Where it fits
Medium-strength well construction where K55 is specified and the connection, pressure rating and service environment have been approved by the well designer.
API 5CT · OCTG grade reference
API 5CT K55 casing and tubing reference
API 5CT K55 casing is a grade-specific reference for engineering selection and RFQ preparation. HONGFENG verifies grade suffix, dimensions, connection, test requirements and documents for each order.
Updated 13 November 2026 · HEBEI HONGFENG IMPORT & EXPORT CO.,LTD
Grade scope
How to read API 5CT K55 casing
Casing or tubing reference grade; product specification level, weight, R1–R3 length and coupling/thread are confirmed per order.
What not to assume
K55 and J55 share the same yield band, but K55 has a higher minimum tensile requirement of 655 MPa versus 517 MPa for J55. They are not a specification-free substitution pair.
Mechanical snapshotReference values; project and MTC govern
| Property | Reference |
|---|---|
| Yield strength | 379–552 MPa |
| Minimum tensile strength | 655 MPa |
| Product form | Casing / tubing |
| Delivery condition | Casing or tubing reference grade; product specification level, weight, R1–R3 length and coupling/thread are confirmed per order. |
RFQ data
What to send for K55
- Standard edition, grade and delivery suffix
- Product form and outside diameter
- Wall thickness or weight and length range
- Connection, coupling, thread or end preparation
- CVN temperature, energy or project testing
- Quantity, inspection scope, destination and date
Send the grade, dimensions and test requirements
Availability, delivery condition, test regime and documents are confirmed for the exact order. The signed contract and final MTC govern acceptance.
Related grade pages
Grade-specific technical pages
FAQ
API 5CT K55 casing
What is API 5CT K55 yield and tensile strength?
The reference ranges are 379–552 MPa yield and minimum 655 MPa tensile. Product specification level and heat-treatment requirements remain part of the order.
What is the difference between J55 and K55 casing?
Both share the 379–552 MPa yield band, but K55 has a 655 MPa minimum tensile versus 517 MPa for J55. Selection follows the well design and purchase specification.
Which K55 connection and length should I request?
State STC, LTC, BTC or a project-specific connection, coupling type, OD, wall or weight, and R1, R2 or R3 length range. Do not leave the connection to a generic “casing” description.