Page 326 - Improving Machinery Reliability

Life Cycle Cost Studies 295

Table 5-1 1
Non-annualized Acquisition and Sustaining Costs for Solo ANSI Pump

ANSI Pump:
CoslE,emenl Year Year Year Year Year Year Year Year Year Year Year
0 1 2 3 4 5 6 7 8 8 10
Aquisdion Cos&
Picgram Managemenl 0
Engineering Design 0
Engineernng Data 0
Spare pans B Lagisbu 0
Faulilies 8 ConsVucLon 0
lnieal Training 0
Technical Data 0
Capital Equlpmenl 0
Suseining Costs
DOwmenlaliOn Coas 0
Disposal Costs 3000
TOM 0 0 0 0 0 0 0 0 0 0 3000

Alternative #2: Add redundant ANSI pump. Use the following details from plant
experience.
This case results in pumps installed in parallel but operated as a standby redundant
system as the redundant components are not energized but are literally standing by
waiting to be used when failure of the operating system is detected. Of course, the
detectiodswitching device is very important for calculating overall system reliabili-
ty, and for this case the reliability is assumed to be 100%. Also for simplicity, the
reliability of the system is calculated as if the redundant pumps are operating in par-
allel. Furthermore, experience in most chemical plants and refineries shows impend-
ing failure is usually detected and redundant systems are usually started in a timely
manner to avoid lost production from the failing device; therefore, assume no loss of
production by use of redundant pumps.
Capital costs for the redundant ANSI pumps are $8,000 plus $3,000 for checkhso-
lation valves, plus $2,500 for construction and installation along with US$l,OOO for
program management, US$1,500 for engineering design, and US$l,OOO for docu-
mentation. Likewise, the plant maintenance organization will incur US$l,OOO for
engineering documentation costs to put the equipment into the paperwork system.
Lost gross margin occurs at US$4,000/hour when the process is down for repairs,
Annual power cost for running the pump is US$165/year per horsepower. Remem-
ber. either the old pump runs or the new pump (not both at the same time). The plant
incurs 1.6 power outages each year for an average downtime of 0.5 hours, and this
cost is charged into plant overhead rather than to individual pieces of equipment.

Annual power costs are (US$165/hp-year) * (100 hp) = US$16,500
Assume no lost production time by use of the redundant pumps. Keep all other
costs as described for the single ANSI pump and depreciate the assets over the ten
year project life.