Safety zone for pneumatic testing
Safety zone for pneumatic testing
(OP)
Hi All,
Does anyone know if there is a safety zone when performing pneumatic testing? I couldn't find anything in Asme B31.3.
Any feedback is appreciated.
Rgds,
Brighton
Does anyone know if there is a safety zone when performing pneumatic testing? I couldn't find anything in Asme B31.3.
Any feedback is appreciated.
Rgds,
Brighton





RE: Safety zone for pneumatic testing
EJL
RE: Safety zone for pneumatic testing
Joe Tank
RE: Safety zone for pneumatic testing
DiegoMartinez ? You might want to look at these threads:
thread378-145123: Safety distance for pneumatic test; thread378-156328: Hydrostatic Testing; and thread794-26767: Equivalent Energy.
Patricia Lougheed
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RE: Safety zone for pneumatic testing
I don't know of any specific distance requirements, though I'd be interested in seeing that NASA document eliebel mentions. Regardless, there will always have to be someone within that area to do the test.
Note that the piping code requires a leak test, not a proof test. If you're looking to do a proof test (ie: 1.5 times MAWP), then what is typically done is to disassemble the piping system and do a hydrostatic pressure test, and then reinstall the system and do the leak test. The proof test isn't required by code.
ASME B31.3 requires a "leak test" at 1.1 times design pressure. They also require a relief valve set at 10% above that pressure. We always put this relief device at the source of the test pressure, and ensure by calculation that the relief device is large enough to handle the flow from the test source.
When pressurizing the piping system, you should also verify you are only pressurizing those portions of the piping system that are rated for the pressure. Creating a test plan is imperative. Color code a P&ID or something along those lines. Make sure you know what lines you're pressurizing, and make sure the test plan incorporates valve open/close requirements, blanked off piping sections, etc...
I'd also suggest bringing up pressure slowly - in 10% increments. Hold for 5 minutes at each level, and do a soap bubble leak test at each level.
Leak testing requires someone to do the test, so they will always be near the piping during the test. One primary reason for keeping others back isn't just to keep them safe from potentially dangerous pressure, it is to maintain some control over piping and valve configuration. You need to keep people away from valves or other controls that need to be kept in a specific position during test, especially because you're generally in a construction mode and people may be less aware of lockout/tagout procedures.
RE: Safety zone for pneumatic testing
TECHNICAL REVIEW ASME PCC 2 for details.
RE: Safety zone for pneumatic testing
From what I've learned from my colleagues, many (if not most) LNG facilities are constructed with very few joints, so testing in smaller, risk-managable sections is not an option.
It is an understood fact that in these cases, if pneumatic chosen method of testing the pipework, the stored energy limitations will always be exceeded. For interest's sake, I'd really like to take a look at the code that outlines this stored energy limit. Does anyone know which code/standard addresses this?? I've been through B31.3....
RE: Safety zone for pneumatic testing
RE: Safety zone for pneumatic testing
LNG implies cryogenic piping (unless you're after vapourization, but still...) which means that you will have a minimum of mechanical joints, as you mention. This is to ensure leak-proof operation (cryo fluid leaks can ruin everybody's day), fewer crevices for particulate collection and, to a lesser extent, reduced cooldown time during startup (less mass that retains heat).
If possible, get in contact with some engineering people from Air Liquide, Air Products or Praxair that have cold box experience. They may not be willing to share their secrets though.
RE: Safety zone for pneumatic testing
Yes, we deal directly with Air Liquide. They don't tend to call the shots in these cases, but I bet they would know which codes & standards deal with stored energy calculations. Don't know why I didn't think of calling them...
I have a feeling that it's an API standard I'm looking for. I just don't want to keep purchasing standards until I find it.
Thanks for the input ; )
RE: Safety zone for pneumatic testing
(c) Carbon dioxide pipelines may use inert gas or carbon dioxide as the test medium if—
(1) The entire pipeline section under test is outside of cities and other populated areas;
(2) Each building within 300 feet (91 meters) of the test section is unoccupied while the test pressure is equal to or greater than a pressure that produces a hoop stress of 50 percent of specified minimum yield strength;
RE: Safety zone for pneumatic testing
1. Change of State Equation based on reversible adiabatic, isothermal conditions( Reference "Mark's Standard Handbook for Mechanical Engineers". Ninth Edition pg 4-10).
AND
2.Isothermal Compression Equation also referenced in "Mark's".
RE: Safety zone for pneumatic testing