Instrument Installation Philosophy
Instrument Installation Philosophy
All work shall be of the highest quality craftsmanship and shall conform to the
best applicable engineering practices, and, relevant codes referred in the bid
document.
All instruments shall be installed in a neat workmanlike manner ensuring ease of
operation and maintenance.
The Contractor shall prepare hook-up and installation detail drawings regarding
each type of instrument for the Company’s approval, and shall carry out the
installation in accordance with these approved drawings.
The Contractor shall install instruments and equipment with due consideration of
the following:
1. No instrument with the exception of pressure gauges and temperature
indicators, shall be installed in such a way that it depends on its impulse
piping or electrical connections for its support.
2. Positioning of equipment shall not constitute a safety hazard. Where possible,
instruments shall be mounted so that they are protected from the effects of
rain and sun, while maintaining the requirements for access and visibility.
Where this is not possible, the Contractor shall provide a fixed cover or hood
to protect instruments, without impairing access or visibility.
3. Visibility and accessibility for both maintenance and operations purpose.
4. Ease of access for lifting heavy items of equipment such as valves.
5. All instruments and valves shall be free from vibration.
6. Instruments shall be mounted / connected so as not to stress vessel nozzles
or pipe tapping.
7. All local process-connected instruments shall be located as close as possible
to the point of measurement while still being accessible from the deck, ladder
or a platform.
8. Instruments requiring frequent routine access (including hand-valves, manual
resets, manual switches, etc) shall be mounted approximately 1.4m above the
deck or platform for ease of accessibility.
9. Instruments shall be properly supported on brackets or mounted on
subplates, or placed on a suitable pedestal, pipe stand or structural support.
Pipe or structural stands may be welded directly onto platform plate, with a
suitable penetration in the grating, where applicable.
10. Instruments, tubing, cables and cable ladder shall not be fixed to gratings or
handrails.
11. Instruments (other than pressure instruments) shall not be mounted directly
on process piping without the Company’s written approval.
12. Instruments or instrument lines shall not be supported on handrails unless
approved by the Company.
13.Fittings such as instrument isolating valves and instrument air or gas
regulators shall be supported either on the instrument stand or closecoupled
to the instrument in a manner that no undue stress is imposed o the tubing or
instrument.
Instrument stands or panels shall be in accordance with the approved drawings,
with consideration for:
- The most direct routes for tubing and piping to and from the stand, using
common tubing runs and avoiding crossovers.
- Ease of inter-connections between instruments.
- Ease of access for on-site calibration and / or removal of instruments.
- Minimum interference between tubing, piping and cabling to instruments.
A 316 SS filter regulator with gauge shall be provided for each instrument
requiring regulated gas or air supply.
All drains on field instruments shall be made to face downwards if it is already not
so. All open ports (vents/drains) shall be fitted with bug screens.
Instrument Inspection & Testing Philosophy
The Contractor’s quality plan shall include a comprehensive fully documented
inspection and testing plan specific to the project.
The procedures shall include inspection specifically for compliance with
hazardous areas requirements, including current certificate, without which no
circuit or loop shall be energized.
All testing, calibration and pre-commissioning shall be done by the
Contractor. The Contractor shall also provide assistance as required during
commissioning activities.
The Contractor shall provide suitable workshop facilities and shall provide all
necessary test and calibration instruments and equipment.
The Company reserves the right to reject any or all test and calibration work if
found not complying with the Specification requirement. The Contractor shall
complete and submit documentation for all calibration, testing and
precommissioning. Company Representative prior to shipment shall check
out panels, consoles, and packaged instrument assemblies for their
compliance with specification requirements.
The Contractor shall in the presence of the Company Representative, verify
by inspection, calibration and loop testing, that, all instrumentation in field and
control room including local and remote/central control panels, are complete
and operable as per specification requirement. All testing and calibration shall
be subject to approval of the Company.
In addition to calibration/testing, loop checking, setting for safety devices like
process switches, safety valves etc. and simulation testing of all interlock and
shutdown systems, done at fabrication yards, the same shall also be carried
out at offshore site as well.
In general, the pipes and tubes shall be cleaned before testing. They shall
then be subject to hydrotest (or other applicable tests) and then blow dried.
2. Flushing of Lines
The Contractor shall remove in line instruments like flow meter, control
valves/safety valves, if necessary, and provide spool pieces/flanges prior to
flushing of lines.
3. Instrument Supply Lines
Instrument air/gas piping and tubing shall be disconnected upstream of all
filter/regulators before testing, the piping and tubing shall then be hydrotested
as explained below and then shall be blown down to remove hydrotest water,
slag and mill scale from lines.
Instrument air supply lines shall be blown with instrument air prior to
connecting to instruments. Instrument air/gas mains shall be isolated from the
instrument and pressurized to 11/2 times maximum working pressure with
instrument air, they shall be isolated from the pressure source and the
pressure reading on a test gauge shall not fall by more than one psig in ten
minutes.
4. Instrument Signal Lines
Instrument signal lines shall be blown with instrument air prior to connecting
to instruments. All air/gas tubing shall be tested and inspected by one of the
methods given in Instrument System & Automation Society (formerly known
as Instrument Society of America) Recommended Practice RP 7.1
“Pneumatic control circuit pressure test”. Clean, oil free instrument air shall b
e used for the test.
5. Impulse Lines
All process impulse lines shall be disconnected and flushed with potable
water. Air lines shall be blown down with filtered air. Hydraulic lines shall be
flushed with hydraulic oil.
After flushing process impulse lines shall be isolated from the instrument and
pressurized hydraulically to 11/2 times maximum working pressure corrected
for ambient temperature. They shall then be isolated from the pressure
source and the pressure reading on a test gauge shall not fall at a rate
exceeding one psig/hour.
6. Direct Mounted Instruments
For direct mounted instrument such as level gauges, level transmitters
(displacer type), level switches etc, the installations shall be pressurized to
maximum operating pressure slowly and steadily with the instruments. The
installations shall then be isolated from main pressure source. The pressure
shall not fall at a rate exceeding one psig/hr.
7. Wiring
Wiring shall be checked to ensure that it is correctly connected and properly
grounded. Insulation test shall be carried out on all wiring taking necessary
precautions. Correct connections of all electric or pneumatic switches shall be
checked.
8. Calibration & Testing
a. The Contractor’s instrument personnel shall calibrate instruments. This
calibration shall when possible, be done with the instrument or system in
place, otherwise calibration prior to installation or removal for calibration
shall be done. The Contractor shall provide written results of all instrument
calibration in prescribed format and shall submit such formats well in
advance for Company’s approval. The Contractor shall submit document
confirming that the testing equipment to be used for calibration purpose
are certified and calibrated.
b. In general, all tests shall simulate, as closely as possible, design process
Comments
Post a Comment