Page 163 - Improving Machinery Reliability

Machinery Reliability Audits and Reviews 135

Again, this provides a final wrapup of certified drawings for the purchaser’s per-
manent records.
The vendor will usually issue official operating and maintenance manuals around
the time the completed machine leaves his factory. While this may be acceptable in
view of the fact that all of these data had previously been made available to the pur-
chaser or his contractor, any delay in the originally scheduled transmission of essen-
tial documents may have serious impact on the completion of construction and,
therefore, machinery startup targets. To forestall any such delays, project managers
would be well advised to link progress payments to the timely and diligent execution
of all data-transmittal requirements. Once full payment has been made while certain
review documents are yet outstanding, the purchaser loses virtually all his leverage
and may not be able to proceed with critically important review or audit efforts.
For additional discussion of machinery-related documentation, refer to Chapter 1,
“Specifying Machinery Documentation Requirements.”

Auditing and Reviewing Steam Turbines
Reliability audits and reviews for steam turbines differ little from those described
earlier for centrifugal compressors. While in-depth audits are rarely justified for
small, general purpose steam turbines, such audits are well worth pursuing for the
majority of special purpose machines, some of which are now driving process plant
compressors in the 60,000-KW range. Conventional, on-going reliability reviews are
appropriate for both special- and general purpose steam turbines
API Standard 612 lists most of the documentation helpful in this job. Virtually all
of the documents tabulated must be reviewed for general purpose and special pur-
pose turbines. In addition, audits are recommended for special purpose turbine docu-
mentation identified with an asterisk (*).

1. Certified dimensional outline drawing, including list of connections
2. Cross-sectional drawings and bill of materials, including:
*a. Journal-bearing clearances and tolerance
b. Rotor float (axial)
*c. Seal clearances (shaft end and internal labyrinth) and tolerance
*d. Axial position of wheel(s) relative to inlet nozzle or diaphragms and toler-
ance
e. OD of all wheel(s) at blade tip
3. Rotor assembly drawing, including:
a. Axial position from active thrust-collar face to:
1. Each wheel (inlet side)
2. Each radial probe
3. Each journal-bearing centerline
4. Key phasor notch
b. Thrusk-collar assembly details, including:
* 1. Collar-shaft fit with tolerance
“2. Concentricity (or axial run-out) tolerance