Most hydraulic systems operate at pressures between 200 and 350 bar, while some applications operate at significantly higher pressures. At these pressure levels, even minor installation defects can result in leakage, loss of performance, equipment damage or unplanned downtime.<\/p>\n
Although pressure testing is often associated with commissioning, many contractors choose to perform an initial pressure test before flushing operations begin.<\/p>\n
The reason is practical. Discovering a leaking fitting or incorrectly assembled connection after several hours of flushing can result in unnecessary delays, additional contamination and increased project costs. Identifying problems early allows corrective actions to be taken before significant resources are invested in cleaning and commissioning activities.<\/p>\n
Another important reason is temperature stability. During flushing operations, hydraulic oil is often heated significantly above ambient temperature. Since hydraulic oil expands when heated and contracts when cooled, pressure readings taken immediately after flushing may be influenced by temperature rather than actual system integrity.<\/p>\n
For this reason, pressure testing is often performed before flushing, allowing the system to be verified under more stable conditions and avoiding unnecessary waiting time for the oil to cool down before reliable pressure measurements can be taken.<\/p>\n
A common industry practice is to pressure test hydraulic systems at approximately 1.5 times the maximum working pressure. Once the target pressure has been reached, the test circuit is isolated from the pressure source and monitored over a specified period. Depending on project requirements, the holding time is typically between 20 and 30 minutes, with acceptance criteria based on maximum allowable pressure loss. Many specifications allow a maximum pressure drop of approximately 2%, although exact requirements vary between clients and projects.<\/p>\n
However, pressure readings alone do not always tell the full story.<\/p>\n
One of the most misunderstood aspects of pressure testing is the effect of temperature on hydraulic oil. Hydraulic oil expands when heated and contracts when cooled. As the oil cools, system pressure naturally decreases even if no leakage is present.<\/p>\n
When evaluating pressure test results, temperature must always be considered. In hydraulic systems it is commonly accepted that a 1\u00b0C change in oil temperature may result in approximately 10 bar pressure variation in a closed test circuit.<\/p>\n
A pressure drop observed during testing may therefore be caused by thermal contraction rather than an actual leak. Pressure loss alone should never be used as the sole indication of leakage.<\/p>\n
In many cases, failed pressure tests are not caused by the tubing itself but by installation and assembly errors. One of the most common causes is incorrect preparation of the tube end before assembly of cutting ring fittings.<\/p>\n
Poor cutting quality, insufficient deburring, damaged sealing surfaces or incorrect cutting ring installation can all create leakage paths. These defects may remain unnoticed during assembly but become immediately apparent once the system is exposed to test pressure.<\/p>\n
Correct tube preparation is therefore just as important as the pressure test itself. The tube end must be cut square, properly deburred and free from contamination. Cutting rings must be installed according to the manufacturer’s instructions and verified before final assembly. Attention to these details significantly reduces the risk of leakage during testing and operation.<\/p>\n
Visual inspection remains an important part of every pressure test. All tubing, piping, hoses, fittings and test connections included in the test scope should be inspected throughout the testing process. In many cases, leaks or installation issues can be identified visually before any significant pressure loss is observed on the gauges.<\/p>\n
It is important to note that pressure testing is often limited to the tubing, piping and hose assemblies. Valves, actuators, cylinders, instruments and other sensitive system components are frequently isolated or tested separately according to their own specifications and pressure limitations.<\/p>\n
Modern pressure testing procedures often include continuous recording of both pressure and temperature throughout the test period. While temperature measurements provide valuable information for interpreting pressure fluctuations, the success of the test is ultimately determined by the pressure loss observed during the test period. Temperature data serves as a supporting parameter, helping to identify whether pressure changes are caused by thermal effects or by actual leakage within the tested system.<\/p>\n
For offshore, marine and industrial projects, pressure testing is not only a technical requirement. It is also an important quality assurance activity. Properly documented pressure testing demonstrates that the system has been assembled correctly and provides confidence before commissioning begins.<\/p>\n
Pressure testing should not be viewed as an isolated activity. Reliable hydraulic systems are created through a combination of correct tube fabrication, proper fitting installation, pressure testing, flushing and contamination control. Each stage contributes to the overall integrity and long-term reliability of the system.<\/p>\n
A successful pressure test confirms far more than the absence of leaks. It confirms that the installation has been assembled correctly, that the components can safely withstand operating conditions and that the system is ready for the next stage of commissioning.<\/p>\n
In hydraulic systems, preventing problems is always less expensive than correcting them after start-up. Pressure testing therefore remains one of the most effective methods of reducing risk, improving reliability and protecting long-term system performance.<\/p>\n
Ekke Hydraulics AS provides complete hydraulic tubing services, including STEP-based tube bending, prefabrication, installation, pressure testing, flushing and contamination control for offshore, marine and industrial projects. Our focus is on delivering hydraulic systems that are built correctly the first time and remain reliable throughout their operational lifetime.<\/p>\n
If you are planning a hydraulic installation or commissioning project, our team will be happy to discuss the most suitable testing and verification approach for your application.<\/p>\n","protected":false},"excerpt":{"rendered":"
Hydraulic pressure testing is one of the most important verification steps in any hydraulic tubing installation. The purpose is simple: verify that the system is leak-free and capable of operating safely at its intended working pressure before it is put into service. Most hydraulic systems operate at pressures between 200 and 350 bar, while some […]<\/p>\n","protected":false},"author":1,"featured_media":3496,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[76,72,74,69,70,68,71,31,75,73,78,77],"class_list":["post-3502","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-insights-2","tag-commissioning","tag-cutting-ring-fittings","tag-flushing","tag-hydraulic","tag-hydraulic-oil","tag-hydraulic-pressure-testing","tag-hydraulic-tubing","tag-hydrauliske-rorsystemer","tag-idriftsettelse","tag-leak-testing","tag-marine-hydraulic-systems","tag-offshore-hydraulics"],"yoast_head":"\n