HYDRAULIC PRESSURE TESTING | Explained with Templates

This article will cover many areas relating to what it is, how it works, types of systems deployed upon, guidelines/regulations, calculation method, testing method, tolerances, checklists/requirements, reports, certification, templates, and general questions are asked.

Table of Contents

🟩 What Is Pressure Testing

Hydrostatic (or hydraulic) pressure testing evaluates the strength, integrity, and reliability of pipework, vessels, and other components designed to contain fluids or gases.

After the pipework, components, and system have been installed and inspected, it will be filled with a liquid – typically water – before pressuring it to a specified or calculated level. This pressure will normally be above the system’s maximum operating pressure to check for any leaks, deformations, or weaknesses.

The pressure is then held for a specified and agreed amount of time to allow any issues to appear, which, if any are noted, will be addressed before the system is put into service.

From a safety point of view, pressure testing is also used as a safety measure to ensure that components can safely withstand the pressures they will encounter during these normal operations.

Use the table of contents to navigate this article and locate the Pressure Testing Certificate and Template Method Statement that can be downloaded.

🟩 Can Hydrostatic Testing cause damage to a System

Yes, hydrostatic pressure testing a system can, if not completed by experienced operatives and engineers who fully understand the requirements, cause damage. Sometimes catastrophic, life-threatening, and extremely expensive.

🟩 What Testing Methods Can Be Used

The testing method can be different depending on the type of system, materials used, the fluid being transported, and other safety factors.

If we concentrate on normal practice, in a standard commercial construction project, water is usually transported, so there would be three types of testing methods that could be utilized:

• Hydraulic Pressure Test only
• Pneumatic Leak Test followed by a Hydraulic Pressure Test
• Pneumatic Leak Test followed by a Pneumatic Pressure Test

🟩 When would you ONLY use a Hydraulic Pressure Test

Completing only a hydraulic pressure test is quite common, omitting the pneumatic, but should be conducted only once an evaluation has been conducted to understand if there are any risks with the surroundings in case of failure – resulting in damage to existing installations or furnishings.

If there are no risks, then this would be acceptable; if any hazards are noted, a pneumatic test should be conducted prior.

🟩 Other Phrases For Pressure Testing

We have all encountered different phrases used when doing this type of when depending on where we are. Here are a few we have heard; drop us a line on Linkedin if you have any others that can be added:

• Pipework pressure testing,
• Hydrostatic pressure testing,
• Hydronic testing,
• Water pressure testing,
• Hydrostatic leak testing,
• Hydrostatic burst testing,
• Water line testing.

🟩 Pressure Testing Definitions

There are a few definitions, as below, that we need to understand and will aid us in our understanding:

🟩 Types Of Systems And Materials Testing Covers

Within the construction industry, pressure testing can be used on the following types of systems and types of materials:

🟩 How Does Hydraulic Pressure Testing Work?

Pressure testing involves filling the pipework system or component with water and then pressurizing it to a level that exceeds its normal operating/design pressure, testing its integrity.

The pressure is usually created using a hand pump or compressor in a larger system.

As the pressure inside the pipework/system increases, it starts to exert a ‘hydraulic force’ on the internal walls of the pipework and any joints or fittings that are connected and installed.

If there are any weak points in the system, such as a faulty joint or a crack in a pipe, the hydraulic pressure will cause the system to fail at that point, either by causing a leak or by causing the system to rupture – resulting in a failed test. If there are no weak points, the pressure will remain in line with the pressure that was created.

Overall, hydraulic pressure testing is a way to ensure that pipework systems are safe and reliable by subjecting them to high levels of pressure to test their strength and integrity.

OPEN TEMPLATE of our PNEUMATIC & HYDRAULIC PRESSURE TESTING Method Statement including INSTRUCTIONS, that can be downloaded allowing editing and clean exporting for your project/company use.

All as per the format and layout are shown in the sample document, at the end of this article.

🟩 What Testing Pressure Should Be Used?

Similar to the above, this will depend on the type of system and project requirements; as an example, if we are looking at chilled water, condenser water, mains water, or heating hydraulic system that has been installed using carbon steel, copper or galvanized Pipework the expected pressure used will be 1.5 times the design pressure, according to BESA – see table in next section.

⚠️ As noted, check the project specifications – if nothing is indicated, then 1 hour should suffice, and BESA can be referenced as an industry standard.

🚀 BESA – Building Engineering Services Association | Document TR6 Guide to Good Practice – Site Pressure Testing of Pipework. [BESA Publication | Details of your selected Publication (thebesa.com)]

We have added a Pressure Conversion Table to the site see 'PRESSURE CONVERSION TABLE | Bar, Pa, Kpa & Psi' if want to read more

🟩 How Long Should Pressure Testing Take?

This will depend on the type of system and project requirements; as an example, if we are looking at chilled water, condenser water, mains water, or a heating hydraulic system that has been installed using carbon steel, copper, or galvanized Pipework, the time period required according to BESA is for the system to hold steady for 1 hour.

⚠️ As noted, check the project specifications – if nothing is stated, then 1 hour should suffice, and BESA can be referenced as an industry standard.

🟩 Reference Table – Pressure, Time, and Tolerances

For most systems requiring a hydrostatic test, it would be in line with the below table/graphic that details the requirements of a hydrostatic test, including the length of time for testing and pass/fail tolerances.

Testing Tolerances provide clear direction as to what the allowable error within the testing results will be acceptable and is represented by a +/- value. If the testing result falls within the tolerances, it will be deemed a ✅ PASS; if it does not, it will be deemed a ❌ FAIL.

If a result is ‘out of tolerance,’ then a retest must be completed.

As shown in the table below, testing tolerance for a general water pressure test following BESA would be 0% drop or gain.

⚠️ This table is provided as an example, and for your specific requirements, the specifications and contract documentation should be checked.

*See our pneumatic pressure testing article for further information

🟩 Pressure Testing Guidelines & Regulations

🟧 Guidelines

Although pressure testing is seen as a quick basic test that anyone can complete with a hand pump and a calibrated gauge, there are currently four guidelines that can be referred to that would allow the testing to be specified properly.

• BESA TR/6 Site Pressure Testing of Pipework [UK developed]
• ASME Power Piping Code B31.1 [USA developed]
• ASME Process Piping Code B31.3 [USA developed]
• ASME Code for Pressure Piping B31.9 [USA developed]

These Guidelines are similar in process and outcome, but in our opinion – BESA provides better information on the requirements and methods of testing. Especially for different types of pipework.

🟧 Regulations

Within the United Kingdom, pressure testing pipework regulations are covered by ‘the Provision and Use of Work Equipment Regulations 1998 (PUWER)’.

These should be referenced to understand your responsibilities as an employer when carrying out these types of activities.

🟩 Hydrostatic Pressure Testing Calculations

To understand the ‘Hydraulic Testing Pressure’ requirement that the system needs to be exposed to, we first need to calculate the following:

• System Static Pressure
• System Pump Pressure
• Maximum Working System Pressure

🟧 System Static Pressure Calculation

System Static Pressure [SSP] refers to the pressure exerted by a hydraulic water column when it is not in operation and is influenced by a couple of factors:

• Type of Fluid
• Density of Fluid
• Height of the System

If the static pressure is not provided within the design documents, it can be calculated by using the following equation:

p = ρ × g × h + p0

p = hydrostatic pressure [Bar, kpa, psi]

ρ = density of the fluid [kg/m³, slugs/ft³]

g = gravitational acceleration [9.81m/s²] [32.174 ft/s²]

h = height of the water column [m] [ft]

p0 = external pressure [101.33 kPa atmospheric]

🚀 System Static Pressure Calculation Example

To find the static pressure of a chilled water system using pure water, with a total vertical water column height of ’10’m [‘32.81’ft], the hydrostatic pressure would be:

p = ρ × g × h + p0

p = 1000kg/m³ × 9.81m/s² × 10m + 101.33

Below is a table showing different static pressures for various water column heights:

🟧 Maximum Working System Pressure Calculation

This will calculate the total pressure that the overall system will experience when in operation; it can be calculated by using the following equation:

MWSP = SSP + SPP

MWSP = Maximum Working System Pressure [Bar, kpa, psi]

SSP = System Static Pressure [Bar, kpa, psi]

SPP = System Pump Pressure [Bar, kpa, psi]

Once this has been understood, the Hydraulic Testing Pressure can be worked out, providing the pressure to which the system is to be pressurized.

🚀 System Maximum Working Pressure Calculation Example

A chilled water system has a System Static Pressure [SSP] of 98.2kpa and a System Pump Pressure [SPP] of 147kpa. What is the Maximum System Working Pressure [MWSP] in the system, expressed in bar, kPa, and psi?

MWSP = SSP + SPP

MWSP = 147 kpa + 98.2 kpa

MWSP = 245 kPa, 2.45 bar, 35.6 psi.

🟧 Hydraulic Testing Pressure Calculation

To calculate the actual testing pressure that the system will be exposed to, use the following:

HTP = MWSP x 1.5

HTP = Hydraulic Testing Pressure

MWSP = Maximum Working System Pressure

1.5 = as per BESA TR/6

🚀 Hydraulic Testing Pressure Calculation Example

A chilled water system has a Maximum Working System Pressure [MWSP] of 245kpa. What is the Hydraulic Testing Pressure [HTP] that the system should be tested too in Bar, kPa, and psi?

HTP = 245 kpa x 1.5

HTP = 367.5 kpa, 3.67 bar, 53.22 psi

🟩 Reference Chart – Bar to PSI to kPa Chart

Below is a chart showing the conversion between the Bar, kPa, and psi pressure units.

For additional information and conversions up to 50 bar, see our article | '***'

🟩 How to check hydraulic pressure

🟧 New System

If a new system is to be installed, the hydraulic pressure would be provided by the HVAC designer of the system; note that this should include the pump operating pressure.

Where this information is not included within the design documents, then an RFI [request for information] should be raised.

🟧 Existing System

Where a system exists without design data, the system’s hydraulic pressure can be checked via instruments and pressure sensors.

If none are installed, a temporary calibrated pressure gauge at the lower part of the system can be useful.

Here are some steps to do this:

🟨 Step 1 – Locate a pressure tap or test port

A pressure tap or test port is a point in the system where a temporary instrument can be installed so that a pressure measurement can be taken; there is usually an isolation valve that can be used to open and close the system to the gauge.

They are usually located near a pump.

🟨 Step 2 – Attach a temporary pressure gauge or sensor

Attach the temporary pressure gauge or sensor to the pressure tap or test port. Ensure the connections are tight and secure, checking for leaks.

🟨 Step 3 – Open the isolation valve

Open the isolation valve that controls the flow to the pressure tap or test port. This will allow the fluid to flow through the gauge or sensor.

🟨 Step 4 – Check the pressure reading

Check the pressure reading on the gauge or sensor.

🟨 Step 5 – Record the reading

Record and document the pressure reading for future reference and use when determining the hydraulic testing pressure.

🟩 Testing Equipment to Be Used [PDF]

The following equipment will be utilized during the Hydraulic Pressure Testing works.

• Hand Pump: A pump that generates the required hydraulic pressure within the system.
• Hoses: these are flexible tubes/pipes, rated at the correct pressure, connected from the pump to the system under test. They can also be used for looping and connecting other systems.
• Calibrated Pressure Gauges: used to measure and monitor the pressure within the system that is under test.
• Pad Locks and Chains: to lock off valves or other system components to ensure they cannot be inadvertently opened during the test.

🟩 Pressure Testing Safety Checklist

A few requirements are needed before starting the work to ensure the testing is completed safely.

To download these checklists [MS Word / PDF], click on the button below to be taken to our shop:

🟧 Personal Protective Equipment [PPE]

Personal Protective Equipment [PPE] refers to any equipment or clothing worn by anyone involved in the works to protect themselves from the hazards they will be exposed to.

Each project should be evaluated for its specific risks, but in general, the PPE that will be worn would be:

🟧 Site Safety Equipment

Where PPE is worn to protect those completing or involved with the tasks, site safety equipment is used to allow them to carry out the work safely.

Items of equipment that could be used would be:

This can include items such as safety harnesses, anchor points, and safety nets.

🟩 Hydrostatic Pressure Testing Method

Below are the steps necessary to deliver a successful pressure test.

🟧 Step 1 – Complete General Pre-Requisites Checks

The checks, as detailed below, should be completed to ensure that everything is set up for the testing to commence.

Status B - Testing can proceed as long as comments have been addressed and do not affect the testing.

Status B - Testing can proceed as long as comments have been addressed and do not affect the testing.

🟧 Step 2 – Pipework Installation Checklist/Inspection Record

Before the testing and commissioning phase takes place, the following will be checked.

Here is our open copy [MS Word] of the GENERAL PIPEWORK Pre-Functional Checklist, for making life a little easier.

We have also recently formatted this checklist to [MS Excel] and included it as a Bonus for FREE.

So get an MS Word & MS Excel for the same price.