The ASME B16.5 Class 1500 Threaded Flange standard covers pipe flanges and flanged fittings for sizes ranging from NPS 1/2 through NPS 24. A threaded flange (sometimes referred to as a screwed flange) features an internal thread that matches the external tapered thread of a pipe. HT PIPE supply all different types and scales of flanges. Please feel free to contact us for further product information and pricing.
Why Choose Class 1500 Threaded Flanges?
Zero Welding Required: Ideal for highly volatile or explosive environments (such as gas processing facilities) where hot work or structural welding is structurally prohibited or dangerous.
Extreme Pressure Capability: A Class 1500 rating indicates a highly robust design capable of managing intense pressure loads, depending on the working temperature and metallurgy.
Size Restrictions: Under the strict parameters of ASME B16.5, high-pressure threaded flanges like the Class 1500 series are typically limited to smaller nominal pipe sizes (NPS 1/2 to NPS 2-1/2) to ensure structural integrity under load.
Critical Geometric Parameters & Thread Specifications
To ensure proper sealing and structural fitment, an engineer must look beyond basic outer diameters. Key dimensional design features include:
1. The Bore and Thread Standards
The internal bore of a Class 1500 threaded flange is machined with a taper that mirrors standard pipe threads. By code default, these are National Pipe Thread (NPT) profiles conforming to ASME B1.20.1. The precision of the thread depth determines the gauge point-ensuring that when the pipe is fully torqued, it sits tight against the flange face without over-penetrating.
2. Counterbore Requirements
ASME B16.5 specifies a minimum counterbore at the front face of the thread. This slight, unthreaded recess guides the pipe during engagement and shields the starting threads from mechanical deformation or high-velocity fluid erosion.
3. Length Through the Hub
Because Class 1500 systems face profound axial and bending stresses, the hub is noticeably elongated compared to lower classes (such as Class 150 or 300). This additional material stabilizes the threaded joint, preventing localized pipe wall fatigue.
