ISO 11960:2020 Overview
1. Standard Information
Full Title: ISO 11960:2020(E) – Petroleum and natural gas industries — Steel pipes for use as casing or tubing for wells
Edition: 6th (Updated from 2014)
Committee: ISO/TC 67 SC 5 – Materials, Equipment and Offshore Structures for Petroleum, Petrochemical, and Gas Industries.
2. Key Revisions
Removal of “Groups” and “Product Specification Level (PSL)” classifications.
Main technical requirements integrated into the core text and Annex A.
Addition of Annex H – High Collapse Requirements.
Updated NDT provisions for sulfide stress corrosion resistance levels.
3. Scope and Application
The standard specifies delivery conditions for:
Casing pipe, tubing, pup joints, coupling stock, and accessories.
Applicable connections include SC, LC, BC, NU, EU, and IJ types.
Covers steel grades H40, J55, K55, N80, L80, C90, R95, T95, P110, C110, and Q125.
(For threading dimensions and inspection, see API Spec 5B.)
4. Key Definitions
Casing Pipe: Lines the walls of a drilled well.
Tubing: Used for production or fluid injection.
Coupling: Internally threaded connector joining two pipes.
Seamless Pipe: Hot-worked steel tube without weld seams.
Electric-Welded Pipe: Pipe with a single longitudinal weld formed by electric-resistance or induction welding.
SSC: Sulfide stress cracking.
5. Conformance and References
Dual reference system (ISO/API/ASTM/ANSI) accepted under technical equivalence.
Both SI and USC units are valid.
Main references: ISO 643, ISO 9712, ISO 10893, ISO 15156.
6. Purchaser Information
Orders must specify:
Pipe type, quantity, and connection type.
Coupling inclusion.
Steel grade and suitability for special environments (e.g., H₂S per ISO 15156 / NACE MR0175).
7. Manufacturing Requirements
Fine-grained steelmaking is mandatory.
Pipes may be Seamless (S) or Electric-Welded (EW).
High-grade steels (C90, T95, C110, Q125) require quenching + tempering.
Welds must be heat-treated at ≥ 540 °C.
Typical Heat Treatment by Grade:
J55 / K55: None or normalizing
N80 Type 1: Normalizing or normalize + temper
N80Q / R95: Quench + temper
L80 / C90 / T95 / C110 / Q125: Quench + temper, with minimum tempering temperature control
Material Requirements
1. Chemical Composition
|
Steel Grade |
C |
Mn |
Si |
S |
P |
Cr |
Mo |
Ni |
|
J55 |
≤0.36 |
≤1.50 |
≤0.35 |
≤0.030 |
≤0.030 |
— |
— |
— |
|
N80 |
≤0.48 |
≤1.70 |
≤0.45 |
≤0.030 |
≤0.030 |
≤0.20 |
≤0.25 |
≤0.20 |
|
L80-13Cr |
≤0.15 |
≤1.00 |
≤1.00 |
≤0.010 |
≤0.020 |
12.0–14.0 |
≤0.80 |
≤0.50 |
|
C95/T95 |
≤0.40 |
≤1.60 |
≤0.50 |
≤0.020 |
≤0.020 |
≤0.80 |
0.40–1.00 |
≤0.50 |
|
P110 / Q125 |
≤0.50 |
≤1.90 |
≤0.45 |
≤0.020 |
≤0.020 |
≤1.00 |
≤0.60 |
≤0.50 |
2. Mechanical Properties
|
Steel Grade |
Yield Strength (MPa) Min. |
Yield Strength (MPa) Max. |
Tensile Strength (MPa) Min. |
Elongation (%) Min. |
|
H40 |
276 |
— |
414 |
21 |
|
J55 |
379 |
— |
517 |
19 |
|
N80 Type 1 |
552 |
— |
689 |
18 |
|
L80 |
552 |
— |
655 |
18 |
|
C95 |
655 |
— |
758 |
15 |
|
T95 |
655 |
862 |
758 |
15 |
|
P110 |
758 |
965 |
862 |
15 |
|
Q125 |
862 |
1035 |
931 |
14 |
3. Impact Toughness (Charpy V-Notch)
High-grade steels (L80, C90, T95, C110, Q125) require longitudinal CVN testing.
Typical minimum energy absorption: ≥40 J (C90/T95), ≥54 J (Q125).
Test temperature: room temperature or -20 °C, as specified by agreement.
4. Sulfide Stress Corrosion (SSC)
Grades C90, T95, and C110 must pass NACE TM0177-2016 Method B testing to ensure resistance to sulfide stress cracking.
5. Hardness Requirements
Maximum hardness:
L80 / C90 / T95 / C110 ≤ 23 HRC
Q125 ≤ 25 HRC
Dimensional Requirements
Outer Diameter: 26.7 – 406.4 mm
Wall Thickness: 4.83 – 25.4 mm
Length Grades:
Range 1: 6.10 – 7.32 m
Range 2: 8.53 – 9.75 m
Range 3: 11.58 – 12.80 m
Tolerances
OD: ±0.75 % or ±0.79 mm (greater applies)
Wall Thickness: –12.5 % to +10 %
Weight: ±1 % (single) / ±0.5 % (batch)
Straightness: ≤ 0.002 L
Length: ±0.5 % or per Table C.27
Thread Ends: API round or buttress; special ends by agreement.
Inspection & Testing
Chemical Analysis: Furnace & product level
Mechanical Testing: Tensile, impact, hardness, SSC
Hydrostatic Test: 100 % per pipe
NDT: Ultrasonic, magnetic particle, or electromagnetic testing per ISO 10893 / ASTM E213 / E570
Marking & Protection
Marking includes steel grade, size, heat number, manufacturer, and standard.
Color codes identify steel grades.
Thread protectors must be verified; bare protectors prohibited for L80 13Cr.
Apply anti-corrosion coating for long-term storage or transport.
Summary
ISO 11960:2020 sets global standards for casing and tubing in oil & gas wells, covering steel grades, dimensions, mechanical properties, and testing.
The new edition removes outdated PSL grouping, adds high-collapse and sulfur resistance requirements, and aligns fully with API 5CT, ensuring better clarity, safety, and international consistency.
