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API 5L SSAW Line Pipe

OD Range :

219mm – 3620mm（8″ – 142″）

WT Range :

6mm – 25.4mm

Length :

6m / 9m / 12m

Tolerance :

Length: ±50mm, Outer Diameter: ±1%, Wall Thickness: -12.5%, Ovality: ≤1% Outer Diameter

Material :

Gr.B、X42、X46、X52、X56、X60、X65、X70

Standard :

API 5L（PSL1 / PSL2）

Surface :

Black paint, spray paint, 3LPE, FBE, epoxy coal tar pitch, hot-dip galvanizing

Application :

Oil pipelines, natural gas transmission, water conservancy projects, urban water supply and drainage, piling projects, structural support

Introduction :

API 5L SSAW spiral submerged arc welded pipeline is made of low-alloy high-strength steel coils, spirally formed and welded, and is suitable for large-diameter, long-distance transportation projects.

I. What is API 5L SSAW Line Pipe?

API 5L SSAW line pipe is a spiral welded steel pipe manufactured according to the API 5L standard, primarily used for long-distance, large-diameter, continuous transportation projects.

Its core advantages are:

Capable of producing large diameter pipes
Relatively low cost
Suitable for medium and high pressure transmission
Suitable for large-scale infrastructure projects

i. Applicable Project Types

i. Applicable Project Types

1. Long-Distance Oil and Gas Pipelines
Suitable for long-distance onshore transmission of crude oil or natural gas.

Features:
Long transmission distance (tens to hundreds of kilometers)
High design pressure
Strict requirements for weld quality
Mostly buried

Recommended Steel Grades:
X52 / X60 / X65
Requirement: PSL2 grade

2. City Gas Main Pipeline
Suitable for city natural gas trunk pipeline systems.

Features:
Medium pressure
Large pipe diameter
Primarily underground installation

Recommended steel grades:
X42 / X52
Generally PSL1 or PSL2

3. Large-scale water transmission projects

Including:
Inter-regional water transfer projects
Industrial park water supply systems
Municipal water supply and drainage trunk lines

Characteristics:
Typically large pipe diameters
Predominantly medium to low pressure
Focus on corrosion resistance

Recommended steel grade:
Gr.B / X42
Can be fitted with 3PE or epoxy anti-corrosion coating

4. River/Sea Crossing Projects

Suitable for:
River crossings
Subsea laying

Characteristics:
Complex construction
High requirements for strength and corrosion resistance
Requires reinforced anti-corrosion coating

Recommended:
X60 and above steel grade
PSL2
Reinforced 3PE anti-corrosion coating

5. Piling and Structural Applications

Although primarily used for pipelines, it can also be used in some projects as:
Foundation piling
Bridge pile foundations
Temporary support structures
This application does not have high pressure resistance requirements, but does have requirements for wall thickness and diameter.

ii. Applicable conveying medium

Different media have a significant impact on material selection.

1. Crude Oil

Characteristics:
May contain corrosive substances
Large temperature variations during transport

Recommendation:
PSL2
Internal and external corrosion protection
Use X52 or higher steel grade

2. Natural Gas

Characteristics:
High transport pressure
High safety requirements

Recommendation:
PSL2 (mandatory)
Impact test
High steel grade (X60–X70)

3. Refined Oil

Characteristics:
Low corrosivity
Medium pressure

Recommendation:
X42–X52
Impact test optional depending on temperature

4. Industrial Water

Characteristics:
Low pressure
More emphasis on corrosion resistance

Recommendation:
Gr.B or X42
Corrosion protection treatment

5. Seawater

Characteristics:
Highly corrosive
Long service life requirements

Recommendation:
External reinforced 3PE corrosion protection
Internal corrosion protection coating if necessary
PSL2 recommended

II. Common Steel Grades and Classes for API 5L Spiral Submerged Arc Welded Pipelines

i. Common Steel Grades and Application Instructions

Steel Grade	Minimum Yield Strength (MPa)	Typical Applications	Suitable Project Types
Gr.B	245 MPa	Medium and low pressure transportation	Water transmission projects, general oil & gas transportation
X42	290 MPa	Medium pressure pipelines	City gas main pipeline networks
X52	360 MPa	Medium-high pressure transportation	Long-distance oil and gas pipelines
X60	415 MPa	High-strength transportation	Long-distance crude oil / natural gas trunk pipelines
X65	450 MPa	High-pressure pipelines	Large energy infrastructure projects
X70	485 MPa	High-strength long-distance transportation	High-pressure oil and gas trunk pipelines

Selection Guidelines:
A higher steel grade number indicates a higher yield strength.
Higher strength allows for greater allowable design pressure, but also increases cost.
Long-distance oil and gas projects typically use X60 and higher steel grades.
For water transport or medium-to-low pressure projects, Gr.B or X42 can be selected.

ii. Difference between PSL1 and PSL2

In the API 5L standard, line pipes are divided into two product specification levels: PSL1 and PSL2.

Comparison Item	PSL1	PSL2
Quality Level	Basic requirements	Higher quality requirements
Chemical Composition Control	Standard control	More stringent control
Impact Test	Not mandatory	Mandatory
Non-Destructive Testing (NDT)	Standard inspection	More stringent ratio and methods
Hydrostatic Test	Required	Required
Applicable Projects	General transportation	High-pressure and critical oil & gas projects
Traceability Requirements	Basic	More stringent
Price	Lower	Slightly higher

iii. How to Choose PSL1 or PSL2?

Situations where PSL1 is chosen:
Water transmission projects
General industrial fluids
Low design pressure
Cost-sensitive projects
Situations where PSL2 is recommended:
Long-distance crude oil or natural gas pipelines
High-pressure transmission
Offshore or complex engineering projects
Mandatory requirements from the owner or project proponent

Note: In international oil and gas projects, PSL2 is usually the default requirement.

III. Comparison Table of SSAW and LSAW Procurement Selection

Selection Dimension	SSAW Spiral Submerged Arc Welded Pipe	LSAW Longitudinal Submerged Arc Welded Pipe	Procurement Recommendation
Procurement Cost	Lower	Higher	Budget-sensitive projects should prioritize SSAW
Price per Ton	Usually 5%–15% lower	Higher	Cost difference becomes significant for bulk projects
Delivery Time	Faster	Relatively slower	Urgent projects should prioritize SSAW
Maximum Diameter Capacity	Can produce extra-large diameters	Limited by steel plate width	Choose SSAW for ultra-large diameters
Maximum Wall Thickness	Moderate	Thicker wall possible	Choose LSAW for thick-wall high-pressure pipelines
High-Pressure Suitability	Medium to high pressure	High / ultra-high pressure	LSAW preferred for high-pressure trunk pipelines
High Steel Grade Capability	Generally up to X70	Up to X80 or higher	LSAW preferred for high-grade oil & gas pipelines
Weld Structure Risk	Longer spiral weld seam	Shorter weld seam	LSAW preferred for high-risk projects
Owner Acceptance	Widely accepted	Preferred for oil & gas trunk pipelines	Depends on project technical specifications
Inspection Requirement Compatibility	Can meet PSL2	Mostly PSL2	Both suitable for high-requirement projects
Typical Projects	Water transmission, city gas pipelines, medium-pressure oil & gas	Long-distance oil & gas trunk pipelines, core energy projects	Select according to project importance

IV. API 5L Common Corrosion Protection Types for Spiral Submerged Arc Welded Pipelines

Coating Type	Description	Applicable Environment
Black Paint	Surface coated with anti-rust paint to prevent rust during transportation and short-term storage	Indoor structures, temporary projects
FBE (Fusion Bonded Epoxy)	Single-layer epoxy powder coating with strong adhesion	Water transmission, general oil & gas pipelines
3PE Coating	Three-layer anti-corrosion structure (epoxy + adhesive + polyethylene)	Buried oil & gas pipelines
Reinforced 3PE Coating	Thickened three-layer coating with stronger corrosion resistance	Subsea pipelines, highly corrosive environments
Internal Epoxy Coating	Internal pipe wall coating to reduce corrosion and flow resistance	Water transmission, seawater projects

Selection Recommendations:
Ordinary Buried Engineering → 3PE
Long-Distance Oil and Gas Transportation → 3PE / PSL2
Seawater Environment → Reinforced 3PE
Water Transportation Projects → Can be supplemented with internal epoxy

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Nominal Pipe Size NPS (inch)	Outside Diameter OD (inch)	Outside Diameter OD (mm)	Common Wall Thickness WT (mm)	Typical Applications
8″	8.625″	219.1	6 – 12	Water transmission / Low-pressure pipelines
10″	10.75″	273.0	6 – 14	Water transmission / Gas pipelines
12″	12.75″	323.9	6 – 16	Natural gas main pipelines
14″	14.00″	355.6	6 – 18	Oil & gas pipelines
16″	16.00″	406.4	6 – 20	Oil & gas transportation
18″	18.00″	457.2	6 – 22	Oil / Water transmission pipelines
20″	20.00″	508.0	6 – 22	Water transmission / Oil & gas
24″	24.00″	609.6	8 – 25	Trunk line transportation
28″	28.00″	711.2	8 – 25	Long-distance pipelines
32″	32.00″	812.8	8 – 25	Main trunk pipelines
36″	36.00″	914.4	10 – 25	High-flow transportation
40″	40.00″	1016.0	10 – 25	High-capacity pipelines
48″	48.00″	1219.0	10 – 25	Large-scale water conservancy projects
56″	56″	1422.0	12 – 25	Oil & gas trunk pipelines
60″	60″	1524.0	12 – 25	Large infrastructure pipelines

API 5L is a standard for pipeline steel pipes developed by API 5L, used for pipeline transportation projects involving oil, natural gas, water, and others.

This standard specifies:
Chemical composition of the steel pipe
Mechanical properties (yield strength, tensile strength)
Welding quality requirements
Non-destructive testing and hydrostatic testing
Product grade (PSL1 / PSL2)

Core function: To ensure the safety and reliability of pipeline pipes during long-term transportation of media such as oil, gas, or water.

Steel plate → Cutting and coiling → Forming → Spiral welding → Weld straightening → Heat treatment → Inspection → Surface treatment → Packaging and shipping

Detailed Step-by-Step Instructions

1. Steel Plate Selection → Select API 5L standard steel coils

2. Cutting and Leveling → Cut the steel coils to the appropriate width, ready for rolling

3. Coiling and Forming → Roll into a spiral cylindrical pipe blank

4. Spiral Submerged Arc Welding → Weld the inner and outer seams simultaneously to form a complete steel pipe

5. Weld Correction → Correct the shape of the weld and pipe body to ensure roundness and straightness

6. Heat Treatment (if required) → Eliminate welding stress and improve mechanical properties

7. Dimensioning and Non-Destructive Testing → Outer diameter, wall thickness, and ovality measurement + ultrasonic/radiological inspection of welds

8. Hydrostatic Testing → Ensure the pipeline’s pressure-bearing capacity

9. Surface Treatment/Corrosion Protection → 3PE/FBE/Black Paint, etc.

10. Packaging and Shipping → Secure with wooden frames, stack, and ship to the customer.

Inspection Item	Inspection Content	Inspection Requirement / Value	Applicable Standard / Description
Visual Inspection	Pipe surface and weld seam	Surface should be smooth, free of cracks, scratches, zinc lumps, and weld defects	Visual inspection, in accordance with API 5L / GB/T 9711.1
Outside Diameter (OD) Measurement	Actual outside diameter of the pipe	±1%	API 5L
Wall Thickness (WT) Measurement	Pipe wall thickness	-12.5% / +15% (stricter tolerance available upon request)	API 5L
Length Measurement	Pipe length	±50 mm	API 5L
Ovality	Roundness of the pipe	≤1%	API 5L
Straightness	Pipe bending	≤0.2% L (pipe length)	API 5L
Weld Non-Destructive Testing (NDT)	Ultrasonic testing / X-ray inspection	Weld seam and heat-affected zone must be free of cracks, porosity, and lack of fusion	API 5L / AWS / GB/T 9711.1
Chemical Composition Test	C, Mn, P, S, etc.	Must comply with steel grade requirements (Gr.B / X42–X70)	API 5L / ASTM A106 / ASTM A53
Mechanical Property Test	Yield strength, tensile strength, elongation	According to steel grade: Gr.B: 245 MPa Yield; X42: 290 MPa Yield; X52: 360 MPa Yield; X60: 415 MPa Yield; X65: 450 MPa Yield; X70: 485 MPa Yield	API 5L / ASTM A106
Impact Test	Charpy V-notch impact test	PSL2 mandatory: impact energy ≥ 27 J at -10°C or -20°C (depending on project requirements)	API 5L
Hydrostatic Test	Hydrostatic pressure test	Tested at 1.5 times the design pressure, pipe must have no leakage	API 5L / Customer design requirements
Coating Thickness	External anti-corrosion coating	3PE: 0.5–0.7 mm; FBE: 0.25–0.35 mm	Project requirements, not mandatory in standards

1. What medium are we transporting?

Answer:
The first step in selecting pipe materials is to determine the type of medium being transported: crude oil, natural gas, refined oil, industrial water, or seawater, etc. Different media affect the steel grade, wall thickness, and internal corrosion protection requirements.
For example, when transporting seawater or corrosive liquids, internal and external corrosion protection treatments are necessary.

2. What is the design pressure of the project?

Answer:
The design pressure directly determines the pipe diameter and wall thickness. Medium and low-pressure pipelines can use standard wall thicknesses and steel grades, while high-pressure pipelines require high-grade steel (X52–X70) and thicker walls to ensure a safety factor. The design pressure (MPa) must be confirmed before procurement.

3. Is PSL2 required?

Answer:
PSL2 has stricter requirements for chemical composition, mechanical properties, and weld inspection. Long-distance oil and gas pipelines, offshore pipelines, or high-pressure pipelines typically require PSL2, while municipal water, gas, or medium- and low-pressure projects may choose PSL1.

4. Are there any low-temperature impact requirements for the operating environment?

Answer:
Low-temperature environments can affect the toughness of the pipe. PSL2 pipes typically require a Charpy impact test at -10°C or -20°C to ensure the pipe does not fail due to brittle fracture. It is necessary to confirm whether the project has low-temperature toughness requirements before purchasing.

5. Is anti-corrosion treatment required?

Answer:
Anti-corrosion treatment depends on the soil corrosion level or the corrosiveness of the medium. Common methods include FBE, 3PE, reinforced 3PE, and internal epoxy coating. Reinforced anti-corrosion treatment must be selected for seawater or highly corrosive environments.

6. Are there any restrictions on transportation and installation conditions?

Answer:

The length, outer diameter, and weight of the pipe will affect the transportation and on-site lifting plan. Large diameter or long pipe sections may require segmented transportation or on-site welding. Confirming site conditions in advance can avoid additional costs and construction risks.