Safety during Hydrotest

[sree60]

Hello members

A query related to safety during hydrotest of pressure vessel.The hydrotest pressure is 285 bar. Are there any guidelines for safe cordon off distance for various pressures during hydrotest?
For lower pressures we used to maintain arond 2 metres cordon off distance. since this vessel will be tested in fabrication shop where other works will be underway in adjacent areas we need to have a safe cordon off distance
Any help will be greatly appreciated

sree60

 

[davefitz]

The injuries that I am aware of for hydrotests were all related to winter time hydro test , metal temperatures were below ductile brittle transition temperature, pre-existing weld cracks propagated at speed of sound in metal, vessel failed catastrophically and dropped large metal pieces onto workers. So, for hydrotest, no worker located below vessel being tested and cleared off the sidelines by 2 M sounds correct.

Of course, a totally different criteria applies to pnuematic tests.

 

[weldtek]

The suggestions above are probably ok for most hydro tests, but, each situation must be scrutinized and evaluated.
Many years ago the company I worked for was hydrotesting some 24" spools that had Victaulic fittings on the ends. During hydro one of the ends let go and sent a 2" thick blank hurtling down the shop. It travelled about 40 feet or so before coming to a stop. We were lucky in that no one was hurt, and we had an opportunity to reevaluate our procedure.
By the way, I'm not bad mouthing Victaulic fittings. During our investigation we determined that our machining tolerances we're not tight enough, and that the clamps were not designed for multiple cycles.

 

[sree60]

Thanks for the inputs. We have only blind flanges on the vessel nozzles and they are ASME flanges with correct ratings.There is no low temperature involved also .
Hoping for a incident free testing

Sree 60

 

[unclesyd]

Take a look at thread292-225652 for some additional information.

 

[boilerone]

For boiler hydros, as an example, the safety regulation requires any unrelated personnel to evacuate the building except for the inspectors who carry out the tests. To talk about inspector's own safety when they go all around to check out when pressure is being held, like people said above, beware of any possible sudden failing and/or flying objects.

Nevertheless, the pressure itself is not so dangerous as some might think of. The water used is always just at ambient temperature even though the pressure can be high, such as your 285 bar, but is still about as much as that of some high-pressure household pressure washers. You don't normally hear people badly injured or even killed by pressure washers even though being directly shot at. Only high temperature water or steam, even at low-enough pressures, are the dangerous killers.