How to Start preparing for and Finalize a Hydrostatic Test
                     How to Start 
preparing for 
and Finalize a 
Hydrostatic Test
Hydrostatic (Hydro) testing is a process that evaluates the strength 
and leakage of components such as piping systems, gas cylinders, 
boilers, and pressure vessels. Hydrostatic tests are frequently required 
following shutdowns and repairs to ensure that the equipment will 
operate under the desired conditions when it is returned to service.
Furthermore, hydrostatic testing cannot be performed during normal 
operations and cannot detect leaks in equipment after the test has 
been completed. An effective fixed equipment mechanical integrity 
programmed is the best way to manage on-stream equipment integrity.
Although Hydrotesting is considered nondestructive, equipment can 
rupture and fail if the inspection exceeds a specified test pressure or a 
small crack propagates quickly.
What Is the Process of 
Hydrotesting?
Hydrostatic testing is a type of pressure test 
that involves completely filling the 
component with water, removing the air 
within the unit, and pressurizing the system 
up to 1.5 times the unit's design pressure 
limit. The pressure is then maintained for a 
set period of time in order to visually inspect 
the system for leaks. Visual inspection can be 
improved by adding tracer or fluorescent 
dyes to the liquid to pinpoint the location of 
cracks and leaks.
Common Hydrostatic Testing Methods
To test small pressure vessels and cylinders, three common hydrostatic testing 
techniques are used: 
1. The water jacket method, 
2. The direct expansion method, 
3. And the proof pressure testing method.
Water Jacket Technique
● To perform this method, the vessel is filled with water and loaded 
into a sealed chamber (referred to as the test jacket) that is also 
filled with water. After that, the vessel is pressurized inside the test 
jacket for a set period of time. This causes the vessel within the test 
jacket to expand, causing water to be forced out into a glass tube 
that measures total expansion. After recording the total expansion, 
the vessel is depressurized and shrinks to its original size. Water 
flows back into the test jacket as the vessel deflates.
● The vessel does not always return to its original size. Permanent 
expansion refers to the second size value. The difference between 
total and permanent expansion determines whether or not the 
vessel is serviceable. The higher the percentage expansion, the 
more likely it is that the vessel will be decommissioned.
Method of Direct Expansion
Filling a vessel or cylinder with a specific amount of water, pressurizing the system, and 
measuring the amount of water expelled once the pressure is released is the direct expansion 
method. The permanent and total expansion values are calculated by keeping track of the 
amount of water forced into the vessel, the test pressure, and the amount of water expelled 
from the vessel.
Method of Proof Pressure
The proof pressure test uses an internal pressure to determine whether the vessel has any leaks or 
other weaknesses, such as wall thinning, that could lead to failure. In the United States, this method 
is only permitted when the US Code of Federal Regulations does not require the recording of 
permanent and total expansion values.
Alternative Techniques
Some equipment may be incapable of handling the loads required for a 
pressure test. Alternative methods, such as pneumatic testing, should be used 
in these cases. Another type of pressure test is pneumatic testing, which 
involves pressurizing the vessel with a gas other than water, such as air or 
nitrogen. However, when performing pneumatic testing, special care should 
be taken because gaseous mediums can be compressed and contained in 
greater quantities than hydrostatic testing.
Read More:
https://www.articleted.com/article/590648/165446/How-
to-Start-preparing-for-and-Finalize-a-Hydrostatic-Test
Cortec® also provides mothballing to water 
treatment plants.
Contact Details:
Cortec® Middle East
Sidra Tower, Office 1307 Sheikh Zayed Road 
P.O. Box 115133 Dubai, United Arab Emirates
Tel: +971 4 434 0669
Fax: +971 4 434 0669
Email: [email protected] 
Website: https://cortec-me.com/ 
THANK YOU