ASTM A795 Pipe Specification

ASTM A795/A795M - Standard Specification for Black and Hot-Dipped Zinc-Coated (Galvanized) Welded and Seamless Steel Pipe for Fire Protection Use

This specification covers black and hot-dipped zinc-coated (galvanized) welded and seamless steel pipe for fire protection use. The pipe may be bent, but it is not intended for bending made at ambient temperature wherein the inside diameter of the bend is less than twelve times the outside diameter of the pipe being bent. The steel shall conform to the required chemical composition. Each length of pipe shall be subjected to a hydrostatic test without leakage through the pipe wall. As an alternative to the hydrostatic test, and when accepted by the purchaser, each pipe shall be tested with a non-destructive electrical method. Finally, flattening test shall be performed on the pipe in accordance with, electric-resistance-welded pipe, and furnace-welded pipe.

ASTM A795 pipe size range: NPS 1/2″ to NPS 10″ (DN 15 to DN 250).

Dimensions and Weight:

1. Lightweight Thick-Wall Fire Pipe (Schedule 10/10A)

NPS	DN	OD (mm)	WT (mm)	Weight (kg/m)
3/4″	20	26.7	2.11	1.28
1″	25	33.4	2.77	2.09
1¼″	32	42.2	2.77	2.69
1½″	40	48.3	2.77	3.11
2″	50	60.3	2.77	3.93
2½″	65	73.0	3.05	5.26
3″	80	88.9	3.05	6.46
4″	100	114.3	3.05	8.37
6″	150	168.3	3.40	13.85
8″	200	219.1	4.78	25.26
10″	250	273.1	4.78	31.62

NPS DN 外径 (mm) 壁厚 (mm) 重量 (kg/m) 1/2″ 15 21.3 2.77 1.27 3/4″ 20 26.7 2.87 1.69 1″ 25 33.4 3.38 2.50 1¼″ 32 42.2 3.56 3.39 1½″ 40 48.3 3.68 4.05 2″ 50 60.3 3.91 5.44 2½″ 65 73.0 5.16 8.63 3″ 80 88.9 5.49 11.29 4″ 100 114.3 6.02 16.07

NPS DN 外径 (mm) 壁厚 (mm) 重量 (kg/m) 1/2″ 15 21.3 2.77 1.27 3/4″ 20 26.7 2.87 1.69 1″ 25 33.4 3.38 2.50 1¼″ 32 42.2 3.56 3.39 1½″ 40 48.3 3.68 4.05 2″ 50 60.3 3.91 5.44 2½″ 65 73.0 5.16 8.63 3″ 80 88.9 5.49 11.29 4″ 100 114.3 6.02 16.07

NPS DN 外径 (mm) 壁厚 (mm) 重量 (kg/m) 1/2″ 15 21.3 2.77 1.27 3/4″ 20 26.7 2.87 1.69 1″ 25 33.4 3.38 2.50 1¼″ 32 42.2 3.56 3.39 1½″ 40 48.3 3.68 4.05 2″ 50 60.3 3.91 5.44 2½″ 65 73.0 5.16 8.63 3″ 80 88.9 5.49 11.29 4″ 100 114.3 6.02 16.07

2. Standard Thick-Wall Fire Pipe (Schedule 30/40)

NPS	DN	OD (mm)	WT (mm)	Weight (kg/m)
1/2″	15	21.3	2.77	1.27
3/4″	20	26.7	2.87	1.69
1″	25	33.4	3.38	2.50
1¼″	32	42.2	3.56	3.39
1½″	40	48.3	3.68	4.05
2″	50	60.3	3.91	5.44
2½″	65	73.0	5.16	8.63
3″	80	88.9	5.49	11.29
4″	100	114.3	6.02	16.07

Pipe types and surface treatments:

a. By surface condition
Black Pipe: Uncoated, usually marked with red anti-rust paint, suitable for indoor fire sprinkler systems;
Hot-dip galvanized Pipe: Zinc-coated for corrosion protection, suitable for outdoor, humid, or corrosive environments.

b. By manufacturing process
ERW (Electric Resistance Welded): The most common and cost-effective choice, the mainstream option for small and medium diameter fire hoses;
Seamless: Higher cost, less commonly used in special applications.

c. Classification by wall thickness series
Light Wall Series: Schedule 10 / 10A
Standard Wall Series: Schedule 30 / 40

NPS DN 外径 (mm) 壁厚 (mm) 重量 (kg/m) 1/2″ 15 21.3 2.77 1.27 3/4″ 20 26.7 2.87 1.69 1″ 25 33.4 3.38 2.50 1¼″ 32 42.2 3.56 3.39 1½″ 40 48.3 3.68 4.05 2″ 50 60.3 3.91 5.44 2½″ 65 73.0 5.16 8.63 3″ 80 88.9 5.49 11.29 4″ 100 114.3 6.02 16.07 Heavy Wall Series: Schedule 80

Connection Methods: 

Different connection methods are permitted depending on the pipe's wall thickness series:

Thin-walled fire-fighting pipe (SCH 10/10A): Suitable for rolled grooves, welded connections, and flush-end fittings.
Standard heavy-duty fire-fighting pipe (SCH 30/40): Suitable for cut or rolled grooves, threaded connections, welded connections, and flush-end fittings.
Heavy Wall Series (SCH 80): Optional, for high-pressure systems.

For pipe sizes outside the standard tables, the connection method must be compatible with the pipe size. See ASME B36.10 and B36.19 for a complete list of standard light-walled pipe sizes.

Testing and Inspection:
To ensure the integrity and safety of the pipeline, each steel pipe must undergo rigorous testing:

Hydraulic Pressure Test: Each section of steel pipe shall undergo a hydraulic pressure test, and no leakage is permitted.
Non-Destructive Electrical Testing (NDT): With the buyer's approval, NDT methods (such as eddy current testing) may be used as an alternative to the hydraulic pressure test.
Flattening Test: The steel pipe shall undergo a flattening test according to the relevant standards for resistance-welded pipes and furnace-welded pipes to verify their plastic deformation capacity.
Weld Inspection: Resistance-welded pipes and laser-welded pipes shall meet the NDT (non-destructive testing) requirements in the standards, typically 100% weld inspection.

Main Application Areas:
● Automatic Sprinkler Systems: Sprinkler networks in office buildings, shopping malls, industrial plants, and hospitals;
● Fire Hydrant and Riser Systems: Main fire water supply pipes within buildings;
● Dry/Wet Riser Systems in High-Rise Buildings: Dry riser or dry piping systems;
● Fire Water Distribution Systems: Fire water distribution lines requiring galvanized corrosion protection;
● Industrial Fire Protection Networks: Fire hydrant networks and sprinkler systems in industrial safety systems.

ASTM A795 vs ASTM A53:

Comparison Dimensions	ASTM A795 (Fire Protection Only)	ASTM A53 (General Purpose Pipe)
Design Application	Specifically for fire protection systems;	General purpose for water, gas, steam, structural, fire protection, etc.
Specification Range	NPS 1/2″ – 10″	NPS 1/8″ – 26″
Wall Thickness Series	SCH 10/10A, 30/40	SCH 5, 10, 20, 30, 40, 80, etc.
Straightness Requirement	≤ 0.25% Pipe Length	No special requirements
Weld Inspection	100% non-destructive testing of welds	inspection on demand
Temperature Range	-20℃ ~ +50℃	-30℃ ~ +80℃

FM Certification:
FM 1630 This is one of the most authoritative international certification standards for fire protection pipes. Passing this certification means:

● The steel pipe has passed extreme tests such as pressure resistance, long-term service life, and real fire simulation.
● ASTM A795 pipes with FM certification are the preferred product for international fire protection engineering projects.

Purchase Confirmation Checklist:

Standards and Versions: ASTM A795/A795M: 2021
Dimensions: NPS, Wall Thickness Series (SCH 10/40/80)
Surface Treatment: Black Tube / Hot-Dip Galvanized
Certification Requirements: FM 1630 or UL Certification Required?
End Treatment: Plain End / Threaded End / Grooved End
Length Requirements: Single Random Length (6-7m) / Double Random Length (12-14m)
Coating Requirements: Color Code (e.g., Red for Firefighting), Film Thickness (Recommended ≥30μm)

Frequently Asked Questions:

1. What steel pipes does ASTM A795 apply to?
ASTM A795 applies to black and hot-dip galvanized (zinc-plated) welded and seamless steel pipes used in fire protection systems. The pipes can be manufactured using resistance welding (ERW/high-frequency welding), furnace welding, or seamless processes without joints.

There are two main surface types: black steel pipes (uncoated, for indoor sprinkler systems) and hot-dip galvanized steel pipes (zinc-coated for corrosion protection, for outdoor or humid environments).

2. What is the size range of ASTM A795 steel pipes?
The standard covers steel pipe sizes from NPS 1/2 to NPS 10 (DN 15 to DN 250), with wall thicknesses following the specifications in Tables 1 (Lightweight Fire Protection Pipes) and 2 (Standard Weight Fire Protection Pipes) of the standard. If customers require steel pipes with other wall thicknesses, they can be supplied as long as the outer diameter conforms to the specifications in Table 2 and meets all other requirements of the standard.

3. What are the differences in testing requirements between ASTM A795 and ASTM A53? 

ASTM A795 is a standard specifically designed for fire protection systems, with testing requirements optimized for fire protection applications. Compared to the general-purpose pipe standard ASTM A53:

A795 has stricter requirements for weld inspection, typically requiring 100% non-destructive testing of welds; 

the hydrostatic testing standard is specifically designed for the pressure requirements of fire protection systems; 

and A795 also adds optional requirements for fire protection-specific certifications such as FM 1630.

4. What Chinese grade corresponds to ASTM A795 Grade B?
ASTM A795 Grade B (black pipe and hot-dip galvanized welded steel pipe) typically corresponds to Q235B in the Chinese standard GB/T 3091. The equivalence between the two is mainly reflected in:

Comparable mechanical properties (Q235B has a yield strength of 235 MPa, while A795 has 205 MPa, Q235B is slightly higher); both dimensional systems are based on wall thickness schedules and are suitable for fire sprinkler systems.

Read more: SCH 40 Black Steel Pipe or MS and GI Pipe Difference