:/Pipe Class and Piping Specifications

Pipe Class and Piping Specifications

When working on piping, the pipe class and its specifications play an important role in designing and choosing the right pipes. Different pipe classes can handle different loads and materials, being fit for specific situations. Understanding what pipe classes and pipe specifications are will help buyers know what kind of pipe to choose for the job.

Before we discuss what pipe class and pipe specifications are, it will be best to learn what piping is.

What is Piping?


In the industrial field, piping refers to the system of pipes and tubes used to transfer oils, gases, or other fluids from one location or another. Mainly seen in processing plants, refineries and petrochemical complexes, piping systems carry out the raw material through the refining and manufacturing stages.

A piping system is a combination of several components that are joined together to perform specific tasks like distribution, mixing, discharge, and control of gases and fluids. Aside from pipes, the system can also include materials like tubes, fittings, flanges, separators, control valves, and drip rings, among others.

Furthermore, the term piping can also refer to the piping design, or the detailed specification of the layout needed within a commercial building or processing plant. Originally done with drafting or technical drawing, piping design nowadays is made with designers using computer-aided design software or CAD.

Pipes and Pipe Class

pipe class

Generally, pipes are categorized based on their manufacturing method, which are mainly either welded or seamless. Welded pipes are preferred if large-diameter pipes are needed, while seamless ones work for projects that require small or medium pipes. Welded pipes are further classified into other types, each with its own benefit. As pipes come in different types, it is imperative that the specific class of pipe is defined for the project at hand.

This is where pipe class comes in. According to definition, pipe class (or pipe classification) is a document that contains the definition of pipes and its related components to be used on a specific pressure or temperature condition. Usually prepared by the engineer or facility operator, this document normally includes information like the material specification, dimensional data, schedule, flange ratings, pipe types and valve types.  Each pipe class is defined by its base material, corrosion requirements, temperature and pressure range, and other special requirements.

Most of the time, the pipe class document contains short codes or abbreviations to make the information as detailed as possible.  The definitions of these codes are placed either at the beginning or at the end of the document. To make identifying the required material easier for the field construction engineer, the pipe class is indicated on the line number.

Additionally, the pipe class is part of the piping specification that covers the whole section of a plant or building.

Piping Specifications

pipe specification

Abbreviated as ‘Pipe Spec”, piping specification is a prepared document listing the specification for the pipes and its components for a specific service. Prepared during the design phase of the project, it also lists additional requirements regarding materials that go beyond the standards.

To be more specific, a pipe spec gives definition and instruction to the following:

  • Design – minimum requirements for thermal expansion, allowance rates, and the like.
  • Procurement – here we see the list of material requirements that go beyond allowed standards, like heat treatment.
  • Fabrication – includes instruction on how the materials should be fabricated, welded, and installed on the piping system. This also talks about painting and cleaning processes.
  • Engineering – description on how the designs are to be prepared and how the plant layout should be.

The Piping Specification document is not only used during the construction phase, but is also beneficial for repairs and maintenance works. As the pipe spec has all the information regarding a specific section of the piping system, it is used as a key reference for any changes done on the system.

One thing to note about the pipe spec document is that it is made specifically for a certain section of the plant or building. This means the information on one pipe spec may not apply to another section, making it important to specify which section the pipe spec is for.

Similar to pipe class, pipe specs also use short codes and numbers to provide as much detailed information as it can. Understanding how to read a pipe spec is important for optimal use of the document.

For example, on the Process and Instrument Diagram, the quoted line is 12-FW-1014-1CS1P. This can be deciphered as follows:

  • 12 – The line’s nominal pipe size.
  • FW – Refers to the contents of the pipe, also known as the service code. For this example, FW stands for Fire Water.
  • 1014 – This is the pipeline number, a unique set of numbers allocated to a specific section or run of pipe. This information is placed during the design stage.
  • 1CS1P -This is the short-hand reference into the piping specification document for the pipe specification number. It is unique to that document, with the first number normally referring to the system’s pressure rating.

Once the pipe spec number is located, you can then go to the specific page on the document to get the necessary information.

Hope this article helps you understand pipe class and pipe specifications better. If you have any thoughts, feel free to comment down below!

2019-10-27T14:56:03+00:00 September 1st, 2019|

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