Page 31 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Project Best Practices Be st Practice 1.3

Input from project team – propylene refrigeration duty data sheet
Calculations and vendor discussions showed that duty required
a prototype machine in regards to rotor bearing span and shaft
diameter (shaft stiffness)
Risk class was determined as multiple component inexperience
Vendors were invited to pre-screening design review meetings to
determine action
Based on meeting reviews with three vendors, it was determined that
bearing span had to be reduced and that two compressor cases, in
series, were required for proven reliability
Costs of second case were assembled along with supporting data
and cost figures for exposure to reduced availability and
benchmarks of problems experienced with the one case option
(this ‘lesson learned’ information was obtained from experienced
plant maintenance and operations personnel)
The management presentation was successful and additional
$5mm was approved for purchase and installation of the second
compressor casing

Fig 1.2.3 Refrigeration compressor selection case history

Best Practice 1.3Practice 1.3
Best
Screen preferred vendors list by corporate and plant Excessive time spent in reviewing vendor bids only to disqualify
experience for the project requirements. them based on experience
Review potential vendors, experience against specific process A large exception to specifications list resulting in additional review
conditions for the project to confirm that they have experience for this time
project. The potential of accepting an unproven machine for the application,
Obtain past project and field experience details for each potential based on a lower quoted price
vendor from corporate and plant machinery specialists. Reduced reliability during operation, resulting in large revenue
Do not hesitate to eliminate a potential vendor for this project based losses.
on lack of experience.
If a vendor is eliminated from quoting, discuss the reasons openly Benchmarks
with them, and ensure the vendor that this elimination will not affect This best practice has been used since the 1970s, and ensures mini-
future project proposals and is in their interest in terms of proposal cost mum machinery review time, optimum safety and reliability, and
savings. maximum revenue over the life of the process. It has been incorporated
globally in all upstream and downstream projects. It has resulted in
Lessons Learned minimum machinery design times, minimum change orders, smooth
Not screening vendors for experience for the project at FATs (Factory Acceptance Tests) and trouble free start-ups. These
hand will result in schedule delays in the selection process facts have resulted in reduced project costs and schedules and mini-
mum start-up times, resulting in early start-ups and increased product
and lower unit reliability.
revenue.
Not properly screening vendors for experience for the project
specific conditions will result in:

B.P. 1.3. Supporting Material
Past project experience –design errors, manufacturing problems,
Key screening factors for vendor experience for the specific
delays, etc.
project requirements are noted in Figure 1.3.1.
Past field experience – availability, maintainability, field support,
Once these facts are obtained, a list of acceptable vendors etc.
for this specific project can be prepared. It is important to note Vendor's reference lists for the specific project application
that each specific project will have different requirements and detailing flow, head, efficiency, etc.
some vendors will not be in the same position as their com- Networking with industry peers (API, symposiums, etc.)
petition in terms of design experience and/or manufacturing
capability.
Fig 1.3.1 Determine potential vendor capabilities
5