Page 67 - Improving Machinery Reliability

Requirements Specification 39

Table 1-3
Estimated Average Maintenance Cost for U.S. Process Plants (1 997)
Electric Motors
* Mean time between failures: 50 operating months
* Average overall maintenance cost for plants with 50,000-150,000 installed motor horsepower:
$2.75/hp/yr
Centrifugal Pumps
Mean time between failures: 56 operating months (good plant)
Average cost of shop materials and labor, exclusive of field, technical support, and overhead
charges for plants with 50,000 to 150,000 installed motor horsepower: $9.70/hp/yr
Probable actual cost of average pump repair, exclusive (inclusive) of burden, field labor, and tech-
nical support expenses: $2000/event ($9000/event)
Motor-Driven Reciprocating Compressors in Clean Service
* Mean expenditure: $9.20/hp/yr, in approx. 1000 hp size machines
$20.00/hp/yr, in approx. 300 hp size machines
Motor-Driven Reciprocating Compressors in Severe Service
* Mean expenditure: $25.00/hp/yr, over 1000 hp size machines
$37.90/hp/yr, up to 1000 hp size machines

Integral Gas-Engine Reciprocating Compressors
For plants with installed total horsepower in the 10,000 to 30,000 hp range: $45,00/hp/yr
Motor-Driven Centrifugal Compressor Trains (Clean Service)
9 Average overall maintenance cost for plants ranging from 60,000-1 80,000 installed hp:
$6.40/hp/yr

Steam Turbine-Driven Centrifugal Compressor Trains
* Average overall turbomachinery train maintenance cost for plants ranging from 60,000- 180,000
installed hp: $9.20/hp/yr
Gas Turbines
0 Average overall maintenance cost:
$13,lO/hp/yr, 4-10 gas turbines, gas-fired, 6,000-18,000 hp range
$lO.OO/hp/yr, 4-10 gas turbines, gas-fired, 25,000 hp and higher

Gas Turbine-Driven Centrifugal Compressor Trains
Average overall maintenance cost, trains in 40,000 hp range, natural gas-fired, clean compression
service: $35/hp/yr
Diesel Engines
0 Average overall maintenance cost, diesel engines only: $42/hp/yr

Experience slhows that major contractors and owner’s project engineers orient
their initial data-collection efforts primarily toward construction-related documenta-
tion. As the project progresses, more emphasis is placed on obtaining design-related
machinery documentation as listed in the appendixes of API specifications for major
machinery. These requirements are generally understood by contractors and machin-
ery manufacturers. Before the project is closed out, this collection of data is assem-
bled in many volumes of mechanical catalogs.