Understanding Pressure Ratings for Stainless Steel Pipes (Chart Included)

Selecting the right stainless steel pipe for your project requires a clear understanding of pressure ratings. These ratings determine the maximum pressure a pipe can safely handle, which is critical for ensuring the integrity and safety of any piping system. This guide will help you navigate the key factors influencing these ratings and how to interpret them.

The Fundamentals of Pressure Ratings
The pressure capacity of a stainless steel pipe is primarily determined by three factors: the material grade, wall thickness, and outer diameter.

A fundamental formula used to calculate this pressure is:
P = 2 × S × T / D
where P is the allowable pressure (in MPa), S is the allowable stress of the material (based on its tensile strength), T is the wall thickness, and D is the outer diameter .

For example, common grades like 304/304L have a typical tensile strength of 520 MPa, while 316/316L has a tensile strength of 485 MPa . A safety factor (often 0.4) is usually applied to these values for conservative design .

Pressure Rating Reference Chart
The following chart provides illustrative pressure ratings for common stainless steel pipe sizes under ambient temperature conditions. These values are based on standard calculations and may vary with specific application conditions.

Outer Diameter (mm) Wall Thickness (mm) Estimated Pressure Rating (MPa) for 304 Stainless Steel
25 2.5 ~41.6 
159 3 ~7.84 
159 5 ~12.2 (for 316L) 
Note: This table is for reference only. Always consult technical specifications for critical applications.

Key Factors Influencing Pressure Capacity
Material Grade: Grades with higher tensile strength and better corrosion resistance, like 316L, are often chosen for more demanding environments .

Temperature Effects: Pressure ratings are temperature-dependent. As the operating temperature increases, the maximum allowable pressure for a given pipe typically decreases . The applicable standards provide detailed pressure-temperature tables.

Industry Standards: Pipes are manufactured and tested according to standards like ASTM A312 and ASME B31.8 , which govern their pressure performance. For thin-walled water pipes, national standards like GB/T 29038 apply to systems with pressures not exceeding PN 25 .

Selecting the Right Pipe for Your Application
Choosing the correct pipe involves more than just pressure. Consider the medium being transported (water, chemicals, gas) , ambient temperature, and required safety margins. For specialized applications, it is crucial to work with a knowledgeable manufacturer who can provide detailed technical data and guidance.

As a manufacturer, Rui Xiang Steel emphasizes that understanding these principles ensures the selection of pipes that are not only efficient but also safe and durable for their intended service.