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GR.B-GR.ASeamlessStructurePipe

K55 - J55 Seamless Casing Pipe

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K55 / J55 Seamless Casing Pipe - Strong, Economical, Full Well Condition Adaptability

Product Introduction

K55 and J55 are the most widely used carbon-manganese steel grades for seamless casing pipes, strictly manufactured accordingAPI 5CT (11th Edition)andISO 11960. Both grades offer good weldability, threadability, and corrosion resistance, suitable for onshore & offshore oil/gas wells, CBM wells, geothermal wells, and water injection wells.

J55: Conventional economic grade for shallow to medium-depth wells, low-pressure formations.

K55: Slightly higher strength than J55, suitable for moderately stressed or medium-depth wells.

Mechanical Properties

Property

J55

K55

Yield Strength (psi)

55,000 - 80,000

55,000 - 80,000

Yield Strength (MPa)

379 - 552

379 - 552

Tensile Strength (psi)

≥ 75,000

≥ 95,000

Tensile Strength (MPa)

≥ 517

≥ 655

Elongation (2″ gauge)

≥ 20%

≥ 20%

Hardness (HRC)

≤ 23

≤ 24

Impact Energy (0°C, J)

≥ 27

≥ 27

Key difference: K55 has significantly higher tensile strength, offering better overload resistance.

Size Range & Thread Types

Parameter

Specification

Outer Diameter (OD)

2″ - 20″ (60.3mm - 508 mm)

Wall Thickness (WT)

0.055″ - 1.602″ (1.65mm - 26.97 mm)

Thread Types

STC, LTC, BTC, EU, NU

Key Advantages

Seamless Manufacturing, Structural Integrity2026-05-25 174154

Hot-rolled piercing + controlled cooling/cold drawing process-no weld seam defects.

Tight wall thickness tolerance.

Excellent Burst & Collapse Resistance

Collapse resistance tablesavailable per grade & WT.

Each pipe hydrostatically tested per API requirements.

Reliable Thread Seal & Galling Resistance

Threads are phosphated or copper-coated to reduce friction during make-up.

Thread protectors provided for shipping.

Wide Application Scope

Conventional oil & gas wells

Water injection & observation wells

Low to medium pressure gas wells

Surface, intermediate, and production casing

Optional Treatments

Corrosion protection: External black paint or transparent anti-rust oil.

Sour service: NACE MR0175 / ISO 15156 compliant (hardness & composition control) for H₂S environments.

NDT methods: 100% UT or ET, optional flux leakage inspection.

Quality Assurance System

Spectrochemical analysis per heat.

Hydrostatic test, dimensional check (OD, WT, thread profile) on each pipe.

TraceableMill Test Certificate(EN 10204 Type 3.1 or 3.2).

Certifications: API 5CT Monogram, ISO 9001, ISO 14001, OHSAS 18001.

 

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