Hydrocarbon Processing - May 2021 - 39

Maintenance and Reliability
TABLE 4. Process system
Process system

Minimum process adequacy/Limitations check requirements

KODs

* Separation adequacy, adequacy against revised design conditions/settle out conditions, revisit PRV
systems, adequacy of inlet/outlet and oriﬁce size of PSVs, revisit alarms and trip settings, revisit emergency
depressurization system, re-run depressurization study (ﬁre case and adiabatic case) and ensure the ESDV
system is adequate and low temperature compatibility of the material, check MOC compatibility against
new composition/condition

Nozzle

* Check nozzle pressure drop, velocity criteria, ρV2 criteria, noise criteria

Piping system

* Pressure drop, velocity criteria, ρV2 criteria, noise criteria, re-routed piping must be checked
* Adequacy of existing drain header, vent header and other piping must be checked
* Check adequacy against revised duty
* Check material compatibility

Heat exchangers/coolers

* Check vibration/two-phase ﬂow
* Check design conditions for revised settle out/design conditions
* Check adequacy of ﬁnal protection elements
* Check requirement revising alarm settings

Alarms and trips

* Check requirement revising trip settings
* Margin between the operation, alarm and trip must revisit along with operation team to avoid frequent alarm,
trip and maintain operator response time
* Check compatibility against the new composition

Lube/seal systems

* Check against new operating and design conditions
* Check the adequacy in terms of load, capacity, consumption, lube pump/driver capacity, relief system capacity
* Check viability of other techno-economical viability available in the market
* Compatibility with respect to new composition and operating and design condition must be checked

Material

Driver capabilities

* Hazardous area classiﬁcation/temperature class of the equipment/electrical/instruments should be checked
against new composition/operating and design condition
* Driver capabilities against required duty, speed
* Changes in the utility/ambient conditions on turbine, motor to be reviewed
* Check impact on the downstream equipment/piping/instrument for revised operating and design conditions

Operating envelope

* Check alarm, trip, PSV set pressures, ESDV set pressures against revamped conditions
* Update the operating procedures
* Check the additional utility required and availability

Utiilty system

* Perform adequacy check of existing utility lines/facilities
* Perform adequacy check of vent/ﬂare/relief headers
* Space constraint for additional/rerouting of equipment/piping must be checked
* Adequacy of DCS/ESD system for additional/modiﬁcation of inputs/alarms/trips to be checked
* Aging factor/structural strength of the supports must be considered for revamping the system

Other

* Existing piping/equipment adequacy for revamping condition shall be checked for adequacy with respect to
available thickness (inspection report based)
* Integrity assessment, design review and risk assessment to be carried out and recommendations of these
reviews must be incorporated
* Requirement of hot/cold anti-surge staged anti-surge/capacity control measures must be checked
* Adequacy of existing anti-surge system must be checked

Process challenges and the ripple effect on a process
system. KODs, piping/nozzles, relief systems, interstate/dis-

charge coolers, drain and vent systems, emergency shutdown
and depressurization systems, alarm and trips schedule, area
classification and its impact, impact on material corrosion,
lube and seal systems, utility requirements, rerouted piping
system, operating envelop, driver capabilities, etc., should be

revisited during the restaging/revamping of the compressor
system, as tabulated in TABLE 4.
Impeller trimming. Impeller trimming is often used to im-

prove energy efficiency to optimize the oversized compressor
and alter the exit mach number of an impeller for different
molecular weight.
Hydrocarbon Processing | MAY 2021

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Hydrocarbon Processing - May 2021

Table of Contents for the Digital Edition of Hydrocarbon Processing - May 2021
