Guide to Pipeline Hydrostatic Testing
While there are various modes of transporting fuel resources, pipeline systems happen to be amongst the safest. To guarantee its safety, the overall integrity of the systems must be ensured before they are deployed into service. Hydrostatic testing is commonly used to test and confirm this integrity. This article presents a general overview of pipeline hydrostatic testing as well as its benefits, limitations, and requirements.
What Is Hydrostatic Testing?
Hydrostatic testing is a process that ensures the safety and structural integrity of certain pressure vessels such as storage tanks, gas cylinders, plumbing systems, and pipelines through the use of hydro-testing equipment. It is an industrial pressure testing technique that lets you identify leakages in vessels by applying pressure, thereby examining their strengths.
How Does Hydrostatic Testing Work?
As earlier stated, hydrostatic pressure testing involves testing and verifying the overall integrity of pressure vessels. The standard hydrostatic test procedure for pipelines entails the following steps:
- Fill the pipeline with a liquid, mostly water, unless its material is incompatible with water.
- Apply pressure to the pipeline to bring it to its acceptable test pressure. This pressure is usually greater than the pipeline’s design working pressure.
- Hold the pressure for a required timeframe to examine the pipeline for possible leakages.
- Depressurize the pipeline after confirming that the test is complete and meets the specifications and industry standards.
Note that the vessel must have vents that allow air to escape as it is being filled with water. Additionally, fluorescent dyes can be applied to the testing fluid to aid inspection and analysis. After confirming that the pipeline holds at the acceptable test pressure, it can be certified safe to be deployed into service.
Common Applications of Hydrostatic Testing
There are various uses for hydrostatic testing in the industrial sector. It is applied to determine the integrity and inform the effective repair of:
- Heat exchangers
- Gas, water, and other fluid piping systems that are recently installed or modified
- Air compressor and storage and distribution systems
- Fire suppression systems
- Leads, tanks, and reactors used in industrial processes
In general, hydrostatic testing detects breaks, holes, or gaps in vessels that result during their fabrication from casting or welding. Some other possible flaws it can detect are gas pinholes, ductile tears, sand inclusion, and localized hard spots. Applications include flaw detection in industrial manufacturing, storage, and transportation equipment.
Benefits of Outsourcing Hydrostatic Testing
Outsourcing hydrostatic testing services has its benefits. The services of reputable hydrostatic pressure testing companies can be employed as they offer the following benefits:
- Proven years of experience on how to hydrostatic pressure test to industry’s and client’s standards.
- By owning advanced hydro testing equipment, they always comply with the Department of Transportation’s (DOT) specifications.
- Eliminates labor requirements related to procuring hydrostatic testing equipment.
- Saves time and money involved with running the tests by yourself and keeping the equipment’s certification up-to-date.
Limitations of Pipeline Hydrostatic Testing
Although pipeline hydrostatic testing has proven to be the most reliable, safest, and most common pressure testing method, it is not ideal for some systems, and it fails to detect some flaws. These two key limitations are discussed below.
Unsuitable for Certain Systems
Hydrostatic pressure testing methods are generally known to be unsuitable for retesting existing systems. The reason for this is that the test procedure requires all contents of the vessels or systems must be removed or purged. That implies that they (the vessels or systems) are temporarily put out of service resulting in downtime. This downtime means that unless you have a backup system or vessel that will serve as a substitute during the test, you will experience inefficient productivity during this time.
Inability to Detect Some Flaws
This pressure testing method is observed as being unable to detect subcritical flaws in a system. These flaws require the systems to be exposed to higher internal pressure ranges to be detectable and measurable. Since hydrostatic testing depends on visual inspection and sometimes expansion measurement to certify the equipment or system safe for use, subcritical flaws often go unnoticed or are worsened by the test.
Hydrostatic Test Requirements
The American Society of Mechanical Engineers (ASME) published the ASME B31.1 and ASME B31.3 codes to define hydrostatic testing requirements for process piping. These codes specify that the test pressure must be at least one and a half the design working pressure of the pipeline system at all times during the test. This specification can be altered only when the design and operating temperature are greater than the test temperature. In that case, a minimum allowable pressure can be evaluated following the codes.
NiGen Offers Hydrostatic Pressure Testing for Pipelines
At NiGen, we offer smart technological solutions to our partners in various manufacturing industries. For industrial players seeking cost-effective pipeline hydrostatic pressure testing services, NiGen is the best fit.
To learn more about the services we proffer to our partners in the O&G industry, contact us online.