API 5CT C90 Pipes

API 5CT C90 pipes are used as casing and tubing in sour oil and gas wells where hydrogen sulphide exposure creates a risk of sulphide stress cracking. Amardeep Steel supplies C90 for applications requiring controlled yield strength and hardness along with specified sour service performance. C90 has a higher specified strength level than API 5CT L80 pipes and tighter mechanical property controls than API 5CT N80 tubing. For other oilfield requirements, our range of seamless pipes and tubes includes additional API 5CT grades.

Each order is supplied with mill test certificates, hardness test records and applicable sulphide stress cracking test documentation to support material verification and sour service requirements.

What Are API 5CT C90 Pipes?

API 5CT C90 is a Group 2 restricted yield grade. Its yield strength must fall between 621 and 724 MPa, and its hardness may not go above 25.4 HRC. These limits, together with a mandatory cracking test, make C90 a grade built specifically for sour wells.

Operators use C90 when a sour well needs more strength than L80 can give, for example in deeper wells where the string carries more weight and pressure.

How C90 Resists Sulphide Stress Cracking

C90 is a chromium molybdenum steel. Molybdenum and chromium let the steel harden right through the wall during quenching, and a high tempering temperature then turns it into a uniform tempered structure. Very low sulphur and phosphorus limits reduce the inclusions where hydrogen cracks can start. The result is a steel that stays tough and resistant to cracking at a higher strength level.

API 5CT C90 Colour Code

C90 pipe is identified by one purple band, and the grade is stencilled on every length along with size, weight and heat number.

SSC Testing of API 5CT C90 Pipes

C90 must pass a sulphide stress cracking test to NACE TM0177 Method A. Test specimens are loaded at a threshold stress of at least 80 percent of the specified minimum yield strength and held in an H2S saturated solution. A pass shows the steel can carry high load in sour conditions without cracking.

Applications of API 5CT C90 Casing and Tubing

• Production tubing in sour gas and gas condensate wells
• Intermediate and production casing in deep sour wells
• Offshore and onshore fields with high hydrogen sulphide content
• Replacement strings in older sour wells

Testing and Documentation

Every order of API 5CT C90 pipe goes through the checks below at our testing facility or approved third party labs.

• Heat and product chemical analysis
• Tensile test for yield, tensile strength and elongation
• Hardness survey across the wall section
• Charpy V-notch impact test
• Sulphide stress cracking test to NACE TM0177 Method A
• Hydrostatic test on every length
• Full length drift test
• Ultrasonic or electromagnetic inspection of the pipe body
• Thread gauging, visual and dimensional inspection
• Third party inspection on request

Mill test certificates are issued to EN 10204 3.1, with 3.2 available on request. You can view our approvals on the certificates page.

Packing and Marking

Each length is stencilled with the manufacturer name, API 5CT, size, weight, grade, connection and heat number, and carries the API colour band for its grade. Threads are protected with steel or plastic thread protectors, and pipes are bundled or loaded loose with spacers depending on size. Read more about our packing and despatch process.