Argon cylinder that won't be filled again
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RoyJackson
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Sometimes when metals are drawn or rolled, an impurity or void from the original ingot can be "stretched" (for lack of a better term) until it becomes a pipe (elongated void...frequently referred to as a "linear defect"). Metals also have a grain, just like wood, when processed in certain ways, And, like wood, the grains may have weaker areas.
I'd guess the split resulted from one of the defects I wrote about above. Plus cycles of pressurizing and depressurizing stressed the cylinder.
I have no idea what non-destructive testing is done on a gas cylinder. I believe magnetic particle (Magnaflux) would be the most logical, along with hydro test or even a cylinder leak-down. However, due to the costs involved, I'd guess the only inspection is visual.
I'd guess the split resulted from one of the defects I wrote about above. Plus cycles of pressurizing and depressurizing stressed the cylinder.
I have no idea what non-destructive testing is done on a gas cylinder. I believe magnetic particle (Magnaflux) would be the most logical, along with hydro test or even a cylinder leak-down. However, due to the costs involved, I'd guess the only inspection is visual.
Big Barn
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The label SHOULD read:
"$324. Pressure Relief Mechanism tested and fully functional. "
Terry
Mark @ Everlast
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The marks where the cylinder was drawn looks rough to me. It could have created a weakness if the die equipment they used was damaged or faulty when it was drawn.
k0ua
Epic Contributor
I noticed the marks, but did not think much about them... Can anyone explain what is actually done in a "hydro test" and why is it call a hydro test?... What does water have to do with it?
MinnesotaDaveChalmers
Platinum Member
Part of a hydro test is using water to pressurize the cylinder instead of air.
When a cylinder splits with water, the pressure reduces very fast and no explosive decompression occurs like with air.
When a cylinder splits with water, the pressure reduces very fast and no explosive decompression occurs like with air.
lilranch2001
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per Wikipedia
Testing procedures[edit]
Hydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid - usually water or oil - pressurised to test pressure, and examined for leaks or permanent changes in shape. Red or fluorescent dyes may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar). Water is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If high pressure gas were used, then the gas would expand to V=(nRT)/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury. This is the risk which the testing is intended to mitigate.[citation needed]
Water jacket test
Small pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurized for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurized vessel. The vessel is then depressurized, and the permanent volume increase due to plastic deformation while under pressure is measured by comparing the final volume in the measuring tube with the volume before pressurization. A leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurized vessel by closing the inlet valve for a period before depressurizing, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.[citation needed]
The information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.[citation needed]
A simpler test, that is also considered a hydrostatic test but can be performed by anyone who has a garden hose, is to pressurize the vessel by filling it with water and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurized by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.[citation needed
Testing procedures[edit]
Hydrostatic tests are conducted under the constraints of either the industry's or the customer's specifications, or may be required by law. The vessel is filled with a nearly incompressible liquid - usually water or oil - pressurised to test pressure, and examined for leaks or permanent changes in shape. Red or fluorescent dyes may be added to the water to make leaks easier to see. The test pressure is always considerably higher than the operating pressure to give a factor of safety. This factor of safety is typically 166.66%, 143% or 150% of the designed working pressure, depending on the regulations that apply. For example, if a cylinder was rated to DOT-2015 PSI (approximately 139 bar), it would be tested at around 3360 PSI (approximately 232 bar). Water is commonly used because it is cheap and easily available, and is usually harmless to the system to be tested. Hydraulic fluids and oils may be specified where contamination with water could cause problems. These fluids are nearly incompressible, therefore requiring relatively little work to develop a high pressure, and is therefore also only able to release a small amount of energy in case of a failure - only a small volume will escape under high pressure if the container fails. If high pressure gas were used, then the gas would expand to V=(nRT)/p with its compressed volume resulting in an explosion, with the attendant risk of damage or injury. This is the risk which the testing is intended to mitigate.[citation needed]
Water jacket test
Small pressure vessels are normally tested using a water jacket test. The vessel is visually examined for defects and then placed in a container filled with water, and in which the change in volume of the vessel can be measured, usually by monitoring the water level in a calibrated tube. The vessel is then pressurized for a specified period, usually 30 or more seconds, and if specified, the expansion will be measured by reading off the amount of liquid that has been forced into the measuring tube by the volume increase of the pressurized vessel. The vessel is then depressurized, and the permanent volume increase due to plastic deformation while under pressure is measured by comparing the final volume in the measuring tube with the volume before pressurization. A leak will give a similar result to permanent set, but will be detectable by holding the volume in the pressurized vessel by closing the inlet valve for a period before depressurizing, as the pressure will drop steadily during this period if there is a leak. In most cases a permanent set that exceeds the specified maximum will indicate failure. A leak may also be a failure criterion, but it may be that the leak is due to poor sealing of the test equipment. If the vessel fails, it will normally go through a condemning process marking the cylinder as unsafe.[citation needed]
The information needed to specify the test is stamped onto the cylinder. This includes the design standard, serial number, manufacturer, and manufacture date. After testing, the vessel or its nameplate will usually be stamp marked with the date of the successful test, and the test facility's identification mark.[citation needed]
A simpler test, that is also considered a hydrostatic test but can be performed by anyone who has a garden hose, is to pressurize the vessel by filling it with water and to physically examine the outside for leaks. This type of test is suitable for containers such as boat fuel tanks, which are not pressure vessels but must work under the hydrostatic pressure of the contents. A hydrostatic test head is usually specified as a height above the tank top. The tank is pressurized by filling water to the specified height through a temporary standpipe if necessary. It may be necessary to seal vents and other outlets during the test.[citation needed
k0ua
Epic Contributor
Thanks guys, I try to learn something new each day... :thumbsup:
lilranch2001
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You question made me go look Jim
As a scuba diver and being a welder back when I was a young man, I always knew the term "hydro test, and have paid for quite a few over the years, but it was the first time I really knew what it entailed, so thanks for giving me the impetuous to go and look
As a scuba diver and being a welder back when I was a young man, I always knew the term "hydro test, and have paid for quite a few over the years, but it was the first time I really knew what it entailed, so thanks for giving me the impetuous to go and look
Stimw
Elite Member
On How It's Made IIRC they were Hydro-ing the new cylinder at 5500 lbs.
They showed making from blank to finished cylinder!
They showed making from blank to finished cylinder!