PetroStreet

What are the general safety guidelines to be followed during a hydrotest? Which code governs these requirements? OSHA?
We have to test a piping circuit at 285 bar and the holding time is 4 hours. The circuit contains pipe sizes ranging from 4" to 12". What should be the minimum cordoned off distance?

Hydro test is a potentially hazardous activity specially the pressure you have mentioned. We at our site conducted dozens of the hydro tests. We conducted a JSA / JHA before the activity and the general control measures we identified were
-Process engineer decided the pressurization rates (to avoid sudden pressurization)
-Similarly de pressurization rates
-Test was conducted preferably during lunch time
-The end blind weld was dpt tested
-The cordoned area was decided according to the location by the participants
-Two PIs are to be used
-Needle valve was used for good pressure control during pressurization
-Calibrated PSV was used
-Signage to keep people away
-However the pneumatic test (more hazardous) was conducted at remote location and a bunker was provided for the QC inspector

This is what I have found regarding the safe distance during a hydrotest activity.

safe distance = (0.15) x (D) x (a)^0.4 x (p)^0.6

where D - internal diameter (m)
a - length / diameter of piece (m)
p - test pressure (bar)

Hope this would help.

can u quote the reference?

This is what I came across on another discussion forum.
There the reference was given to a Norwegian Specification.

thx

All systems (piping and equipment) while being hydrostatic tested shall be protected from being over pressured by the following :
- A relief valve of adequate capacity set to relieve at 5 percent above the test pressure shall be installed. Sizing of these relief valves used for testing shall follow the requirements of API RP 520, Part 1. The relief valve shall be tested, certified, dated, and tagged within one month prior to the test

- In addition to the pressure relieving device, a bleed valve shall be provided to protect the piping and equipment from overpressure. The bleed valve shall be readily accessible in case immediate depressurisation is required.

- An isolation valve shall be provided between the pressure testing manifold and the system being tested. The isolation valve shall be rated for the manifold test pressure when in the closed position.
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Thanks all for the useful inputs.
One thing I ask from moe is, should relief valve be installed on every hydrotest activity regardless of the test pressure?

absolutely Sir, each hydro test manifold should have a relief valve installed on it.

Moe,
Further can you please provide the reference of relief valve set pressure of 5% above test pressure?
In ASME B31.3 I have read the following:
"A pressure relief device shall be provided, having a set pressure not higher than the test pressure plus the lesser of 345 kPa (50 psi) or 10% of the test pressure".