Robert B. Adams
President and CEO
EST Group, Inc.
Pressure testing is required by most piping codes to verify that a new, modified,
or repaired piping system is capable of safely withstanding its rated pressure and
is leak tight. Compliance to piping codes may be mandated by regulatory and
enforcement agencies, insurance carriers, or the terms of the contract for the con-
struction of the system. Pressure testing, whether or not legally required, serves
the useful purpose of protecting workers and the public.
Pressure testing may also be used to establish a pressure rating for a component
or special system for which it is not possible to establish a safe rating by calculation.
A prototype of the component or system is subjected to a gradually increasing
pressure until measurable yielding first occurs or, alternatively, to the point of
rupture. Then by using derating factors specified in the code, or the standard,
appropriate to the component or system, it is possible to establish a design pressure
rating from the experimental data.
There are a great many codes and standards relating to piping systems. Refer to
Chap. A4 for a comprehensive listing and overview of codes and standards for piping
systems, covering many different applications. Two codes of major importance for
pressure and leak testing are the ASME B31 (previously called ANSI B31) Pressure
Piping Code and the ASME Boiler and Pressure Vessel Code. While these two
codes are applicable to many piping systems, other codes or standards may have
to be met as required by the authorities, insurance companies, or the owner of
the system. Examples might be AWWA standards for water transmission and
distribution system piping.
The ASME B31 Pressure Piping Code has several sections. They are
● ASME B31.1 for Power Piping
● ASME B31.2 for Fuel Gas Piping
● ASME B31.3 for Process Piping
● ASME B31.4 for Liquid Transportation Systems for Hydrocarbons, Liquid Petro-
leum Gas, An