Doubtful Temperature Readings threatens Soaking Pit Wrecks

Instrumentation engineering root cause analysis of doubtful temperature readings of temperature recorder that threatens soaking pit wrecks.

Article Type:Root Cause Analysis (RCA)
Category:Instrumentation
Equipment Type:Instruments
Author:S. Raghava Chari

Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.

Soaking Pit Doubtful Temperature Readings

The pit supervisor asserted the temperature recorder read temperatures are incorrect and stubbornly refused ingots charging, though the temperature recorder and supporting temperature indicator read the same. The instrument crew repeatedly calibrated both and assured all are OK!

The author was called upon to resolve the issue checked the pit wall temperature with an optical pyrometer and agreed with the pit supervisor.

He checked with the crew who made the thermocouples and found that they had by mistake made the TC out of Pt. Rh 10%-Pt. wire pair and not out of recorder & indicator calibrated Pt. Rh 13%-Pt. wires – the problem root cause.

He appreciated the pit supervisor for his judgment; Charged, Ingots would have melted and ruined the revamped pit. Clearing the solidified steel out of the pit and revamp would have put the pit and reduced the rolling mill output several weeks.

Doubtful Temperature Readings

Problem Repeats Eliminated

Since that plant’s most temperature measurements calibration is Pt. Rh 13% – Pt.

The author eliminated the recurrence of the problems thus:

  1. Made Pt Rh 13-Pt TC wires the plant standard
  2. Exchanged the unused Pt-Rh Pt TC wire rolls with Pt Rh 13 – Pt wire rolls
  3. Changed the measuring circuit card of all Pt Rh 10 – Pt calibrated instruments with Pt Rh 13 Pt cards and marked the scales Pt Rh 13 Pt and verified the calibration   

Author: S. Raghava Chari

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Doubtful Temperature Readings threatens Soaking Pit Wrecks

 
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