ASTM A795 is a widely recognized standard for steel pipes used in fire protection systems. This specification covers black and hot-dip zinc-coated (galvanized) welded and seamless steel pipes. Understanding the dimensions of ASTM A795 pipes is crucial for engineers, contractors, and facility managers involved in designing and implementing fire protection systems. In this article, we'll explore the various dimensional aspects of ASTM A795 pipe, including size range, weight, outer diameter, and thickness.
1. Size range:
ASTM A795 standard covers a wide range of pipe sizes to accommodate various fire protection system requirements. The size range spans from NPS (Nominal Pipe Size) 1/2 to NPS 10. This range is particularly suitable for industrial applications, where different pipe sizes are needed to meet specific flow rates and pressure requirements.
The NPS system is used to designate pipe sizes in North America. It's important to note that NPS is not a direct measurement of the pipe's inner or outer diameter. Instead, it's a nominal or approximate size designation. Here's a breakdown of the NPS sizes covered by ASTM A795:
- NPS 1/2 (15mm) - NPS 3/4 (20mm) - NPS 1 (25mm) - NPS 1-1/4 (32mm) - NPS 1-1/2 (40mm) - NPS 2 (50mm) - NPS 2-1/2 (65mm) - NPS 3 (80mm) - NPS 3-1/2 (90mm) - NPS 4 (100mm) - NPS 5 (125mm) - NPS 6 (150mm) - NPS 8 (200mm) - NPS 10 (250mm)
This size range allows for flexibility in system design, enabling engineers to select the most appropriate pipe size for each section of the fire protection system. Smaller sizes like NPS 1/2 and NPS 3/4 are often used for branch lines and sprinkler connections, while larger sizes such as NPS 6, 8, and 10 are typically employed for main distribution lines in larger industrial facilities.
2. Weight:
The weight of ASTM A795 pipe is an important consideration for system design and installation. Pipe weight affects factors such as support requirements, handling during installation, and overall system load. The weight of ASTM A795 pipes varies depending on the pipe size and wall thickness.
ASTM A795 pipes are available in different wall thicknesses, commonly referred to as schedules. The most common schedules for fire protection systems are Schedule 10 and Schedule 40. Schedule 10 pipes are lighter than Schedule 40 pipes of the same nominal size.
Here are some examples of approximate weights for ASTM A795 pipe (in pounds per foot):
- NPS 1, Schedule 10: 1.41 lbs/ft - NPS 1, Schedule 40: 2.05 lbs/ft - NPS 2, Schedule 10: 2.87 lbs/ft - NPS 2, Schedule 40: 3.66 lbs/ft - NPS 4, Schedule 10: 6.31 lbs/ft - NPS 4, Schedule 40: 10.79 lbs/ft - NPS 6, Schedule 10: 10.25 lbs/ft - NPS 6, Schedule 40: 18.97 lbs/ft
It's important to note that these weights are approximate and may vary slightly depending on the manufacturer and specific production processes. When designing a fire protection system, engineers must consider the total weight of the piping network to ensure proper support and compliance with building structural requirements.
3. Outer Diameter: 1/2"-72":
While ASTM A795 covers pipe sizes from NPS 1/2 to NPS 10, the actual outer diameter (OD) of these pipes can range from 1/2" to 72". This wide range of outer diameters allows for the accommodation of various system requirements and connection types.
It's important to understand that the nominal pipe size (NPS) doesn't directly correspond to the actual outer diameter of the pipe. For example:
- NPS 1/2 has an actual OD of 0.840 inches - NPS 1 has an actual OD of 1.315 inches - NPS 2 has an actual OD of 2.375 inches - NPS 4 has an actual OD of 4.500 inches - NPS 6 has an actual OD of 6.625 inches - NPS 10 has an actual OD of 10.750 inches
The difference between the NPS designation and the actual outer diameter is historical and relates to the internal diameter of the pipe when using different wall thicknesses. This system allows for consistent fitting sizes across different pipe schedules.
For larger industrial applications, pipes with outer diameters up to 72 inches may be used, although these larger sizes are less common in typical fire protection systems and may fall under different ASTM standards.
4. Thickness: SCH10-SCH160:
ASTM A795 pipes are available in various wall thicknesses, typically referred to as schedules. The schedule number roughly corresponds to the pressure rating of the pipe, with higher numbers indicating thicker walls and higher pressure capabilities. For fire protection systems, the most commonly used schedules are SCH10 and SCH40, but the full range can extend from SCH10 to SCH160 for certain applications.
Here's an overview of the wall thicknesses for some common pipe sizes and schedules:
NPS 1: - SCH10: 0.109 inches - SCH40: 0.133 inches - SCH80: 0.179 inches NPS 2: - SCH10: 0.109 inches - SCH40: 0.154 inches - SCH80: 0.218 inches NPS 4: - SCH10: 0.120 inches - SCH40: 0.237 inches - SCH80: 0.337 inches NPS 6: - SCH10: 0.134 inches - SCH40: 0.280 inches - SCH80: 0.432 inches
The choice of pipe schedule depends on factors such as system pressure requirements, corrosion allowance, and structural considerations. In fire protection systems, SCH10 is often used for sizes 2-1/2 inches and larger, while SCH40 is typically used for sizes 2 inches and smaller. However, specific system requirements and local codes may dictate the use of different schedules.
5. China ASTM A795 pipe:
LONGMA GROUP is one such manufacturer committed to delivering high-quality ASTM A795 pipe. They prioritize fast delivery and competitive pricing while maintaining strict adherence to international standards. Their product range covers the full spectrum of ASTM A795 pipe dimensions, including various sizes, weights, outer diameters, and thicknesses discussed in this article.
If you're in the market for ASTM A795 pipe and considering Chinese manufacturers, LONGMA GROUP invites you to reach out to them at info@longma-group.com for more information on their products and services. They can provide detailed specifications and assist in selecting the right pipe dimensions for your specific fire protection system requirements.