K55 Casing — API 5CT Seamless OCTG Pipe
Premium API 5CT K55 Casing Pipe for Oil & Gas Wells
K55 is a normalized or normalized-and-tempered grade defined under API 5CT, delivering a minimum yield strength of 55,000 psi,the same as J55,but with a higher minimum tensile strength of 95,000 psi. This enhanced tensile performance gives K55 superior resistance to burst and collapse pressures, making it the preferred upgrade for wells that demand extra reliability without moving to costlier high-alloy grades.
- Applicable Product:Casing 4½″–20″.
- Thread Types: BC, STC / LTC.
- Available Lengths: R1 / R2 / R3.
Chemical Composition
K55 shares the same chemical composition requirements as J55 per API 5CT. The composition is not tightly specified.The standard allows the manufacturer flexibility, provided the final product meets mechanical performance targets through appropriate heat treatment.
| Element | C | Mn | Mo | Cr | Ni | Cu | P | S | Si |
| Max % | — | — | — | — | — | — | 0.030 | 0.030 | — |
| Typical Range | 0.34–0.39 | 1.25–1.50 | ≤ 0.15 | ≤ 0.15 | ≤ 0.15 | ≤ 0.15 | ≤ 0.020 | ≤ 0.015 | 0.15–0.35 |
Mechanical Properties
K55 achieves its properties through normalizing or normalizing-and-tempering heat treatment. It shares the same yield strength window as J55 but requires a significantly higher minimum tensile strength 655 MPa vs 517 MPa.Providing better burst and collapse resistance.
| Property | Value | Unit |
| Yield Strength (min) | 379 | MPa (55,000 psi) |
| Yield Strength (max) | 552 | MPa (80,000 psi) |
| Tensile Strength (min) | 655 | MPa (95,000 psi) |
| Elongation (min) | 15 | % |
| Hardness (max) | — | HRC (not specified) |
| Heat Treatment | Normalized or Normalized & Tempered | |
K55 steel is a carbon-manganese grade with a minimum yield strength of 55 ksi (379 MPa) and a minimum tensile strength of 95 ksi (655 MPa). According to API 5CT, the heat treatment requirements for K55 depend on the product type:
| Product Type | Heat Treatment Requirement | API 5CT Condition Code |
| Seamless Pipe | Delivered as-rolled or normalized. | “None” or “N” |
| ERW Pipe | Full pipe body must receive heat treatment at ≥ 540 °C (1000 °F), Or the weld seam must be normalized after welding. | “None” (with seam treatment) or “N” |
API 5CT Grade K55
Heat Treatment Curve
Temperature-time profiles for K55 casing pipe under normalizing and normalizing & tempering processes, per API 5CT requirements.
NORMALIZING
N&T
ERW SEAM TREATMENT
Process Notes
Normalizing (N): The pipe is heated to the austenitizing temperature range (900–920 °C) and held for uniform soaking, then air-cooled. This refines the grain structure and produces a homogeneous ferrite-pearlite microstructure with improved toughness compared to the as-rolled condition.
Normalizing & Tempering (N&T): After normalizing, the pipe is reheated to a tempering temperature (typically 600–650 °C) and held before final air cooling. Tempering relieves residual stresses from normalizing and further improves ductility and impact toughness.
ERW Seam Treatment: For ERW-manufactured K55 pipe, the weld seam and heat-affected zone must be heat-treated at ≥ 540 °C (1000 °F) to eliminate untempered martensite. This localized treatment ensures the seam properties match the pipe body.
Temperatures and hold times shown are representative of typical mill practice. Actual parameters may vary by manufacturer, wall thickness, and purchaser specifications. All processes must ensure the final product meets API 5CT K55 mechanical property requirements.
BSCO — Ready Stock Program
API 5CT K55 Casing Pipe — Inventory & Pricing
BSCO maintains large-volume inventory of the most common K55 casing sizes from 9-5/8″ to 20″, enabling rapid delivery for your drilling operations worldwide.
Common Dimensions & Pricing
K55 Casing Pipe Specifications
All products are manufactured to API 5CT, seamless process, available in BTC/STC/LTC thread types and R1/R2/R3 lengths. Prices are FOB China in USD per foot.
| Size (inch) | Weight (lb/ft) | OD (mm) | WT (mm) | NLM (kg/m) | Stock (Tons) | Price (USD/ft) | Lead Time |
|---|---|---|---|---|---|---|---|
| 9-5/8″ CASING — OD 244.48 mm | |||||||
| 9-5/8″ | 43.5 | 244.48 | 11.05 | 64.74 | 32 | $15.20 | Instant |
| 9-5/8″ | 47 | 244.48 | 11.99 | 69.94 | 263 LARGE STOCK | $16.42 | Instant |
| 9-5/8″ | 53.5 | 244.48 | 13.84 | 79.62 | 663 LARGE STOCK | $18.70 | Instant |
| 9-5/8″ | 58.4 | 244.48 | 15.11 | 86.91 | 32 | $20.41 | Instant |
| 9-5/8″ | 59.4 | 244.48 | 15.47 | 88.40 | 110 | $20.76 | Instant |
| 9-5/8″ | 64.9 | 244.48 | 17.07 | 96.58 | 23 | $22.68 | Instant |
| 9-5/8″ | 75.6 | 244.48 | 20.24 | 112.51 | 22 | $26.42 | Instant |
| 13-3/8″ CASING — OD 339.72 mm | |||||||
| 13-3/8″ | 54.5 BEST SELLER | 339.72 | 9.65 | 81.10 | 10 | $19.04 | Instant |
| 13-3/8″ | 61 BEST SELLER | 339.72 | 10.92 | 90.78 | 753 LARGE STOCK | $21.32 | Instant |
| 13-3/8″ | 68 BEST SELLER | 339.72 | 12.19 | 101.19 | 963 LARGE STOCK | $23.76 | Instant |
| 13-3/8″ | 72 | 339.72 | 13.06 | 107.15 | 50 | $25.16 | Instant |
| 20″ CASING — OD 508 mm | |||||||
| 20″ | 94 BEST SELLER | 508 | 11.13 | 139.89 | 306 LARGE STOCK | $32.85 | Instant |
| 20″ | 106.5 | 508 | 12.70 | 158.49 | 32 | $37.21 | Instant |
Customer Favorites
Most Popular K55 Specifications
These are the two most requested K55 products by our global clients, available for immediate dispatch from BSCO warehouses.
API 5CT Seamless Casing 13-3/8″ 54.5 lb/ft K55 BTC R3
OD: 339.72 mm · WT: 9.65 mm · Thread: BTC
Length: Range 3 · Process: Seamless · Grade: K55
Length: Range 3 · Process: Seamless · Grade: K55
API 5CT
SEAMLESS
BTC
R3
BEST SELLER
API Buttress Coupling for K55 Casing BTC 20″ 94 PPF
OD: 508 mm · Weight: 94 lb/ft · Thread: BTC
Type: Buttress Coupling · Grade: K55
Type: Buttress Coupling · Grade: K55
API 5CT
COUPLING
BTC
20″
BEST SELLER
Project Reference
Proven Track Record
Case Study — Africa
API 5CT Seamless Casing Shipment to Luanda, Angola
BSCO successfully delivered thousands of tons of API 5CT K55 seamless casing pipe to Luanda, Angola for Halliburton's drilling operations. The project required multiple vessel shipments with strict API 5CT compliance, full traceability documentation, and on-time port delivery — all fulfilled from BSCO's ready-stock program.
1,000+
Tons Shipped
100%
On-Time
API 5CT
Certified
Get Started
Request a Quotation
Contact BSCO for competitive pricing on K55 casing, coupling, and accessories. Volume discounts available for orders over 100 tons.
Why Choose BSCO
BSCO vs. API 5CT Casing Pipe Suppliers in India
As a professional API 5CT K55 casing pipe manufacturer, BSCO offers distinct advantages in certification, quality control, traceability, and delivery reliability over typical Indian OCTG suppliers.
Head-to-Head Comparison
Manufacturer vs. Supplier — The Critical Differences
A side-by-side comparison of BSCO's capabilities as a vertically integrated manufacturer versus typical API 5CT casing pipe suppliers operating out of India.
| Criteria |
BSCO
MANUFACTURER · CHINA
|
Typical India Suppliers
TRADING / STOCKHOLDING
|
|---|---|---|
| Business Model |
Vertically integrated manufacturer with in-house steelmaking, pipe rolling, threading, and coupling production. Full control from billet to finished goods.
DIRECT MANUFACTURER |
Predominantly traders, stockholders, or re-sellers sourcing from multiple mills. Limited or no control over production process, heat treatment, or raw material selection.
TRADER / STOCKHOLDER |
| International Certifications |
Holds API 5L, API 5CT, ISO 11960, CE Marking, and TÜV certification. Monogram licenses verified and current.
5 MAJOR CERTIFICATIONS |
Suppliers may claim API certification but often cannot provide monogram-stamped products. CE and TÜV certifications are rarely held by trading firms.
VARIES BY SUPPLIER |
| Quality Inspection |
Full EN 10204 Type 3.2 third-party inspection (TPI) available throughout the entire production process — from raw material acceptance through final dispatch. BSCO supports client-appointed inspectors on-site.
FULL 3.2 TPI SERVICE |
Inspection is typically limited to visual and dimensional checks at the warehouse. No control over mill-level QC. Third-party inspection certificates are often unavailable or sourced secondhand.
LIMITED / NONE |
| Material Traceability |
Permanent heat number and batch number traceability from raw steel billet through to finished casing pipe. Every pipe is traceable to its original melt with complete MTC documentation.
100% TRACEABLE |
Traceability depends on the original mill's documentation. When sourced through multiple intermediaries, heat number records may be incomplete, duplicated, or untraceable back to the original melt.
PARTIAL / UNRELIABLE |
| Ready Stock & Delivery |
3,000+ tons of common K55 casing sizes (9-5/8″ to 20″) in warehouse. Instant dispatch available. New production lead time 30–45 days for custom orders.
LARGE INVENTORY |
Stockholding varies. Popular sizes may be available; less common specifications require sourcing from mills with unpredictable lead times of 60–120 days.
VARIABLE |
| Pricing Transparency |
Factory-direct pricing with no intermediary markup. Clear FOB, CIF, and CFR quotations with published per-foot pricing for standard sizes.
FACTORY DIRECT |
Multiple intermediary margins built into pricing. Final cost often includes trading margins, domestic logistics, and re-export handling fees.
MULTI-LAYER MARKUP |
| Export Track Record |
Proven deliveries of thousands of tons to major operators including Halliburton, with shipments to Africa (Angola), Middle East, Southeast Asia, and South America.
GLOBAL DELIVERIES |
Export experience varies widely. Many India-based suppliers primarily serve domestic or regional markets. Documentation for international compliance may be unfamiliar territory.
VARIES |
BSCO Certification System
Internationally Recognized Quality Certifications
BSCO maintains a comprehensive portfolio of international certifications that ensure every K55 casing pipe meets the most demanding global standards.
API 5CT
Casing & Tubing for oil and gas wells
API 5L
Line Pipe for transport of oil, gas & water
ISO 11960
Petroleum & natural gas steel pipe specification
CE Marking
European conformity for EU market access
TÜV
German technical inspection & product safety
EN 10204 Type 3.2
Full-Process Supervision Service
BSCO provides comprehensive EN 10204 Type 3.2 third-party inspection throughout the entire manufacturing process. Unlike trading companies that can only inspect finished stock, we open every stage of production to your appointed inspector.
1
Raw Material Inspection
Chemical composition verification, billet inspection, and incoming material certification against API 5CT requirements.
2
In-Process Monitoring
Heat treatment parameter witnessing, dimensional checks during rolling, and real-time quality monitoring at every production stage.
3
Finished Product Testing
Hydrostatic testing, NDT (UT/EMI), mechanical testing, thread gauging, and visual inspection on 100% of finished pipes.
4
Certificate & Traceability
Complete MTC documentation with permanent heat number and batch number traceability. Every pipe traceable from melt to shipment.
BSCO Advantages
Why Global Operators Choose BSCO Over Indian Suppliers
Manufacturer, Not Middleman
BSCO controls the entire production chain from steel billet to threaded, coupled finished casing. No third-party sourcing uncertainty, no multi-layer markups, no finger-pointing when quality issues arise.
Permanent Traceability
Every pipe carries permanently stenciled heat and batch numbers traceable to the original melt. Full EN 10204 3.1/3.2 documentation ensures zero ambiguity in your material records.
Rapid Delivery from Stock
Over 3,000 tons of the most in-demand K55 casing sizes sit ready in our warehouse for immediate dispatch — no 60–120 day wait while a trader hunts for material from unknown mills.