Chapter 9: Project Maintenance

9.1 Maintenance Basics 20782077207320712070

Maintenance includes the repair or preservation of an existing facility, preventing deterioration to an unsafe or aesthetically unacceptable condition, and rehabilitation or treatment of an existing facility.

Why Maintenance is Needed 2078 2077 2073 2071 2070

• A facility may be deteriorated due to gradual failure of mechanical components in the system
• Structural failure: The whole or part of a structure may fail or collapse due to various reasons
• Mechanical failure: Some mechanical component when used under continuous service reduces in effective size and failure occurs

Objectives of Maintenance 2078 2073

To achieve adequacy, reliability, and efficiency in project operation, effective and regular maintenance is essential.

• The project which has poor management increases cost for rehabilitation more than repair
• Frequent and costly rehabilitation is avoided through effective and regular maintenance
• "A small repair in time would save costly rehabilitation in the future"
• It is cheaper to carry out preventive works than extended rehabilitation

9.2 Types of Maintenance 20812079207820772076207420732072207120702069

1. Planned Maintenance 2079 2078 2074 2073 2071

Maintenance works organized and carried out with forethought and use of records to a predetermined plan. Planned maintenance involves evaluation of all plant with the intention of carrying out maintenance before it is actually needed through monitoring performance, with the aim of reducing associated costs.

a) Preventive Maintenance

Maintenance carried out at predetermined intervals or according to prescribed criteria, intended to reduce the probability of failure or the degradation of functioning of an item. It aims to prevent breakdowns before they happen.

b) Corrective Maintenance

Maintenance carried out to restore an item to an acceptable standard where repair is needed. The time of maintenance depends on the criticality of the item as indicated by priority rating.

c) Routine/Schedule Maintenance

Activities that relate to the general up-keeping of the facility. These occur on a regular daily or weekly basis and require relatively basic training or skills.

2. Unplanned Maintenance 2079 2074 2073

a) Emergency Maintenance

Maintenance where breakdown or damage occurs unexpectedly. Emergency works arise but they have to be solved otherwise they may cause great damage to the system of the project. This type of maintenance includes repairing works of damages caused by major disasters.

b) Breakdown Maintenance

Maintenance work implemented only when facilities or equipment fail and are then repaired at a considerable cost.

3. Diagnostic Maintenance 2070

Diagnostic Maintenance (also called Predictive Maintenance or Condition-Based Maintenance) is a type of maintenance where the condition of equipment, structures, or systems is continuously or periodically monitored using diagnostic instruments and techniques to detect potential failures before they actually occur.

• Principle: Uses monitoring instruments (vibration analyzers, thermography, ultrasonic testing, oil analysis) to assess the actual condition of the asset rather than relying on fixed time schedules.
• Purpose: To predict when maintenance should be performed so that maintenance is done only when needed, reducing unnecessary servicing while preventing unexpected breakdowns.
• Techniques Used:
  • Vibration monitoring — detecting bearing wear, shaft misalignment
  • Infrared thermography — detecting hot spots in electrical systems, insulation failures
  • Ultrasonic testing — detecting cracks, corrosion, delamination in structures
  • Oil/lubricant analysis — detecting metal particles indicating wear
  • Visual inspection with endoscopes/borescopes for internal components
• Advantages: Reduces downtime, extends equipment life, eliminates unnecessary maintenance, prevents catastrophic failure, optimizes maintenance cost.
• Disadvantage: Requires investment in monitoring equipment and trained personnel; not suitable for all types of assets.
• Example: Monitoring vibration levels of a concrete batching plant motor — when vibration exceeds threshold, maintenance is scheduled before the motor fails completely.

Preventive vs Corrective Maintenance 2081 2079 2078 2077 2076 2074 2072 2070 2069

Preventive maintenance is better than corrective maintenance because:

• It prevents breakdowns before they happen, saving time and cost
• Corrective maintenance is reactive and often more expensive
• Regular preventive maintenance extends the useful life of the facility
• Less disruption to project operations
• "A stitch in time saves nine" / "Prevention is better than cure"

9.3 Planning and Scheduling of Maintenance 2079207620732072

Maintenance Planning 2079 2076 2073 2072

Planning is the process by which the elements required to perform a task are determined in advance of the job start. Good planning is a prerequisite for sound scheduling.

Planning comprises preparation of:

• The work order
• Bill of material
• Purchase requisition
• Necessary drawings
• Labor planning sheet including standard times
• All data needed prior to scheduling and releasing work order

Planning Procedures

1. Determine the job content
2. Develop a work plan — entails activities in the job and establishing best methods and procedures
3. Establish crew size for the job
4. Plan and order parts and material
5. Determine if special tools and equipment are needed

Levels of Planning Process

• Long-range planning: Covers a period of 3 to 5 years, sets plans for future activities and long-range improvement
• Medium-range planning: Covers a period of 1 month to 1 year
• Short-range planning: Covers a period of 1 day to 1 week, focuses on determination of all elements required to perform maintenance tasks in advance

Maintenance Scheduling

The process by which jobs are matched with resources and sequenced to be executed at a certain point in time.

• Scheduling deals with the specific time and phasing of planned jobs together with work orders
• Monitoring, controlling, and reporting on job progress
• Successful scheduling requires access to plant production schedule (when facilities will be available for maintenance without interrupting production)
• Well-defined priorities for maintenance work
• Information about jobs already scheduled (backlog)

Scheduling Techniques

• Modified Gantt chart
• CPM (Critical Path Method)
• PERT (Program Evaluation and Review Technique)
• Integer and stochastic programming

Effective planning and scheduling contribute significantly to:

• Reduced maintenance cost
• Improved utilization of maintenance workforce by reducing delays and interruptions
• Improved quality of maintenance work by adopting best methods and procedures and assigning the most qualified workers

Important Things to Consider