14
MT 237 – EN ed.2015 (Rev.A)
6.0
MAINTENANCE
6.1
GENERAL
Maintenance, inspection and operation activities have to be carried out in compliance with the regulations in force on the matter in the place
of installation of the equipment (type and frequency). Before performing any kind of intervention, it is important to ensure that the slam-shut
valve has been closed, that the inlet & outlet isolating valves have been closed and that all of the pressure has been discharged from the
piping between the slam-shut valve and those isolating valves. Maintenance interventions are strictly bound to the quality of the conveyed
gas (impurities, humidity, gasoline, corrosive substances) and to the filtration efficiency.
Therefore, it is always recommended to perform preventive maintenance interventions whose periodicity shall be determined according to
the following aspects, unless specified by regulations already in force:
The quality of the conveyed gas;
The status of cleaning and preservation of the piping upstream of the regulator: as a rule, for example, after the first start of the
plants, more frequent maintenance interventions are required due to the uncertain internal cleanliness of the piping;
The reliability level required by the reduction plant.
Before starting disassembling the equipment make sure:
To have a series of original spare parts available. Spare parts shall be original spare parts by Pietro Fiorentini bearing in mind
that the most important parts such as membranes are marked.
To have a set of tools as shown in table 6.4.
For proper maintenance, the recommended spare parts are unequivocally identified by tags indicating:
The SS layout drawing number of the equipment in which they can be used;
The position given on the SS layout drawing of the equipment; it is suggested to replace all rubber parts; for this purpose, use the
suitable spare part kit available on Pietro Fiorentini website.
NB. The use of non-original parts relieves Pietro Fiorentini S.p.A. from any liability whatsoever.
Pay attention to discharging vents & drains to a safe area during the depressurization activities. To avoid risks related to the formation of
sparks due to particles of impurities inside the discharge lines, it is recommended to keep fluid speed lower than 5 m/sec.
Moreover, for those parts that can be positioned or oriented in more than one way during re-assembly, it is suggested to add reference
marks on those parts before disassembling.
Finally, it shall be underlined that the O-rings and the sliding mechanical parts (stems, etc.) have to be lubricated before reassembling them,
by applying a thin layer of silicone grease. Before commissioning, it is necessary to verify the external tightness of the equipment at a
suitable pressure for assuring the absence of external leaks.
The internal tightness of the slam-shut devices, when they are used as safety accessories according to the PED Directive, must be checked
at a suitable pressure able to assure the internal tightness at the maximum working pressure expected.
These checks are essential in order to assure the safe use at the intended operating conditions; they shall, in any case, comply with the
national regulations in force.
