API 5CT OCTG Casing and Tubing Pipe Manufacturer & Exporter
China leading API Spec 5CT licensed direct manufacturer and worldwide supplier of premium Oil Country Tubular Goods (OCTG). Supplying full range of Seamless Steel Casing (4-1/2″ to 20″) and Production Tubing (1.9″ to 4-1/2″). Available in standard steel grades H40, J55, K55, N80-1/N80-Q, L80 (1/9Cr/13Cr sour service), C90, T95, P110, and Q125 with API connections (BTC, LTC, STC, NUE, EUE) and gas-tight Premium Connections for onshore and offshore drilling wells.
Figure: API Spec 5CT Casing & Tubing Pipes (J55, N80, L80, P110) with High-Grade Thread Protectors for Oilfield Drilling
1. API 5CT OCTG Steel Grade & Mechanical Property Classification
API Spec 5CT categorizes OCTG oilfield pipes into four primary metallurgical groups according to well depth, collapse pressure, burst limits, and corrosive H2S / CO2 environmental conditions:
| API Group | Steel Grade | Yield Strength (psi / MPa) | Tensile Strength (min psi / MPa) | Well Condition & Environment |
|---|---|---|---|---|
| Group 1 | H40, J55, K55, N80-1, N80-Q | 40,000 – 80,000 / 276 – 552 | 60,000 – 100,000 / 414 – 689 | Shallow to medium-depth standard oil & gas wells (sweet service) |
| Group 2 (Restricted) | L80-1, L80-9Cr, L80-13Cr, C90, T95 | 80,000 – 95,000 / 552 – 655 | 95,000 – 105,000 / 655 – 724 | Sour service (H2S stress cracking resistant) & high-CO2 wells |
| Group 3 (High Strength) | P110 | 110,000 – 140,000 / 758 – 965 | 125,000 / 862 | Deep wells and ultra-high pressure formations |
| Group 4 (Special) | Q125 | 125,000 – 155,000 / 862 – 1069 | 135,000 / 931 | Deepest offshore & ultra-deep drilling HPHT reservoirs |
2. Oilfield Casing vs. Production Tubing Dimensions & Thread Connection
| Category | Outer Diameter (OD) | Wall Thickness (Nominal) | Connection & Thread Type | Length Range (API Range) |
|---|---|---|---|---|
| Oilfield Casing Pipe | 4-1/2″ to 20″ (114.3mm – 508mm) | 5.21mm – 16.13mm (9.5 – 133 lb/ft) | BTC (Buttress), LTC (Long Round), STC (Short Round), Premium Gas-Tight | Range 1 (4.88-7.62m), Range 2 (7.62-10.36m), Range 3 (10.36-14.63m) |
| Production Tubing Pipe | 1.9″ to 4-1/2″ (48.3mm – 114.3mm) | 3.18mm – 6.88mm (2.4 – 12.75 lb/ft) | NUE (Non-Upset), EUE (External Upset), Premium Flush Joint | Range 1 (6.10-7.32m), Range 2 (8.53-9.75m), Range 3 (11.58-12.80m) |
3. Precision Thread Protection & Seaworthy Export Packaging
Thread integrity is paramount in OCTG operations. Sino East Steel adheres to strict oilfield protection protocols:
- Composite Thread Protectors: Heavy-duty steel-composite plastic thread protectors fitted to both pin and box ends to withstand severe maritime impact and transit vibration.
- API Modified Thread Compound: High-grade anti-galling and anti-corrosion API thread dope applied before protector fitting.
- Tubing Bundle Rigging: High-tensile steel strapping with dedicated nylon lifting slings and wooden spacers to prevent metal-to-metal rubbing during container stuffing and vessel loading.
- Third-Party Stamping: Full NDT (Magnetic Particle + Ultrasonic Inspection) and MPI thread inspection witnessed by BV, SGS, or TUV prior to container sealing.
4. Frequently Asked Questions (FAQ) – API 5CT OCTG Procurement
Q1: What are the main differences between J55, N80, and L80 casing grades?
J55 (55 ksi yield strength) is the standard cost-effective grade for shallow sweet wells. N80 (80 ksi yield strength) is heat-treated (normalized or quenched & tempered) for deeper formations with higher collapse pressures. L80 (80 ksi yield strength) has controlled hardness (max 23 HRC) and strict metallurgy specifically designed to resist sulfide stress cracking in sour (H2S) environments.
Q2: When should we specify BTC vs LTC vs Premium connections?
BTC (Buttress Thread) is the industry standard for large casing diameters offering superior tensile load capacity and faster make-up. LTC (Long Round) is suitable for medium-depth vertical wells. Premium Connections (metal-to-metal seal with torque shoulder) are required for deep gas wells, horizontal drilling, and high-pressure gas-tight applications where zero leakage is mandatory.
Q3: How does Sino East Steel handle OCTG shipping to the Middle East and African ports?
We offer direct breakbulk vessel charters and specialized 40ft containerized shipments with timber crating to major energy hubs including Dammam, Jebel Ali, Basra, Alexandria, Lagos, and Port Gentil, complete with Form M / SONCAP / PAAR compliance documents.