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XMI-L Heat Tracing Repair Guide

Low Temperature

Sheath MI Heating

Cable

Summary of Contents for XMI-L

Page 1: ...XMI L Heat Tracing Repair Guide Low Temperature Sheath MI Heating Cable ...

Page 2: ...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 she...

Page 3: ...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 ...

Page 4: ...fication 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...

Page 5: ...elines 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 cab...

Page 6: ...ting 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 sectio...

Page 7: ...ation 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 Ty...

Page 8: ...omponents 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 repa...

Page 9: ...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 ...

Page 10: ...ter 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 Compr...

Page 11: ... 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 ar...

Page 12: ...a 10 in 25 cm A 56T silver braze rod D 1 ea Joint packing rod E 2 ea Pressure port plug F 1 ea Syringe assembly with MgO and steel needle vacuum sealed G 2 ea Corrugate union H 1 ea 24 in 61 cm fine grit emery cloth 180 grit I 1 ea 24 in 61 cm medium grit emery cloth 80 grit J 2 ea 4 5 in 11 4 cm long repair sleeve K 1 ea Nylon mesh sanding pad L 1 ea Jar of white flux M 1 ea Flux brush MSDS for w...

Page 13: ...ss machine screw D 1 ea 10 in 25 cm A 56T silver braze rod E 1 ea Joint packing rod F 1 ea Nylon mesh sanding pad G 1 ea Syringe assembly with MgO and steel needle vacuum sealed H 1 ea Corrugate union I 1 ea Pressure port plug J 1 ea 24 in 61 cm fine grit emery cloth 180 grit K 1 ea 24 in 61 cm medium grit emery cloth 80 grit L 1 ea 4 5 in 11 4 cm long repair sleeve M 1 ea Jar of white flux N 1 ea...

Page 14: ...1 ea 10 in 25 cm A 56T silver braze rod E 1 ea Syringe assembly with MgO and steel needle vacuum sealed F 1 ea End cap body G 1 ea Threaded end cap plug H 1 ea 24 in 61 cm fine grit emery cloth 180 grit I 1 ea 24 in 61 cm medium grit emery cloth 80 grit J 1 ea 1 in 25 mm threaded stud K 1 ea Pressure port plug L 1 ea Jar of white flux M 1 ea Flux brush MSDS for white flux and silver braze rod not ...

Page 15: ...leeve 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 Sil...

Page 16: ...le 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...

Page 17: ...uired 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 ...

Page 18: ...ficult 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 facili...

Page 19: ...s 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...

Page 20: ... 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 ...

Page 21: ...heating cable sheath Verify continuity of all conductors using a multimeter or ohmmeter See Appendix B for details Check the insulation resistance IR of the cable sections at this point using a 1000 V DC Megohmmeter Figure 11 Further details on IR testing can be found in Appendix B The IR test checks for the presence of moisture in the magnesium oxide insulation A value greater than 20 MΩ should b...

Page 22: ...e has been removed from the MI heating cable see Appendix D on removing moisture from the MI cable Once the MI heating cable is heated out and IR is at an acceptable value slide a corrugate union only required if an extra 10 of corrugate was removed and the 10 in 25 cm section of corrugate back onto the heating cable Prior to fitting the parts together polish both ends of the corrugate and the cor...

Page 23: ...should be used for each side of the union corrugate joint Once the union has been brazed use emery cloth and the nylon mesh sanding pad to clean the corrugate union and corrugate Use only the nylon mesh sanding pad on the corrugate it has a thin sheath and can be easily damaged Emery cloth may be used on the corrugate union Remove all flux Note Always ensure all flux has been removed from the corr...

Page 24: ... heating cable and cold lead cable Figure 14 Figure 14 Measure cable diameters Hot hot joint Using the table in Appendix C select the correct drill bit size for the MI heating cable diameter measured above the drill bit should be 4 1000 in 0 1 mm to 10 1000 in 0 25 mm larger than the cable diameter Drill a hole straight through the joint using the pilot hole as a guide Check the joint to ensure th...

Page 25: ... 4 to 3 8 in 6 to 9 mm past the fill hole Check the joint to ensure there are no burrs inside and verify that fill hole is tapped Figure 16 Fill hole Hole drilled to diameter of cold lead cable Hole drilled to diameter of MI heating cable Figure 16 Cross section of drilled hot cold joint Hot hot joint Ensure the end of each heated section is straight for approximately 12 in 30 cm Hot cold joint En...

Page 26: ...for details on stripping the cable sheath Score Figure 18 Remove sheath from cold lead cable Note Do not cut too deep with the tube cutter as this will cause the sheath to be pushed inwards towards the conductors possibly resulting in cable failure Hot hot and Hot cold joint Polish about 2 in 5 cm of each end of the cable sheaths with emery cloth Figure 19 The surface must be clean for brazing Eme...

Page 27: ... over the end of each section of MI heating cable to be joined and over the corrugate until it stops Figure 21 Next slide the joint body over either end of the MI heating cable and make sure that it will easily slide over the other end If the MI heating cable sheaths flare out and bind on the joint body touch up with flat file or emery cloth to allow the joint body to slide over both ends Slide jo...

Page 28: ...joint body over MI heating cable Slide repair sleeve over cable and corrugate Heating cable Figure 22 Place repair sleeve and joint body on cable Hot hot and Hot cold joint If heating cable conductors are longer than 3 16 in 5 mm done to read IR in some cases trim conductors to 3 16 in 5 mm Before brazing the conductors take a moment to confirm that all parts are on the cables and test fit them to...

Page 29: ...cold lead cable as silver braze is applied only to the face of the conductor Hot hot joint Apply a small amount of white flux to the tip of the conductor Take care not to get any flux near the end of the cable where it might contaminate the magnesium oxide powder Using a small flame see Appendix E heat the conductor with the oxy acetylene torch this does not take much heat and at the same time tou...

Page 30: ...ch this does not take much heat and at the same time touch silver braze rod to the face of the conductor and apply enough braze to form a small bead on the conductor face Figure 26 Repeat for remaining cold lead conductor Cold lead Bead Figure 26 Form bead on cold lead conductors Tin the conductors on the MI heating cable using the procedure above for the hot hot joint Note Bend the two conductors...

Page 31: ...d be taken not to overheat the conductors during this process Pull lightly to test for strength Heating cable Heating cable Oxy acetylene torch Figure 27 Braze hot hot joint conductors Hot cold joint Align the two cables so that the conductor tips butt together and heat the larger cold lead conductors one at a time so that the braze on the tip melts then push the smaller heating cable conductors i...

Page 32: ...by the ball of braze but not actually bonded and an open circuit failure will occur Figure 29 Completed hot cold junction Hot hot and Hot cold joint Remove all trace of flux from the conductors with the emery cloth Figure 30 Straighten the conductors with needle nose pliers such that the conductors will be as far from the inside wall of the joint body as possible This must be done delicately Avoid...

Page 33: ...cable Hot cold joint Conductors from cold lead to the heating cable should be formed as shown in Figure 31 Hot hot and Hot cold joint Slide the joint body over the exposed conductors ensuring that the fill hole faces up and is centered over the conductor junction Figure 32 Use caution when sliding the joint body If the joint body sticks or binds on the cable gently free it Avoid damaging the delic...

Page 34: ...5 cm of heating cable should be exposed stopping 1 2 in 13 mm from the joint body Figure 33 heat out 4 5 in 11 cm on the cold lead side Repeat procedure for cable on other side of joint body Immediately proceed to next step 4 1 2 11 cm Sizzling flame Cold lead 1 2 13 mm Figure 33 Heat out the cable on both sides of the joint Note Details on heating out drying out the cable may be found in Appendix...

Page 35: ...ture deposit a large bead of silver braze on the top part of the area to be joined Apply heat to both the joint body and the cable and move the flame slowly around the circumference of the joint body Figure 35 This will cause the braze to wick its way around the joining area and also draw the braze inside the joint body making a stronger braze Add more braze as needed Ensure that the braze flows t...

Page 36: ... the plastic tip cap and replace with 1 1 4 in 3 2 cm long steel needle keeping syringe facing upwards until ready to use Do not remove red cap While joint body is still hot use syringe to fill the joint with magnesium oxide powder Use an engraving tool or other vibration method to pack the powder Figure 36 If using an engraving tool reverse the engraving bit so that the blunt end is visible and p...

Page 37: ... required add more powder to fill joint body and repeat packing procedure using both the vibrating tool and the packing rod until the joint body is completely full Figure 37 Packing rod Figure 37 Pack MgO powder With pliers insert the brass screw approximately 2 full turns into the fill hole ensuring that the screw does not protrude into the joint and touch the conductors Figure 38 Brass screw 2 t...

Page 38: ...e File in one direction Figure 39 File groove Check the insulation resistance IR again Figure 40 A value greater than 20 MΩ should be attained If the IR is lower remove the moisture from the cable by following the drying out procedure in Appendix D and then repeat IR test If it is necessary to dry out the cable do not heat above a dull red color Higher heat could re melt the braze and create a def...

Page 39: ...int body and apply a small amount of white flux over the screw Continue heating and completely fill the recessed area with silver braze then remove the heat Figure 41 Holding the heat on the joint body for very long will lead to outgassing from the MgO and this can cause pinholes in the braze If this occurs allow joint body to cool for a couple of minutes and then repair Small flame Figure 41 Appl...

Page 40: ...l be hot Do not touch joint or cable with bare hands Again test the insulation resistance with a 1000 V DC Megohmmeter Figure 43 Minimum IR should be 20 MΩ Quench with a rag soaked in water by wrapping it tightly around the joint Figure 44 Be careful to not get water inside the repair sleeve or corrugate If needed a rag can be tied around the MI heating cable at the sleeve to prevent water from ru...

Page 41: ...3 Heating Cable Repair 38 nVent com Figure 43 Check insulation resistance Water soaked rag Figure 44 Wrap joint with water soaked rag ...

Page 42: ...ue recorded in Section 3 1 The resistance should not be any more than 3 lower than the value measured previously If open circuit cut off joint and repeat procedure The finished joint hot cold joint is shown in Figure 45 Heating cable Cold lead Figure 45 Completed joint Hot hot and Hot cold joint The steps following show the procedure to braze the repair sleeve for the hot cold repair For a hot hot...

Page 43: ...face Then braze the repair sleeve to the corrugate on heating cable side of joint taking care to apply the majority of the heat to the sleeve this will help draw braze into the joining area and prevent damage to the corrugate Figure 47 Approximately 1 in 25 mm of the brazing rod should be used to complete this joint Caution The corrugate is thin and can quickly overheat if directly heated with the...

Page 44: ...r sleeves and corrugate Water inside the corrugate can lead to corrosion and early failure of the sheath Note Always ensure all flux has been removed from the corrugate to prevent corrosion Hot water may be used to remove the flux Nylon mesh sanding pad Figure 48 Clean brazed areas When the joints are clean and cooled attach the air fitting to the pressure port and pressurize the corrugate to 5 ps...

Page 45: ...eak detector or soapy water to look for leaks in any of the brazed sleeve joints sleeve to joint body and sleeve to corrugate Be careful not to introduce excessive bubbles when applying liquid leak detector or soapy water from bottle Figure 50 If bubbles are found release the pressure unhook the air fitting and repair the braze Figure 50 Test brazed areas for leaks ...

Page 46: ...ng a small flame fill the pocket above the pressure port plug with braze material until the pocket is full with a smooth slightly concave dome of braze material over the pressure port plug and along the inside walls of the port Figure 52 Small flame Figure 52 Seal pressure port Using the nylon mesh sanding pad clean the pressure port The hot cold repair is now complete If making a hot hot repair f...

Page 47: ...in 10 cm to allow access when brazing see repair jig in Appendix G Using the tube cutter cut the corrugate 1 2 in 13 mm from the corrugate plug ARO fitting Once cut turn the plug counter clockwise to unscrew the plug from the heating cable end cap Figure 53 1 2 13mm Corrugate plug Corrugate Threaded rod Turn corrugate plug counter clockwise to remove Figure 53 Cut corrugate and unscrew corrugate p...

Page 48: ...Figure 55 Remove old end cap 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 XMI L cable tag must be ordered see Section 2 3 Note 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 ...

Page 49: ...20 MΩ should be attained If the IR is lower remove the moisture from the cable by following the drying out procedure in Appendix D Repeat IR test Figure 56 Check insulation resistance Verify continuity of conductors using a multimeter or ohmmeter Using a vernier caliper or micrometer measure the outside diameter of the MI heating cable Figure 57 Select the end cap body and threaded end cap plug fr...

Page 50: ...n the cable diameter Drill a hole straight through the end cap body using the pilot hole smaller hole as a guide and check it for burrs Figure 58 End cap body cross section Threaded end cap plug cross section Figure 58 Drill end cap body Polish the end about 2 in 5 cm of the MI heating cable sheath with emery cloth Figure 59 The surface must be clean for brazing Emery cloth 2 5 cm Figure 59 Polish...

Page 51: ...nd end with the largest hole faces outwards Figure 60 Heating cable End cap body Larger end Figure 60 Place end cap body on cable Using side cutters strip the sheath back about 3 8 1 2 in 9 13 mm taking care to flare the sheath of the cable slightly outward Figure 61 See Appendix F for detailed instructions on stripping cable sheath Figure 61 Remove MI heating cable sheath ...

Page 52: ...y cloth or use side cutters to lightly scrape conductor surface Figure 62 conductor surface must be free of powder for silver braze to bond Emery cloth Figure 62 Clean conductors Using pliers twist conductors together through approximately two full 360 turns Figure 63 Figure 63 Twist conductors ...

Page 53: ...ake much heat and at the same time touch the brazing rod to the end of the twisted conductors and apply enough braze to form a small bead Figure 64 Brazing rod Figure 64 Braze twisted conductors Slightly fan torch back and forth several times to draw the silver braze backwards about 1 4 in 6 mm along the twisted conductors Remove heat Care must be taken to avoid over heating the conductors and to ...

Page 54: ...ch may have contaminated the magnesium oxide powder Figure 65 Pick 1 4 6 mm Figure 65 Remove contaminants Slide the end cap body as far forward as possible the flare on the cable sheath will stop it then move it back 3 16 in 5 mm to ensure proper placement of the heating cable in the end cap body see cross section in Figure 66 End cap body 3 16 5 mm Figure 66 Position end cap body for brazing ...

Page 55: ...ody and stopping 1 2 in 13 mm from the end cap body Figure 67 Immediately proceed to next step Note Details on heating out drying out the cable may be found in Appendix D 12 30 cm 1 2 13 mm Sizzling flame Figure 67 Heat out cable Reduce sizzling flame to a large flame see Appendix E Apply white flux around end where the end cap body will be brazed to the cable sheath Ensure that the flux is applie...

Page 56: ...rge flame Figure 68 Braze end cap body to cable Note While brazing it is important to avoid using excess heat on the portion to be brazed Direct flame contact can oxidize the metal surface preventing the braze from adhering to the metal Care must also be taken not to overheat the end cap body which can cause the conductor joint junction to melt Reposition end cap body facing upwards Assemble powde...

Page 57: ...ot touch with bare hands 3 16 5 mm Engraving or vibrating tool End cap body Figure 69 Fill end cap body with MgO powder Insert the threaded end cap plug with threaded hole facing up and firmly and gently tap it down to further compress the powder Figure 70 Do not strike too hard as this may deform the threaded hole which is needed later in this process Threaded end cap plug Figure 70 Gently tap pl...

Page 58: ...peat IR test Figure 71 Recheck insulation resistance Using oxy acetylene torch with a large flame apply heat to the end cap sweeping the flame from bottom to top of end cap 4 to 5 times This will aid in removing any moisture trapped in the powder Apply white flux around area where the plug will be brazed to the end cap body Using the silver solder braze the plug to the end cap body Figure 72 Large...

Page 59: ...e the end cap body The cross section below shows placement of the cable end cap body and plug Figure 73 Magnesium oxide powder Plug Figure 73 Cross section of completed end cap Note While brazing it is important to avoid using excess heat on the portion to be brazed Direct flame contact can oxidize the metal surface preventing the braze from adhering to the metal Care must also be taken not to ove...

Page 60: ...with a rag soaked in water by wrapping it tightly around the end cap Figure 75 Be careful to not get water inside the braze sleeve or corrugated sheath If needed a piece of rag can be tied around the heating cable at the sleeve to prevent water from running down the cable Also the cable can be repositioned in a horizontal or downward orientation Leave on for 4 to 5 minutes If there are any remaini...

Page 61: ...r cable with bare hands Check resistance of heating cable using an ohmmeter and compare with the measured value recorded in Section 3 1 The resistance should not be any more than 3 lower than the value measured previously If open circuit cut off end cap and repeat procedure The completed end cap is shown below Figure 76 Figure 76 Completed end cap Install corrugate union and reinstall 12 in 30 cm ...

Page 62: ...on using a large flame see Appendix E To avoid damage to the thin corrugate hold the flame on the corrugate union not on the corrugate Figure 78 Approximately 1 in 25 mm of braze rod should be used for each side of the union corrugate joint Once the union has been brazed use emery cloth to clean the corrugate union and the nylon mesh sanding pad to clean the corrugate Use only the nylon mesh sandi...

Page 63: ...the corrugate plug will fit inside Figure 79 3 4 19 mm Figure 79 Flare end of corrugate Screw the threaded stud into the corrugate plug a minimum of 5 threads is to be engaged Figure 80 Figure 80 Screw stud into corrugate plug Thread assembly into the end cap so that the corrugate is seated against the shoulder of the corrugate plug Figure 81 Corrugate plug Corrugate Figure 81 Screw assembly into ...

Page 64: ...ot use emery cloth on the corrugate it has a thin sheath and can be easily damaged Note Always ensure all flux has been removed from the corrugate to prevent corrosion Hot water may be used to remove the flux When the joint is clean and cooled attach the air fitting to the plug port and pressurize the corrugate to a maximum of 40 psi Figure 83 Figure 83 Pressurize corrugate Note Some working envir...

Page 65: ...ot to introduce excessive bubbles from liquid leak detector hose Figure 84 Figure 84 Check for air leaks If bubbles are found release the pressure from the corrugate unhook the air fitting and repair the braze If bubbles are not found release the pressure and disconnect the fitting Place a pressure port plug into the pressure port Figure 85 Pressure port plug Figure 85 Insert pressure port plug ...

Page 66: ...e pocket above the pressure port plug with braze material until the pocket is full with a smooth slightly concave dome of braze material over the pressure port plug and along the inside walls of the port Figure 86 Figure 86 Seal pressure port Clean the corrugate plug with the nylon mesh sanding pad The repair is now complete ...

Page 67: ...leted Original Tag Information may be found on the metal identification tag attached to the cold lead Do NOT fill in this area Original Tag information Ne Serial No Amps Max Surface Temp C Cable Design Cable Reference Cable Length Ft Meter F Watts Volts Cold Lead Length Ft Meter Cold Lead Code or AWG Joint Type Connector Ordinary Location Desig Haz Location Desig Haz Groups Tag no Measured Resista...

Page 68: ...any Telephone Fax Email New Tag Information For Internal Use Only Ft Meter TIONS Signature Date Please fill in this form and e mail to ntm techsupport nVent com nVent will review the change and advise if the modification is appropriate ...

Page 69: ...hich might not otherwise show up for some time If this is not practical a rag soaked in water should be wrapped around the joint while it is still hot this procedure is used in the installation instructions for both the in line hot hot joint and hot cold joint repair and the end termination repair A decrease in insulation resistance indicates the presence of pin holes that must be fixed before pro...

Page 70: ...ating cable identification tag Note This measured value is the resistance at the ambient air temperature the calculated value is the resistance at the operating temperature and may be higher than the measured value Test Procedures Insulation Resistance and Continuity Test 1 De energize the circuit 2 Disconnect the temperature controller or thermostat if installed 3 Disconnect the heating cable fro...

Page 71: ...ontinuity resistance of the heating cable between the two tails or between the conductors conductors at far end may have to be shorted Note the resistance value and compare to the calculated value 13 Disconnect the multimeter 14 Reconnect heating cable and temperature controller or thermostat once repairs are completed Figure B1 Checking insulation resistance and continuity Tails Test 1 Insulation...

Page 72: ...34 Q 0 176 0 177 15 0 335 0 339 R 0 178 0 180 14 0 340 11 32 0 181 0 182 13 0 341 0 343 8 5mm 0 183 0 184 3 16 0 344 0 349 S 0 185 0 186 12 0 350 0 353 9 0mm 0 187 0 188 11 0 354 T 0 189 0 191 10 0 355 0 359 23 64 0 192 0 194 9 0 360 0 363 9 25mm 0 195 0 196 8 0 364 0 370 U 0 197 0 198 7 0 371 0 372 3 8 0 199 13 64 0 373 0 377 V 0 200 6 0 378 0 381 9 7mm 0 201 0 204 5 0 382 0 385 W 0 205 0 208 4 0...

Page 73: ...he cable beginning 5 in 13 cm back from the end of the cable heat cold lead first if making a hot cold joint If IR is still low and it was necessary to remove an additional 10 in 25 cm to 12 in 30 cm of cable begin heating out the cable 12 in 30 cm back from the end of the cable Alloy 825 sheath cable should be heated to a dull red color Use a short sweeping motion of the torch and heat about 2 in...

Page 74: ...e sheath stop the sweeping motion of the torch 1 2 in 13 mm from the joint body or end cap as shown in Figure D2 If you heat toward the end of the cable too quickly you may skip over the moisture and drive it further back into the cable 2 5 cm Stop here Fill hole 1 2 13 mm Figure D2 Sweep flame to end of cable On completion check IR with a 1000 V DC insulation tester Megohmmeter Test between the t...

Page 75: ...uctors together 3 16 in 5 mm Figure E1 Small oxidizing flame Use a large neutral flame when brazing the joint or end cap to the sheath of the cable 3 16 in 5 mm Figure E2 Large nefutral flame Use a sizzling reducing carbonizing flame to dry out the cable 1 5 in 38 mm Figure E3 Sizzling reducing carbonizing flame ...

Page 76: ...s stripped The correct depth of score one third the thickness of the sheath Note Do not cut too deep with the tube cutter as this will cause the sheath to be pushed inwards towards the conductors possibly resulting in cable failure Figure F1 Score cable sheath Grip the edge of the sheath between the jaws of the sidecutters and twist clockwise then take a new grip and rotate through a small angle F...

Page 77: ...ore Figure F3 Strip cable sheath Continue removing the sheath to the score mark When about to break into the score bring sidecutters to right angle with cable Finish off with point of sidecutters held parallel to the cable Figure F4 The sheath will peel away leaving a clean cut when the score mark is reached Ensure that the sheath is not flared inward Figure F4 Sidecutter angle for final stripping...

Page 78: ...re F5 a In b the sheath is neither flared outwards nor beveled inwards but is acceptable Ensure that the sheath is not curved or beveled inward as shown in c This will occur if the score made with the tube cutter is too deep In this case remove a further 1 4 in 6 mm of sheath Unacceptable Acceptable Preferred c b a Figure F5 Cable end preparation ...

Page 79: ... to form shape as shown in Figures G1 and G2 Each cable is clamped to the 4 in 10 cm upper surface and meet in the middle If working on a pipe middle section may be clamped to the pipe 4 in 10 cm 6 in 15 cm 12 in 30 cm 4 in 10 cm Figure G1 Front of repair jig Figure G2 Back of repair jig ...

Page 80: ...pecifications without notice Raychem IM H59002 XMILHeatingTracingRepair EN 1901 nVent com North America Tel 1 800 545 6258 Fax 1 800 527 5703 thermal info nvent com Europe Middle East Africa Tel 32 16 213 511 Fax 32 16 213 604 thermal info nvent com Asia Pacific Tel 86 21 2412 1688 Fax 86 21 5426 3167 cn thermal info nvent com Latin America Tel 1 713 868 4800 Fax 1 713 868 2333 thermal info nvent ...

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