Introduction to Pipe sizes and Pipe schedule

Introduction

Pipe size calculation is a critical step in food factory design and industrial piping projects. It ensures that the selected piping dimensions align with process flow, pressure conditions, and end equipment. In engineering consulting, especially for food manufacturing plants, precise pipe sizing is essential to prevent cost overruns and operational issues.

Poor pipe selection can lead to:

• Increased project cost due to oversizing
• Complicated designs and layout inefficiencies
• Process disturbances and flow instabilities

Accurate pipe sizing plays a vital role in efficient communication between the piping design team and the execution team, ultimately affecting the success of food processing facility construction.

Pipe sizing

Pipe size is specified with two non-dimensional numbers,

a.    Nominal Pipe Size (NPS)                                         

b.    Schedule Number (SCH)

    And the relationship between these numbers determines the inside diameter of a pipe.

Nominal pipe size and its importance

Pipes are referred to using terms like:

• Nominal Pipe Size (NPS) – North American standard based on outer diameter
• Nominal Bore (NB) – European equivalent of NPS
• Nominal Diameter (DN) – Metric approximation used for international standardization

These notations are frequently used in food plant utility design, especially when integrating process piping with sanitary equipment.

Nominal Pipe Size (NPS)

Defines the pipe’s outer diameter, irrespective of wall thickness. For example, 2 NPS implies an OD of 2.375 inches (60.3 mm)

Nominal diameter (DN): Used in metric systems, this is a rough approximation of the internal diameter, crucial in sizing pipe fittings in international projects

Nominal Bore (NB): Represents the internal diameter approximation across a pipe’s cross-section. NB is often used in food processing consultant projects for selecting compatible pipe connections and equipment..

What is schedule Number?

The schedule number indicates the wall thickness of a pipe, affecting:

• Pipe strength
• Pressure-handling capacity
• Material cost

The formula is:

Schedule Number = P / S

(Where P = service pressure in psi, S = allowable stress in psi)

In food factory utility systems, pipe schedule selection must consider sanitation, CIP (clean-in-place) compatibility, and process safety.

Conclusion  

Proper pipe sizing is a foundational element in designing efficient and compliant food processing facilities. Whether it’s understanding Nominal Pipe Size (NPS), Nominal Bore (NB), or selecting the appropriate pipe schedule, these decisions significantly impact the safety, cost-efficiency, and reliability of food manufacturing operations. As a leading food processing consultant and engineering services provider, we at PMG Engineering ensure every pipeline is meticulously calculated to support high-performance processing systems. Investing in accurate pipe sizing helps prevent operational failures, supports regulatory compliance, and optimizes the overall performance of your food factory design.

Reference

1.     https://www.theprocesspiping.com/nominal-pipe-size-and-schedule/

2.     https://blog.enerpac.com/pipe-diameters-a-simple-guide-to-sizing-and-schedules/

3.     https://www.allaboutpiping.com/what-is-piping/

4.     https://anchoragegroup.com.au/pipe-sizes-schedules-materials/