STI RTQ Series, Instruction Manual, Page: 24 / 44

STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5300, rev. 09 06/2020 – RTQS 20
9 MAINTENANCE
9.1 Service limit
Design life prior to actuator replacement is 30 years; the validity of this life is subject to periodic inspection
as per next paragraph 8.2 and special maintenance as per next paragraph 8.3, if necessary.
Important At the end of design life the actuator can be scraped or can be totally refurbished:
this decision must be taken by Plant Responsible considering the general condition
of the actuator.
In case of refurbishment all the seals and other components made in soft materials,
grease and all other parts subject to wear like bushes and sliding blocks must be
changed. All other parts, with special attention to the spring cartridge, that shows
significant signs of corrosion must be replaced.
At the end of this activity the actuator must be completely repainted.
9.2 Periodic Inspections
Inspect the general conditions at regular intervals: recommended frequency of inspection is one time every
two years, but this frequency could be changed depending on the installation and working conditions.
- Check that the actuator operates the valve correctly and with the required operating times. If the actuator
operation is very infrequent, carry out a few opening and closing operations with all the existing controls
(remote control, local control, emergency controls, etc.), if this is allowed by the conditions of the plant.
- Check that the signals to the remote control desk are correct.
- Check that the pneumatic supply pressure value is within the required range.
- If there is an air filter on the actuator, bleed the condense water accumulated in the cup by opening the
drain cock. Disassemble the cup periodically and wash it with soap and water; disassemble the filter: if
this is made up of a sintered cartridge, wash it with nitrate solvent and blow through with air. If the filter
is made of cellulose, it must be replaced when clogged.
- Check that the external components of the actuator are in good conditions.
- Check all the paint-coat of the actuator. If some areas are damaged, repair the paint-coat according to
the applicable specification.
- Check that there is no leak in the pneumatic connections. If necessary, tighten the nuts of the pipe-
fittings.
Warning
Take care that a build-up of dust or dirt on the actuator can inhibit cooling and
contribute to increase surface temperature. The user should plan and provide for a
periodic cleaning/maintenance program that will maintain the external surface of
the actuator free from excessive layer of dust.
Important
Use only STI original spare parts. STI cannot accept responsibility for any damages that
occur from using spare parts or fastening materials from other manufacturers.
If STI products (i.e. gasket, O-ring, etc) have been on store for longer periods check these
for corrosion or deterioration before using these products.