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7. COMMISSIONING
7.1. Flow diagram
Single block
Single block & bleed
Double block
Double block & bleed
Handle Colors:
-
Red =drain/vent
-
Blue = isolate
7.2. Pressurization
After installation check that installation of the lines,
included bleeding line, is correctly executed and that
bleed valve is closed.
Check that balls are open.
Before pressurizing with process gas, the entire line shall
be purged by means of inert gas (nitrogen). During the
line purging the valve shall be cycled a few times to
ensure the purging of the body cavity.
Purging of the lines shall be done according to a detailed
procedure from the customer or the contractor in charge
for the plant installation.
After purging, slowly pressurize the plant or plant section
with process fluid by means of upstream process valve
or other system.
During the pressurization with process fluid, cycle the
valve few times to ensure the pressurization of the body
cavity.
After the pressurization, set the valve in the required
position.
7.3. Check of external tightness
Valves have been already pneumatically and
hydrostatically factory tested so the valves do not need
to be retested at site.
Tightness test on flange between valves and line is
required.
The tightness test of the flange connections to the plant
shall be carried out in accordance to the customer
procedures.
Flange tightness test can be performed with foaming
solution applied to the joints: if no bubble appears than
test is acceptable.
In case of liquids, tightness is ensured if no visible leaks
appear.
It is suggested to pressurize the plant step-by-step and
to perform the flange leak test each step.
7.4. Control of internal tightness (only DBB
models)
After line pressurization close both the ball valves.
To check the internal tightness remove the plug on bleed
line, if any, and open the bleed valve.
Check that there is no constant fluid leak from the bleed
line.
