Page 469 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

446 Major Process Equ@ment Maintenmrce and Repair

Operational philosophy also has a bearing on which type of mainte-
nance is most cost effective for a given company. One pipeline company
may elect to run all of its units hard for 8,000 hours and then overhaul on
a regular basis. If they operate their own maintenance facility and the
volume of work is within their capability, then this approach could mini-
mize the amount of unscheduled downtime experienced and maintain a
consistent workload in their shop. If the company was sending all of this
work to an OEM’s shop, their return would not be so great and there
would be more incentive in extending run lengths. Another pipeline, de-
pending on their particular situation, could run every engine until it
showed some sign of distress before doing an overhaul and do a lot less
overhauls. This type of approach would necessitate more conscientious
monitoring and a good routine inspection program so as not to experience
catastrophic failures.
Heavy duty industrial turbines are more frequently installed in facili-
ties which have some on-site maintenance forces and in many cases ex-
tensive engineering staffs. These types of facilities have a few more op-
tions in terms of maintenance philosophy than do the remote locations.
As was stated previously, there are as many different approaches to gas
turbine maintenance as there are users. Which one is right for each user
depends upon the application which his turbine or turbines are in, the
value the user places on downtime, his proximity to the OEM or a non-
OEM maintenance facility. The relation~p between his company and
the OEM, and the relative strength or weakness of the people on site also
influence the type of maintenance which is practical.
Four approaches to heavy duty industrial turbine maintenance follow,
beginning with the approach requiring the least owner involvement:

1. A service contract with the OEM for all maintenance, including
routine inspections and overhauls.
2. In-house maintenance supervision with engineering and service
support fmm the OEM and a contract maintenance crew to perform
the work.
3. In-house maintenance supervision and repair crew, with engineer-
ing from a third party (either a consultant or another part of the us-
er’s company) and assistance from the OEM’s service engineering.
4. A multidiscipline team approach by the user, drawing from internal
company resources (mechanical, metallurgical, instrumentation,
maintenance planning and supervision, etc.) with minimal assis-
tance by the OEM.

As was the case for the aircraft derivative engines, each approach has
certain advantages and disadvantages. The approach taken is highly de