©COMEV
AL
V
AL
VE SYSTEMS
Technical Dept. Ref. IOM - PIST
ON (LIFT
DISC) CHECK V
AL
VES, UNIFLOW® 3P-35 - Ed.18/02
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 - PISTON (LIFT DISC) CHECK VALVES, UNIFLOW® 3P-35
Page 4
ATTENTION!
Screwed ends valves:
- Make sure that the pipe screw has the correct finish and compatible cone for the valve.
- Use proper sealant according to duty when needed, such as hemp core, Teflon, etc.
- Check that pipe introduction in the valve does not exceed its thread, leave a safety margin of minimum 1 mm.
- Tighten with a plain or adjustable wrench on the hexagon end of the valve only. Apply force to other area of valve
may seriously damage the valve. Do not use hook spanners or other wrenches that could damage the hexagon
surface. Valve should be threaded smoothly. If not, do not try to force the thread and avoid wrench extensions since
this could lead to breaking the valve or damaging the thread. A general recommendation is not to exceed the tighte-
ning torque of 30Nm.
WeldIing ends valves:
- Welding works must be carried out in accordance with approved procedure and following appropriate safety mea-
sures. Check correct pipe alignment. Clean valve and pipe connections carefully, tack-weld each end of the valve
on to the pipe in 4 or more points depending on size and weight. Put trim away if containing any soft part to prevent
heat exposure. Only put the trim back once the valve is cooled down. Take the necessary precautions to prevent
thermal stressing/overheating of the valve.
- In case of PWHT, temperature, gradient and time exposure should be controlled to the minimum required depen-
ding on the material. PWHT should be applied firstly to one end and secondly to the other end (not simultaneously),
and only to a limited area of each end of the valve, in order to limit the temperature exposure on the welding area,
rest of the valve body and trim. An appropriate method is the use of ceramic blankets covering the length of the
welding area plus a minimum additional length that is determined by the standard of the pipe, being the heating zone
limited to the minimum necessary as mentioned before. Electrical resistances must be set carefully in order to allow
uniform heating and avoid too hot points. Permanent control and register of the temperature should be carried out
during the process in order not to exceed the established temperature/time cycle. Also the adjacent areas should be
monitored to control reached temperatures.
5.2 Requirements at the place of installation
- Downstream from a disruptive element (pump, valve, elbow, pipe reduction) leave as much distance as possible; mini
-
mum distance recommended: 6 times the valve diameter (6xDN).
- Upstream from a disruptive element leave at least a distance of 2xDN.
- Aggressive environmental conditions may reduce the life span of the product. Consider special construction/protective
measures in such a case.
- Consider the interaction between the system and the equipment. Foresee elements to absorb vibrations, pipe dilata-
tions, guides, anchoring and proper support according to the weight of the components.
- The system and operation protocol should be conceived in such a way to avoid high velocities. Prevent pulsing flow or
water hammers, which are very harmful for valves and the rest of the components.
- Flooding of the product is not recommended.
- Allow enough space for valve installation, operation and maintenance.
- It is recommended to install a proper sized mesh strainer upstream the valve in order to protect seating surfaces from
abrasion or erosion that could lead to seat leakage.
- Planners / construction companies or the owner are responsible for positioning and installing products.
6. COMMISSIONING & OPERATION
ATTENTION!
- Before commissioning the valve, check the material, pressure, temperature, flow direction 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. Ensure that the corres-
ponding warning signs are displayed on the valve or surrounding area, or isolate the equipment in case of danger.
- Leakage of media through valve,connections or at closing 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.
