Basically these are the equipment that do not have a prime mover driven rotating component will be considered a static equipment, and here's some example with what sort of Offline/On-line preventive maintenance which are usually carried out on the static equipment. Corrective maintenance will be discussed at the end of this post, as it is what we wish to avoid.
Piping & Typical PM jobs:
- Thickness monitoring(5y or less, depending on code used API570:Piping or API580:RBI)
- Visual Inspection (1y or less)
- Insulation reconditioning (When necessary)
- Painting (1y or more, depending on visual inspection)
- Pressure testing (Usually 10y or less, if critical or national code requires)
Pressure Vessel & Typical PM jobs:
- Thickness monitoring(10y or less depending on code used API510:PV or API580:RBI)
- External Visual Inspection (1y or less)
- Internal Visual Inspection (half est. remaining life of the vessel, if remaining life is less than 4y internal inspection shall be every 2y)
- Insulation reconditioning (When necessary)
- Painting (1y or more, depending on visual inspection)
- Pressure testing (Usually 10y or less, if critical or national code requires)
- Types of inspection may vary if the vessel operates in potentially damaging susceptible services
Above ground tanks & Typical PM jobs:
- Thickness monitoring(10y or less depending on code used API653:AGT or API580:RBI)
- External Visual Inspection (1y or less)
- Internal Visual Inspection (12y or less, unless with internal lining or leak detection installed)
- Insulation reconditioning (When necessary)
- Painting (1y or more, depending on visual inspection)
- Types of inspection may vary if the vessel operates in potentially damaging susceptible services
Heat exchangers & Typical PM jobs:
- Thickness monitoring(10y or less depending on code used API510:PV or API580:RBI)
- External Visual Inspection (1y or less)
- Internal Visual Inspection (half est. remaining life of the vessel, if remaining life is less than 4y internal inspection shall be every 2y)
- NDT Inspection, WFMPI, eddy current, ultrasonic leak test (when leaks are suspected, or when service is critical, in corrosive media)
- Insulation reconditioning (When necessary)
- Painting (1y or more, depending on visual inspection)
- Pressure testing (Usually 10y or less, if critical or national code requires)
- Types of inspection may vary if the vessel operates in potentially damaging susceptible services
Distillation/Absorption columns & Typical PM Jobs
- Thickness monitoring(10y or less depending on code used API510:PV or API580:RBI)
- External Visual Inspection (1y or less)
- Internal Visual Inspection (half est. remaining life of the vessel, if remaining life is less than 4y internal inspection shall be every 2y)
- Insulation reconditioning (When necessary)
- Painting (1y or more, depending on visual inspection)
- Pressure testing (Usually 10y or less, if critical or national code requires)
- Tray/Packing replacement (Usually 2y or more, depending on manufacturer design or efficiency)
- Types of inspection may vary if the vessel operates in potentially damaging susceptible services
Reactors & Typical PM Jobs
- Thickness monitoring(10y or less depending on code used API510:PV or API580:RBI)
- External Visual Inspection (1y or less)
- Internal Visual Inspection (half est. remaining life of the vessel, if remaining life is less than 4y internal inspection shall be every 2y)
- Insulation reconditioning (When necessary)
- Painting (1y or more, depending on visual inspection)
- Pressure testing (Usually 10y or less, if critical or national code requires)
- Catalyst replacement (Usually 2y or more, depending on manufacturer design or efficiency)
- Types of inspection may vary if the vessel operates in potentially damaging susceptible services
Separators vessels & Typical PM Jobs
- See Pressure vessel above.
Steam traps & Typical PM Jobs
- Downstream steam check (1y or less, Live steam (faulty), lazy steam(working))
- Ultrasonic testing (1y or less, functionality check)
Manual Valves/Pressure relief valves & Typical PM Jobs
- These are usually done offline during shutdowns, unless the valves can be positively isolated for removal.
- Refacing of valve seat/trim
- Repacking of seal
- Replacement of corroded/ parts
- Overhaul of soft kit/spring/actuator/etc
- Overpressure test (MV), Set pressure test (PRV)
Source: Wikipedia
Note: About positive isolation - Positive isolation is done for safety reasons, usually either by closing two valves both up/downstream OR closing one valve with a blind installed both up/downsteam, to prevent any passing process media from escaping when maintenance works are carried out.
Valves are usually neglected by operators, they operate these valves using pipe wrench of various sizes. The huge torque applied with this leverage tool usually will speed up damage of the seats and as a result we experience passing of process media. Therefore, positive isolation is good practice to protect maintenance workers.
Filters/Strainers
- Differential pressure monitoring (Frequently)
- Backflushing or cartridge replacement(See manufacturer's recommended interval and action)
What sort of Plant maintenance should be carried out?
Preventive Maintenance
These type of maintenance are pre-scheduled on the plant's CMMS (Computerized Maintenance Management Systems). The benefits of having a preventive maintenance program is that, there will always be some work for the contractors to carry out (be it to clock time sheet or earn earn extra cash??) Okay, the real benefit is that the manufacturer/code/national recommended maintenance intervals can be practised and followed up, so as to prolong the equipment life.
Types of preventive maintenance for Static equipment
- As discussed above at the top of this post.
- This type of maintenance are carried out offline or on-line, depending on the type of plant operations adopted or code requirements which may or may not permit carrying it out on-line.
Corrective Maintenance
These type of maintenance are usually carried out because preventive maintenance is not well practised, due to natural causes, design flaws, operating not according to manufacturer's prescribed conditions and many more reasons.
Types of corrective maintenance for Static equipment
- Box-in/Leak-sealing of pinhole leakage on pipe/vessel/weldments
- Pipe Spool replacement of piping due to the above
- Vessel/tank repair by cladding, shell course replacement, lap patch, plate lining due to thinning
- Steam trap replacement due to malfunction
- Heat exchange tube plugging due to tube leakage
- Unplugging of catalyst/packing/trays/filters by manual intervention
*Source: All images are from Wikipedia.org, except steam traps from Spirax Sarco. All photos are taken from open sources educational sites which allows for their material to be shared. Credits are given to the rightful image owner in this statement. Please drop me a comment should you be the rightful owner of the image and would like to request compliance for credit to be given to you directly.
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