Equipment Maintenance and Repairs

Breakdown Trigger Repairs and Corrective Actions

• Equipment breakdowns should activate two actions:
  • Fast repair of malfunctioning equipment
  • Development of a program to eliminate the cause of the malfunction and prevent future repairs

Extent of Repairs

• Perform just enough repairs to get equipment running again
• Repair the malfunction and replace worn parts
• Replace old equipment with new equipment

Advantages of Worker-Performed Machine Repairs

• Increased flexibility
• Faster minor repairs
• Prevention of minor repairs through cleaning, lubrication, adjustments, and servicing machines
• More careful operation of machines

Reasons for Preventive Maintenance (PM) Programs

• Reduce frequency and severity of equipment malfunctions
• Extend the useful life of equipment
• Reduce total maintenance costs by substituting PM costs for repair costs
• Ensure a safe working environment
• Improve product quality by maintaining proper equipment adjustment

PM Database Requirements

• Detailed records or ongoing history must be maintained for each machine
  • Dates and frequency of breakdowns
  • Descriptions of malfunctions
  • Costs of repairs
• Machine specifications/checklists for PM inspection
• Computerized records can be kept in a plastic pocket on a machine

Modern Approaches to PM

• Workers are responsible for preventing breakdowns by performing PM on their own machines
• Workers should listen for indications of potential equipment malfunction
• Workers should maintain maintenance-related records

Decision Analysis in PM

• Determining the number of spare parts to carry for repairs
• Determining how often to perform PM on groups of machines
• Planning and controlling large-scale PM projects

Maintenance Management and Control

• Maintenance management encompasses the control of maintenance activities and the establishment of maintenance policies
• The importance of maintenance management increases with the size of the maintenance activity and group
• Traditionally, maintenance groups comprise 5-10% of the operating force, but their proportion has increased significantly.

Maintenance and Maintenance Management Differences

• Maintenance is the daily function of keeping industrial plants in working order, managed by production management
• Maintenance management is concerned with planning, organizing, and directing maintenance efforts to control plant availability

Objectives of Maintenance Management

• Minimize production downtime
• Minimize time spent on repairs and associated costs
• Minimize production downtime due to stoppages
• Maintain effective use of maintenance personnel and equipment

Impact of Poor Maintenance Management

• Reduced production capacity
• Increased production costs
• Reduced product and service quality
• Diminished customer satisfaction

Maintenance Department Function and Organization

• Maintenance departments plan and implement repairs to equipment/facilities that meet established standards
• They develop preventive maintenance programs, perform work associated with repair operations, and maintain financial records to track material/personnel costs
• Maintenance staff should be kept up to date with maintenance activities and procedures.
• Staff should also be trained in safety and other related practices.

Types of Scheduling

• Fixed scheduling: Problems of backlogs are common
• Dynamic scheduling: Accounts for all practical constraints in all situations

Cost Reduction Through Maintenance Planning and Scheduling

• Utilizing shutdown time for work repairs
• Finalizing shutdown work plans well in advance
• Planning work procedures for optimal effectiveness during shutdowns

Work Executed During Breakdowns

• Minor maintenance tasks, such as cleaning and repair, are prioritized to minimize shutdown time
• During major shutdowns, maximum maintenance tasks are performed so that they are completed

Minor Downtime Importance

• Minor downtime periods can be used to perform tasks that cannot be done during normal operation; these are included in long-term plans to keep maintenance up to date with the equipment.

Importance of Maintenance Scheduling History

• Reviewing repair histories for accurately estimating time, material, and expenses
• Avoid using past budget figures during budget creation

Planning Shutdown Work

• Thorough planning enables more work to be completed by fewer personnel

Maintenance Reliability and Probability

• Reliability is the probability an item performs its intended function under specified conditions.
• Reliability = Probability
• Methods to improve reliability include better component design, improved production techniques, and improved testing procedures.

Non-Destructive Testing (NDT) Methods

• A variety of NDT methods are used to inspect and diagnose issues without damaging the inspected object/item
  • Acoustic Emission Testing (AET)
  • Acoustic Resonance Testing (ART)
  • Electromagnetic Testing (ET)
  • Infrared Testing (IRT)
  • Leak Testing (LT)
  • Magnetic particle testing (MT)
  • Dye penetrant testing (PT)
  • Radiographic Testing (RT)
  • Ultrasonic testing (UT)
  • Visual testing (VT)

Common NDT Methods

• Visual inspection
• Dye penetrant inspection (DPI)
• Magnetic particle inspection (MPI)
• Ultrasonic testing (UT)
• Radiography testing

Storage Tank Inspection

• Robotics crawlers and cameras are used for wall and interior inspection, respectively

Aircraft Inspection

• NDT is used throughout aircraft design and operation phases for routine maintenance and diagnostics

Jet Engine Inspection

• Aircraft engines undergo periodic overhaul inspection and repair
• Fluorescent penetrant inspection checks for cracks

Pressure Vessel Inspection

• Radiography and ultrasonic tests are used to maintain pressure vessels for safety
• NDT is critical in ensuring the integrity of pressure vessels

Rail Inspection

• Specialized cars equipped with NDT equipment check for track cracks and ensure safety

Bridge Inspection

• Visual inspections and NDT are performed on bridges every few years to detect and prevent potential safety issues

Pipeline Inspection

• NDT helps prevent environment-damaging leaks in various pipeline infrastructure

Maintenance of Pumps

• Friction is reduced through lubrication
• Lubrication mechanisms such as hydrodynamic and boundary lubrication techniques are used to reduce friction costs.

Types of Lubricants

• Liquid, solid, or gases

Typical Lubricants-Applications

• Rust preventives
• Heat transfer
• Refrigeration
• Rubber process oils
• Ink process oils

Function of Lubricants

• Lubricate- Reduces friction
• Cooling- Heat transfer
• Cleaning- Detergency
• Noise Reduction- Preventing metal-to-metal contact
• Sealing- Prevents high-pressure gas leakage
• Protection- Against wear and tear

Additive Properties of Engine Oils

• Corrosion/rust inhibitor
• Anti-wear additives
• Detergents
• Dispersants
• Friction modifiers