Page 52 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 2 .1
Be st Practice 2 .2 Pump Best Practices

Best
Best Practice 2.1Practice 2.1
Use plant, company and industry lessons learned to select The writer has continuously experienced pump reliability issues
the proper type of pump. that were present in similar pumps in the plant but were not corrected
First, accurately determine all of the operating conditions to be in new projects or revamps. It is most important to list all pump re-
accomodated. Process conditions not anticipated in the selection liability issues and make them known to plant management and
phase account for 80% or more of pump reliability problems. Then use project teams as early as possible in the project phase (pre-FEED
company guidelines for selection of the pump type if they are available. phase).
Whether company guidelines are available or not, determine the
pump type by site and industry lessons learned to avoid plant safety Benchmarks
and reliability issues. Since the 1990s this best practice has been used for duplicate
Finally, indicate the selected pump type on the data sheet with all plants in the ammonia, ethylene, LNG, and methanol refineries. All
pump best practices dictated by plant, company and industry lessons past pump reliability issues were evaluated to produce a best
learned noted. practice pump type selection list for each application, along with
other best practice guidelines to be included on the pump data
Lessons Learned sheet. Typical pump MTBFs using this best practice exceeded
Not using lessons learned from past problems to select the 80 months.
type of pump required will lead to lower pump reliability.

Best Practice 2.2Practice 2.2Practice 2.2
Best
Best
Pre-select centrifugal pumps (before the EP&C does) and Lessons Learned
modify the pump data sheet to include all details. Letting the EP&C select pumps can lead to lower pump
Select the pump for the noted performance conditions, and de- reliability and most likely a narrower range of operation.
termine the pump selections using the acceptable vendor’s pump data Many centrifugal pump field reliability issues can be traced back to
books or website information. improper selection of the pump. We have found that pumps which
Select the pump to operate as closely as possible to its best effi- suffer damage from operation at high or low flows frequently were
ciency point. selected such that the specified rated point was either in the overload
Notify the EP&C of the selections for each acceptable vendor for the region (selecting too small a pump) or close to the minimum flow point
project, noting specific component requirements and all best practice (selecting too large a pump).
requirements on the data sheet.
Pre-selection of all centrifugal pumps assures that: Benchmarks
All pump operating points will be in the Equipment Reliability Since the mid 1970s a standard practice has been to pre-select cen-
Operating Envelope (EROE) resulting in optimum pump safety trifugal pumps for the stated operating conditions, and note all best
reliability and performance. practice requirements on the pump data sheets. This practice has
Specific component best practice requirements will be met (impeller resulted in trouble free pump start-up reliability of the highest level
type, journal bearings, thrust bearings, seal and auxiliary systems). (MTBFs greater than 80 months).
All company best practices will be incorporated into the pump
design prior to sending the out the ITB (invitation to bid) to vendors.

B.P. 2.2. Supporting Material (P) (U) Pump application and operating mode (single or parallel)
(P) (U) Detailed operating conditions
Start with a data sheet to completely define (P) (U) Accurate site and utility requirements
(M) Pump performance
requirements (P) (M) Pump construction and experience
(P) Spare parts required
One of the single most important factors in selecting a pump to (P) (M) Driver details
meet the requirements of a process system is to completely and (P) QA inspection and test requirements
accurately state all the requirements on a data sheet. A cen- Note: to be completed by:
trifugal pump data sheet, courtesy of the American Petroleum P = Purchaser
Industry (API 610) is supplied at the end of this supporting M = Manufacturer (vendor)
U = User
material.
Regardless of the source, all pump data sheets should contain
the categories of information shown in Figure 2.2.1. Fig 2.2.1 Minimum data sheet requirements

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