©COMEV
AL
V
AL
VE SYSTEMS
Technical Dept. Ref. IOM-DBB MONOFLANGE GLOBE V
AL
VES, UNIFLOW® 8F - Ed.22/03
Comeval V
alve Systems reserves the right to alter any technical data contained in this Manual without prior notice. Regularly updated data on www
.comeval.es
IOM - DBB MONOFLANGE GLOBE VALVES UNIFLOW® 8F
Page 5
6. COMMISSIONING & OPERATION
ATTENTION!
- Before commissioning the valve, check the material, pressure, temperature and other essential parameters.
Always use the product within the scope of intended service and operating duties.
- Before commissioning, make sure previous chapters are thoroughly followed.
- Regional safety instructions should be adhered to.
- It is essential to flush the pipe system thoroughly to eliminate all the particles and impurities which could remain in
the pipes and particularly welding residue, chips, tool remains, etc. that could damage the equipment during start-
up. Ensure that during cleaning of the pipe system, any chemicals used and temperature are compatible with the
valve construction.
- Temperatures above 50ºC or below 0ºC may cause personnel injuries if valves are touched.
- Leakage of media through valve stem, connections or at closing (end of pipeline) may also cause scalding, health
harm, pollution, fire or damage to other parts of the installation depending on the media. Use suitable protection
equipment when approaching the valve, ensure that the corresponding warning signs are displayed on the valve or
surrounding area, and/or isolate the equipment in case of danger.
- Before commissioning a new plant or restarting it after repairs or modification, always ensure that:
- All work has been completed correctly.
- The valve is in the correct position for its function.
- Safety devices/measures have been implemented.
- Valve operation, filling, warming-up and starting-up shall be gradual so as to avoid any inadmissible stress. Check
for tightness in valve connections, body/bonnet union, and stem, and retighten crosswise and gradually if necessary
until leakage elimination.
- For steam systems, proper system layout and operation procedure should be well established and followed. It is
essential to ensure condensate properly drained, gradual filling of the system and slow valve operation to avoid
water hammer / thermal shock do to revaporizing
- Valves with packing: The packing is tightened at factory in a moderate way to pass the pressure tests. After a while
before installation, packing rings experiment a relaxation and some retightening might be needed during start-up.
Over tightening the bolts will increase operating torque, and will reduce life of the packing. Also after several open
and close ooperations of the valve the stem gains some play with the packing rings, thus packing tightness should
be checked periodically and retighten gradually when necessary.
- Ensure valve surface is in good condition and retouch coating protection when needed.
- Once the valve installed, make an initial opening and closing operation to check its proper operability, without additional
tools.
- In case of risk of media freezing inside the valve, take due measures to avoid it.
7. CARE AND MAINTENANCE
The operator must define maintenance and maintenance-intervals to meet requirements.
- Check for body, seat and connections tightness, and valve smooth operation without additional tools.
ATTENTION!
- In the event of infrequent use, operate the valve as frequently as possible to avoid deposits of dirt and valve
blocking.
- Before disassembling the valve, note chapters 3, 10 & 12.
- Only carry out maintenance work in the pipework when the valve has been secured from operation.
- Check the valve surface inside and outside and retouch coating protection when needed. If advanced corrosion
or erosion is observed, double check service and valve features and replace the valve properly.
- Keep exposed machined surfaces cleaned and greased when necessary.
- If the valve is leaking through the stem, try first to retighten the packing gland without compromising stem smooth move
-
ment.
- If leakage cannot be corrected, old packing must be replaced. Remove packing gland, remove old packing by means of
a wooden dowel, make sure that stem and packing area are thoroughly cleaned and place new packing rings ensuring its
correct position. If stem is worn out or scratched replace it. Then place back packing gland and tighten gland bolts mode
-
rately. Test the valve under pressure and if necessary retighten gradually until leakage disappears.
After any maintenance work please refer to chapters 5 and 6 for installation / commissioning.
Recommended Spare parts:
Use only original spare parts.
It is advisable to keep packing rings as spare parts. In many cases a good choice is to keep complete valves as spare part.
