​How do you pressure test; Pressure testing Procedures

Most equipment and appliances, both at home and in the factories, work with mechanical systems controlled by pressure. We must ensure they are working as planned, and one of the ways to test the integrity of the equipment is by applying pressure it typically receives under working conditions and ensuring it does as it should. It is necessary to apply a higher pressure and ensure no pressure loss before we continue to use them if they pass, repair, or completely replace them if they fail a pressure test.

Why pressure test?

Pressure testing is carried out to investigate a vessel's various limits, which will test areas of reliability, maximum capacity, leaks, joint fittings, and pressure. It is done on hydraulic and air hoses retaining cylinders, gas cylinders, pipelines, and hoses without testing and ensuring this information. The owners and operators cannot put materials not tested into service except if they know that it meets set pressure test requirements to function.

The information from pressure testing helps maintain the safety standards and the upkeep of the facility or equipment tested. When conducting pressure testing, they are conducted under the industry or customer specifications—depending on the type of testing, filling the vessel with an incompressible liquid like oil or water and then, in some instances, include dyes. The dyes can help facilitate detecting any leaks. When under appropriate pressure, the vessel is examined for any leaks or changes in shape. The vessel's pressure is always considerably higher than the normal operating pressure; this allows for any unexpected pressure levels on the vessel for maximum safety.

Information you get after the tests is stamped onto the tested vessel, including a serial number, manufacturer, and manufacturer date. This stamped information is usually recorded on a computer system, allowing the owner to track when the tests was done taken place or need to be scheduled for a later date. There may be other information such as REE (Rejection Elastic Expansion) and maximum expansion specified by the manufacturer for safety. Data management of this information is essential for recall when another test is scheduled in the future.

Types of pressure testing

As initially explained, pressure tests are performed to ensure pressure systems' safety, reliability, and leak tightness. Pressure testing is essential especially for a new pressure system before use or an existing one after repair or modification. There are two types of pressure tests. Hydrostatic and pneumatic. A hydrostatic test uses water as the test medium, whereas a pneumatic test uses air, nitrogen, or any non-flammable and nontoxic gas. Most times, pressure tests must be hydrostatic unless pneumatic tests can be justified. It is essential to note that Pneumatic testing is considered dangerous.

Equipment for Pressure testing

The various equipment used for pressure testing includes; pressure gauges, temperature and pressure recorders, and hydrostatic test pumps.

Pressure Gauge

Pressure gauges are relatively inexpensive mechanical devices that, for the most part, are read manually.

One of the most well-known types is the Bourdon gauge, patented in France by Eugene Bourdon in 1849.

Temperature and pressure recorder-receiver

A temperature and pressure recorder receiver is designed for general temperature and applications and records controlled temperature and pressure on a graph.

Hydrostatic Test Pumps

A Hydrostatic Test Pump is a self-contained, portable, low volume, high-pressure pump powered by hand, air, electric, or gas engines, and with a high-pressure hose connected to the equipment. The pump is used to check the tested component and is filled up with an incompressible liquid, usually water. Example of a test pump is this Three Stage Electric Hydraulic Pump Torcstark SP304 although used for torque wrench but can also be used for hydrostatic tests.

Pressure testing procedures.

The procedures written here do not replace paid consultations from testing experts but give you a starter idea of what it entails and how to start your decision-making as provided by SLAC National Accelerator Laboratory Environment, Safety & Health Division Pressure Systems.

All pressure tests will be conducted using a gauge calibrated within the previous 12 months. The pressure gauge should be sized, so the test pressure is in the middle third of the gauge's pressure range. Gauge materials and fluids are to be compatible with the test fluid. When possible, the use of blind/blank flanges or caps should be considered for test boundaries to prevent damage to valves.. Pressure tests must always be performed under controlled conditions, following an approved test plan, and documented in a test record. A single approved test plan may be used for several similar tests, but a separate test record is required for each.

Test Procedures

Various test procedures and the persons responsible for each are indicated below:

Planning Phase

Step 1. Mechanic Completes pressure test plan after consulting the project engineer and submits for approval

Step 2. Supervisor Approves plan

Step 3. FCM in charge of test Approves plan

Step 4. Pressure systems program manager Approves plan (not required for routine testing of existing systems)

Performing phase

Step 5. Mechanic Ensures the pressure gauges used have current calibration stickers

Step 6. Mechanic Removes pressure relief valves or non-reclosing relief devices from the vessel or test boundary where the test pressure will exceed the set pressure of the valve or device OR Holds down each valve by means of an appropriate test clamp and pressurizes both sides of non-reclosing relief devices Installs temporary, higher-rated devices where

Practical Phase

Step 7. Mechanic Installs the calibrated test gauge so it is visible at all times

Step 8. Mechanic Ensures the skillet blanks, test plugs, or clamps are appropriate for use and are free of obvious defects

Step 9. Mechanic Removes all persons not directly involved with the test from the pressure test exclusion zone. Posts barricades, signage, etc. as specified in Pressure Test Plan to prevent unauthorized personnel entry.

Step 10. Inspector Reviews approved test plan; reviews test setup; verifies test equipment is appropriate for the test

Step 11. Inspector Witness entirety of test 12. Mechanic Verifies that the pressure is continually monitored to ensure that pressure never exceeds the designated test pressure of the system

Step 13. Mechanic Hydrostatic testing: Fills and vents system as necessary to remove as much air as practical

Step 14. Mechanic Pressurizes system following testing protocol specified in Pressure Test Plan. Holds pressure at test pressure for specified time noting any drop in pressure.

Step 15. Mechanic Pneumatic testing: reduces the pressure to the design pressure (or as specified in Pressure Test Plan) before proceeding with the inspection; holds the pressure for a sufficient period of time to permit inspection of the system

Step 16. Mechanic Pneumatic testing: Applies a soap solution to accessible welds, screwed pipe joints, flanges, etc. where leakage is suspected

Step 17. Mechanic If there is evidence of structural distortion, either rejects the system or repairs as advised by the inspector

Step 18. Mechanic If there is leakage in the system, performs the following as appropriate: Ensure repairs is performed and returns to Step 13 or Rejects the system

Step 19. Mechanic Pneumatic testing: When the test is completed, vents the test pressure to approved discharge location and returns relief devices to normal configuration Hydrostatic testing: Relieves pressure and disposes of test fluid as described in Pressure Test Plan and returns relief devices to normal configuration

Recording and documentation phases

Step 20. Inspector Signs pressure test record

Step 21. Mechanic Completes pressure test record and submits copy to the pressure systems program manager and to the Building Inspection Office (when applicable)

Step 22. Mechanic Submits copies of the test plan and test record to the custodian

Test Pressure Codes and standards organizations

(ASME, NFPA) and state regulations (California Code of Regulations) specify test pressures and procedures applicable to various systems. The test pressure for a piping system is based on the maximum design pressure of the system, and for a pressure vessel based on the maximum allowable working pressure (MAWP) of the vessel. Systems undergoing retesting should not be tested at pressures higher than the original testing pressure. The project engineer and the pressure system mechanic are responsible for defining and documenting the pressure test plan on the Pressure Test Plan Form. The following table provides guidance in selecting the appropriate test pressure and in developing the test procedure. Unless otherwise noted below, there should be no pressure drop in the system for the required test duration.

Required test pressures

Test Pressure Codes and standards organizations (ASME, NFPA) and state regulations (California Code of Regulations) specify test pressures and procedures applicable to various systems. The test pressure for a piping system is based on the maximum design pressure of the system, and for a pressure vessel based on the maximum allowable working pressure (MAWP) of the vessel. Systems undergoing retesting should not be tested at pressures higher than the original testing pressure. The project engineer and the pressure system mechanic are responsible for defining and documenting the pressure test plan on the Pressure Test Plan Form.

Use the following table provided by SLAC here for guidance in selecting the appropriate test pressure and in developing the test procedure. Unless otherwise noted; there should be no pressure drop in the system for the required test duration.

What should be contained in a typical test plan

Test Plans A pressure test plan, at a minimum, contains the following formation:

• Approved Pressure Test Plan Form
• Drawings of the system being tested. Identify the location of the test setup, and test boundaries, and identify all blank/blind flange locations if applicable
• Drawing showing the exclusion zone with the location of signage, barricades, or other controls
• Detail of the test setup. Identify the pressure ratings of all components and pressure relief valve settings.
• Provide product data sheets if needed.
• Pressure gauge calibration sheet
• Detailed test procedure

Record-Keeping

The following recordkeeping requirements apply for this procedure:

The custodian of a given pressure system must maintain copies of test plans and records for five years.

The pressure systems program manager maintains copies of all pressure test plans and records permanently.

With team members that have diverse work experience in this field reach to us for support for hydrostatic and pneumatic test equipment and services.