Test Pressure Detail from Codes

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“Strict testing process.Codes, standards or specifications being used for the test have differing details of test pressure such as the exact value, measurement unit, or the duration.The content of codes, standards, relevant to tests applied must be reviewed to establish a company’s respective test pressure stipulations.” "This knowledge is commonly contained within the technical documentation that is provided by the manufacturer, in industry standards, or in regulatory requirements." In general, test pressure is used to ensure the safety, reliability, and performance of a system or component, and the specific test pressure requirements will depend on the particular application and the intended use of the system or component.

Test-Pressure-Detail-from-Codes

CodeTest typeTest pressure minimumTest pressure maximumTest pressure holding timeExamination
ASME B31.1Hydrostatic(1)1.5 time designMax allowable test pressure any component or 90 percent of yield10 minutesDesign pressure
ASME B31.1Pneumatic1.2 times design1.5 times design or max allowable test pressure any component10 minutesLower of 100 psig or design pressure
AMSE B31.1Initial serviceNormal operating pressureNormal operating pressure10 minutes or time to complete leak examinationNormal operating pressure
ASME B31.3Hydrostatic1,5 times design (2)Not be exceed yield stressTime to complete leak examination but at least 10 minutes1.5 times design
ASME B31.3Pneumatic1.1 times design1.1 times design plus the lesser of 50 psi or 10 percent of test pressure10 minutesDesign pressure
ASME B31.3Initial service (3)Design pressureDesign pressureTime to complete leak examinationDesign pressure
ASME IHydrostatic1.5 times max allowable working pressure (4)Not to exceed 90 percent yield stressNot specified, typically 1 hrMax allowable working pressure (4)
ASME III Division 1 Subsection NBHydrostatic1.25 times system design pressure (5)Not to exceed stress limits of design section NB-3226 or maximum test pressure of any10minutesGreater of design pressure or 0.75 times test pressure
ASME III Division 1 Subsection NBPneumatic1.25 times system design pressure (6)Not to exceed stress limits of design section NB-3226 or maximum test pressure of any10 minutesGreater of design pressure or 0.75 times test pressure
ASME III Division Subsection NCHydrostatic1.5 times system design pressureIf minimum test pressure exceeded by 6 percent establish limit by the lower of analysis of all10 or 15 minutes per inch of design minimum wall thickness for pumps and valvesGreater of design pressure of 0.75 times test pressure
ASME III Division 1 Subsection NCPneumatic1.25 times system design pressureIf minimum test pressure exceeded by 6 percent establish limit by the lower of analysis of all10 minutesGreater of design pressure or 0.75 times test pressure
ASME III Division 1 Subsection NDHydrostatic1.5 times system design pressure for completedIf minimum test pressure exceeded by 6 percent establish limit by the lower of analysis of all10 minutesGreater of design pressure or 0.75 times test pressure
ASME III Division 1 Subsection NDPneumatic1.25 times system design pressureif minimum test pressure exceeded by 6 percent establish limit by the lower of analysis of all10 minutesGreater of design pressure or 0.75 times test pressure

Test Pressure Detail from Codes

Information on test pressure is an important part of codes and standards that regulate the procedures of pressure tests and inspections of pressure vessels, pipelines, and other PCC structures. These details define pressures and methods of testing for these systems in order to ascertain the safety measures that have been put in place. While specific requirements may vary depending on the applicable code or standard, here are some common test pressure details found in codes like ASME Boiler and Pressure Vessel Code and API (American Petroleum Institute) standards:

Hydro-static Test Pressure:

  • Hydro-static test is one of the most effective methods used in the assessment of pressure containing capacity of the pressurized vessels and pipelines.
  • With regard to the type of equipment, the test pressure is defined in relation to the design pressure as a percentage. Common values include 1. Where the design pressure of the vessel is the vessel-design factor the design pressure for the pipes should be 3 times this amount while the vessel thickness should be one cycle of the pipe thickness. 5 times for pipelines.
  • The medium used is often water; however, any other harmless medium may be used for the test.

Pneumatic Test Pressure:

  • The pneumatic tests mainly include the use of compressed air or other inert gases to determine the leakage and the pressure containment parts’ integrity.
  • The test pressure is often stated in relation to the design pressure for instance 110% or 120% of the design pressure.
  • Pneumatic tests are commonly applied when water or other liquids can be dangerous, for instance, in systems that work with aggressive or poisonous fluids.

Hold Time:

  • Codes state the time for which the test pressure has to be sustained. This is referred to as the hold time and is commonly stated in minutes.
  • The hold time is used to determine if there is any pressure loss which may suggest there are some leaks or other forms of weakness in the system.


 

Leakage Criteria:

  • Codes set the guidelines of the permissible leakage rates during the test. The criteria may define a maximum pressure drop at the end of the hold time or a maximum leakage rate in terms of cc/min.

Test Medium Temperature:

  • Some codes may require that the temperature of the test medium that is being used in the test (water or air for instance) be stated. Temperature can be room temperature or controlled to a level that is close to the working conditions of the specimen.

Test Location and Procedure:

  • According to codes, one gets to know the region where the test must be done (for instance, the whole vessel or only some parts) and the order of the process.
  • It may comprise of visual checks, pressure checks, or any checks that may be deemed fit to check the condition of the system.

 safety measures:

  • Some of the measures that should be provided for during the test include relief devices to avoid over pressurization and protection of the people involved.
  • documentation:
  • Codes necessitate the documentation of the test in detail; this includes the test pressure records, the test results, and any deviation from the code.

Requalification:

  • Sometimes, there may be a need to carry out further requalification tests after repairs or alterations of pressure equipment to check on the equipment’s fitness and compliance to the laid down standards.

It is necessary to state that pressure test parameters can be different based on certain code, type of equipment, or its function. Hence, it is recommended to rely on the code or standard being followed and consult engineers and inspectors when carrying out pressure tests to conform to the necessary standards and prevent risks.

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