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ASTM A795 Grade B is a type of Stee grade that is commonly used for sprinkler pipes. This Stee grade is available in both seamless and welded varieties. The seamless variety is manufactured using an extrusion process, while the welded variety is made using a welding process. Both types of pipe are strong and durable, making them ideal for use in a variety of applications. ASTM A795 Grade B pipe is typically used in high-pressure applications, such as sprinkler systems. This Stee grade is also often used in other applications, such as in water treatment facilities and industrial piping systems.
ASTM A795 is the standard specification for black and hot-dipped galvanized welded and seamless steel pipe. This pipe is used for fire sprinkler systems because it is durable and resistant to corrosion. The wall thickness of this pipe ranges from 1/2 inch to 10 inches, and it can be either seamless or welded. This pipe is available in various lengths, and it can be cut to size as needed. This pipe is also compatible with different fittings, making it easy to install. Lastly, this pipe is easy to maintain, and it has a long lifespan. ASTM A795 is an American Standard that covers two different grades of steel, Grade A and Grade B. The weld seam of ERW pipe in Grade B must be heat-treated after welding to a minimum of 1000℉ （540℃）so that no untempered martensite remains. If this is not done, the pipe may be processed in such a way that no untempered martensite remains. This standard is important because it helps to ensure the safety and quality of the finished product.
The standard guides how to properly analyze the chemical composition of ASTM A795 Grade B pipes. According to the standard, two pipes shall be sampled from each lot of 500 lengths, or a fraction thereof. The chemical composition thus determined shall conform to the requirements in the table below. By following this standard, manufacturers can ensure that their pipes meet the necessary specifications for quality and performance. In addition, this standard helps to protect consumers by ensuring that they are receiving products that meet their expectations.
| Steel Grade | C, max | Mn | P | S | Mo | Ni | Cr | Cor | Others |
| Grade B | 0.3 | 1.2 | 0.035 | 0.035 | – | – | – | – | – |
| TABLE 1 Dimensions, Weights, and Test Pressure for Light-Weight Fire Protection ASTM A795 Pipe—Schedule 10A | ||||||||||
| NPS Designator | Outside Diameter | Nominal Wall Thickness | Weight Plain End | Test Pressure | ||||||
| Furnace-Welded | Seamless and Electric-Resistance-Welded | |||||||||
| in. | mm | in. | mm | lb/ft | kg/m | psi | MPa | psi | MPa | |
| 3/4 | 1.05 | (26.7) | 0.083 | (2.11) | 0.86 | (1.280) | 500 | (3.45) | 700 | (4.83) |
| 1 | 1.315 | (33.4) | 0.109 | (2.77) | 1.41 | (2.090) | 500 | (3.45) | 700 | (4.83) |
| 1.25 | 1.66 | (42.2) | 0.109 | (2.77) | 1.81 | (2.690) | 500 | (3.45) | 1000 | (6.89) |
| 1 1/2 | 1.9 | (48.3) | 0.109 | (2.77) | 2.09 | (3.110) | 500 | (3.45) | 1000 | (6.89) |
| 2 | 2.38 | (60.3) | 0.109 | (2.77) | 2.64 | (3.930) | 500 | (3.45) | 1000 | (6.89) |
| 2 1/2 | 2.88 | (73.0) | 0.12 | (3.05) | 3.53 | (5.260) | 500 | (3.45) | 1000 | (6.89) |
| 3 | 3.5 | (88.9) | 0.12 | (3.05) | 4.34 | (6.460) | 500 | (3.45) | 1000 | (6.89) |
| 3 1/2 | 4 | (101.6) | 0.12 | (3.05) | 4.98 | (7.410) | 500 | (3.45) | 1200 | (8.27) |
| 4 | 4.5 | (114.3) | 0.12 | (3.05) | 5.62 | (8.370) | 500 | (3.45) | 1200 | (8.27) |
| 5 | 5.56 | (141.3) | 0.134 | (3.40) | 7.78 | (11.580) | B | B | 1200 | (8.27) |
| 6 | 6.63 | (168.3) | 0.134 | (3.40) | 9.3 | (13.850) | B | B | 1000 | (5.51) |
| 8 | 8.63 | (219.1) | 0.188C | (4.78) | 16.96 | (25.260) | B | B | 800 | (4.83) |
| 10 | 10.75 | (273.1) | 0.188C | (4.78) | 21.23 | (31.620) | B | B | 700 | (6.89) |
| A：Schedule 10 corresponds to Schedule 10S as listed in ANSI B 36.19 for NPS 3⁄4 through 6 only. | ||||||||||
| B：Furnace-welded pipe is not made in sizes larger than NPS 4. | ||||||||||
| C：Not Schedule 10. | ||||||||||
| TABLE 2 Dimensions, Weights, Test Pressures for Standard-Weight Fire Protection ASTM A795 Pipe—Schedule 30 and Schedule 40 | ||||||||||
| NPS Designator | Outside Diameter | Nominal Wall Thickness | Weight Plain End | Test Pressure | ||||||
| Furnace-Welded | Seamless and Electric-Resistance-Welded | |||||||||
| in. | mm | in. | mm | lb/ft | kg/m | psi | MPa | psi | MPa | |
| 1/2 | 0.84 | (21.3) | 0.109 | (2.77) | 0.85 | (1.270) | 700 | (4.83) | 700 | (4.83) |
| 3/4 | 1.05 | (26.7) | 0.113 | (2.87) | 1.13 | (1.690) | 700 | (4.83) | 700 | (4.83) |
| 1 | 1.32 | (33.4) | 0.133 | (3.38) | 0.68 | (2.500) | 700 | (4.83) | 700 | (4.83) |
| 1 1/4 | 1.66 | (42.2) | 0.14 | (3.56) | 2.27 | (3.390) | 1000 | (6.89) | 1000 | (6.89) |
| 1 1/2 | 1.9 | (48.3) | 0.145 | (3.68) | 2.72 | (4.050) | 1000 | (6.89) | 1000 | (6.89) |
| 2 | 2.38 | (60.3) | 0.154 | (3.91) | 3.66 | (5.450) | 1000 | (6.89) | 1000 | (6.89) |
| 2 1/2 | 2.88 | (73.0) | 0.203 | (5.16) | 5.8 | (8.640) | 1000 | (6.89) | 1000 | (6.89) |
| 3 | 3.5 | (88.9) | 0.216 | (5.49) | 7.58 | (11.290) | 1000 | (6.89) | 1000 | (6.89) |
| 3 1/2 | 4 | (101.6) | 0.226 | (5.74) | 9.12 | (13.580) | 1200 | (8.27) | 1200 | (8.27) |
| 4 | 4.5 | (114.3) | 0.237 | (6.02) | 10.8 | (16.090) | 1200 | (8.27) | 1200 | (8.27) |
| 5 | 5.56 | (141.3) | 0.258 | (6.55) | 14.63 | (21.790) | C | C | 1200 | (8.27) |
| 6 | 6.63 | (168.3) | 0.28 | (7.11) | 18.99 | (28.290) | C | C | 1200 | (8.27) |
| 8 | 8.63 | (219.1) | 0.277A | (7.04) | 24.72 | (36.820) | C | C | 1200 | (8.27) |
| 10 | 10.75 | (273.1) | 0.307A | (7.80) | 34.27 | (51.050) | C | C | 1000 | (6.89) |
| A：NPS 1⁄2 through 6—Schedule 40; NPS 8 and 10—Schedule 30. | ||||||||||
| B：Based on 20-ft (6.1-m) lengths. | ||||||||||
| C：Furnace-welded pipe is not made in sizes larger than NPS 4. | ||||||||||
- Hydrotest of ASTM A795 Grade B Pipes
According to the standard, each length of ASTM A795 Grade B pipe must be subjected to a hydrostatic test by the manufacturer. The hydrostatic test is a pressure test that checks for leaks in the pipe wall. The test pressure is specified in the Dimension & Size table above. The manufacturer may choose to test at a higher pressure if they wish. The hydrostatic test may be applied to pipe with plain ends, with threads only, or with threads and couplings. It can be applied to single or multiple lengths of pipe. The hydrostatic test must be applied without any leakage through the pipe wall. This ensures that each length of pipe meets the required standards.
- Nondestructive Electric Test of ASTM A795 Grade B Pipes
According to ASTM A795, the standard for black and hot-dipped zinc-coated (galvanized) welded and seamless steel pipe for fire protection use, an alternative to the hydrostatic test is the nondestructive electric test. This type of test uses an electric current to detect any defects in the pipe that may not be visible to the naked eye. If the buyer accepts this type of testing, each pipe must be tested individually. The benefits of using a nondestructive electric test include being able to test a larger number of pipes in a shorter amount of time and being able to detect any defects that may not be visible to the naked eye.
- Flattening Test of ASTM A795 Grade B Pipes
To ensure the safety of pipes, the standard requires a flattening test to be performed on ASTM A795 Grade B pipes. This test is used to assess the ductility of the weld, as well as the pipe itself. The specimen is placed between two plates and flattened in 3 steps.
1. The first test is for ductility, which measures the ability of the weld to stretch without breaking. The pipe is placed between two plates, and the distance between the plates is gradually decreased. If no cracks or breaks occur on either the inside or outside surfaces of the pipe before the distance between the plates is less than two-thirds of the original outside diameter, then the weld is deemed ductile.
2. The second test is for ductility exclusive of the weld, which means that no cracks or breaks can occur on the inside or outside surfaces until the distance between the plates is less than one-third of the original outside diameter. However, this distance must be no less than five times the wall thickness of the pipe. If any evidence of laminated or unsound material is revealed during this test, then the weld is rejected.
3. Finally, a soundness test is conducted to assess whether there are any defects in the weld. The pipe is again placed between two plates, and the flattening process is continued until the specimen breaks or until the opposite walls of the pipe meet. Any evidence of incomplete welds will result in rejection.
