Part 5: Wear location mapping by industry and equipment

A wear-location map helps identify areas that commonly deteriorate early within a production line. However, the value of the map does not lie in memorizing a list of equipment, but in understanding why one location fails before the adjacent location.

The general principle is to follow the material flow. Locations where the flow changes direction, velocity, or state are often where the conditions acting on the surface change or where multiple mechanisms occur simultaneously. Once this principle is understood, technical personnel can continue narrowing down the locations that need to be inspected even on production lines for which no map is yet available.

1. Early-failure locations are often where the material flow changes

The location that deteriorates first is not necessarily the one subjected to the highest load. In many cases, it is where the material flow changes direction, changes velocity, or transitions to a different state of motion.

Type of change	Example	Effect at the location
Change in direction	Bends, elbows, tee connections, points where the flow strikes the wall	Particles do not continue along their previous trajectory but instead act directly on the surface
Change in velocity	Reduced cross-sections, downstream of valves, downstream of fans	A change in flow velocity changes the level of particle action on the surface
Change in flow state	From falling to sliding, from dry to moist	The mechanism acting on the surface may change directly at the transition point

In many cases, a change in direction is an indication that should be prioritized for inspection. At bends or elbows, particles have inertia and therefore do not change direction completely with the flow, but continue to impact the wall.

Therefore, bends and elbows may deteriorate faster than straight pipe sections even though they are on the same line and carry the same flow rate. The difference lies in the direction in which particles act on the surface.

1.1. Locations where multiple mechanisms occur simultaneously need to be inspected separately

A location may also deteriorate rapidly when two adverse conditions occur simultaneously, for example:

the flow changes direction while operating at high temperature
the location is subjected to both impact and material with high moisture content

When multiple mechanisms reinforce each other, the deterioration rate may differ significantly from that observed when each factor is considered separately.

The method for identifying cases where multiple mechanisms occur simultaneously is presented in Part 1: 4 types of wear and their identifying signs on the surface.

2. Wear-location map in the cement industry

The material flow can be followed from inlet to outlet to identify locations that should be prioritized for inspection.

Location	Material flow	Conditions requiring attention
Reducer section and discharge outlet of the ore silo	Raw ore, with moisture varying by season	Reduced cross-section; moist material may simultaneously cause wear and build-up
Bottom and sidewalls of the discharge chute	Ore, sliding flow	The flow transitions from falling to sliding
Outer edge of the separator blade	Fine coal powder, high velocity	Tangential velocity increases toward the outer edge
Mill casing	Powder and particles in swirling flow	The flow continuously acts on the wall
Recirculation hopper	Fine powder, potentially moist	A narrow cross-section and slow flow increase the risk of material sticking

The outer edge of the separator blade is a typical example of the effect of tangential velocity. On the same blade, velocity increases with radius, so the outer edge may be subjected to more severe conditions than the area closer to the center.

This also shows that it should not be assumed that an entire component requires the same level of protection. The area subjected to greater action needs to be identified before determining the scope of material application.

3. Wear-location map in the iron and steel industry

In an iron and steel production line, operating conditions vary significantly between coke making, sintering, blast-furnace operations, dust collection, and slag handling.

Process	Location requiring attention	Main operating conditions
Coke making	Coal bunker, coke transfer pipe	Sharp-edged coke and multiple flow-direction changes
Coke wharf	Edges, sliding surfaces, and both sidewalls	Areas respectively subjected to impact, sliding wear, and heat
Sintering	Vibrating chute, hot-material screen	Hot material combined with vibration and repeated loading
Sintering	Dust-collection hopper	Fine dust combined with high temperature
Sintering	Flow-direction change zone	High-velocity particle flow changing direction simultaneously
Sintering	Wind box	Dust-laden gas flow passing through changing cross-sections
Blast furnace	Inclined distribution chute, charging hopper	Large lump material and impact during falling
Blast furnace	Fan casing, pressure-equalizing pipe	High-velocity particle-laden gas flow
Blast furnace	Skip charging car	Repeated impact with each charging cycle
Dust collection	Cyclone cone, dust-collection cone	Swirling flow forces particles toward the wall
Slag handling	Slag granulation chute, braking box, screw conveyor	Sharp, hot, and potentially moist slag
Slag handling	Bends, elbows, and tees in slag-discharge piping	Multiple consecutive flow-direction changes

3.1. Cyclone walls wear as a result of the equipment’s operating principle itself

A cyclone operates by generating a swirling flow and directing particles toward the wall. Therefore, the equipment wall is continuously subjected to the action of particle-laden flow.

In this case, the objective cannot be to eliminate the acting mechanism entirely. The problem instead becomes correctly identifying the operating conditions and selecting a material group capable of maintaining a more appropriate service life at that location.

4. Wear-location map in the thermal power industry

Location	Material flow or condition	Cause requiring investigation
Fine-coal bunker	Fine coal, potentially moist	Slow flow through a narrow cross-section, potentially indicating a material-sticking problem
Mill body, grinding rollers	Raw coal, grinding load	High and repeated loading
Separator cone and cage	Pulverized coal in gas flow	Changes in cross-section and flow velocity
Pulverized-coal three-way pipe	High-velocity pulverized coal	Multiple flow-direction changes within the same component
Burner flame guide	High-velocity pulverized coal, close to the heat source	Particle-laden flow combined with heat
Stationary blades of the flue-gas fan	Flue gas carrying fine ash	Ash-laden flow continuously acts on the blades
Ash pipeline	Dry ash or ash slurry	Bends and elbows create additional flow-direction change points
Inclined chute, hot-slag discharge hopper	Hot slag, potentially moist	Impact combined with thermal and moisture conditions
Slag-boat floor	Moist slag, high load	Impact during discharge and the influence of moisture
Limestone line	Limestone	The effect of hardness needs to be distinguished from impact and flow rate

The pulverized-coal three-way pipe clearly demonstrates the principle of flow-direction change. A component with three branches can create multiple zones subjected to different forms of action rather than a single common wear point.

4.1. Low particle hardness does not mean that the operating conditions are mild

Limestone has a hardness of approximately 3 on the Mohs scale, significantly lower than quartz. If only scratching potential is considered, this is not a high-hardness particle group.

However, the limestone line may still require wear protection because the governing mechanism is not necessarily scratching.

When limestone passes through the line with large particle size, significant drop height, and high flow rate, impact may become the primary factor.

Therefore, material evaluation at this location needs to consider impact resistance and toughness rather than prioritizing only the highest hardness.

This example shows that one mild factor does not mean that the entire location is under mild operating conditions. Actual conditions need to be evaluated based on the factors acting simultaneously.

5. Wear-location map in the mining industry

Location	Operating conditions requiring attention
Excavator bucket	Scratching along the bucket surface combined with impact at the cutting edge
Floor and sidewalls of a heavy-duty haul truck body	Impact during loading, followed by sliding during unloading
Hoppers and conveyor transfer chutes	The flow transitions from falling to sliding in a restricted cross-section
Conveyor transfer station	The flow falls and changes direction over a short distance
Crusher feed hopper	Large lump material falling from height, with impact as the governing factor
Hydrocyclone discharge spigot	Slurry and particles concentrated at the discharge zone
Ore distribution pipes, chutes	Particle-laden slurry flow, particularly at flow-direction change points
Flotation-cell walls	Continuous agitation combined with a chemical environment
Ore-slurry pump shaft	High relative velocity in the outer region

5.1. A haul truck body is subjected to two forms of action within the same cycle

The floor and sidewalls of the haul truck body operate under two different conditions.

During loading, the surface is subjected to impact. During unloading, the material continues to slide along the surface.

Therefore, the conditions at this location need to be evaluated under both mechanisms simultaneously, rather than optimizing the material for only one form of action.

5.2. The same principle can occur in different types of equipment

A hydrocyclone discharge spigot and a dust-collection cyclone differ in application but share one principle requiring attention: flow motion causes particles to concentrate in a specific region of the equipment.

Similarly, the outer region of an ore-slurry pump shaft and the outer edge of a separator blade are both associated with changes in velocity with radius.

These examples show that the map is not a list to be memorized. Some material-flow principles can recur across many types of equipment. By understanding the principle, technical personnel can predict locations that should be prioritized for inspection on a production line that has never previously been surveyed.

6. A wear-location map can be developed by following the material flow

For production lines outside the four industries above, the process can begin with a material-flow diagram rather than attempting to find a corresponding equipment list.

Step	Activity
1	Draw the material-flow direction from inlet to outlet
2	Mark all locations where the flow changes direction
3	Mark locations where the flow velocity changes, including changes in cross-section, downstream of fans, or downstream of valves
4	Mark locations where the flow state changes, such as from falling to sliding or from dry to moist
5	Prioritize inspection of locations where two or more types of change occur simultaneously
6	Measure the influencing factors at the identified locations

The first step is particularly important. If only the equipment is drawn, the diagram primarily shows where the equipment is located. When the material-flow direction is drawn, technical personnel begin to see where the operating conditions change.

Locations where multiple types of change occur simultaneously require particular attention because multiple mechanisms may be acting at the same time.

7. The order of intervention does not depend solely on the severity of wear

The map helps identify which locations are at risk of early deterioration, but it does not directly determine which location should be addressed first.

Four criteria need to be considered together:

Evaluation priority	Criterion	Meaning
1	Whether the damage stops one item of equipment or affects the entire line	The extent of impact on operations differs
2	Frequency of intervention required during the year	A location requiring frequent repair creates repeated shutdowns and maintenance work
3	Whether the location can be accessed during a shutdown	Some locations can only be addressed during an extended plant shutdown
4	Whether a baseline has already been established for monitoring	Initial data provide a basis for evaluating results after the solution is changed

Accessibility is a factor that is easily overlooked.

A severely deteriorated location that can only be accessed during a major overhaul may not necessarily be the first task that can be implemented. However, it is a location that needs to be planned early so that the appropriate shutdown window is not missed.

The severity of damage and the implementation sequence are therefore related issues, but they are not entirely the same.

8. Scope of the map

The map in this content was compiled from 39 survey projects within the records used to develop the map, combined with application data from manufacturers’ documentation.

The four industries for which data were compiled are:

iron and steel
cement
thermal power
mining

The figure of 39 projects represents the sample of project records used to develop this map, not the total number of projects completed by GAC.

For production lines outside these four industry groups, the material-flow method in Section 6 can be used to identify the locations that should be inspected first.

9. Responsibilities of the departments

Developing and using the map requires coordination between survey personnel, operations, and the maintenance planning department.

Activity	Person or department responsible
Draw the material-flow diagram	Survey engineer in coordination with the operations department
Confirm the actual flow direction	Operations department
Confirm whether the damage affects one item of equipment or the entire line	Operations and maintenance planning departments
Provide the shutdown schedule and shutdown duration	Maintenance planning department
Determine the implementation sequence	Plant

The order of intervention depends not only on the severity of wear but also on the production plan, accessibility, and the level of impact on operations.

Therefore, the solution provider may support the technical analysis but does not determine the implementation priorities on behalf of the plant.

10. Notes when applying this knowledge

First, the map indicates locations that commonly face a risk of early deterioration, but the actual order may differ between plants. The same process stage may still operate under different material-flow and operating conditions.

Second, the current map focuses on four industries because this is the scope of the data that have been compiled. For production lines outside these four industries, the material-flow principle needs to be used to identify the locations requiring inspection.

Third, the map only indicates where attention is required; it does not indicate the specific severity of wear. The extent of damage still needs to be determined using data from the actual location and monitored over time.

Fourth, the final prioritization decision belongs to the plant. The criteria relating to extent of impact, intervention frequency, shutdown duration, and baseline data only provide a framework to support the decision.

A wear-location map is valuable when it is used to interpret material flow and operating conditions rather than merely to memorize a list of equipment. Locations where the flow changes direction, velocity, or state are points that should be prioritized for inspection; the severity of damage and the order of intervention must then still be determined using actual operating data from each plant.