MS ERW Pipe Specifications for Fire Lines: Standards & Selection

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

MS ERW Fire Pipe Common Specifications 

Standard	Nominal Size	Outer Diameter	Wall Thickness / Schedule
EN 10255 (Medium)	DN15 – DN150	21.3mm – 165.1mm	2.6mm – 5.0mm
EN 10255 (Heavy)	DN15 – DN150	21.3mm – 165.1mm	3.2mm – 5.4mm
ASTM A53 Gr.B ERW	NPS 1" – 6"	33.4mm – 168.3mm	Commonly SCH 40; SCH 80 available
ASTM A795	NPS 1" – 6"	33.4mm – 168.3mm	SCH 10, SCH 40, SCH 80
IS 1239 (Medium)	25 NB – 150 NB	33.7mm – 165.1mm	3.2mm – 5.0mm
IS 1239 (Heavy)	25 NB – 150 NB	33.7mm – 165.1mm	4.0mm – 5.4mm

ASTM A795 Fire Fighting Pipe Wall Thickness Series Details:

● 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.

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.

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)

Note: Values above are for reference at ambient temperature. Actual working pressure depends on specific design codes, temperature derating, and connection types.

Applications

1. Fire risers in high-rise buildings
2. Sprinkler systems in underground parking garages
3. Fire protection networks in industrial plants

4. Outdoor fire hydrant systems

MS ERW Fire Pipe Selection Recommendations

FAQs

Q1: Can ASTM A53 and ASTM A795 pipes be used interchangeably?
A: Not strictly. ASTM A53 is a general-purpose pipe standard, while ASTM A795 is dedicated to fire sprinkler systems. While both may be used in fire lines, A795 specifies exact wall thicknesses (SCH 10, 40, 80) tailored for fire protection hydraulics. For critical projects, always follow the design engineer's specified standard.

Q2: Do MS ERW fire pipes require a hydrostatic test?
A: Yes. According to standards like ASTM A795, every pipe must undergo a hydrostatic test (typically 500 psi or 1.5 times the working pressure) before leaving the factory to ensure leak-tightness. Alternatively, 100% non-destructive testing (eddy current or ultrasonic) can be performed in place of the hydrostatic test.

Q3: Are ERW welds prone to leakage in fire protection systems?
A: No, if properly manufactured. Modern high-frequency ERW pipes have strong, uniform welds. When specified under strict standards (like A795) with proper groove or thread connections, the weld is highly reliable. Routine inspections and compliance with pressure testing requirements prevent potential leaks.

Q4: Is SCH 40 or SCH 80 better for fire protection piping?
A: SCH 40 is the most common standard wall thickness for standard fire risers and mains. SCH 80 is a thicker, high-pressure series used for high-pressure fire pump piping and exposed areas requiring extra mechanical strength.

Related topics

● ERW Pipe Thickness Chart & Sizing Guide
● MS ERW Pipe Weight Chart (IS 1239) & Calculation Formula

● MS ERW Pipe IS Code 1239 & 3589

● ERW Steel Pipe Production Line