API 5CT L80-1 Oil Country Tubular Goods

API 5CT L80-1 Oil Country Tubular Goods (OCTG) is a medium strength petroleum specific pipe material that complies with the American Petroleum Institute (API) 5CT standard. It is mainly used for the production of casing and tubing in oil and gas wells and is suitable for low corrosive environments.

L80-1 is a foundation type under the L80 steel grade, with "L80" indicating a minimum yield strength of 80 ksi (approximately 552 MPa), which has good mechanical properties and economy. L80-1 is made of carbon manganese steel, which does not contain significant alloying elements and has no special corrosion resistance. It is usually protected against corrosion by an external coating (such as epoxy resin).

It is widely used in onshore conventional oil and gas wells, shallow gas reservoirs, and shale gas horizontal wells with low corrosion risks. It is the lowest cost and highest market share model in the L80 series. According to the API 5CT standard, L80-1 can be made into casing, tubing, and drill pipe, with a common outer diameter range of Φ 114.3-508mm and a wall thickness of 5.21-16.13mm. The length is divided into three categories: R1, R2, and R3.

Still worried about frequent replacement of oil casing due to poor compression resistance? API 5CT L80-1 oil casing, made of high-strength material suitable for complex downhole conditions, click to obtain exclusive solutions

 

Chemical Composition Table

Element	Content Requirement (%)	Notes
Carbon (C)	≤0.45	Controls hardenability, prevents welding cracks
Manganese (Mn)	0.60–1.35	Enhances strength and toughness
Phosphorus (P)	≤0.030	Strictly limited to prevent cold brittleness
Sulfur (S)	≤0.025	Reduces hot cracking and corrosion initiation
Silicon (Si)	0.10–0.45	Deoxidizer, improves strength
Chromium (Cr), Nickel (Ni), Molybdenum (Mo)	No specific requirement	No significant alloy content, distinguishing it from L80-9Cr/L80-13Cr

 

Mechanical Properties Table

Property	Standard Value (API 5CT)	Typical Measured Value
Yield Strength (YS)	‌≥552 MPa‌	580–650 MPa
Tensile Strength (TS)	655–827 MPa	700–780 MPa
Elongation (A)	≥18%	20–25%
Hardness (HB)	≤255	220–240
Impact Toughness (-20℃)	≥40 J	50–60 J

 

Color Band Identification

Per API 5CT standards, the color band marking for L80-1 is as follows:

‌Primary Band: Red‌

‌Secondary Band: None‌

‌Marking Method‌: A ‌25mm wide red circumferential band‌ is painted on both ends of the pipe body for rapid field identification of the grade.

 

Production Casing Size Table

Nominal Casing Size (inches)	Outside Diameter (mm)	Common Wall Thickness (mm)	Application Segment
4½	114.3	6.35, 7.37, 8.56	Intermediate-depth production zones
5	127.0	7.52, 9.19	Conventional oil & gas wells
5½	139.7	7.72, 9.17, 11.51	Main production casing
7	177.8	8.05, 10.36, 12.65	Deep well completion sections
9⅝	244.5	9.53, 11.05, 13.84	Surface/intermediate casing

 

‌API 5CT L80 Type 1 Casing Tolerance Table

Item	Tolerance Requirement
Outside Diameter (OD)	±0.75% (for wall thickness ≥5.21mm)
Wall Thickness (WT)	+12.5% / -10.0%
Length	R1: +100mm / -200mm; R2/R3: +100mm / -150mm
Ovality	≤0.75% OD
Straightness	≤3mm/m, total ≤12mm
Thread Parameters	Must comply with API 5B standard, with strict tolerances on pitch, taper, and thread height

 

Casing Connection Types

Connection Type	Abbreviation	Typical Application
Buttress Thread Casing	BTC / BC	Widely used for medium and deep wells requiring high axial load capacity
Short Thread Casing	STC	Commonly used for shallow to medium-depth wells
Long Thread Casing	LTC	Provides improved connection strength compared with STC
Premium Connections	-	Used for high-pressure, HPHT, and gas-tight sealing requirements

For severe production conditions, premium connections with metal-to-metal sealing designs may be selected to improve gas tightness and connection performance.

 

Material Selection Guide: L80-1 vs L80 9Cr vs L80 13Cr

Different L80 grades are designed for different corrosion challenges.

Factor	L80-1	L80 9Cr	L80 13Cr
Material Type	Carbon-manganese steel	9% Chromium alloy steel	13% Chromium martensitic stainless steel
Main Advantage	Controlled hardness and cost efficiency	Improved CO₂ corrosion resistance	Excellent CO₂ corrosion resistance
H₂S Service	Commonly selected when hardness control is required	Requires service condition evaluation	Requires service condition evaluation
CO₂ Resistance	Limited	Good	Excellent
Relative Cost	Lowest	Medium	Highest
Availability	Widely available	More specialized	More specialized
Typical Application	Sour-service wells, general production wells	Moderate CO₂ corrosion environments	Severe CO₂ wet gas environments

 

Mandatory Heat Treatment: Quench and Temper

API 5CT L80-1 requires quench-and-temper (Q&T) heat treatment to achieve the required combination of strength, toughness, and hardness control.

The process includes:

Quenching

Full-length heating followed by rapid cooling to produce a hardened martensitic structure.

Tempering

Controlled reheating to transform the brittle quenched structure into tempered martensite with improved toughness and controlled hardness.

The purpose of Q&T treatment is to achieve:

Yield strength between 552–655 MPa

Maximum hardness of 23 HRC

Uniform mechanical properties along the pipe length

Improved resistance to SSC susceptibility

Unlike some N80 products that may be supplied in normalized conditions, L80-1 requires quench-and-temper treatment according to API 5CT requirements.

 

Inspection and Testing Requirements

API 5CT L80-1 products undergo inspection and testing to verify chemical composition, mechanical properties, dimensions, and service reliability.

The exact inspection scope depends on:

Product specification level (PSL)

Manufacturing method

Customer requirements

Applicable project specifications

 

Delivery Documentation

Each API 5CT L80-1 shipment is supplied with quality documentation for material traceability.

Typical documentation includes:

Material Test Certificate (MTC)

Heat number identification

Chemical composition report

Mechanical test results

Hardness test records

Heat treatment records

NDT inspection reports

Dimensional inspection report

Thread inspection and gauging report

Complete documentation allows customers to verify compliance with API 5CT requirements and maintain traceability throughout project execution.

 

API 5CT L80-1 OCTG Factory

 

API 5CT L80-1 Casing pipe test and inspection

 

FAQ

What does API 5CT L80-1 mean?

API 5CT L80-1 is a carbon-manganese OCTG grade designed according to API Spec 5CT for casing and tubing applications. The grade provides a minimum yield strength of 80,000 psi (552 MPa) and requires controlled hardness of maximum 23 HRC (241 HBW). The "-1" designation refers to the Type 1 carbon-manganese version of the L80 family.

 

Is API 5CT L80-1 suitable for sour service?

API 5CT L80-1 is commonly selected for sour-service applications because its mandatory hardness control helps reduce susceptibility to sulfide stress cracking (SSC). However, suitability must be evaluated according to the actual well environment and NACE MR0175 / ISO 15156 requirements, including H₂S partial pressure, temperature, and stress conditions.

 

What is the maximum hardness of API 5CT L80-1?

The maximum hardness of API 5CT L80-1 is:

23 HRC

241 HBW

This hardness limit is a mandatory API 5CT requirement and is one of the key differences between L80-1 and N80.

 

What is the difference between API 5CT L80-1 and N80?

The main difference is hardness control.

Both grades have similar yield strength levels:

L80-1: 552–655 MPa

N80: 552–655 MPa

However:

L80-1 requires a maximum hardness of 23 HRC

N80 does not have the same mandatory hardness limitation under API 5CT

Because hardness control is important for reducing SSC susceptibility, L80-1 is commonly preferred for sour-service applications.

 

Can API 5CT L80-1 be manufactured by ERW?

Yes.

Among the L80 family grades, L80-1 is the grade permitted for both seamless and ERW manufacturing under API 5CT.

ERW L80-1 must meet applicable requirements for:

Heat treatment

Weld seam quality

Inspection

Testing

Seamless L80-1 remains the most common supply form for critical oil and gas applications.

 

What heat treatment is required for API 5CT L80-1?

API 5CT L80-1 requires quench-and-temper (Q&T) heat treatment.

The process improves:

Strength consistency

Toughness

Hardness control

Resistance to SSC susceptibility

The final product must meet API 5CT mechanical property and hardness requirements.

 

What are the common connections for L80-1 casing and tubing?

Common API 5CT L80-1 casing connections include:

BTC (Buttress Thread Casing)

STC (Short Thread Casing)

LTC (Long Thread Casing)

Common tubing connections include:

EUE (External Upset End)

NU (Non-Upset)

For high-pressure gas wells or demanding production conditions, premium gas-tight connections with metal-to-metal seals may be selected.

 

Is L80-1 better than N80?

Neither grade is universally better.

The correct choice depends on well conditions.

Choose L80-1 when:

Sour-service conditions require controlled hardness

SSC resistance is a priority

Reliable OCTG performance is required

Choose N80 when:

Sour-service requirements are not present

Cost efficiency is the main consideration

Service conditions are suitable for N80 properties

Material selection should always follow engineering requirements and applicable standards.

Hot Tags: api 5ct l80-1 oil country tubular goods, China api 5ct l80-1 oil country tubular goods manufacturers, suppliers, 316 Stainless Steel Welded Pipe