Electric Heat Tracing System Installation Guide for Petrochemical Plants

This article is about Electric Heat Tracing System Installation used in Buildings and Petrochemical Plants. What is basics and working principal of heat tracing system? We will discuss about calculation, design, wiring diagram of Electric Heat Tracing System. All diagrams and Installation techniques of different equipment for heat tracing system in plants and building are to be discussed. For example Mechanical Piping, Valves, Instrument and Electrical Panels, Cold box Heat tracing Installation. We mentioned also testing procedure of electrical heat tracing.    International Codes and Standards globally use IEC 62395 Electrical resistance trace heating systems for industrial and commercial applications or IEC 60079-30 Explosive atmospheres – electrical resistance trace heating.

Electric Heat Tracing System Installation Guide for Petrochemical Plants

Basics and Working Principle of Electrical Heat Tracing System

Heat tracing is also called Trace Heating or Surface Heating, It is method to maintain required heat (temperature) for products liquid, powder and gas in Pipework, Vessel or Equipment to avoid any processing difficulties.

There are two types of Heat tracing energy sources.

1. Electricity
2. Steam

Steam heat tracing is rarely controllable, in case when excess steam is available. Due to leaking of steam traps, it has high maintenance and running cost. Anyhow if there is excess steam, covert into generating electricity, then it will be highly efficient heat tracing system.

Here details discussion about Electrical Heat Tracing and following component are part of this

– Heating cable together with termination components
– Junction boxes and fixing materials
– Temperature control devices (sometimes / optional)
– Monitoring / alarm facilities (sometimes / optional)
– Power distribution

For More Information Please Checkout IEC Electrical Trace Heating Installation in Process Plants

List of Manufacturers for Electrical Heat Tracing System

There are number of manufacturers worldwide, but here we list only top manufacturers for Electrical Heat Tracing Installation.

1. Heat Trace
2. CHROMALOX Advanced Thermal Technologies
3. Thermon
4. BARTEC
5. Emerson NELSON Heat Trace
6. Raychem

There are four generic types of heat tracer

1. Parallel Self-Regulating
2. Parallel Constant Power
3. Series Resistance
4. Skin-Trace

Following is circuit diagram of Electrical Heat Tracing System.

Following picture represents construction of heating cable

TRACE HEATING TAPE INSTALLATION DETAILS

NOTE 
1. ALL STEEL ITEMS MUST BE HOT DIP GALVANISED.

TYPICAL INSTALLATION FOR PIPE ELBOW/RISER

TYPICAL INSTALLATION FOR ALL SIZE VALVES.

WINTERISATION – JUNCTION BOX ARRANGEMENT

1. MOUNTING BRACKET
2. RETAINING TAPE
3. WEATHERPROOF JUNCTION BOX – TO SUIT
4. STEEL FIXING STRAP (SIZE TO SUIT PIPE OVERALL DIAMETER
5. HEATING TAPE – TO SUIT
6. WEATHER PROOF CABLE GLAND
7. WEATHER PROOF SEALING GLAND & CONNECTION
8. POWER SUPPLY CABLE

TYPICAL TRACE HEATING SYSTEM

1. HEATING TAPE
2. CONNECTION KIT
3. JUNCTION BOX
4. SPLICE KIT
5. END SEAL.
6. INSULATION ENTRY KIT
7. GLASS FIBRE TAPE
8. J.B. SUPPORT BRACKET.
9. PIPE STRAP – TO SUIT

NOTES.
1. FOR ACTUAL DETAILS OF PIPING TO BE TRACED SEE PIPING ISOMETRICS AS LISTED IN THE DATA SHEETS.
2. SEE ELECTRICAL BILL OF MATERIAL FOR DETAILS OF EQUIPMENT AND SUPPLIER.

TRACE HEATING GUIDELINES FOR PIPES

TYPICAL INSTALLATION DETAILS –

Trace pipe fittings as shown allow easy maintenance Consult the design specification or Manufacturers product literature for the tracing requirements for fittings and supports .

• Refer to design specification for loop length
• Fix with glass cloth tape
• Thermally insulate and weatherproof to specification including valve stem)

TRACE HEATING GUIDELINES FOR PIPES

• Fix heater to outside long) radius of elbow
• Fix with glass cloth tape
• Thermally insulate and weatherproof to specification

• Do not clamp heating cable with support. Heater must be over the support.
• No additional heating cable is required for bar or rod pipe hangers,
• Fix with glass cloth tape.
• Thermally insulate and weatherproof to specification

• Additional heating cable is 2 times diameter of pipe
• Fix with glass cloth tape
• Thermally insulate and weatherproof to specification

• Fix with glass cloth tape
• Thermally insulate and weatherproof to specification

Leave a 0.5m heating cable service loop at all power connection, splice, tee and end seal locations.
Add additional heating cable to trace the fittings and supports as specified by design specification.
Protect all heating cable ends from moisture, contamination and mechanical damage or other Interference if left exposed for long periods of time before component Installation.

Heating Attachment Recommendations

The heating cable shall be installed straight, as required by the design specification or manufacturers product literature.
Do not use metal attachments, vinyl electrical tape or duct tape as heating cable damage may result.

Plastic cable ties must have a temperature rating that matches the system exposure temperature.
Fix in to place with glass cloth tape (see figure 1 at 300 mm Intervals and additionally where necessary.

Straight tracing

1. Straight trace the pipe, only spiral if specified in the design documents.
2. On horizontal pipes fix on lower quadrant as shown in Figure 1 and not on the bottom of pipe.
3. Thermally insulate and weatherproof to specification.

Fiberglass tape is recommended for general purpose and for use on stainless steel surfaces and lower temperature Installations
Only use Aluminum tape if called for In the design specification. This Improves the heat transfer and increases the power output of the heating cable.
Attach the heating cable to the pipe as shown In Figure 2.

TRACE HEATING CABLE TESTING

RECOMMENDATIONS

INSULATION RESISTANCE TESTS

• BEFORE INSTALLING THERMAL INSULATION.
• PRIOR TO INITIAL START-UP;
• AND AS PART OF THE PERIODIC MAINTENANCE.

TEST METHOD

AFTER COMPLETING HEATING CABLE INSTALLATION, THE INSULATION RESISTANCE BETWEEN THE CONDUCTORS AND THE HEATER BRAID OR METAL PIPE SHOULD BE CHECKED USING A 2500 VDC MEGGER (500 VDC MINIMUM. MINIMUM READINGS SHOULD BE 10 MEGOHMS REGARDLESS OF THE HEATING CABLE LENGTH. THE INSTALLER SHOULD RECORD THE ORIGINAL VALUES FOR EACH CIRCUIT ON THE INSTALLATION RECORD SHEET.

FOR HEATING CABLE WITH BRAID AND OVERSHEATH :
TEST A : TEST BETWEEN HEATING CABLE ANO BRAID.
TEST B : TEST BETWEEN HEATING CABLE BRAID AND PIPE.

FOR HEATER WITHOUT BRAID ON METAL PIPE:
TEST BETWEEN HEATING CABLE CONDUCTORS AND PIPE.

FOR HEATER WITH BRAID (NO OVERSHEATH) :
TEST BETWEEN HEATING CABLE CONDUCTORS AND BRAID.

TRACE HEATING OF PUMPS

1. IN-LINE SPLICE JUNCTION BOX
2. TRACE HEATING TAPE – TO SUIT

NOTES.
1. THE TAPE RUNS SHOWN FOR BOTH PUMPS ARE INDICATIVE ONLY AND SHALL BE FINALLY DECIDED ON SITE IN CONDUCTION WITH THE INSULATION CONTRACTOR OR ENGINEER.
2. AN IN-LINE SPLICE IN THE TAPE SHALL BE MADE IN A JUNCTION BOX INSTALLED EITHER SIDE OF THE PUMP FOR MAINTENANCE REMOVAL PURPOSES.

TRACE HEATING GUIDELINES FOR INSTRUMENTS

1. HEATING TAPE
2. GLASS FIBRE TAPE
3. INSTRUMENT ENCLOSURE

NOTES.

1. WHERE HEATER CABLE IS APPLIED TO THE AREA DESIGNATED ‘BOLT AREA’, ALUMINIUM TAPE SHALL BE USED TO AID HEAT TRANSFER.

2. REFER TO TRACE HEATING SCHEDULE FOR DETAILS OF EQUIPMENT, TAPE LENGTH & CIRCUIT.

3. WHERE SPECIFIED THE INSTRUMENT SHALL BE HEAT TRACED AND LAGGED (BY OTHERS). THE INSTRUMENT MAY BE ENCLOSED IN AN INSTRUMENT ENCLOSURE WHICH MAY BE …
a). HEATED, IN WHICH CASE THE IMPULSE LINE SHALL BE TRACED UP TO THE ENCLOSURE LIMIT.
b). NOT HEATED ,IN WHICH CASE THE INSTRUMENT SHALL BE TRACED AS USUAL.
4.INSULATION DESIGN & INSTALLATION BY OTHERS.

TRACE HEATING GUIDELINES FOR INSTRUMENTS

1. SELF LIMITING HEATING TAPE

NOTES.
1. INSULATION DESIGN & INSTALLATION BY OTHERS.
2. TAPE TO BE FIXED TO PIPE & INSTRUMENT USING GLASS FIBER TAPE.
3. REFER TO TRACE HEATING SCHEDULE FOR DETAILS OF EQUIPMENT, TAPE LENGTH & CIRCUIT.
4. A/R DENOTES AS REQUIRED.

FOUNDATION HEATING GUIDELINES

PLAN ON TYPICAL COLD BOX FOUNDATION

TYPICAL ONE LINE DIAGRAM FOR COLD BOX FOUNDATION HEATING CONTROL PANEL

NOTES

I. THE COLUMN BOX AREA HAS 9 * 20mm CONDUITS CAST IN ITS FOUNDATION & USING HEATING CABLE GIVES HEAT INPUT TO FOUNDATION OF 66 W/m².
2. THE NON-COLUMN BOX AREA HAS 5 x 20 mm CONDUITS CAST IN ITS FOUNDATION & USING HEATING CABLE GIVES HEAT INPUT TO FOUNDATION OF 37 W/m².
3. CONDUITS FOR HEATERS TO BE SUITABLY PLUGGED TO AVOID INGRESS OF WATER.
4. THE CONTROLLER SHALL HAVE TWO SET POINTS, ONE FOR CONTROL AT 3 DEGREES CELCIUS AND THE OTHER FOR ALARM AT I DEGREE CELCIUS. THE UNIT SHALL INCORPORATE DOWN-SCALE BURN-OUT PROTECTION.
5. THE PT100 RTD LEAD LENGTHS SHALL BE ARRANGED TO SUIT INSTALLATION REQUIREMENTS.
6. WEATHER PROOF JUNCTION BOXES & WEATHER PROOF SEALING GASKETS SHALL BE USED TO AVOID INGRESS OF MOISTURE IN JUNCTION BOXES.
7. CONTROL PANELS AND EQUIPMENT SHALL BE IN ACCORDANCE WITH COLD BOX FOUNDATION HEATING DATA SHEET.

Heat Tracing Installation Manual

Guys, For your knowledge we summarize some top vendor heat tracing manuals for information and design.

“Raychem Heat Trace Installation Manual“
“Nelson Heat Trace Installation Manual“
“Thermon Heat Trace Installation Manual“
“Pentair Heat Trace Installation Manual“
“Chromalox Heat Trace Installation Manual“
“Electric Heat Trace Installation Manual“
”Bartec Heat Trace Installation Manual”