nVent RAYCHEM XMI-L User manual

XMI-L Heat Tracing Repair Guide
Low Temperature
Sheath MI Heating
Cable

ii |nVent.com
Important Safeguards
WARNING: Fire and shock hazard. nVent RAYCHEM
heating cables must be installed correctly to ensure
proper operation and to prevent electrical shock
and fire. Read these important warnings and
carefully follow all the installation instructions.
• To minimize the danger of fire from sustained
electrical arcing if the heating cable is damaged
or improperly installed, and to comply with the
requirements of nVent, agency certifications, and
national electrical codes, ground-fault equipment
protection must be used on each heating cable
branch circuit. Arcing may not be stopped by
conventional circuit protection.
• Damaged heating cable and/or corrugated sheath
can cause electrical arcing or fire. Repair or replace
damaged heating cable, corrugated sheath, or
terminations. Contact factory for assistance.
• When drying out cable, care must be taken not to
trap moisture as this could cause the cable to burst,
possibly causing injury.

nVent.com |iii
Table of Contents
1 General Information 1
1.1 Introduction 1
1.2 Safety Guidelines 2
1.3 Electrical Codes 2
1.4 Heating Cable Configurations 2
1.5 Heating Cable Identification 4
2 Pre-Repair Information 5
2.1 General 5
2.2 Safety Precautions 5
2.3 Changes to the Heating Cable Length 6
2.4 Tools and Materials Required 7
2.5 Repair Kit Components 8
2.6
Cross-section of Completed Joints and End Cap 12
3 Heating Cable Repair 13
3.1 General 13
3.2 Selecting the Correct Size of Joint 14
3.3 Inline Joint Procedure 15
3.4 End Termination Procedure 44
4 Appendix A:
Field Modification Approval Request Form 64
5 Appendix B:
Heating Cable Testing 66
5.1 Testing: 66
5.2 Insulation Resistance (Megohmmeter)
Test – Test 1 66
5.3 Continuity (Resistance) Test – Test 2 67
6 Appendix C:
Cable Size vs Drill Bit Selection Chart 69
7 Appendix D:
Drying Out Procedure 70
8 Appendix E:
Flame Size for Oxy-acetylene Torch 72
9 Appendix F :
Stripping the Cable Sheath 73
10 Appendix G:
Typical Repair Jig 76

General Information
1
nVent.com |1
1.1 Introduction
The purpose of these instructions is to provide a
procedure for the repair or modification of nVent
RAYCHEM XMI-L mineral insulated (MI) heating
cables with a corrugated sheath manufactured by
nVent. They must be carefully followed to ensure that
the heating cable performs safely and as intended.
During the installation of XMI-L cables or during
plant maintenance processes, the cables may be
damaged, cut or broken. In the event that it is not
possible to return the cable to the manufacturer, field
repair may be necessary.
The successful repair or modification of these
cables is a specialized procedure, and as such, only
qualified personnel at industrial establishments,
with the necessary competency (proficiency in silver
brazing with an oxy-acetylene torch is a prerequisite),
are permitted to repair or modify XMI-L heating
cable sets. Where the work involves a change to
the existing design, participation in the redesign
is required by the manufacturer; or alternately, the
design may be carried out by a professional engineer
using design tools provided by the manufacturer.
For field service, assistance, technical support, or
other information regarding the repair of XMI-L
cables, please contact your nVent representative or
nVent directly.
nVent
7433 Harwin Drive
Houston, TX 77036
USA
Tel: [phone]
Fax: [phone]
[email protected]
nVent.com

General Information
1
2 |nVent.com
1.2 Safety Guidelines
The safety and reliability of any heat tracing system
depends on both the quality of the products selected
and the manner in which they are installed and
maintained. Incorrect design, handling, installation, or
maintenance of any of the system components can
cause damage to the heating cable system, and may
result in system failure, electric shock, or fire. The
guidelines and instructions contained in this manual
are important. Follow them carefully to minimize
these risks and to ensure that the XMI-L system
performs reliably.
1.3 Electrical Codes
Refer to the appropriate sections of the National
Electrical Code (NEC) and Canadian Electrical Code
(CEC) regarding the field repair or modification of MI
electrical heat tracing cables. The repair of MI heat
tracing cables must comply with all national and local
codes.
1.4 Heating Cable Configurations
The Field Repair Kit includes components to allow
for field repair or modification of the heating cable
configurations shown in Table 1.

General Information
1
nVent.com |3
TABLE 1:
MI HEATING CABLE CONFIGURATION
XMI-L
cable
design
Heated length
End Termination Hot/cold joint
Hot/cold jointHot/cold joint
Cold lead length
Heated
length
Cold lead
length
Cold lead
length
Number of
conductors Configuration
Dual conductor
(XMI-L32 &
XMI-L62 series)
Dual conductor
(XMI-L32 &
XMI-L62 series)
D
E
A sectional view of a Design D XMI-L heating
cable is shown in Figure 1. All of the cables include
both a heated section and a non-heating cold lead
section. These sections are joined at the hot-cold
joint where the heating element is spliced into larger
bus wires. A final transition at the end of the cold
lead section provides an environmental seal and tails
for the electrical connection. At the opposite end
of the cable, the conductors of Design D cables are
joined and hermetically sealed within an end cap.
The entire heated section of the cable is then
enclosed in a hermetically sealed flexible corrugated
conduit sheath.
Pot
Tails
(standard length
12" (30 cm))
Bus wires Gland
connector
Hot/cold
joint
Cold leadHeated section
Heating
element
End
Termination
Corrugate
Figure 1: Sectional view of Design D XMI-L cable

General Information
1
4 |nVent.com
1.5 Heating Cable Identification
Each XMI-L heating cable is supplied with an
identification tag (Figure 2) on which the heating
cable catalog number is permanently printed. In
addition to its identification purposes, the catalog
number provides information regarding the heating
cable length, power output, and operating voltage.
Also printed on the tag are the designer’s circuit
identification number (optional), serial number and
maximum cable sheath temperature. If the cable has
been designed for a hazardous location, the area
classification is printed in the Haz. Locations section
of the tag.
Figure 2: Typical XMI-L heating cable tag (front)

2
Pre-Repair Information
nVent.com |5
2.1 General
XMI-L cables can be field repaired or modified only by
qualified personnel. An appropriate field repair kit can
be used to complete one of the following:
• The Hot/Hot (H/H) Repair Kit includes the
components required to perform a repair in the
heated section on either a D or E configuration.
• The Hot/Cold (H/C) Repair Kit includes the
components required to perform a repair at the
Hot/Cold joint, or to replace a cold lead, on either a
D or E configuration.
• The End Termination Repair Kit includes the
components required to perform a repair on
the end cap for a D configuration.
Stainless steel joints and end caps are used to repair
or modify XMI-L heating cables and are suitable for
exposure temperatures up to 842°F (450°C).
Note: If the attempted repair cannot be done
successfully, please contact nVent for assistance.
2.2 Safety Precautions
• Safety glasses and gloves must be worn when
making field repair joints
• Take care to avoid burns when handling welding
torches and hot work pieces
• Wear a welding apron when working with welding
torches
Follow all safety instructions supplied with the
equipment you are using
Caution: When drying out cable, care
must be taken not to trap moisture as this
could cause the cable to burst, possibly
causing injury.

2
Pre-Repair Information
6 |nVent.com
Caution: Shortening the length of the heated
section will decrease the resistance, resulting in
increased current draw and wattage. Similarly,
increasing the length of the heated section will
increase the resistance, resulting in decreased
current draw and wattage. Pay special attention
to the over-current protective device to ensure
that it will still conform to the requirements
of national and local codes when such
modifications are made to heating cables.
Warning: A significant decrease in the length
of the heated section may result in a considerable
increase in wattage and cable sheath temperature
with the potential of starting a fire. Verify the
cable design before applying power.
2.3 Changes to the Heating Cable Length
A new tag is not required for repaired or
modified heating cables provided the total
length of the heated section of the cable is not
changed by more than 3%. Where the heated
section of the cable set is changed by more than
3%, to facilitate the repair or where the cable is
modified, then a new XMI-L cable tag must be
ordered. In these cases, the XMI-L Heating Cable
Field Modification Approval Request Form in
Appendix A must be filled in and reviewed by
nVent before proceeding with the repair or
modification and a permanent record of the
modification must be retained.

2
Pre-Repair Information
nVent.com |7
2.4 Tools and Materials Required
TABLE 2: TOOLS AND MATERIALS
1000 V DC Megohmmeter
Small hammer
Ohmmeter (multimeter)
Needle nose pliers
Drill press and bits (see Appendix C)
Ruler or tape measure
Vernier caliper (or Micrometer)
Flat file (3/16 in thick)
Small tube cutter
Round file
Diagonal (side) cutters
Hacksaw
An oxy-acetylene torch with No. 0 welding tip or
equivalent
Flat nose pliers
Vise grip pliers or nVent PYROTENAX Handvise
Scribe or pick
Cotton cloth or rag
Small screwdriver with flat blade
Bottle of water
Steel repair jig or equivalent and two ‘C’ clamps to hold
cable firm when welding (see Appendix G)
Engraving tool (Dremel®Model 290-01 or equivalent)
Compressed air supply 5 to 40 psi maximum with 1/4"
female ARO fitting
Liquid leak detector or soapy water

2
Pre-Repair Information
8 |nVent.com
2.5 Repair Kit Components
Six different repair kits are available, depending on
size of corrugate and type of repair being done. The
corrugate is available in small, 0.49 in (12.4 mm) OD, and
large, 0.57 in (14.5mm) OD.
• The small corrugate has an ID of 0.31 in (8 mm).
• The large corrugate has an ID of 0.39 in (10 mm).
• The repair kit is specific to a corrugate size.
• The repair kit is also specific for the type of repair.
• H/H kits are for repairs requiring a heating cable
in-line joint, called a hot/hot repair.
• H/C kits are for repairs requiring replacement of the
joint between the heating cable and the cold lead,
called a hot/cold repair.
• End termination kits are for repairs requiring
replacement of the end cap for D design cables,
called an end termination repair.
Each kit contains the parts for the small or large
corrugate and the type of repair needed. The six repair
kits are:
REPKITCSHH – H/H repair kit for small corrugate
REPKITCSHC – H/C repair kit for small corrugate
REPKITCSEND – End termination repair kit for
small corrugate
REPKITCLHH – H/H repair kit for large corrugate
REPKITCLHC – H/C repair kit for large corrugate
REPKITCLEND – End termination repair kit for
large corrugate

2
Pre-Repair Information
nVent.com |9
A
B
C
G
H
I
D
E
F
J
K
L
M
TABLE 3: FIELD REPAIR KIT FOR XMI-L HOT/HOT JOINT
REPKITCSHH or REPKITCLHH
Item Qty Description
A1 ea 1/2 in (12.7 mm) XMI-L H/H joint body
B2 ea #6-32 brass machine screw
C2 ea 10 in (25 cm) A-56T silver braze rod
D1 ea Joint packing rod
E2 ea Pressure port plug
F1 ea Syringe assembly with MgO and steel needle
(vacuum sealed)
G2 ea Corrugate union
H1 ea 24 in (61 cm) fine grit emery cloth (180 grit)
I1 ea 24 in (61 cm) medium grit emery cloth
(80grit)
J2 ea 4.5 in (11.4 cm) long repair sleeve
K1 ea Nylon mesh sanding pad
L1 ea Jar of white flux
M1 ea Flux brush
MSDS for white flux and silver braze rod
(not shown)

2
Pre-Repair Information
10 |nVent.com
A
B
C
D
E
G
F
N
H
I
J
K
L
M
TABLE 4: FIELD REPAIR KIT FOR XMI-L HOT/COLD JOINT
REPKITCSHC or REPKITCLHC
Item Qty Description
A1 ea 1/2 in (12.7 mm) XMI-L H/C joint body
B1 ea 3/4 in (19 mm) XMI-L H/C joint body
C2 ea #6-32 brass machine screw
D1 ea 10 in (25 cm) A-56T silver braze rod
E1 ea Joint packing rod
F1 ea Nylon mesh sanding pad
G1 ea Syringe assembly with MgO and steel needle
(vacuum sealed)
H1 ea Corrugate union
I1 ea Pressure port plug
J1 ea 24 in (61 cm) fine grit emery cloth (180 grit)
K1 ea 24 in (61 cm) medium grit emery cloth (80 grit)
L1 ea 4.5 in (11.4 cm) long repair sleeve
M1 ea Jar of white flux
N1 ea Flux brush
MSDS for white flux and silver braze rod (not shown)

2
Pre-Repair Information
nVent.com |11
TABLE 5: FIELD REPAIR KIT FOR XMI-L END TERMINATION
REPKITCSEND or REPKITCLEND
Item Qty Description
A1 ea Corrugate plug (1/4” ARO fitting)
B1 ea Corrugate union
C1 ea Nylon mesh sanding pad
D1 ea 10 in (25 cm) A-56T silver braze rod
E1 ea Syringe assembly with MgO and steel
needle (vacuum sealed)
F1 ea End cap body
G1 ea Threaded end cap plug
H1 ea 24 in (61 cm) fine grit emery cloth (180 grit)
I1 ea
24 in (61 cm) medium grit emery cloth
(80grit)
J1 ea 1 in (25 mm) threaded stud
K1 ea Pressure port plug
L1 ea Jar of white flux
M1 ea Flux brush
MSDS for white flux and silver braze rod
(not shown)
E
F
G
A
B
C
D
H
I
J
K
L
M

2
Pre-Repair Information
12 |nVent.com
2.6 Cross-section of Completed Joints and End Cap
Figures 3, 4 and 5 show cross sections for the hot/
hot joint, hot/cold joint and end termination.
Heating
cable
Corrugate Sleeve
Plug
Magnesium
oxide
Joint
6-32 Brass
screw
Union
Silver
braze
Silver
braze
Figure 3: Completed hot/hot joint
Figure 4: Completed hot/cold joint
Heating
cable
Corrugate
Plug
Magnesium
oxide
Joint
Cold lead
6-32 Brass
screw
Union
Silver
braze
Silver
braze
Silver
braze
Figure 5: Completed end termination
Corrugate
plug
Plug
Threaded
stud
Heating
cable
Union Corrugate
Silver
braze
Silver
braze
Silver
braze

3
Heating Cable Repair
nVent.com |13
3.1 General
• Before commencing field modifications/repairs,
heating cable resistance should be checked with an
ohmmeter to ensure that it is within ± 10% of the
cable’s calculated resistance. Record the measured
value for comparison with the measured value on
completion of repairs.
Calculated resistance = heated length (ft) x Ω/foot;
(heated length (m) x Ω/meter)
Note: Ω/foot (Ω/meter) of heating cable may be
obtained from the product data sheet H59079 for
XMI-L heating cables.
• For field repairs, check continuity of both sections
of cable to be joined using the ohmmeter. If open
circuited, do not attempt to fabricate the joint.
-For two conductor heating cable, conductors on
far end of cable may have to be shorted together.
• Check insulation resistance (IR) of both cables to
be joined with a 1000 V DC Megohmmeter
(Appendix B); a value greater than 20 megohms
should be attained. If satisfactory follow
appropriate repair procedure to make a joint
(Section 3.3) or end cap (Section 3.4), otherwise
follow insulation drying procedure in Appendix D
before proceeding.
• When silver brazing, avoid excessive heating of
parts to be joined as this can lead to embrittlement
of materials and take care not to overheat the joint
body as the braze at the conductor joint may melt.
Also avoid overheating the corrugate as excessive
heat can damage the corrugate.
• Once a joint or end cap installation has been
started, it must be completed without interruptions.
This will prevent the cable from absorbing moisture
and causing a decrease in the insulation resistance.

3
Heating Cable Repair
14 |nVent.com
3.2 Selecting the Correct Size of Hot/cold Joint
When repairing a hot/cold joint or replacing the cold
lead, a hot/cold repair kit is required. Each repair
kit is supplied with a 1/2 in (12.7 mm) and a 3/4 in
(19 mm) joint body. Use a vernier caliper or
micrometer to measure the outside diameter of the
MI cold lead and select the 1/2 in (13 mm) or 3/4 in
(19 mm) joint body from Table 6.
TABLE 6: SELECT HOT/COLD JOINT BODY
Max diameter of
cold lead cable
1/2” (12.7 mm)
joint body
0.360 in
3/4 in (19 mm)
joint body
0.543 in

3
Heating Cable Repair
nVent.com |15
3.3 In-line Hot/hot Joint and Hot/cold Joint
Repair Procedure
The instructions following apply to both hot/hot
and hot/cold joint repairs. Read these instructions
completely before attempting to complete the
repair or modification and refer to the Appendices
for additional information where indicated. Where
appropriate, the instructions which apply specifically
to a hot/hot or hot/cold joint are clearly identified and
must be followed.
Note: Shield work area from environmental
factors such as wind as it will cool the joint
temperature making brazing difficult.
Remove insulation and banding from heating cable
so that 12 in (30 cm) on either side of the joint or
failure point is accessible.
Ensure that the portion of the cable being worked on
can be moved away from the surface at least 4 in
(10cm) to allow access when brazing (see repair jig
in Appendix G).
Note: Do not remove more than 3% of length of
heated section. If more than 3% must be removed
to facilitate the repair or modification, a new MI
cable tag must be ordered (see Section 2.3).
Hot/hot joint: Using the tube cutter, cut through
the corrugate at the damaged area. Pull back the
corrugate to expose the MI heating cable; it will be
necessary to release and retighten the clamps on
to the corrugate to keep it in position. Next, use a
hacksaw to cut the heating cable at the damaged
area (Figure 6).

3
Heating Cable Repair
16 |nVent.com
Cut heating cable
Corrugate
Release clamp and
pull corrugate back
after cutting
Release clamp and pull
corrugate back after cutting
Lorem ipsum
Figure 6: Cut Heating cable as close to damaged
location as possible
Hot/cold joint: Using a hacksaw, cut through the cold
lead just behind the joint. Next, use a tube cutter to
cut the corrugate about 1 in (25 mm) from the joint
and then cut the MI heating cable with the hacksaw
and remove the joint (Figure 7).
Figure 7: Cut Cold lead and corrugate close to
hot/cold joint
Hot/cold
joint
Cut corrugate with tube
cutter 1” (25mm) from
end of joint and then cut
MI cable with hacksaw
Cold lead
1” (25 mm)

3
Heating Cable Repair
nVent.com |17
Hot/hot joint: Using the tube cutter, cut the corrugate
5in (12.7 cm) back from both cut ends. Remove the cut
corrugate and discard (Figure 8).
Hot/cold joint: Using the tube cutter, cut the corrugate
5 in (12.7 cm) back from the cut end. Remove the cut
corrugate and discard (Figure 9).
Figure 8: Cut and remove corrugate from both ends
Heating
cable
Cut and remove corrugate
from both ends
5”
(12.7cm)
5”
(12.7cm)
Figure 9: Cut and remove corrugate from MI
heating cable end
Cut and remove corrugate
from MI heating cable end
Cold lead
5” (12.7 cm)
Corrugate
MI heating
cable