P110 PSL 2 R3 SMLS Casing (Suitable for Sour Service Applications)

API 5CT P110 PSL 2 R3 seamless casing with Premium Connection is a high-strength oil country tubular goods (OCTG) product designed for deep, high-pressure, and complex well conditions. It is manufactured in accordance with API Specification 5CT (10th Edition, 2022) and thread inspection requirements of API Spec 5B, and is widely used in oil and gas drilling and well construction projects requiring high structural integrity and reliable sealing performance.

This product combines a quenched and tempered high-strength steel grade (P110), seamless manufacturing process (SMLS), higher specification level (PSL 2), optimized length range (R3), and premium threaded connection system for demanding downhole environments.
 

1. Full Term Definition: P110 SS PSL 2 R3 SMLS Casing Premium Connection

1.1 P110 Steel Grade

P110 is a high-strength casing grade defined by API 5CT with the following mechanical property range:

• Yield strength: 758–965 MPa (110,000–140,000 psi)
• Minimum tensile strength: ≥ 862 MPa
• Heat treatment condition: quenched and tempered (Q&T)

P110 is designed for high-load applications in deep and high-pressure wells. It provides higher strength capacity compared to L80 and N80 grades, but is not specifically designed for sour service unless additional material requirements are specified by project standards (e.g., NACE MR0175 / ISO 15156 compliance where applicable).
 

1.2 Sour Service (SS)

Used in procurement specifications to indicate suitability for hydrogen sulfide (H₂S) environments, where resistance to sulfide stress cracking (SSC) and other forms of hydrogen-induced damage is required in accordance with NACE MR0175 / ISO 15156 standards.
 

1.3 PSL 2 (Product Specification Level 2)

PSL 2 defines a higher quality level than PSL 1 under API 5CT.

PSL 2 requirements typically include:

• Mandatory impact toughness testing (where applicable by specification)
• Enhanced non-destructive testing (NDT)
• Stricter dimensional tolerances
• Full material traceability requirements
• More stringent documentation and certification control

PSL 2 is generally specified for critical wells, deep wells, and high-pressure applications depending on operator and project requirements.

1.4 R3 Length Range

API 5CT defines casing length ranges as R1, R2, and R3.

R3 range:

• 10.36 m to 14.63 m (34 ft to 48 ft)

Engineering significance:

• Reduces total number of threaded connections in casing string
• May reduce potential leak points depending on installation and make-up quality
• Commonly used in deep and extended-reach wells

1.5 SMLS (Seamless Steel Pipe)

SMLS refers to seamless steel pipe manufactured without longitudinal weld seams.

Compared with welded (ERW) casing, seamless casing provides:

• More uniform mechanical properties
• Improved resistance to internal and external pressure
• Better performance in high-strength grades such as P110

Seamless manufacturing is commonly used for high-strength OCTG applications.

1.6 Premium Connection

Premium Connection refers to proprietary high-performance threaded connections designed for enhanced sealing and torque capacity.

Unlike standard API BTC/LTC/STC threads, premium connections typically provide:

• Improved gas-tight sealing performance
• Higher torque resistance
• Better fatigue resistance under cyclic loading conditions

Selection and performance depend on manufacturer qualification and make-up procedures defined by connection design specifications.

2. Core Technical Parameters & Compliance Standard

• Standard: API 5CT 10th Edition (2022)
• Thread standard: API Spec 5B (16th Edition)
• Grade: P110
• Manufacturing: Seamless (SMLS)
• Specification Level: PSL 2
• Length range: R3 (10.36–14.63 m)
• Connection: Premium Connection
• Yield strength: 758–965 MPa
• Tensile strength: ≥ 862 MPa
• Hardness: controlled per API 5CT requirements (project dependent)
• Chemical composition: controlled per API 5CT limits for P110 grade

3. Main Functions & Application Scenarios

3.1 Core Functions

As a permanent downhole casing string, P110 SS PSL 2 R3 SMLS Casing with Premium Connection undertakes four core functions:

1. Stabilize the wellbore and prevent formation collapse;
2. Isolate different geological zones and avoid cross flow of oil, gas and water;
3. Withstand extreme internal and external pressure differentials to ensure well control safety;
4. Adapt to corrosive media including hydrogen sulfide (H₂S) and carbon dioxide (CO₂).

3.2 Typical Application Scenarios

• This specification is commonly used in:

• Deep wells and ultra-deep wells
• High-pressure (HP) oil and gas wells
• Extended-reach and directional wells
• Gas wells requiring high-integrity sealing systems
• Critical wells requiring PSL 2 quality assurance

• Note: For sour service (H₂S environments), material selection must comply with NACE MR0175 / ISO 15156 requirements, and alternative grades may be required depending on severity.

4. Quality Inspection & Required Documentation

Each batch of API 5CT PSL 2 casing is typically subject to the following inspection scope:

• Chemical composition analysis
• Mechanical property testing (tensile, yield)
• Hardness testing
• Hydrostatic testing (as applicable)
• Non-destructive testing (UT, MPI as specified)
• Dimensional inspection (OD, WT, length)
• Thread gauging and inspection (API Spec 5B for premium connections where applicable)
• Drift testing

Required documentation:

• Mill Test Certificate (MTC)
• Heat number traceability records
• NDT reports
• Dimensional inspection reports
• Thread inspection reports

API 5CT P110 Casing test and inspection

API 5CT P110 Casing pipe certificate

5. FAQ

Q 1: What is the difference between PSL 1 and PSL 2 for API 5CT casing?

PSL 2 has stricter quality control than PSL 1. It requires more comprehensive non-destructive testing, stricter dimensional tolerance control, higher frequency of mechanical sampling and full lifecycle material traceability. PSL 2 is used for high-pressure, deep wells and key projects, while PSL 1 is for conventional shallow and medium wells.

Q 2: Why choose R3 length for P110 casing in deep wells?

R3 casing is longer than R1 and R2. Using R3 length reduces the total number of threaded connections in the casing string. Fewer joints mean lower leakage risk and higher overall structural stability, which is critical for deep and ultra-deep well operations.

Q 3: Why is seamless (SMLS) pipe recommended for P110 grade?

Seamless steel pipe has no welding seam, with uniform wall thickness and consistent mechanical properties. It shows better collapse resistance and pressure resistance under extreme downhole loads. ERW welded pipe is only suitable for conventional low-pressure wells, while seamless pipe is the standard choice for high-strength P110 casing.

Q 4: What are the advantages of Premium Connection over standard API threads?

Standard BTC, LTC and STC threads meet general connection demands. Premium connections provide superior gas-tight sealing, higher torque capacity and better resistance to pressure fluctuation. They are commonly used in gas well applications, HPHT wells and sour wells with harsh working conditions.

Q 5: What heat treatment is required for API 5CT P110 casing?

P110 casing must adopt full-length quenched and tempered (Q) heat treatment. Normalizing (N) and normalized & tempered (N&T) are explicitly prohibited by API 5CT 10th Edition, as these processes cannot meet the required strength and toughness of P110 grade.

Q 6: What is the identification feature of API 5CT P110 casing?

According to API 5CT standards, P110 casing is marked with a white band on the pipe end, which is the exclusive visual mark to distinguish P110 from other steel grades such as J55, K55, N80 and L80.

6. Conclusion

API 5CT P110 SS PSL 2 R3 SMLS Casing with Premium Connection is a comprehensive high-strength OCTG product integrating high strength, strict quality grade, optimized length, seamless manufacturing and high-performance thread. Complying with the latest API 5CT 10th Edition, it delivers reliable wellbore integrity for deep, high-pressure, corrosive oil and gas wells. With stable mechanical performance, full quality traceability and excellent sealing capability, it has become a preferred product for mainstream oil and gas operators around the world.

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