Temperature Element Replacement SOP

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• Document control header (SOP INST 017)
• Purpose, scope and references
• Safety, tools and prerequisites
• Numbered step by step procedure
• Acceptance criteria and records
• Approval block for sign off

1. Purpose

To replace failed temperature elements without opening the process and with a correct, verified measurement afterwards.

2. Scope

RTD and thermocouple insert elements in thermowells, with head or remote transmitters.

3. References

• Temperature transmitter and thermowell data sheets
• Spare parts list
• Loop diagram

4. Responsibilities

• Instrument technician: carries out the work and records results.
• Instrument engineer or supervisor: reviews and approves the records.
• Operations: grants the permit, isolates the process and returns the equipment to service.

5. Safety Precautions

• Work only under a valid permit to work and follow the site isolation (lockout tagout) procedure.
• Wear the PPE required for the area: safety helmet, glasses, gloves and safety shoes as a minimum.
• In hazardous areas use certified or intrinsically safe test equipment, or obtain a gas free certificate and hot work permit.
• Inform the control room before starting, and before returning the instrument to service.
• Never remove a thermowell in service; only the element inside the well.
• Elements from hot wells are hot: use gloves.
• If the well is suspected leaking, stop and treat it as a pressure boundary failure.

6. Tools and Equipment

• Replacement element of correct type, length and diameter
• Multimeter or temperature calibrator
• Spanners and heat resistant gloves

7. Prerequisites

• Loop in manual; alarms and trips inhibited as authorised.

8. Procedure

8.1 Remove

1. Disconnect wires, noting terminal positions.
2. Unscrew and withdraw the element; check the well bore for liquid, which indicates a leaking well.

8.2 Check new element

1. Confirm type (Pt100, type K), wiring, length and diameter.
2. Measure resistance or mV at ambient and compare with the table.

8.3 Install

1. Insert until the tip touches the well bottom (spring loaded).
2. Reconnect wires with correct polarity or 3 wire arrangement.

8.4 Verify

1. Compare the reading with a nearby instrument or a portable probe.
2. Remove inhibits and record the replacement.

9. Acceptance Criteria

• Correct element type and length installed, touching the well bottom.
• Reading consistent with process and nearby instruments.

10. Records

Related tools

This is a generic procedure. Adapt it to your site permit system, the manufacturer instructions and your quality system before use.

Frequently Asked Questions