Maintenance Strategies Options

A maintenance strategy or option means a scheme for maintenance, i.e. an elaborate and systematic plan of maintenance action. Following are the maintenance strategies that are commonly applied in the plants.

• Breakdown Maintenance or Operate to Failure or Unplanned Maintenance

• Preventive or Scheduled Maintenance

• Predictive or Condition Based Maintenance

• Opportunity Maintenance

• Design out Maintenance

The equipment under breakdown maintenance is allowed to run until it breaks down and then repairing it and putting back to operation. This strategy is suitable for equipments that are not critical and have spare capacity or redundancy available. In preventive or scheduled Maintenance, maintenance actions such as inspection, lubrication, cleaning, adjustment and replacement are undertaken at fixed intervals of numbers of hours or Kilometers.

An effective PM program does help in avoidance of accidents. Condition monitoring (CM) detects and diagnoses faults and it helps in planned maintenance based on equipment condition. This condition based maintenance strategy or predictive maintenance is preferred for critical systems and for such systems breakdown maintenance is to be avoided. A number of CM techniques such as vibration, temperature, oil analysis, etc. have been developed, which guide the users in planned maintenance.

In opportunity maintenance, timing of maintenance is determined by the procedure adopted for some other item in the same unit or plant. In design out maintenance, the aim is to minimize the effect of failures and in fact eliminates the cause of maintenance. Although it is an engineering design problem, yet it is often a responsibility of maintenance department. This is opted for items of high maintenance cost that are due to poor maintenance, poor design or poor design outside design specifications. It may be mentioned that a best maintenance strategy for each item should be selected by considering its maintenance characteristics, cost and safety.

In addition to the above, new strategies concepts such as Proactive Maintenance, Reliability Centred Maintenance (RCM), Total Productive Maintenance (TPM), etc. have recently been evolved to look it from different perspectives and this has helped in developing effective maintenance. In proactive maintenance, the aim is identify what can go wrong, i.e. by monitoring of parameters that can cause failures. In RCM, the type of maintenance is chosen with reliability of the system in consideration, i.e. system functions, failures relating to those functions and effects of the dominant functional system failures. This strategy in the beginning was applied to critical systems such as aircrafts, nuclear and space applications. At present, this is being extended to critical systems in the plant.

TPM, a Japanese concept, involves total participation of all concerned. The aim is to have overall effectiveness of the equipment with participation of all concerned using productive maintenance system.

Comments

Understanding the Causes of Pump Shaft Breakage

By NTS. Pump shafts are essential in many industrial and commercial applications, providing the necessary mechanical force to move fluids through pipelines and process systems. However, when a pump shaft breaks, it can cause significant downtime, production losses, and safety risks. In this article, we will explore the common causes of pump shaft breakage and how to prevent it from occurring. 1. Excessive Load The most common cause of pump shaft breakage is excessive load. When a pump is overloaded, it places a significant amount of stress on the shaft, causing it to bend, warp, or break. Overloading can be caused by a variety of factors such as a clogged discharge line, worn impeller, or damaged bearings. Proper maintenance, regular inspections, and monitoring of the pump's performance can help prevent overloading. 2. Misalignment If the pump and motor are not properly aligned, it can cause stress on the pump shaft and lead to breakage. Misalignment can occur due ...

[Read more...]

Why Pump Shafts Often Break at the Keyway Area

By NTS Pump shaft failure can lead to significant downtime and repair costs in industrial plants. One of the most common locations for pump shaft failure is at the keyway area. In this article, we will explore the reasons why pump shafts often break at the keyway and what can be done to prevent such failures. The keyway is a high-stress point (weakest point) on the shaft, where a key is inserted to transmit torque between the shaft and the pump impeller or coupling. During operation, the keyway experiences cyclic loading that creates a bending moment in the shaft, which is concentrated in the keyway area. Over time, this cyclic loading can cause fatigue failure in the shaft material, leading to a fracture at the keyway. In addition to cyclic loading, other factors can contribute to shaft failure at the keyway. Improper keyway design or installation can lead to stress concentrations or inadequate clearance between the key and keyway . Misalignment or overloading can also cause ex...

[Read more...]

The 7 guiding principles of a Maintenance 4.0 strategy

Formulating a digital strategy is not easy, but these guidelines can help you get off the sidelines and into the game. By Eitan Vesely and Deddy Lavid (Ben lulu), Presenso It is not uncommon for organizations to struggle with many issues related to digitalization. With the hype around digitalization at fever pitch, it is easy to become overwhelmed by the multitude of options available in the marketplace. But the strongest contributing factor to implementation challenges is a failure to devise a strategy for an extensive period of uncertainty. Formulating a Maintenance 4.0 strategy is not easy. An aggressive strategy based on overinvesting in unproven technologies or a conservative strategy of merely waiting on the sidelines are unrealistic options. Guiding principles The seven guiding principles for a Maintenance 4.0 strategic plan are: 1. Invest based on the business case The primary obligation to shareholders does not change just because of the changes occurring within t...

[Read more...]

Dry Gas Seal Failure Modes

BY BHUSHAN NIKAM. Invented in the mid-20th century and typically equipped in process gas centrifugal, dry gas screw compressors and expanders, dry gas seals (DGS) are the preferred gas lubricated dry seal solutions available on the market. They have become the standard for new machines. DGS are robust, simple, consume less power, and are more efficient in reducing leakage than their predecessor. Various configurations such as tandem with and without an intermediate labyrinth ( Figure 1 ), single ( Figure 2 ), and double ( Figure 3 ) are available & shall be selected based on process requirements. In this article, we discuss the various DGS failure modes and how they should be addressed: PRESSURIZED HOLD/STANDBY Pressurized hold, also called settle-out condition, occurs when the compressor remains at a standstill, but the casing is pressurized. If an alternate process gas lacks sufficient pressure and flow, process gas enters the seal cavity through the process labyrinth ...

[Read more...]

Dry-Running Sealing Technology: Pump Applications (P2)

Solutions to Common Problems The operation of a single contacting seal would be difficult with any of the identified problems. A single contacting seal relies on cooling and lubrication from the process liquid being sealed. Any interruption in the cooling and lubrication processes will result in damage to the seal and leakage to the environment. The non-contacting, dry-running seal is a solution to many of the problems identified by users. An installation to a pump is illustrated in Figure 2. This type of pump seal technology does not require the circulation of liquid for cooling. Instead, a static heat of an inert gas is used to pressurize the space between the seals. Nitrogen gas in normally used to create the barrier between the process liquid and the environment. The gas barrier pressure is normally 20 to 30 psi/1.4 to 2 bar above the seal chamber pressure. The spiral groove geometry of the seal face is responsible for lift-off and separation of the seal f...

[Read more...]

Industrial Maintenance Solutions

Search This Blog