ISO 11960 Casing or Tubing for Wells

ISO 11960:2020 Overview

1. Standard Name

ISO 11960:2020(E) Petroleum and natural gas industries — Steel pipes for use as casing pipe or tubing for wells.

2. Version

6th Edition (Replaces ISO 11960:2014)

3. Technical Committee

ISO/TC 67 SC 5 (Materials, Equipment and Offshore Structures for Petroleum, Petrochemical and Gas Industries — Subcommittee on Casing, Tubing and Drill Pipe)

4. Major Revisions

The “Groups” grouping has been removed.

The “Product Specification Level (PSL)” has been removed, and the main requirements have been integrated into the main text or Annex A.

A new Annex H has been added: High Collapse Requirements.

The non-destructive testing (NDT) requirements for sulfide stress corrosion resistance levels have been modified.

Scope

1. Specified Materials

This document specifies the technical delivery conditions for steel pipes:

casing pipe, tubing and pup joints;

coupling stock, coupling material and accessory material.

By agreement between the purchaser and manufacturer, this document can also be applied to other plain-end pipe sizes and wall thicknesses.

2. Applicable Connection Types

This document is applicable to the following connections:

— short round thread casing (SC);

— long round thread casing (LC);

— buttress thread casing (BC);

— non-upset tubing (NU);

— external upset tubing (EU);

— integral-joint tubing (IJ).

3. Applicable Steel Grades

This document is applicable to products including the following grades of pipe:

H40, J55, K55, N80, L80,C90, R95, T95, P110, C110 and Q125.

This document is not applicable to threading requirements (For thread dimensions and inspection requirements, please refer to API Spec 5B).

Terms, Definitions, Symbols

It defines the main terms related to casing pipe and tubing production, and lists symbols and abbreviations (such as OD, ID, UT, YSmin, etc.). For example:

1. Casing Pipe

Pipe run from the surface and intended to line the walls of a drilled well.

2. Tubing

Pipe placed in a well to produce or inject fluids.

3. Coupling

Internally threaded cylinder for joining two lengths of threaded pipe.

4. Seamless Pipe

Wrought steel tubular product made without a weld seam.

Note 1 to entry: To produce the desired shape, dimensions and properties, it is manufactured by hot-working.

5. Electric Welded Pipe

Pipe having one longitudinal seam formed by electric-resistance or electric-induction welding, without the addition of filler metal, wherein the edges to be welded are mechanically pressed.

6. SSC

Sulfide stress cracking.

Conformance and Normative References

A dual reference system (ISO/API/ASTM/ANSI) is explicitly adopted, and these systems are interchangeable under conditions of technical equivalence.

Both SI units and USC units are used, and the two unit systems are equivalent.

Main reference standards include ISO 643, ISO 9712, ISO 10893, and ISO 15156.

Information to Be Supplied by the Purchaser

The purchaser shall provide:

Pipe type and quantity;

Connection type (SC, LC, BC, etc.);

Whether couplings are included;

Steel grade (especially C90, T95, and C110 must comply with ISO 15156 or NACE MR0175 requirements);

Suitability description for special environments (such as sulfur-containing environments).

Process of Manufacture

Requirements for heat treatment, straightening, traceability, and process validation are specified.

1. Steel must be produced using fine-grained smelting.

2. Pipes can be seamless (S) or electrically welded (EW).

3. High-grade steels (C90, T95, C110, Q125) must undergo quenching and tempering.

4. Welded pipe welds must undergo heat treatment at 540°C or higher.

5. Typical heat treatment requirements for each grade:

J55 / K55: No heat treatment or normalizing is acceptable

N80 Type 1: Normalizing or normalizing + tempering

N80Q / R95: Quenching + tempering

L80 / C90 / T95 / C110 / Q125: Quenching + tempering, minimum tempering temperature requirement must be met.

Material Requirements

1. Chemical Composition

2. Mechanical Properties

3. Impact Toughness (Charpy V-Notch)

Longitudinal CVN test is required for high-grade steels (L80, C90, T95, C110, Q125); 

Typical minimum absorbed energy: ≥40 J (C90/T95) or ≥54 J (Q125); 

Test temperature: room temperature or -20°C as agreed.

4. Sulfide Stress Corrosion (SSC)

Grades C90, T95, and C110 must pass the NACE TM0177-2016 Method B test.

5. Hardness

Maximum hardness (HRC) of L80 / C90 / T95 / C110 ≤ 23; Maximum hardness (HRC) of Q125 ≤ 25.

Dimensions and Tolerances

Standardize permissible deviations for pipe outer diameter, wall thickness, and weight. Clearly define dimensional deviations and marking methods for different connection types.

1. Outer Diameter Range

26.7 mm ~ 406.4 mm

2. Wall Thickness Range

4.83 mm ~ 25.4 mm

3. Length Grades

Range 1: 6.10 m ~ 7.32 m

Range 2: 8.53 m ~ 9.75 m

Range 3: 11.58 m ~ 12.80 m

4. Tolerances

Outer Diameter (OD): ±0.75% or ±0.79 mm (whichever is greater)

Wall Thickness (t): -12.5% ~ +10%

Weight: ±1% (single piece), ±0.5% (batch average)

Straightness: ≤0.002 L (i.e., maximum bend of 2 mm per meter)

Length: ±0.5% or as required by Table C.27

5. Thread Ends

API round thread or trapezoidal thread;

Special Ends End-Finish) subject to separate agreement.

Inspection & Testing

Chemical Analysis: Furnace analysis and product analysis;

Mechanical Properties: Tensile, impact, hardness, SSC;

Hydraulic Testing: 100% for each pipe;

Non-Destructive Testing (NDE):

Ultrasonic, magnetic particle, electromagnetic, or magnetic flux leakage testing;

Compliant with ISO 10893 series and ASTM E213/E570

Protection and Marking

1. Each steel pipe must be marked with: steel grade, size, heat grade, manufacturer, and standard number;

2. Use color codes to distinguish steel grades;

3. Thread protector design verification; bare steel protectors must not be used for L80 13Cr;

4. Anti-corrosion coating must be applied for long-term storage or transportation.

Summary

ISO 11960:2020 is a globally unified standard for the manufacture and inspection of well casing pipe and tubing in the oil and gas industry, comprehensively specifying steel grades, mechanical properties, chemical composition, dimensional tolerances, and inspection procedures. The new version emphasizes high slump and sulfur resistance requirements, eliminates the old PSL system, makes the standard structure clearer and more applicable, and is fully equivalent to API 5CT.