Cylinder Hydro Testing
What is cylinder hydrotesting?
Hydrostatic Testing is a nondestructive test procedure used to check cylinders for leaks, structural flaws, durability, and corrosion. It is used to check a cylinder’s structural integrity. Testing consists of enclosing a cylinder filled with water inside a test jacket filled with water. Pressure is then applied internally to the cylinder, causing the cylinder to expand. The total and permanent volumetric expansions of the cylinder are determined by measuring the amount of water displaced by the expansion of the cylinder when under pressure and after the pressure has been released. An external and internal visual inspection of the cylinder is also performed, along with a dead-ring test for steel cylinders.
We are reputed practitioners of cylinder hydro testing, also known as a hydrostatic stretch test, which refers to testing all gas cylinders. However, due to specific reasons, we don’t test the disposable gas bottles and cylinders of acetylene, carbon dioxide, liquid hydrocarbons and welded gas cylinders regardless of cylinder MOC. We encourage regular hydro testing of all other cylinders to ensure that they are in proper working condition and can be used for future purposes.
Hydrotesting is only performed under specific procedures and can’t monitor the equipment for leakage. Though hydrostatic testing is a non-destructive testing procedure, the equipment tends to rupture or fail should the inspection exceed a certain test pressure or if cylinder walls develop tiny cracks.
We at Alchemie gases & Chemicals pvt Ltd. Offers hydrostatic testing of below specified cylinders which are manufactured as per the standards prescribed by CCOE, petroleum & Explosive safety organisation, ( Government of India)
| 3 lts | 10 Ltrs | 47 Ltrs | 50 Ltrs |
Why is cylinder hydro testing important?
According to the guidelines of The Petroleum and Explosives Safety Organisation (PESO), every gas manufacturing company must perform regular hydro-testing procedures on high-pressure seamless cylinders after every five years. They can undertake this examination at any time of the cylinder’s lifecycle, depending upon their existing condition. Toxic gas and CNG gas cylinders should be regularly hydro-tested every two years or at an interval specified by the PESO.
A cylinder is hydraulically tested at the “test pressure”, which could be 1.5 or 1.66 times the normal working pressure. Of course, the amount depends upon the cylinder’s manufacturing standards and MOC. Regular hydro testing is performed to evaluate the cylinder material’s elasticity as it undergoes elastic expansion or stress during the gas filling process. The elasticity must be checked to see the material has returned to its original position within a specific tolerance limit. With repetition and time, its elasticity deteriorates, making it unsafe for further use.
How is hydro-testing performed?
Hydrotesting refers to a pressure test where the worker fills the container with water, removes the air contained within the unit and pressurizes the system for up to 1.5 times the designed pressure limit of the unit. The worker retains the pressure for a certain amount of time to inspect the system visually for leakage. This is further enhanced by applying fluorescent dyes or tracers to the liquid to check for new leakages and cracks. Three hydrostatic testing methods are used to test small pressure cylinders and vessels:
Direct expansion method
The worker fills up the cylinder or vessels with water, pressurizes the system, and measures the amount of water expelled once the pressure is released. Next, the total expansion and permanent expansion are calculated by recording the amount of water forced into the vessel, the amount of water expelled and the test pressure.
Water jacket method
The worker fills the cylinder with water and loads it into a sealed chamber (the test jacket), also filled with water. Next, the vessel is pressurized inside the test jacket, which causes the vessel to expand and causes the water to force itself into the glass tube that measures the total expansion. Once recorded, the worker depressurizes the vessel, and the water flows back into the test jacket.
If the vessel doesn’t return to its original size, the second size value is renamed permanent expansion. The worker determines the difference between permanent and total expansion, and the vessel is decommissioned if the value is higher.
Proof pressure method
The worker causes internal pressure on the vessels to check for wall thinning, leakage or defects. Pneumatic testing involves the worker pressuring the vessel with nitrogen or air instead of water, which must be carefully performed as gaseous mediums can be compressed in large amounts compared to hydro testing.
Cylinder hydro testing results are measured in terms of the Percentage Permanent Expansion and must fall within limits prescribed by the PESO. Hydro tests for pipelines are conducted out-of-service pipelines, natural gas or oil is turned off, and the line is cleaned before testing. Reach out to us at Alchemie Gases & Chemicals to meet your requirement.