Tym’s Aircraft Repair - Hydrostatic Testing Faq |
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| Tym’s is DOT approved to hydrostatically test most kinds of cylinder assemblies. Testing is also available for foreign, experimental, and engineering sample compressed gas containers. Hydrostatic testing FAQ’s The Department of Transportation (DOT) requires all cylinders to be hydrostatically tested every 3, 5, or 10 years. The time allowed by law is determined by a variety of factors such as the type of material, the gas it contains, its age, and special permits the cylinder may have been manufactured under.  What is a hydrostatic test?A “hydro test” is an approved way to test the structural integrity of a compressed gas container. It is performed by removing the valve, filling the container with water, and then pressuring the container above its operating limit. The expansion of the cylinder is measured, recorded, and analyzed. If cylinder expands beyond certain limits, the cylinder must be condemned. In most cases corrosion or other damage, internal or external, will render a cylinder useless before a failed hydrostatic test. How often is a hydro test required?This depends on the rating of the cylinder and the date it was last tested. The month and year of each hydro test is stamped onto the cylinder between a letter and four numbers identifying the tester. It is 3, 5, or 10 years from this date that the next hydro test is due. All cylinders have ratings that start with “DOT” or “ICC,” followed by the service pressure of the container. For example “DOT 3AA 1800” means a DOT approved cylinder made to the “3AA” specification rated for 1800 psi. Some common ratings and test intervals are below: 5-Year test:DOT 3A ICC 3A DOT 3AA ICC 3AA DOT 3AL 3-Year test: DOT 3HT 10-Year test: DOT 3AA with a “star” following the last hydro test date. Some cylinders have a 5-point star stamped into the cylinder after the last hydro test date making them eligible for a 10-year test under certain circumstances. Various: Other companies do not mention hydro tests, or don’t charge for them, what’s the story?The laws universally apply for all compressed gas containers. Many companies apply the cost of hydro testing to everyone, especially when tanks are exchanged. Tym’s does not charge everyone for hydro testing service. If your tank does not require hydro testing, you don’t pay for it! Unfortunately, some companies break the law and fill out-dated cylinders. What happens if the cylinder fails?In the unlikely circumstance that the cylinder fails the hydro test, a test report will be given to the customer and the cylinder must be destroyed. |
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| Hydrostatic Pressure Test |
