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API standard tubing is a common OCTG product widely used for oil and gas well production, well completion and daily well maintenance. Made in full compliance with API 5CT international standards, this standard tubing offers stable pressure resistance, accurate overall dimensions and universal thread compatibility, suitable for most conventional onshore oil and gas fields.
As a commonly used tubular product for shallow and medium-depth wells, the tubing is manufactured from seamless alloy steel with standardized production processes.
Outer diameter, wall thickness and thread dimensions comply with API requirements, ensuring compatibility with downhole tools and wellbore structures.
The standardized design helps prevent connection problems caused by dimensional deviations, while consistent mechanical properties and sealing performance support safe and continuous operation in oil and gas projects.
| Nominal | OD | Thread | （inch） | Coupling | |||
| /Lb/Ft | O.D. | I.D. | Drift | O.D.（inch） | |||
| API Tubing (Non Upset) | |||||||
| 1-1/2” | 10RD | 2.75 | 1.900 | 1.610 | 1.516 | 2.200 | |
| 2” | 2-3/8” | 10RD | 4.00 | 2.375 | 2.041 | 1.947 | 2.875 |
| 2-1/2” | 2-7/8” | 10RD | 6.40 | 2.875 | 2.441 | 2.347 | 3.500 |
| 3” | 3-1/2” | 10RD | 7.70 | 3.500 | 3.068 | 2.943 | 4.250 |
| 3-1/2” | 4” | 8RD | 9.50 | 4.000 | 3.548 | 3.423 | 4.750 |
| 4” | 4-1/2” | 8RD | 12.60 | 4.500 | 3.958 | 3.833 | 5.200 |
| API Tubing(External Upset) | |||||||
| 1-1/2” | 10RD | 2.90 | 1.900 | 1.610 | 1.516 | 2.500 | |
| 2” | 2-3/8” | 8RD | 4.70 | 2.375 | 1.995 | 1.901 | 3.063 |
| 2-1/2” | 2-7/8” | 8RD | 6.50 | 2.875 | 2.441 | 2.347 | 3.688 |
| 3” | 3-1/2” | 8RD | 9.30 | 3.500 | 2.992 | 2.867 | 4.500 |
| 3-1/2” | 4” | 8RD | 11.00 | 4.000 | 3.476 | 3.351 | 5.000 |
| 4” | 4-1/2” | 8RD | 12.75 | 4.500 | 3.958 | 3.833 | 5.563 |
| API Regular Casing | |||||||
| 4-1/2” | 8RD | 9.50 | 4.500 | 4.090 | 3.965 | 5.000 | |
| 8RD | 11.60 | 4.500 | 4.000 | 3.875 | 5.000 | ||
| 8RD | 13.50 | 4.500 | 3.920 | 3.795 | 5.000 | ||
| 5-1/2” | 8RD | 14.00 | 5.500 | 5.012 | 4.887 | 6.050 | |
| 8RD | 15.50 | 5.500 | 4.940 | 4.825 | 6.050 | ||
| 8RD | 17.00 | 5.500 | 4.892 | 4.767 | 6.050 | ||
| 8RD | 20.00 | 5.500 | 4.778 | 4.653 | 6.050 | ||
| 8RD | 23.00 | 5.500 | 4.670 | 4.545 | 6.050 | ||
| 6-5/8” | 8RD | 17.00 | 6.625 | 6.135 | 6.010 | 7.390 | |
| 8RD | 24.00 | 6.625 | 5.921 | 5.796 | 7.390 | ||
| 7” | 8RD | 20.00 | 7.000 | 6.456 | 6.331 | 7.656 | |
| 8RD | 23.00 | 7.000 | 6.366 | 6.241 | 7.656 | ||
| 8RD | 26.00 | 7.000 | 6.276 | 6.151 | 7.656 | ||
| 8RD | 29.00 | 7.000 | 6.184 | 6.059 | 7.656 | ||
| 8RD | 32.00 | 7.000 | 6.094 | 5.969 | 7.656 | ||
| 8-5/8” | 8RD | 28.00 | 8.625 | 8.017 | 7.892 | 9.625 | |
| 8RD | 36.00 | 8.625 | 7.825 | 7.700 | 9.625 | ||
| 8RD | 40.00 | 8.625 | 7.725 | 7.600 | 9.625 | ||
| 8RD | 44.00 | 8.625 | 7.625 | 7.500 | 9.625 | ||
| 9-5/8” | 8RD | 36.00 | 9.625 | 8.921 | 8.765 | 10.625 | |
| 8RD | 40.00 | 9.625 | 8.835 | 8.679 | 10.625 | ||
| 8RD | 43.50 | 9.625 | 8.755 | 8.599 | 10.625 | ||
| 8RD | 47.00 | 9.625 | 8.681 | 8.525 | 10.625 | ||
This standard tubing is designed to withstand downhole internal pressure, axial tension and mechanical loads during operation. Controlled heat treatment processes maintain consistent material strength and structural performance for continuous downhole service.
All threads are manufactured according to API requirements to match standard tubing accessories and completion equipment. Precise thread machining and inspection help maintain connection integrity and reduce the risk of leakage caused by improper fitting.
With standardized dimensions and thread specifications, the tubing is compatible with commonly used oilfield completion systems and downhole tools. The standardized design simplifies replacement and installation during field operations.
All API standard tubing is manufactured under standardized quality control procedures according to API requirements. Raw materials are verified before production, and each batch undergoes inspection including mechanical property testing, pressure testing, flaw detection and thread accuracy inspection.
Each finished pipe is inspected for dimensions, performance and sealing requirements before shipment. Products are delivered only after meeting specified quality criteria to support consistent performance in field applications.
API standard tubing is used in conventional oil and gas projects for well production, downhole fluid transmission, well completion and well workover operations. It is also applied in oilfield water injection, wellbore protection and other auxiliary downhole services.
With standardized API specifications, the tubing is compatible with commonly used downhole equipment and meets general oilfield installation and operation requirements.
Tubing selection should be based on actual operating conditions:
Deep wells require higher-strength steel grades such as N80, L80 and P110 to withstand higher mechanical loads and pressure conditions.
For applications involving CO₂, H₂S or other corrosive media, select suitable steel grades and corrosion protection solutions according to operating conditions.
EUE threads provide improved sealing performance for applications with higher sealing requirements, while NUE threads are suitable for conventional well operations.
Select tubing specifications based on fluid type, operating pressure, temperature, production rate and other field parameters.
A1: API standard tubing is mainly used for conventional onshore oil and gas wells, including well production, water injection and downhole fluid transmission applications. It is designed for regular pressure conditions and common oilfield operating environments.
A2: The tubing is manufactured according to API 5CT requirements. Dimensions, mechanical properties and thread specifications follow API standards to ensure compatibility with commonly used oilfield equipment.
A3: Standard tubing features unified dimensions, standardized connections and easier compatibility with downhole equipment. It helps reduce installation problems and maintenance difficulties caused by specification differences.
We specialize in manufacturing API standard oilfield tubing with standardized production processes and quality control procedures. Our product range covers different specifications, steel grades and thread types for conventional oil and gas applications.
We provide customized processing according to project requirements, including tubing specifications, material selection and connection types. Technical support, production coordination and after-sales service are available throughout the cooperation process.
Our tubing products are supplied to oil and gas projects worldwide, supporting applications that require API-compliant tubular solutions.
