What is acceptable
The average life time (Mean Time Between Defects) will be
– due to the Defect Symptoms mentioned – generally shorter than ten years.
Indicating also whether a defect can be detected before causing breakdown.
Accepted Deterioration Components
|Standard SLC Code||Description of component and relevant defect symptom||controllable by periodic inspection ?|
|1||electric accumulator – aging||yes|
|2||filter, sieve, separator – collecting foreign matter||yes|
|3||storage of liquid – aging||yes|
|4||storage of liquid – loss||yes|
|5||storage of gas – loss||yes|
|6||link chain, belt, cable – wear||yes|
|7||coal brush and partner – wear||yes|
|8||component touching, guiding, fixing, working solid products and material – wear, erosion||yes|
|9||lamp – defect||no|
|10||permanently disposed medium – consumption||yes|
|11||surface of running wheel and partner – wear||yes|
|12||power switches > 500 V – contact defect||yes|
|13||friction element of clutch and brake – wear||yes|
|14||sensor touching product – contamination, wear, displacement||yes|
|15||packing box or mechanical seal – leakage||yes|
|16||collector and partner – wear||yes|
|17||thermally stressed material (burner, oven) – aging||yes|
|18||heat exchange surface – contamination||yes|
|19||insulation of flexible moving cable – wear||yes|
|20||coating of flexible and moving tube – wear||yes|
|21||position switch (limit switch, photo cell, initiator) – displacement, loosening||no|
The three last components printed in italic are explicit no short-life components. However, very frequently they fail due to poor design and operation. Therefore, they require particular attention.
The defects developing with the components, where the last column indicates “yes”, can be found in time by means of periodic inspections.
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Would you tend to expect more components short-life?
Perhaps you believe still other components to be short-life. Watch out! This is a list allowing for frequent defects. Guess the total number of these components installed in your plant and divide this number by the number of defects per year these components are suffering from the defect symptom mentioned; then you arrive at the “Mean Time Between Failures” MTBF. Only when MTBF is smaller than 10 [years], additional components may be entered into this list.