MS ERW Pipe Specifications for Fire Lines

MS ERW fire line pipes refer to specialized steel pipes for fire protection systems manufactured from mild steel using an electric resistance welding (ERW) process. The following are the main MS ERW pipe specifications and standard requirements.

Commonly Used Standards:

EN 10255: Non-alloy steel pipe, suitable for welding and threaded connections, material grade S195T – Europe/International

ASTM A53: The most common carbon steel pipe standard in the United States, covering seamless pipe (Type S) and ERW welded pipe (Type E), Grade B, widely used in fire protection systems – North America/International

ASTM A795: Specific standard for fire sprinkler systems, covering SCH 10, SCH 40, SCH 80 – North America
IS 1239: Mild steel pipe for water and gas transportation, divided into light, medium, and heavy grades – India
IS 3589: Large diameter (≥DN300) steel pipe for water and sewage – India

BS 1387: Replaced by EN 10255, still used in some areas – United Kingdom

Advantages of using mild steel for MS ERW fire line pipes:

1. Excellent welding performance. Fire protection pipe networks typically use grooved connections as the main method of installation, supplemented by welding. The excellent weldability of low-carbon steel ensures the reliability of on-site repair welding and branch pipe welding, avoiding the risk of leakage due to weld defects.

2. Moderate strength and excellent plasticity balance: Compared with high-strength steel, low-carbon steel has a larger plasticity allowance, making it more adaptable to the slight displacement caused by temperature changes and foundation settlement in fire protection pipe networks, avoiding brittle fracture caused by stress concentration.

3. Excellent cold forming performance: Steel strips can be continuously rolled into round tubes without cracking. The ERW process ensures high-speed production and guarantees the dimensional accuracy of the pipes.
4. Good adaptability to hot-dip galvanizing: MS pipes have a moderate carbon content, resulting in a uniform zinc-iron reaction. The coating has strong adhesion and is not easily peeled off.

EN 10255 Standard Common Specifications:

Medium Size: Outer Diameter: 21.3mm~165.1mm; Wall Thickness: 2.6mm-5.0mm;
Heavy Size: Outer Diameter: 21.3mm~165.1mm; Wall Thickness: 3.2mm-5.4mm.

ASTM Standard Specifications:

1. ASTM A53 Gr.B ERW Pipe

Nominal Size: NPS 1"-6"

Outer Diameter: 33.4mm-168.3mm; 

Wall Thickness: SCH 40

2. ASTM A795 Fire Fighting Pipe
Wall Thickness Series:
SCH 10: Thin wall, lightweight, low cost, commonly used in indoor sprinkler branches.
SCH 40: Standard wall thickness, most commonly used, commonly used in fire risers and main pipes.
SCH 80: Thickened, high strength, commonly used in high-pressure systems and exposed pipes.

Indian IS Standard Specifications:

Nominal Size: 25 NB (1") - 150 NB (6") 

Outer Diameter: 33.7mm - 165.1mm 

Medium Wall Thickness (mm): 3.2mm - 5.0mm 

Heavy Wall Thickness (mm): 4.0mm - 5.4mm

MS ERW Fire Pipe Quality Inspection Parameters:

1. Common Material Grades: ASTM A53 Gr.B / EN10255 S195T; Yield Strength ≥ 195-240MPa

2. Chemical Composition: C ≤ 0.20%, P ≤ 0.035%, S ≤ 0.030%, ensuring weldability and toughness. 

3. Hydrostatic Test: ≥5.0 MPa or 1.5 times the working pressure (test each pipe individually).

4. Non-destructive Testing: Eddy current or ultrasonic testing; 100% testing is required when replacing hydrostatic testing.
5. Length: 11.8-12 meters (fixed length).
6. Pipe End Treatment: Plain end/Bevel/Grooved/Threaded.

Common Surface Treatments for Fire Fighting Pipes:

Black Pipe: Uncoated, coated with anti-rust paint. Suitable for indoor sprinkler systems.
Galvanized Pipe (GI): Suitable for outdoor, humid environments.
Epoxy Coating (FBE): Suitable for highly corrosive environments and buried pipelines.
Polyethylene Wrapping: Such as 3-layer PE/2-layer PE, for buried fire fighting main pipes.

Common Connection Methods:

Threaded Connection: Pipe size ≤ DN80
Grooved Connection: Pipe size DN50-DN600
Welded Connection: Applicable to all sizes

Maximum Working Pressure Reference (EN10255 Heavy Series):

Nominal Size:
DN25 (1"): 50 bar (5.0 MPa)
DN32-40 (1¼"-1½"): 40 bar (4.0 MPa)
DN50-80 (2"-3"): 28 bar (2.8 MPa)
DN100-150 (4"-6"): 25 bar (2.5 MPa)

Applications:
a. Fire risers in high-rise buildings
b. Sprinkler systems in underground parking garages
c. Fire protection networks in industrial plants
d. Outdoor fire hydrant systems

MS ERW Fire Pipe Selection Recommendations:

Project Type	Recommended Standard	Recommended Series	Surface Treatment
Indoor Sprinkler System	ASTM A795 / EN 10255	Medium / SCH 10-SCH 40	Black pipe + red paint
Fire riser (exposed)	EN 10255 / IS 1239	Heavy	Galvanized
Buried fire main pipe	EN 10255 / API 5L ERW	Heavy	3PE/FBE coated
High-pressure fire pump piping	ASTM A53 / A106	SCH 80	Black pipe