HYDRAULIC PRESSURE TESTING | including full Example

January 1, 2023 |

Completed after any new or modification works, Hydraulic/Hydrostatic Pressure System Testing is a non-destructive test that is commonly used to prove the integrity of a pipework system or vessel, ensuring there are no leaks. The method uses a medium of water that is introduced to the system and pressurized via a handpump, providing the specified pressure.

In this article, we will cover the guidelines that can be referenced, understanding of risk/damage to systems, and the steps that can be taken to conduct a successful test.

If you are looking for a method statement for pressure testing pipework, we have included one at the end of this article in [PDF] or an open copy can be bought in our shop.

Table of Contents

Pressure Testing Guidelines & Regulations

Guidelines

Although pressure testing is seen as a quick basic test, that can be completed by anyone with a hand pump and a calibrated gauge, there are currently 2 guidelines that can be referred that would allow the testing to be specified properly.

Both 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.

Pressure Testing Definitions

Before we get into the pressure testing there are a few definitions that will help us understand more of what is happening, the below are commonly heard on most construction projects:

WordingDefinition
Maximum Working PressureMaximum working pressure' is defined as the 'maximum pressure in the system during normal operation' and comprises of:

1. System Static Pressure [head or height of the system].
2. System Pump pressure.

The maximum working pressure is likely to be at the base of the system where the systems static pressure is greatest - very important if dealing with high-rise buildings, etc.
Testing PressureThe test pressure is the pressure to be applied to the system during pressure testing under static conditions [pumps not running].
Total System PressureTotal System Pressure' will cover all pipework, joints, equipment, etc for a complete system. This is usually the best and quickest way to test, but subject to the system size and configuration.

Commonly completed after the Pipework Flushing and Cleaning Stage of the Onsite Commisisoning Process.
Sectional TestSectional Pressure Testing' will involve splitting the complete pipework/equipment into various smaller sections by blanking off each section.

This method is usaully used on larger projects where testing the complete system at once is not feasable.

Usually completed before water flushing etc.
Valve to Valve TestValve to Valve Testing' is used similar to a sectional test, but in this case, the valves are used as the ‘blanks’. Testing will go to the back of the valves or through the valves.

As the valve to valve testing is completed the whole system will be covered
If you would like to read more on pipework flushing and cleaning see our article 'FLUSHING & CLEANING | Pipework Systems Overview'

To download the above graphic [Free] in A4-PDF, click the below button to be taken to our shop:

Can Hydrostatic Testing cause damage to a System?.

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

What Testing Methods are used for Pressure Testing?

The selection of the type of testing procedure to use is important, due to systems and safety factors. It will also depend on the material of pipework and what will be transported within it during normal operations [water, oil, diesel, gases, etc].

If we look at normal practice in a standard Commercial Construction Project, water is usually transported, so there would be 3 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

Note: a Hydraulic Pressure Test could be referred to as a Hydrostatic Pressure Test or Water Pressure Test.

A Pneumatic Leak/Pressure Test could be referred to as an Air Test or Nitrogen Pressure Test.

When would you ONLY use a Hydraulic Pressure Test?

The majority of the time, just a Hydraulic / Hydrostatic Pressure Test will be sufficient and, is the most common type that would be found on a project.

Saying that though, we should still evaluate if the test is suitable for the environment and surroundings it is being conducted in.

Some quick questions and checks can be done to give us that confidence, starting with…

Q1. What are the Expected Impacts, if there are any Leaks?

Within this question there are 2 things we need to look out for and, if the answers are both ‘NO’ or ‘NO RISK’ then a Hydrostatic Pressure Test ONLY could be completed.

Any ‘YES’ or ‘NOTE OF RISK’, we would need to conduct a Pneumatic Leak Test before Hydraulic Testing.

So what are the things we are looking for:

  • Damage to the existing property
  • Cost/fines in $$$ of any repairs, including effects to business operations

The first item to consider is:

‘if we introduce water to this system/installation, could there be an open-end somewhere?’

This question is being asked because it will all depend on the size of the system. If the system is small and only a few people have worked on it then generally would expect it to be ok, with no open ends.

If the system is large and many people have worked on it then there is a good chance of an open end.

Pneumatic & Hydrostatic Pressure Testing Method Statement Template [MS Word]

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.

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The second item to consider is:

‘if the system does leak, either from an open-end or, when under pressure during the testing, could there be significant damage caused to the areas or is there a potential for the operation of the building or business to be interrupted’

This question is asked as in some instances the system/pipework that is being tested can run through existing client areas where they can have expensive artwork, carpets, ceilings or worse, equipment like servers, etc, that if damaged could cause a big fine or affect the business operations.

For a project still under construction, systems can run through finished areas or near/over critical equipment.

What do we do if there are any risks identified?

If there is any risk then a Low-Pressure Pneumatic Leak Test should be conducted before introducing any water to the systems for the Hydrostatic Pressure Testing.

Q2. Is there Easy Access to the System?

This is another critical item that should be reviewed before starting the testing.

If there is easy access to the system and leaks can be fixed then no issues.

But if the access is restricted or an issue then we would also look to complete a Low-Pressure Pneumatic Leak Test. Just to be on the safe side.

Why conduct a Low-Pressure Pneumatic Leak Test before a Hydraulic Pressure Test?

As we saw above – we would ensure a Low-Pressure Pneumatic Leak Test is conducted before Hydrostatic Pressure Test, as it is a low impact / low risk if:

  • there is a risk of any open end on the system.
  • there could there be significant damage caused to the localized areas or, is there a potential for the operation of the building or business to be interrupted and affected.
  • access to the system is difficult after installation.

When would you ONLY use a Pneumatic Pressure Test?

In some instances a Pneumatic Pressure Test would be only used where:

  • a hydrostatic pressure test is not acceptable due to the design of the system/pipework for example Gas Pipework.
  • Water is in short supply.
  • The introduction of water is not preferred as the system is not going to be put into operation until a later date.
  • Code requirements, such as Pre Action / Clean Agent Systems require it.

How to calculate Hydrostatic Testing Pressure?.

For most systems requiring a hydrostatic or pneumatic pressure test, the testing would be in line with the below graphic. In some instances, there will be a requirement to follow local codes or regulations.

These, as well as the other testing, should be reviewed and clarified the full requirements from the project specifications and drawings.

To download the above graphic [Free] in A4-PDF, click the below button to be taken to our shop:

For the general systems that are carrying water and have metal pipework BESA TR/6 notes for testing pressure and time:

For all Metal Pipework Systems**, a test pressure of at least 1.5 times the maximum working pressure of the system shall be applied.

If the test pressure holds steady for one hour, the system is deemed to be satisfactory.

BESA – Guide to Good Practice – TR/6

**excluding fire systems and compressed air as these will be covered under local codes and regulations.

Calculation Examples

Maximum Working System Pressure = System Static Pressure [Height/Head of the building] + System Pump Pressure

Hydraulic Testing Pressure = Maximum Working System Pressure x 1.5**

**from BESA TR/6 – check all specifications for requirements for the specific project.

To download the above graphic [Free] in A4-PDF, click the below button to be taken to our shop:

How to Write a Method Statement for Pressure Testing of Pipework Systems?

So, hopefully, you have got through all that and now we need to understand how to complete a pressure test and what is required from a documentation point of view.

On most construction projects the first step will be to create, write, and, the issue for review/approval a Testing Method Statement or Testing Procedure.

The reviewer would usually be a consultant in the client’s team – Designer or Commissioning Managing Company [CxA / CxP].

As we probably know, many formats can be used for any Method Statement, and for us, the best one is the one that takes the least amount of time to create for each project.

Using a standard layout saves a lot of time and effort across multiple documents. We have covered a detailed method statement format in another post ‘HOW TO WRITE | A Method Statement’

Based upon our previous post we would format the document like the following:

  • Front Cover
  • Index or Contents Page
  • Introduction
  • Reference Data
  • Competency of Engineers Statement and Information
  • Permit to Work System
  • Programme
  • System Installation and Sign Off
  • Equipment Calibration
  • General Pre-Requisites
  • System Testing Information
  • Testing Tolerances
  • Method of Testing [Pneumatic Leak & Hydrostatic Pressure]
  • Pressure Testing Certificate + Information

As this format has been covered within the other article, we will cover here the following:

  • Reference Data,
  • Permit to Work,
  • Equipment Used and Calibration,
  • General Pre-Requisites,
  • System Testing Information,
  • Testing Tolerances,
  • Personal Protective
  • Equipment,
  • Testing Methods, and,
  • the Certificates/documents.

Reference Data

The information that will be needed to allow us to write and include the correct information will be the following:

RefDocument/InformationReason
1Commissioning Plan Commissioning Specification General Mechanical Specification Specific Mechanical Specification

[List the relevant sections within the table of the method statement for easy reference]
Provides us information that is general and also specific to the project, the documents would usually direct us for:

1. Codes / Standards should be using and based the testing upon.

2. Testing Pressures Requirements [1.5x, 2x etc].

3. Testing Times [1, 4, 12, 24 hours].

4. Testing Tolerances +/-
2BESA TR/6 or similar depending upon the country we are working in

[List the document and details in the table of the method statement for easy reference]
If the specifications provide limited information then, these types of documents will give an industry standard for the testing and a good point of reference for you if the consultants start to whine.

Note the project specifications may trump any guidelines so better to understand this also.
3Material / Technical Submissions for the Pipework Materials, Fittings, and Valves.

[List the documents reviewed]
Understanding the types of materials is very important as in some circumstances different testing could be required from the normal.

So check the pipework, fittings, valves, control valves, and important equipment for if can test to the pressures expected.
4Construction Drawings

[List the documents reviewed]
These should be already reviewed and noted Status A, or B.

The drawings will allow you to understand if you can complete a full system test, or need a flange to flange/valve to valve. This will affect your strategy for testing so very important the drawings are reviewed.

Permit to Work

The project will most probably have a permit to work system, and this should be understood during the writing of the document and, included in a table to advise the operatives. Some points of note for us usually are:

RefRisk/EvaluationReason
1Existing SystemsIn some instances, there are requirements where we will need to interact with existing systems.

These systems will be under the control of the facilities management company/operators and works will need to be coordinated with the relevant permits in place.
2System PressuresSystem pressures could be an issue at some point - especially if using Air / Nitrogen to Test.

Health and Safety should be considered and may require a permit
3Flood/Water DamageSimilar to the Existing Systems, there maybe a requirement to have a permit to allow testing due to risk of damage to existing installations or equipment.

For example in a Server Room that is live and we are testing, would generally be a requirement for a permit.
4Tampering/Working in clise proximity to the testingOn the reverse of us obtaining a permit, the project may need to issue a permit if people need to work on or around the pipework under test.

In most circumstances this would mainly be people working around the installation. If they are working on it then we got a bit more of an issue than a permit.

System Testing Information

Within this section there should be a table included to detail the type of system the Method Statement covers, if will be a Hydrostatic/Pneumatic, the expected working pressure of the system, testing requirement, testing pressure, medium used for testing, specification/code/guide/standard used and referenced.

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Testing 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. As long as 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 would need to be completed.

As can be seen in the above graphic, testing tolerance for a general water pressure test following BESA would be 0% drop or gain.

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Personal Protective Equipment Required:

To ensure the testing is completed safely there will be a requirement for the operatives and engineers to wear suitable Personal Protective Equipment [PPE] such as:

  • Hi-Visibility Vest,
  • Safety Goggles,
  • Safety Gloves,
  • Helmet with chin strap,
  • Long Sleeve Shirt,
  • Long Trousers,
  • Safety Boots.

Pressure Testing Method

Ok, now we are ready to write how the testing will be conducted.

Let’s say it has been decided that we need to complete a Pneumatic Leak Test before the Hydraulic Pressure Test and all Pre-Requisites have been completed, excluding filling and venting the system with no observations noted.

Pneumatic Leak Test Method

Instruments and equipment required:

The following equipment will be utilized during this stage of the testing, taken from the equipment list.

  • Signage / Barriers
  • Air Compressor
  • Hoses
  • Pressure Gauge [for air and calibrated]
  • Pad Locks and Chains [to lock off any valves etc]

System Testing Requirements

For a general pneumatic leak test, we are trying to understand if there are any opens ends within the system that is to be Hydrostatically Tested.

With this in mind and, due to the safety concerns surrounding the use of compressing air for pressure testing, we will use only low pressure.

The pressure that should be used to ensure there is limited risk would be less than 0.5 bar for around 30 minutes. [this has to be checked with the site health and safety team to ensure they agree and can provide any comments].

General Pre-Requisites [Pneumatic Leak]

Once the Health and Safety Team is happy then the General Pre-Requisites should be reviewed and completed.

RefDetailsNotes
1All Technical / Material Submissions Status A
2All Drawings of System [Layouts & Schematics] Status A and fully marked-up showing clearly the testing areas and testing numbers, being proved via a visual inspection. Where a different status is shown the following will be allowed:

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

Status C & D - Testing will not proceed
3Testing Method Statement reviewed and provided a Status AWhere a different status is shown the following will be allowed:

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

Status C & D - Testing will not proceed
4All Delivery Records Available for Inspection
5All Installation Inspection Records AvailableFor Inspection showing systems to be tested have been inspected by the Resident Engineering Team and, accepted as being installed in line with the project requirements.

Where not available testing will not be allowed to commence.
6All Permits are in place as noted in the 'Permit to Work' Section & system set up for testing, padlocks, protections, signage, etc.Where not available testing will not be allowed to commence.
7Items of equipment that may be affected by the higher pressures are isolated or removed and replaced with spool pieces.Where not testing will not be allowed to commence.
8All pipework fittings and equipment is rated for the pressure testing requirement.Equipment, Hoses, Valves, Control Valves, Connections, Gaskets.

This is can be an issue in high-rise buildings.
9Calibration Certificates are available for all instruments and equipment and within the date.
10Pressure Gauges are installed at the lowest point and highest/furthest point of the system with a display/range applicable to the testing pressure.If not they will need to be relocated or replaced.
11If a compressor is being used, it is connected to the system at the lowest point.If not there will need to be.
12Power is available if a pump/compressor is being used
13All pipework joints are exposed, i.e not insulated to allow for observing of the system.
14System set up inline with any strategies, valves open/closed / blanks installed etc
15Operative and Engineers fully trained and where required hold a current relevant certificate to complete the works.

Once the above table has been verified and agreed complete the Pneumatic Leak Test can be commenced.

Pneumatic Leak Test Method of Testing Steps

With the compressor, valves, and gauges connected:

Step 1: Raising the System Pressure

  • Open the valves to the compressor,
  • Turn on compressor,
  • Slowly raise the air pressure within system using increments of 0.1 bar / 1.5 psi,
  • Stop when meet the required testing pressure [usually 0.5 bar / 7.5psi].

Step 2: Allow System to Stabalize

  • Once the testing pressure is reached and verified, shut off the valves at the system connection to the compressor and allow the system to settle for 10 minutes,
  • If there is a drop in pressure during the 10 minutes, this could be due to the system settling, use the compressor to top-up the system, ensure the valves are opened prior to turning on the compressor and closed after switching off [this will be the only time a top-up is allowed].

Step 3: Confirm System Stable

  • Once confident that the system is stable complete the pressure testing certificate by documenting the information required,
  • The testing time will now start.

Step 4: Starting the Testing

  • Ensure that at 0.5 bar / 7.5 psi testing pressure is held for at least 30 minutes,
  • During the testing time, check system and gauges for any signs of leakage or loss of pressure.

Step 5: Completion of Testing

  • If there is no pressure loss noted over a 30 minute time frame then the test can be completed and a Pass provided,
  • If there are leaks or pressure loss then they should be investigated, the issues addressed, and then conduct a full retest until the system passes.
  • Once all confirmed complete the commpressor, gauges, and temporary valves/hoses should be removed, with any equipment checked or reinstalled to ensure normal status.

Hydraulic Presusre Testing Method

Instruments and equipment required:

The following equipment will be utilized during this stage of the testing, taken from the equipment list.

  • Signage / Barriers
  • Hand Pump
  • Hoses
  • Pressure Gauges [for water and calibrated]
  • Pad Locks and Chains [to lock off any valves etc]

System Testing Requirements

Referring back to the General Pre-Requisites, after the pneumatic leak test, we need to complete the following checks before testing takes place.

General Pre-Requisites [Hydraulic Pressure]

RefDetailsNotes
1All Technical / Material Submissions Status A
2All Drawings of System [Layouts & Schematics] Status A and fully marked-up showing clearly the testing areas and testing numbers, being proved via a visual inspection.Where a different status is shown the following will be allowed:

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

Status C & D - Testing will not proceed
3Testing Method Statement reviewed and provided a Status AWhere a different status is shown the following will be allowed:

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

Status C & D - Testing will not proceed
4All Delivery Records Available for Inspection
5All Installation Inspection Records AvailableFor Inspection showing systems to be tested have been inspected by the Resident Engineering Team and, accepted as being installed in line with the project requirements.

Where not available testing will not be allowed to commence.
6All Permits are in place as noted in the 'Permit to Work' Section & system set up for testing, padlocks, protections, signage, etc.Where not available testing will not be allowed to commence.
7Items of equipment that may be affected by the higher pressures are isolated or removed and replaced with spool pieces.Where not testing will not be allowed to commence.
8All pipework fittings and equipment is rated for the pressure testing requirement.Equipment, Hoses, Valves, Control Valves, Connections, Gaskets.

This is can be an issue in high-rise buildings.
9Calibration Certificates are available for all instruments and equipment and are within date.
10Pressure Gauge is installed at the lowest point and highest/furthest point of the system with a display/range applicable to the testing pressure.If not they will need to be relocated or replaced.
11If a pump is being used, a consistent water source is available to feed it with water and is connected to the system at the lowest point.If not there will need to be.
12Power is available if a pump/compressor is being used.
13All pipework joints are exposed, i.e not insulated to allow for observing of the system.
14System filled and fully vented free of air.Automatic & Manual Air Vents will need to be manually isolated after venting.
15System set up in line with any strategies, valves open/closed / blanks installed, etc.
16Hoses installed at low-level drain cocks and run to drain.Used in case of a leak in the system and will allow pressure to be reduced quickly
17Operative and Engineers fully trained and where required hold a current relevant certificate to complete the works.

Hydraulic Pressure Testing Method Steps

Once the above table has been verified and agreed to complete the Hydraulic Pressure Test can be commenced.

With the hand pump, valves and gauges connected:

Step 1: Raising the System Pressure

  • Open the valves to the compressor,
  • Using the hand pump,
  • Slowly raise the water pressure within system using increments of 1 bar / 14.5 psi,
  • Stop when meet the required testing pressure [usually 15 bar / 217 psi].

Step 2: Allow System to Stabalize

  • Once the testing pressure is reached and verified, shut off the valves at the system connection to the compressor and allow the system to settle for 10 minutes,
  • If there is a drop in pressure during the 10 minutes, this could be due to the system settling, use the hand pump to top-up the system, ensure the valves are opened prior to pumping and closed after completing [this will be the only time a top-up is allowed].

Step 3: Confirm System Stable

  • Once confident that the system is stable complete the pressure testing certificate by documenting the information required,
  • The testing time will now start.

Step 4: Starting the Testing

  • Ensure that at 15 bar / 217 psi testing pressure is held for at least 4 hours,
  • During the testing time, check system and gauges for any signs of leakage or loss of pressure.

Step 5: Completion of Testing

  • If there is no pressure loss noted over a 4 hour time frame then the test can be completed and a Pass provided,
  • If there are leaks or pressure loss then they should be investigated, the issues addressed, and then conduct a full retest until the system passes.
  • Once all confirmed complete the hand pump, gauges, and temporary valves/hoses should be removed, with any equipment checked or reinstalled to ensure normal status.

Hydraulic Pressure Testing Method Statement Download [Open]

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