API 5CT defines the casing grades that line virtually every well drilled today. Three of them — J55, L80 and P110 — cover the majority of the market, and understanding the jumps between them explains most casing-string economics.
The quick comparison
| Property | J55 | L80 | P110 |
|---|---|---|---|
| Min. yield strength | 55,000 psi | 80,000 psi | 110,000 psi |
| Max. yield strength | 80,000 psi | 95,000 psi | 140,000 psi |
| Min. tensile strength | 75,000 psi | 95,000 psi | 125,000 psi |
| Heat treatment | As-rolled / normalized | Quenched & tempered | Quenched & tempered |
| Sour (H₂S) service | Acceptable at low temps | Yes — the standard sour grade | Not for sour service |
| Relative cost | Lowest | Mid | Highest |
J55 — the workhorse for shallow strings
J55 is the economic choice for surface casing and shallow production strings where loads are modest. It is widely available, easy on connections, and the grade most often stocked for fast delivery. If your well design’s collapse and burst calculations clear with margin at 55 ksi, paying for more yield is wasted budget.
L80 — when sour service or higher loads appear
L80’s quenched-and-tempered microstructure with hardness controlled to ≤ 23 HRC is what makes it the default grade for H₂S service per NACE MR0175 / ISO 15156. Operators also reach for L80 in intermediate strings where J55’s body strength runs out. The 13Cr variant adds CO₂-corrosion resistance for sweet-gas completions.
P110 — deep wells and high pressure
P110 exists for deep, high-pressure wells — intermediate and production strings where burst and collapse requirements simply exceed what lower grades deliver. The trade-offs: it costs more, it is not suitable for sour service (hardness exceeds sulfide-stress-cracking limits), and its higher strength demands more care in connection make-up. Unconventional programs like Argentina’s Vaca Muerta consume P110 at scale for exactly these reasons.
Beyond the big three
The full API 5CT family fills the gaps: K55 (higher tensile than J55), N80 (an older non-sour 80-ksi grade), the restricted-yield sour grades C90, C95 and T95, and Q125 for the most extreme designs. Each has a page with chemistry and mechanical tables in our Casing & Tubing range.
Sourcing casing through CSACI
We supply the complete API 5CT grade family — J55, K55, N80, L80 (including 13Cr), C90, C95, T95, P110 and Q125 — in sizes 2-3/8” to 13-3/8”, with couplings, full MTC documentation and phased delivery scheduling aligned to your drilling program. Request a quote with your casing tally.