JRLAKE, Application is for various centrifugal compressors - 5 to 30 MW rating, 3000 - 14000 rpm, 1 to 30 Bar sealing pressure, 4" to 10" seal size, fitted with Carbon type barrier seals.
What is good value for MTBR of DGS ? 3 yrs ? 5 yrs ? 10 yrs ?
Do any one have MTBR records for DGS in Refinery/Gas plant/Petrochemical plant compressors ?
In old plants we use plunger pumps (20M3/hr, 75 Bar diff. pressure) for water containing lesss than 100 ppm H2S. In upcoming plants I thing we may use multistage centrifugal (higher flow up to 140m3/hr).
One major contributor for the SiC ring crack is shocks to seal happened during transportation or installation. While starting a unit of the refinery I noticed approx. 12 SiC rings cracked out of 120 seals. After careful replacement problem was almost solved.
In my earlier company we had similar plan, but the vent valve was solenoid operated. When pressure rises, it gives alarm and this valve opens up to flare.
If you have manual valve and 2 mm orifice, the valve should be open. When seal leaks, pressure will rise and pressure switch will generate...
We are facing repeated bearing and motor failure for Canned Motor Pumps in Sour Water Service duties.
Pumps are as per API 685. Average head is 30 meter, Flow 20m3/hr and fluid temp. 50 Deg C.
During design stage, EPC contractor considered sour water as a clean service. But practically...
Milkboy, Flush rate mentioned in seal dwg. is 5 lit/min. I understand this is standard rate and does not indicate special consideration for Caustic application. One seal vendor is saying increasing the flushing fluid temp. by steam tracing will help. ; But we are convinced with Upstream pumping...
For 5% and 10% Caustic @ 40 Deg C application which is the best (Optimum) flushing plan ?
We can not use plan 32. Plan 11/62 are in use but still problem of crystalisation and seal failure exist.
It is difficult to judge thickness loss but it is not that bad, after 14 years of operation.
There can be various reasons for this corrosion : Gas entrainment in water, cavitation, operation away from BEP.
Damage is less evident on impeller because of it's superior metallurgy.
symd
Can you please elaborate "free maintenance type" ?
We are thinking to implemet preventive packing adjustment every month and replacement every 3 month. What is your experience ?
Thanks for reply.
btrueblood,
TEG @ 85 Deg C, Disc. pr. 120 Bar. Failure is not chemical attack on rubber, but lose of pressure loss over few days / weeks. Also packing life is few weeks only.
