Standard oilfield K55 pipes are phosphate-coated or threaded-and-coupled with premium anti-corrosion oil. ISO 15156-certified models withstand H2S/CO2 exposure and pass >2000h salt fog tests.

5. Can API 5CT K55 Pipe be used in geothermal or saline water wells?

Yes. K55 with appropriate external/internal coating is suitable for geothermal brine and moderate-salinity applications. However, for strong acid/corrosion, L80/CR grades may be recommended.

6. Are there special requirements for installation?

Pipes should be handled per API RP 5C1: ensure straight, undamaged threads, use proper torque per connection, and never over-tighten to avoid coupling damage.

7. How do you verify delivered pipe meets API 5CT?

Each batch comes with third-party physical/chemical test reports, full MTC (Mill Test Certificate), dimensional/visual inspection records, and marking for traceability.

Delivery Time, After-sales, and Customer Support

Production Cycle: Standard orders: 14–28 days (depending on qty), urgent 1x20’ FCL shipment in 7 days possible
Shipping/Incoterms: FOB, CIF, and DDP available; global delivery
After-sales Process: Any appearance/quality failure, report within 5 days after unloading, technical team responds in 12h with solution plan
Technical Assistance: Installation support, online video call, documentation, and on-site engineer service by arrangement

Certifications & Quality — Reference Standards

API 5CT (American Petroleum Institute, Specification for Casing & Tubing)
ISO 9001:2015 (Quality Management, SGS/TUV Certified)
ISO 14001:2015 (Environmental Management)
NACE/ISO 15156 (Sour Service — H2S, CO2 resistance)
ANSI/NACE TM0177-2022 (Corrosion Test Standard)

References & Further Reading:

“Technical Analysis and Life Cycle of K55 Casing Tubing”, Society of Petrophysicists & Well Log Analysts, 2022
“API 5CT Casing/Tubing Standards”, American Petroleum Institute
"Case Study: Durable Tubulars in High Oil-Field Applications", Journal of Petroleum Technology, SPE
“Annual Review of Oilfield Pipe Reliability”, Journal of Petroleum Science & Engineering

Stainless Steel Pipes Enhanced with GPT-4 Turbo - Durable & Efficient