API 5CT Carbon Steel Oil Casing Pipe — Factory Direct Supplier | Huaxia-Steel
Huaxia-Steel supplies seamless and electric-welded oil casing pipe to API 5CT in grades J55, K55, N80-1, N80Q, and R95, with full traceability, thread protection, and third-party inspection on request. Casing is the structural backbone of a well — it lines the borehole, isolates formation pressures, and protects production tubing — so every joint we ship carries heat-number traceability from billet to thread.
Product Overview
Our casing program covers the full string architecture used in conventional wells: conductor, surface, intermediate, and production casing. Pipe is produced on hot-rolling mills or from ERW lines with full-body heat treatment (normalizing or quench-and-temper depending on grade), then finished with plain ends or premium API threads. Couplings are supplied separately or made up to the pipe per customer instruction. All pipe is hydrostatically tested, drift-tested with a mandrel, and gauged for thread parameters before shipping. Standard lengths are R1 (4.88–7.62 m), R2 (7.62–10.36 m), and R3 (10.36–14.63 m); most export orders specify R2 or R3 for fewer connections per string.
Specifications
| Parameter | Details |
|---|---|
| Size range | 4½” to 20″ OD (114.3–508 mm) |
| Wall thickness | 5.21–16.13 mm depending on size and weight class |
| Weight classes | 9.5 to 133 ppf (pounds per foot) |
| Grades | H40, J55, K55, N80-1, N80Q, R95 (L80/C90/T95 available on request) |
| Manufacturing | Seamless (hot rolled) or ERW, full-body heat treated |
| Connections | STC, LTC, BTC (API 5B gauged); plain end; premium connections by agreement |
| Length ranges | R1 (4.88–7.62 m), R2 (7.62–10.36 m), R3 (10.36–14.63 m) |
| Hydro test | Per API 5CT pressure tables, held minimum 5 seconds |
Reference Dimensions and Weights
| Size (OD) | Weight (ppf) | Wall (mm) | ID (mm) | Drift Ø (mm) |
|---|---|---|---|---|
| 4½” | 11.6 | 6.35 | 101.6 | 98.0 |
| 5″ | 18.0 | 7.52 | 111.96 | 108.4 |
| 7″ | 29.0 | 9.19 | 159.4 | 155.8 |
| 9⅝” | 47.0 | 11.99 | 219.1 | 215.9 |
| 13⅜” | 68.0 | 13.06 | 313.6 | 309.7 |
| 20″ | 106.5 | 12.70 | 482.6 | 478.2 |
Tolerances per API 5CT: outside diameter −0.5% / +1.0% (up to 8⅝”), wall thickness −12.5% of nominal, and drift mandates a minimum-length mandrel pass through every joint. Weight per foot tolerance is −3.5% / +6.0% for welded pipe and −3.5% / +6.0% for seamless per the standard’s tables.
Grade Selection Guide
| Grade | Yield (MPa) | Tensile min (MPa) | Typical service |
|---|---|---|---|
| H40 | 276–552 | 414 | Conductor, shallow wells |
| J55 | 379–552 | 517 | Surface casing, low-pressure wells |
| K55 | 379–552 | 655 | Surface/intermediate, no SRB hardness limit |
| N80-1 | 552–758 | 689 | Intermediate/production, normalized |
| N80Q | 552–758 | 689 | Production, quench-tempered, impact tested |
| R95 | 655–758 | 724 | Higher strength, sour-adjacent applications |
For sour service (NACE MR0175/ISO 15156 environments) we supply L80, C90, and T95 with restricted hardness and SSC testing; state the H₂S partial pressure on your RFQ so we propose the correct grade and test package.
Manufacturing Standards and Testing
Production complies with API Spec 5CT and API Spec Q1 quality systems, with ISO 9001 certification on the mill. Each heat receives full chemical analysis and mechanical testing: tension test on body pipe, impact testing for N80Q and above at temperatures per the annex tables, hardness testing where specified, and flattening/weld seam heat-affected-zone testing on ERW product. Threads are gauged to API 5B with working and check gauges under calibration control. Every joint passes: drift test, hydrostatic pressure test to the grade/size table, and visual plus electromagnetic inspection (API Spec 5LT practices) for laminations and defects. Marking includes grade, size, weight, heat number, mill, thread type, and API monogram where licensed.
Applications
- Conductor, surface, intermediate and production casing strings in onshore wells
- Water injection and disposal wells
- Geothermal wells (K55/N80 with thermal cycling consultation)
- Coalbed methane and shale gas development programs
- Structural casing for mine shafts and large-diameter foundations
Quality Assurance Documents
Standard documentation package with each shipment: API 5CT mill certificate with heat chemistry and mechanical results, hydro and drift test records, thread gauge reports, API 5105-style lot traceability, and optional EN 10204 3.2 witnessed by TUV/SGS/BV. Third-party inspection at the mill is welcome — we arrange witness points for heat treatment, hydro testing, and thread gauging.
Packing and Shipping
Casing ships in bundles of 5–10 joints banded with steel strapping, thread protectors (plastic or steel) on both ends for threaded pipe, and bull-nose protectors for plain-end transport. Bundles are tagged per string section to simplify wellsite tally. Containerized delivery for sizes up to 9⅝” and break-bulk or flat-rack for larger diameters. Varying-length orders are tallied and marked for easier rig-floor handling.
Request an API 5CT Casing Quote
Send your casing design (size, weight, grade, thread, length range) to [email protected] for a mill-direct quotation with test certificates, lead time, and coupling options. Third-party inspection and API monogram documentation available on request.
