Understanding Pressure Ratings in Non-Metallic Piping Systems: What Engineers Should Know
Pressure rating is a big consideration when designing a plumbing or fluid-handling system. The performance, safety, and longevity of a piping system hinge on understanding how much pressure the materials can handle under normal and extreme operating conditions. In this post, we break down the key factors engineers should consider when working with pressure-rated Non-Metallic Piping Systems.
Why Pressure Ratings Matter in Non-Metallic Piping Systems
Non-metallic piping systems like PVC, CPVC, and PE are used across various industries because they are non-corrosive, lightweight, and easy to install. However, these systems behave differently from metal piping under pressure. So, failing to account for their pressure ratings before application can lead to system failures, costly downtime, or safety hazards.
To prevent this, it’s important to factor pressure ratings into selection of non-metallic pipes, taking into account some of the factors that have the biggest influence on how these systems perform under load.
1. Temperature and Pressure Derating: A Crucial Connection
One of the most significant influences on pressure ratings is temperature. As temperatures rise, the pressure capacity of the piping system decreases. For example, a pipe rated at 150 psi at 73°F might only handle around 90 psi at 110°F. Engineers must apply derating factors based on manufacturer specifications to avoid failure under higher operating temperatures.
2. Dimensions, Wall Thickness, and Installation Methods
In non-metallic piping systems, pipe diameter, wall thickness, and how components are joined affect pressure capacity. Thicker-walled pipes generally support higher pressures. Similarly, a system that uses proper solvent welding or compatible mechanical fittings will maintain its pressure integrity better than one with mismatched components or poor installation techniques.
3. Long-Term Stress and Hydrostatic Design Basis (HDB)
Plastic materials can experience long-term stress from sustained pressure exposure. That’s why pressure ratings for non-metallic pipes are determined using long-duration tests, such as ASTM D2837, which assesses hydrostatic design stress. A pipe with a certified HDB ensures performance stability over time, even in high-demand conditions.
What Should Engineers Do?
When designing with non-metallic piping systems, engineers should always refer to industry standards set by organizations like ASTM, NSF, and ISO. These standards ensure the pipe has been tested for safety, durability, and pressure performance. Using pressure-rated pipes that meet recognized standards helps ensure system reliability and regulatory approval.
Partner with a Knowledgeable Supplier
Choosing the correct piping system starts with working with a knowledgeable supplier who understands your industry’s requirements. At WIPCO, we offer a wide range of pressure-rated non-metallic piping systems and provide expert guidance to help engineers and contractors select the right products for their application. Contact us today to speak with a piping specialist and get the technical support you need for a high-performance, pressure-safe installation.
