In-House Testing


Leak Test - Water

Our in-house, Leak Testing process reliably detects leakage rates as well as providing specification of allowable leakage rates and limits. The leak testing process includes filling the components with water and carrying out a visual inspection to check for leaks. Any abnormalities can then be corrected in-house to ensure the safety, reliability and efficiency of each product.

This is a non-destructive, accurate and reliable test which is particularly useful in the testing of most atmospheric vessels or trays which hold liquid, but with no real pressure involved. All Leak Testing is carried out according to appropriate safety and quality standards.

Leak Test – Air

We provide in-house Leak Testing using air processes. Our revolutionary Air Leak Test service is sensitive and pressure-regulated, allowing the safe and accurate testing of all products. We use combined, flexible Leak Testing instruments to test single and multiple parts quickly and efficiently.

We can ensure purity of vessel contents and non-destructive testing (NDT) of the escape of liquids or gases from sealed fabrications. This test is employed on most pressure vessels and columns where internal moisture may be a problem. The test allows us to immediately rectify any faults and therefore continue to maintain our high standards of quality assurance.

Liquid Penetrant Test

Our in-house, non-destructive testing (NDT) also includes Liquid/Dye Penetrant Testing, which extends visual inspection in order to detect flaws in fabrications such as surface cracks, laps and folds, as well as other surface faults. This technique can be used on all non-absorbent materials, including stainless steel or high alloy fabrications. This includes pressure vessels, lifting points and main structural welds, in order to prove the integrity of the component without causing damage.

The process works by placing a dye on the clean surface of the product, allowing soaking time and subsequently removing any excess dye or liquid from the surface. A developer is then applied (usually a dry white powder) which draws out the penetrant from any cracks or flaws on the surface. A range of penetrants may be used which are washable or easily removed by solvents. As this procedure can easily be incorrectly applied, we make sure that our staff are fully trained and qualified, in order to carry out the testing in accordance with the appropriate standards. This is a quick and easy surface inspection technique which is suitable for a wide range of industries.

Hydrostatic Test

Carried out in-house, the Hydrostatic Test is a common test when inspecting for flaws and leaks in pressure vessels, pipelines and valves with welded sections. Using water or oil, the vessel is completely filled and then visually checked for any changes in shape or leakages. Strain gauges and chart recorders can be fitted.

Colour developers and dyes can be used in order for easier identification of flaws. This procedure uses high pressure which is slowly increased and greater than the normal operating pressure, in order for the fabrication to conform to high safety standards. Our highly-specialised engineers and technicians can make sure that the appropriate amount of pressure is applied in order to avoid the closing of leaks due to over-pressurisation.

This method of testing is suitable for the oil and gas industries both on- and off-shore, as well as many other applications including vessels, paper work, valves and pressure systems before they go into service. This avoids having to make costly on-site repairs at a later date.

Vacuum Test

Carried out in-house, Vacuum Testing is highly successful in discovering the strengths of our fabrications. By using specialised vacuum pumps, products are tested under negative pressure.

Both large and smaller fabrications can be tested using this process under different conditions in order to determine the reliability of our products.

The test will determine whether or not the vessel or fabrication will collapse under negative pressure, as well as checking for leaks where a small pressure drop is critical to the process. This is an accurate test which is carried out in accordance with all safety procedures and quality standards by specialist engineers and technicians.

Helium Leak Test

Carried out in-house, Helium Leak Testing has one of the lowest detectable leak rates for the testing and localisation of leaks. With a short recovery time helium leak testing can produce fast and reliable results which make this test invaluable in certain circumstances.

The test can be performed via the vacuum method or the overpressure method. At the "Vacuum method" the object to be examined for leaks is evacuated and sprayed from the outside with a search gas, in this case Helium. The gas enters through any leaks present in the object and is detected by a sensor connected to the leak test instrument.

At the "Overpressure method" the object to be examined for leaks is filled with a search gas, Helium, under slight overpressure. The search gas escapes through any leaks present to the outside and is detected by a detector probe called a "sniffer".

This is an accurate test which is ideal in complex fabrications for the chemical industry. It is carried out in accordance with all safety procedures and quality standards by specialist engineers and technicians.

Magnetic Particle Inspection

Carried out in-house, Magnetic particle inspection is A process of non-destructive testing for detecting surface and sub-surface defects in magnetic retentive materials. The process uses an externally applied magnetic field or the part is magnetized using; either AC or DC current passed through the part. With the principle of magnetic flux a leakage field is created at discontinuities ie (cracks, voids ).

The presence of a surface or sub surface flaw (void or crack ) in the material allows the magnetic flux to leak at the flaw. This deformation of the magnetic field is not limited to the immediate locality of the defect but extends outside the part. The distance the leakage field extends to the surface and to the outside of the part into air relates to the strength of the magnetic field induced into the part. The amount of magnetism relates to the size of the part and amount of current AC or DC or externally applied magnetic field to magnetize the part. This allows different types of magnetic particles commonly Iron Oxide to gather at the leakage field. This is a quick and easy surface inspection technique which is suitable for a wide range of industries.


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Gilwood (Fabricators) Co Ltd have positions available for apprentice Welders, apprentice Sheet metal workers and apprentice machinists; Please see the Job Vacancies Page. Applications should be sent b..more

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Gilwood (Fabricators) Co Ltd have a position available for a Technical Sales Engineer / Estimator, Please see the Job Vacancies Page. Applications should be sent by email including CV's and covering l..more


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"Poole Projects Ltd (Paper Making Engineers) have enjoyed a long standing relationship with Gilwood Fabricators.The quality of their work is outstanding, as is their willingness to assist and cooperate from enquiry stage through design, manufacture and delivery.The paper industry often puts demanding timescales on its suppliers and in these circumstances Gilwood have always been prepared to go the extra mile."

John Poole - Poole Projects Ltd