Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
A REPORT TO
THE BOARD OF COMMISSIONERS OF PUBLIC UTILITIES
Electrical
Mechanical
pWLPYCivil
SIGNAc Protection & Control______Z2L
LAND Transmission & Distribution_______________
Telecontro I
System Planning
REPLACE FUEL OIL HEAT TRACING
Holyrood Thermal Generating Station
Ju'y 2011
newfoundland labrador
hydroa nakor energy company
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro i
Table of Contents
1 INTRODUCTION ................................................................................................................ 1
2 PROJECT DESCRIPTION ..................................................................................................... 4
3 EXISTING SYSTEM ............................................................................................................. 6
3.1 Age of Equipment or System ............................................................................. 10
3.2 Major Work and/or Upgrades ........................................................................... 10
3.3 Anticipated Useful life ........................................................................................ 12
3.4 Maintenance History ......................................................................................... 12
3.5 Outage Statistics ................................................................................................ 13
3.6 Industry Experience ........................................................................................... 13
3.7 Maintenance or Support Arrangements ............................................................ 13
3.8 Vendor Recommendations ................................................................................ 13
3.9 Availability of Replacement Parts ...................................................................... 13
3.10 Safety Performance ........................................................................................... 14
3.11 Environmental Performance .............................................................................. 14
3.12 Operating Regime .............................................................................................. 17
4 JUSTIFICATION ............................................................................................................... 18
4.1 Net Present Value .............................................................................................. 19
4.2 Levelized Cost of Energy .................................................................................... 20
4.3 Cost Benefit Analysis .......................................................................................... 20
4.4 Legislative or Regulatory Requirements ............................................................ 20
4.5 Historical Information ........................................................................................ 20
4.6 Forecast Customer Growth ................................................................................ 20
4.7 Energy Efficiency Benefits .................................................................................. 21
4.8 Losses during Construction ................................................................................ 22
4.9 Status Quo .......................................................................................................... 22
4.10 Alternatives ........................................................................................................ 22
5 CONCLUSION .................................................................................................................. 23
5.1 Budget Estimate ................................................................................................. 23
5.2 Project Schedule ................................................................................................ 24
APPENDIX A ............................................................................................................................. A1
APPENDIX B ............................................................................................................................. B1
APPENDIX C ............................................................................................................................. C1
APPENDIX D ............................................................................................................................. D1
APPENDIX E ............................................................................................................................. E1
APPENDIX F ............................................................................................................................. F1
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 1
1 INTRODUCTION
The Holyrood Thermal Generating Station (Holyrood) is an essential part of Newfoundland
and Labrador’s generating system, delivering electrical energy to retail, industrial, and
residential customers. This plant has three generating units producing a total capacity of
490 MW. The plant was constructed in two stages. Stage 1 was commissioned in 1971
bringing on line generating Units 1 and 2, each rated at 150 MW. Stage 2 was commissioned
in 1979 bringing on line generating Unit 3 also rated at 150 MW. In 1988 and 1989, the
generation capacity of Units 1 and 2 was increased to 175 MW each. Holyrood has the
capacity of generating over 3,000,000 MWh of energy annually which is approximately 40
percent of the Island Interconnected System’s energy requirement.
Figure 1: Holyrood Thermal Generating Station
At this plant, Bunker C fuel oil is burned in large oil burning furnaces, converting water to
steam which is then used to propel turbine generators. A 455 mm diameter insulated pipe,
equipped with electric heat tracing was installed as part of the original construction and is
used to transport Bunker C Fuel Oil from the marine terminal to the facility’s fuel storage
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 2
tanks approximately 1200 m away. The 455 mm diameter pipeline is divided into two
subsections at approximately the midpoint of the pipeline. Each subsection of pipeline
consists of separate heat tracing circuits, designated as North Section and South Section. In
addition, there is a section of 100 mm diameter pipeline, approximately 100 m in length,
which also requires replacement of heat tracing cable.
During the period from September to April, shuttle tankers arrive at the marine terminal
and Bunker C fuel oil is pumped through the 455 mm diameter insulated pipeline to the
tank farm. Before the shuttle tanker attempts to pump oil into the pipeline, the oil is heated
to approximately 60OC onboard the tanker. Because of the thick nature of this oil, to
successfully transport oil through the pipe the oil temperature must be maintained at a
minimum of 30OC throughout its path of flow. To maintain an oil temperature of 30OC
throughout the pipe, an oil heating system known as electric heat tracing (EHT) is installed
along the full length of the pipe. The main component of EHT is the copper conductor which
is heated by the flow of electric current produced by three phase 600 volt power supply.
Figure 2 shows a picture of the existing 455 mm fuel oil pipeline equipped with electric heat
tracing in Holyrood.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 3
Figure 2: Electric Heat Tracing
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 4
2 PROJECT DESCRIPTION
This project is required to replace the electric heat tracing (EHT) on the fuel oil pipeline at
the Holyrood Thermal Generating Station. The existing heat tracing cables have
deteriorated and have resulted in various problems with the performance of the existing
application, including failed sections of heat tracing due to open circuits and ground faults.
This two year project also includes the replacement of fiberglass insulation and metal
cladding for the entire pipeline. The scope of work includes:
• Erection of scaffolding for the shore arm and three expansion joints on the 455 mm
diameter line
• Removal of existing insulation, metal cladding and mineral insulated heating cables
• Testing of 455 mm diameter pipe thickness at prescribed intervals
• Coating of 455 mm diameter pipe for corrosion protection
• Installation of the new electric heat tracing system
• Installation of new insulation and cladding
• Installation of programmable controller with self diagnostics
• Construction Management
• Commissioning of the new system
• Disposal of existing metal cladding, insulation, and heat tracing cable
An external contractor will be required to install the new system. Based on discussions with
the original equipment manufacturer (OEM), Tyco Thermals Controls, of the existing heat
tracing system, it is anticipated that the existing copper heat tracing cable will need to be
replaced with a stainless steel heat tracing cable. Stainless steel heat tracing cables offer
better corrosion resistance than copper heat tracing, making it more suitable for this
application.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 5
It will take approximately four to six months to complete replacement of the entire heat
tracing system. Hydro proposes to complete the work in two sections – the South Section
and 100 mm diameter pipeline to be completed in the summer of 2012 and the North
Section to be completed in the summer of 2013. Each section takes approximately two to
three months to complete.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 6
3 EXISTING SYSTEM
The electric heat tracing equipped on the fuel oil pipeline consists of a High Density
Polyethylene (HDPE), copper sheathed, mineral insulated (MI) electric heat tracing cable.
These cables are strapped to the fuel oil pipe line every three to five linear feet intervals.
They are then insulated with two inches of fiberglass insulation and then wrapped with
metal cladding as shown in Figure 3.
Figure 3: Cross Section of 18” (455 mm) Pipeline
The 455 mm diameter fuel oil pipeline heat tracing consists of two main electric circuits,
North Section and South Section, both of which are approximately 600 meters in length.
Each section of pipeline is then subdivided by heat tracing cable lengths of approximately 50
meters. The North Section runs from the facility tank farm to the midpoint of the pipeline,
and the South Section runs from the marine terminal to the midpoint of the pipeline.
The 100 mm diameter pipeline runs from the marine terminal to approximately three
meters past the control valve located near the base of the shore arm. The shore arm is a
cement structure extending approximately 100 m from the shoreline into the ocean to
support a marine terminal at water depths which allow shuttle tankers to dock and un-load
fuel oil. The purpose of this pipeline is to drain a section of 455 mm diameter pipeline from
the marine terminal to the control valve. This is done so that if ice were to damage the 455
mm diameter pipeline on the shore arm, the pipeline would be empty of fuel and no oil
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 7
would be released into the environment. The shore arm is shown in Figure 4.
Figure 4: Shore Arm
Please refer to Appendix A for a layout drawing of the existing fuel oil pipeline.
From 2004 to 2011, repetitive failures of the existing heat tracing cables have occurred due
to ground faults and open circuits. As a result, attempts to pump oil through the pipeline
have failed because the oil could not be maintained at the required temperature for oil
flow.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 8
The existing heat tracing system was newly installed in 2002 to replace the original bare
copper mineral insulated electric heat tracing. Since 2002, the high density polyethylene
jacket has melted off and the cable is failing prematurely.
Over time, moisture has accumulated within the insulation, and has caused corrosion of the
copper sheath of the cable. The moisture seeps through the outer copper sheath and
causes system failure by creating open electric circuits and ground faults. As a result, in
2009, the original three phase system was modified into a two phase system in order for
the system to remain operational. This system operates on a continuous basis due to the
lack of confidence that the system will re-energize once turned off.
Figures 5 and 6 show pictures of the deteriorated heat tracing cables.
Figure 5: Deteriorated Heat Tracing Cable
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 9
Figure 6: Deteriorated Heat Tracing Cable
Also, the existing heat tracing application on the 100 mm diameter pipeline has experienced
similar problems as the main pipeline. It consists of bare copper mineral insulated heat
tracing cables which were installed during original construction and has exceeded its useful
service life. Over the years moisture has accumulated within the insulation and corroded
the copper sheath, resulting in open electric circuits and ground faults and thus, failure to
heat the oil.
Figure 7 shows a picture of the existing electric heat tracing cable on the 100 mm diameter
fuel oil pipeline.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 10
Figure 7: Deteriorated Heat Tracing Cable
The condition of the existing heat tracing cables on the 455 mm diameter and 100 mm
diameter pipes place the environment, worker safety and system reliability at risk.
3.1 Age of Equipment or System
The heat tracing system on both the North and South section of the 455 mm diameter
pipeline replaced the original in 2002. It has been in operation for nine years. The 100 mm
diameter pipeline was installed during original construction and has been in operation for
40 years.
3.2 Major Work and/or Upgrades
In 2002, the original bare copper electric heat tracing cable on the South Section and North
Section was replaced with a new copper sheathed mineral insulated electric heat tracing
cable, equipped with a high density polyethylene jacket.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 11
Tyco Thermal Controls (TTC) is the Original Equipment Manufacturer (OEM) for the electric
heat tracing installed during original construction, and for the new replacement cable
installed in 2002.
From 2004 to 2011, repetitive failures have been experienced with the cables on both the
North and South Sections of EHT cable which was installed new in 2002. As a result, Hydro
operations personnel modified the three phase electric heating system into a two phase
system to mitigate sections of deteriorated heat tracing cable. This modification was
required for the electric heating system to remain operational, and is a temporary measure
until replacement of the entire electric heat tracing system occurs. The procedure of
eliminating an electrical phase, or "making two phases into one" allowed reenergization of
the heat trace during critical operational periods in the winter months. The trade off for this
is essentially double the rated electrical current flowing through sections of the heat trace
system. This shortens the life of the remaining sections of heat trace. Given the total length
of the fuel oil piping a proper design requires three individual electrical phases, each equally
sharing a component of the total heat trace system.
In September 2009, Hydro contracted the OEM of the existing heat tracing cables to provide
an analysis and opinion to determine the cause of the premature failure of the electric heat
tracing cable installed in 2002. TTC discovered that the HDPE jacketed copper MI cables had
been installed in place of bare copper MI cables. The following is a quote from Page 2 from
the TTC Report dated March 31, 2011: “There are two problems associated with using the
jacketed cable for this installation. The first is that the 26.7 watts/ft output of the heater
exceeds our maximum recommendation of 8-9 watts/ft for jacketed copper MI cables on
metal pipes. The second is that the sheath temperature for these heaters would be in
excess of 405oF and this exceeds the recommended maximum continuous operating
temperature for HDPE of 248oF”. Please refer to Appendix B for more information.
Also, early in 2011, an internal root cause failure analysis was completed to determine the
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 12
reasoning behind the decision to choose the electric heat tracing cable currently installed
on the North and South section of the fuel oil pipeline. Please refer to Appendix C.
3.3 Anticipated Useful life
The anticipated useful life of copper heat tracing cable is 20 years. However, this may vary
depending on environmental and service conditions.
3.4 Maintenance History
The five year maintenance history for the Holyrood Thermal Generating Station electric
heat tracing system is shown in Table 1.
Table 1: Five Year Maintenance History
Year Corrective
Maintenance
($000)
Corrective Maintenance (CM)
2011 9.0 Three CM work orders on malfunctioning of EHT
2010 0.5 One CM work order on malfunctioning of EHT
2009 32.3 Four CM work orders on malfunctioning of EHT. 3 phase
system modified to a 2 phase system
2008 7.9 Five CM work orders on malfunctioning of EHT
2007 0.5 One CM work order on malfunctioning of EHT
Preventive maintenance of the heat tracing system is a component of the annual
maintenance strategy of the fuel oil delivery system. Hydro does not track heat tracing
preventive maintenance costs separately from the total unit maintenance cost. As a result,
specific preventive maintenance costs for the heat tracing system are not available.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 13
3.5 Outage Statistics
No outages have been attributed to failed electric heat tracing at Holyrood.
3.6 Industry Experience
Curtiss Wright, Scientech, is experiencing similar problems such as ground faults and circuit
failures with bare copper electric heat tracing. The outer copper sheath of the heat tracing
cable reacts to the original pipe insulating material, attacking the outer sheath. Over time,
moisture seeps through the outer sheath and causes electrical ground faults resulting in
failure of the electric heat tracing. Please refer to Appendix D.
3.7 Maintenance or Support Arrangements
All maintenance work is performed by Hydro operations personnel.
3.8 Vendor Recommendations
TTC recommends replacement of the entire existing copper heat tracing system with
stainless steel heat tracing. Copper heat tracing is not suitable for this application because
of the moisture levels and sea salt spray experienced in Holyrood. Please refer to Appendix
E.
3.9 Availability of Replacement Parts
Replacement heat tracing cables are readily available within three to four weeks of an
order.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 14
3.10 Safety Performance
The existing heat tracing cables have deteriorated resulting in safety hazards from
potentially failing equipment. Improper functioning of the heat tracing is a serious concern
to the safety of operations personnel when shuttle tankers attempt to pump Bunker C fuel
oil from the marine terminal to Holyrood’s facility tank farm. For successful pumping of oil
through the pipe to the tank farm, the oil must be maintained at a temperature of 30OC.
Improper functioning heat tracing cannot achieve this temperature. As a result, as the
tanker attempts to pump cooled oil (<30OC) through the pipe, there is the possibility for
build-up of excessive back pressure in the pipeline at the marine terminal. Excessive
pressure can result in damaging the pipeline, leading to spillage of hot Bunker C fuel oil,
potentially causing severe burns or a fatality.
3.11 Environmental Performance
The environmental concern present with the condition of the existing heat tracing system is
the potential release of a large volume of bunker C fuel oil into the environment. As
mentioned earlier, a shuttle tanker attempting to pump oil through the pipeline at a
maintained temperature lower than 30OC, can potentially result in excessive back pressure
in the line, bursting the pipe, leading to spillage of Bunker C fuel oil into the Atlantic Ocean.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 15
Figure 8: 455 mm Pipeline
Spillage of Bunker C oil presents serious concern. The release of oil would result in
contamination of the Atlantic Ocean, detrimentally impacting highly populated plant and
marine life. It should also be noted that a nearby public beach would be negatively
impacted as well.
Bunker C oil is very thick and sticky, and has been found to float, sink, or do both in water1.
Bunker C oil properties make it very difficult to treat and clean up when it comes in contact
with the environment.
Clean up of an oil spill of approximately 15,000 barrels would not only require great effort,
but will be very costly as an extensive amount of resources will be required to clean up oil
from the ocean and shoreline. It was estimated that a minimum cost to clean up an oil spill
into the Atlantic Ocean is approximately $1,000,000.
1 - www.buzzardsbay.org/number6oil.htm
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 16
Figure 9 shows a picture of the beach and surrounding area near the Holyrood Thermal
Plant.
Figure 9: Holyrood
Image taken from http://sonyald.blogspot.com/2011/02/my-hometown-holyrood-nl.html
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 17
Figure 10 below is a picture of a bunker oil spill in San Francisco.
Figure 10: Bunker Oil Spill in San Francisco
Image taken from http://thegreenists.com/date/2007/11/page/4
3.12 Operating Regime
Currently, the remaining two phases of heat tracing is in continuous operation because of
the lack of confidence the system will work again if turned off. Operations personnel believe
the existing system has deteriorated to the point that if they de-energize the cables for any
period of time, they will not re-energize when turned back on. The new proposed
installation will allow for the heat tracing system to be switched off during summer months
through the installation of a programmable controller. Seasonal operation will reduce the
total power consumed by approximately 50% of the total power consumed by the existing
system.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 18
4 JUSTIFICATION
This project is justified on the requirement to replace the deteriorated electric heat tracing
system based on safety, operational reliability, and the environment. Due to the highly
corrosive environment that this heat tracing system is exposed to, an anti-corrosive
material is required. The previous installation used a copper sheathed material with a HDPE
jacket. This jacket did not withstand the temperatures it was exposed to and melted.
Stainless steel is the most economic material that will withstand both corrosion and the
required temperatures.
The project is required based on the following reasons:
1. Failure to Receive Oil
The storage of Bunker C fuel oil has to be maintained at sufficient levels in the tank farm to
ensure continuous operation of the Holyrood Generating Station. Electric heat tracing of the
entire length of piping heats the highly viscous oil to enable pumping from shuttle tankers
to the facility tank farm. The existing electric heat tracing system has deteriorated and is
now temporarily repaired for unloading oil from the tankers. On February 22, 2011, a tanker
could not deliver fuel for three days due to failed electric heat tracing, resulting in three
days of demurrage payments of $18,000 to $25,000 per day.
2. Consultant Recommendations
A consultant, AMEC completed a condition assessment and advised Hydro that the system
should be replaced as indicated in the following quote from Page 1 of their condition
assessment report: “The heavy oil electrical trace heating system on the pipeline from the
dock to the receiving point at the south end of the tank farm was replaced but has recently
experienced failures. The plant has managed to get two phases back in working order, but
the failure of these phases is very likely. This issue needs to be resolved and the system
replaced”. See Appendix F.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 19
3. OEM Recommendations
The OEM, Tyco Thermal Controls, has recommended that the existing copper heat tracing
system be replaced with new stainless steel electric heat tracing.
4. Personnel Safety
The insulation of the cables of the existing heat trace system has become brittle. This
reduces the ability of the insulation to protect from electric ground faults and the insulation
resistance has become lower than the acceptable minimum value. The deterioration of the
insulation indicates that there are places where there are leakage currents which endanger
the safety of personnel.
5. Environmental Performance
Release of Bunker C oil into the Atlantic Ocean is a serious environmental concern, and
presents a high risk of severely impacting an environment which is highly populated with
plant and marine life. The pipeline has the capacity to contain approximately 15,000 barrels
of oil. This risk is significantly reduced with the installation of a new heat tracing cable
suitable for this application.
Failure to replace the existing heat tracing cables increases the likelihood of failure to
receive fuel oil and could lead to extensive equipment damage, and poses serious risk to
personnel safety, the environment and operational reliability.
4.1 Net Present Value
A net present value calculation was not performed in this instance as only one viable
alternative exists.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 20
4.2 Levelized Cost of Energy
This project will not affect the levelized cost of energy for the system.
4.3 Cost Benefit Analysis
A cost benefit analysis is not required for this project proposal as there are no quantifiable
benefits.
4.4 Legislative or Regulatory Requirements
There are no legislative or regulatory requirements associated with this project.
4.5 Historical Information
In 2002, the original copper MI heat tracing cables on the fuel oil delivery pipeline was
replaced with new jacketed copper MI heat tracing cables. Please refer to Appendices B and
C.
4.6 Forecast Customer Growth
This project has no effect on forecasted customer growth. Figures 11 and 12 below show
the fuel quantity forecast required to meet the load forecast.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 21
Figure 11: Island Interconnected Peak Demand to be supplied to Holyrood
Figure 12: Holyrood Plant Fuel Forecast
4.7 Energy Efficiency Benefits
There are no energy efficiency benefits associated with replacement of the existing copper
electrical heat tracing system with stainless steel heat tracing.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 22
4.8 Losses during Construction
There are no losses anticipated to occur during construction of this project as the
replacement will be performed during the period from May 1 to August 31 when no oil is
delivered to Holyrood.
4.9 Status Quo
The status quo is not an acceptable alternative because the deteriorated and obsolete
equipment poses safety hazards to Hydro operations personnel and poses risk to the
environment and reliable delivery of service to customers.
4.10 Alternatives
Electric heat tracing is the only viable option to the problems described.
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 23
5 CONCLUSION
The replacement of the fuel oil heat tracing system is justified on the basis of the safety and
environmental concerns and the unreliability of the existing equipment to operate properly.
Without the replacement, operating staff, the environment, and system reliability are
exposed to unacceptable risks associated with failure of the heat tracing cable. To eliminate
known safety, reliability and environmental risks, the entire heat tracing system on the fuel
oil pipeline requires replacement.
5.1 Budget Estimate
The budget estimate for this project is shown in Table 2.
Table 2: Budget Estimate
Project Cost:($ x1,000) 2012 2013 Beyond Total
Material Supply 5.0 5.0 0.0 10.0
Labour 234.1 191.0 0.0 425.1
Consultant 0.0 0.0 0.0 0.0
Contract Work 1,027.0 917.0 0.0 1,944.0
Other Direct Costs 0.0 0.0 0.0 0.0
Interest and Escalation 86.9 213.1 0.0 300.0
Contingency 121.3 87.8 0.0 209.1
TOTAL 1,474.3 1,413.9 0.0 2,888.2
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 24
5.2 Project Schedule
The work is scheduled over a two year period and will be completed during the period from
May through August when no fuel oil is delivered to site. The anticipated project schedule is
shown in Table 3.
Table 3: Project Schedule
Activity Start Date End Date
Planning Initial Project Planning
Design Transmittal Development
Jan 2012 Mar 2012
Design Equipment Tenders
Placement of Orders
Detailed Design Engineering
Mar 2012 Apr 2012
Procurement Equipment Delivery Apr 2012 May 2012
Construction Equipment Installations – South
Section
Equipment Installations – North
Section
Equipment Retirement
May 2012
May 2013
Aug 2012
Aug 2013
Commissioning Equipment in Service – South Section
Equipment in Service – North Section
Sep 2012
Sep 2013
Sep 2012
Sep 2013
Closeout Project Completion and Closeout Dec 2013 Dec 2013
Replace Fuel Oil Heat Tracing
Newfoundland and Labrador Hydro Page 25
Replace Fuel Oil Heat Tracing
Appendix A
Newfoundland and Labrador Hydro A1
APPENDIX A
Fuel Oil Delivery Line Heat Trace
Replace Fuel Oil Heat Tracing
Appendix A
Newfoundland and Labrador Hydro A2
Replace Fuel Oil Heat Tracing
Appendix B
Newfoundland and Labrador Hydro B1
Appendix B
Tyco Thermal Controls – Holyrood Heat Tracing Background
Information
Replace Fuel Oil Heat Tracing
Appendix B
Newfoundland and Labrador Hydro B2
March 31, 2011
Newfoundland Labrador Hydro
Holyrood, NL
A0A 2R0
Attention: Christian Thangasamy, M.Eng., P. Eng.
Reference: EHT system on the 18 inch Fuel Oil Line
Background Information
Christian,
The following represents a summary of the Tyco Thermal Controls (TTC) electric heat tracing
(EHT) system installed on the 18 inch fuel oil line at the Holyrood Generating Facility.
The original installation was done in February 1970. The construction drawings show that
the 4000 foot line was divided into two circuits at approximately the mid-point of the
pipeline. The circuits were designated as North (ccts 1A to 1E) and South (ccts 2A-2D). The
mineral insulated heating cable was Pyrotenax reference R12C: single conductor, 600 volt,
bare copper, 14 watts/linear foot. The system operated as designed for approximately 30
years until 2000 when repair work began.
TTC provided a budget to replace the heat tracing in December 2000 offering 3 options: self-
regulating heating cables, mineral insulated heating cables or STS (skin effect). It was
suggested at this time to change the mineral insulated cables to stainless steel. Alloy 825
heating cables have a higher operating temperature range and offer better corrosion
resistance than copper jacketed cables.
In May 2002 another proposal was submitted offering 2 options: replace all or a part of the
MI heating cable with new MI cables or install a complete new system with self-regulating
heaters. It is our understanding that, for budget considerations, only a few of the heating
cables were replaced on the North circuit. TTC introduced new cable reference numbers
Replace Fuel Oil Heat Tracing
Appendix B
Newfoundland and Labrador Hydro B3
effective March 17, 1997 and the original R12C cable reference was changed to the new
reference 61CC5162. This reference is a copper MI cable.
On May 23, 2002 Tyco sent a letter to Newfoundland Hydro summarizing the existing EHT
system. Over the past number of years many significant changes had been made to the
system.
• Existing circuits 1B, 1D and 1E were not operating.
• Circuit 1B was taken out of service and teck cable was installed as a jumper. This
would reduce the overall resistance in the circuit and increase the power output and
sheath temperature of the remaining cables.
• NL Hydro request made to provide a new design to install 6 each 150 foot MI cables
series connected to the 3 each 366 foot cables of circuit 1A.
• At some time in 2003 Newfoundland Hydro would reconnect ½ of circuit 1D and all
of circuit 1E.
• By connecting the MI cables as detailed above, the copper heating cables would be
operating at 41 volts, producing 26.7 watts/ft and having a sheath temperature of
approximately 407 deg. F. It was noted that TTC normally limits the sheath
temperature of copper cables to 392 deg. F.
TTC was not made aware of whether or not circuit 1D and 1E were ever reconnected. Also, it
is not clear if or when the teck cable was replaced by heating cable.
In September 2009 TTC reviewed this installation again. Insulation was removed to check
the condition of the heater in different sections of the pipe. At this time it was discovered
that HDPE jacketed copper MI (B61CH5162/…) had been installed in place of bare copper
(B61CC5162/…) during the retrofits.There are two problems associated with using the
jacketed cable for this installation. The first is that the 26.7 watts/ft output of the heater
exceeds our maximum recommendation of 8-9 watts/ft for jacketed copper MI cables on
metal pipes. The second is that the sheath temperature for these heaters would be in excess
of 405 deg. F and this exceeds the recommended maximum continuous operating
temperature for HDPE of 248 deg. F. During the visual inspection of the heater it was found
that the jacket had melted off of the copper heating cable which would be expected based
on the calculated sheath temperature. It appears that an incorrect purchase requisition may
have been issued for jacketed copper heating cable. While the HDPE jacket would be
damaged due to temperature, the copper MI cable would still operate. The copper cable,
without the HDPE jacket, may have been subject to increased corrosion.
Later in September TTC sent their field service representative to site to inspect the system
and fault locate many of the cables. Many of the circuits were found to be open or
grounded. A report was submitted outlining the necessary steps to repair some of the
Replace Fuel Oil Heat Tracing
Appendix B
Newfoundland and Labrador Hydro B4
cables. The field service rep returned in October to carry out some of the repairs to the
cables. The system today operates with only 2 of the phases working.
In general, TTC electric heat tracing systems have a 10-year warranty and an expected life in
excess of 20 years. This assumes that the EHT system, which includes not only the heat
tracing cables and controls but also the insulation, cladding and distribution wiring, is
properly maintained.
The existing system appears to have worked for almost 30 years. When repairs were
undertaken it seems that, to meet budget constraints, compromises were made to the
system. As this is a resistance heating system, changes made to some sections of the circuit
design (1A to 1E) caused other heating cables in the circuit to operate at wattages, currents
or temperatures exceeding their recommended design limits.
Please call me if you have any questions concerning this information.
Regards,
Pete Inglis
Regional Manager
Tyco Thermal Controls
3 Kingslea Gardens
Toronto, ON
M8Y 2A7
Phone: 416-234-0886
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C1
Appendix C
Root Cause Failure Analysis of Electric Heat Tracing
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C2
Table of Contents
Root Cause Failure Analysis of Electric Heat Tracing page 1
Appendix 1 Tanker Report
Appendix 2 Acceptance form for offloading oil tankers
Appendix 3 Discharge Pressure Log
Appendix 4 Pumping Log
Appendix 5 Canadian Maritime Agency Statements of Facts
Appendix 6 Tyco’s Inspection Report
Appendix 7 Copy of Cable Tag
Appendix 8 Copy Tyco Specification Sheet for Copper MI Cables
Appendix 9 Copy of Purchase Order Requisition for Copper Sheathed Cable
Appendix 10 Copy of the Quote for 12w/ft copper sheathed cables from vendor with the
words PVC jacket
Appendix 11 Copy of P.O. #40043 OP dated 03/02/17 for R12C
Appendix 12 Copy of the Vendor’s fax dated May 23, 2002 informing delivery time and
price for copper sheathed cables
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C3
HOLYROOD THERMAL GENERATING STATION
INCIDENT REPORT
Root Cause Failure Analysis of Electric Heat Tracing
Marine Terminal to Tank Farm 18 inch Bunker C oil Piping
Date of incident: 19 February 2011
Date of start of investigation: 14 March 2011
Date of final report: 31 March 2011
Incident Cost: $ 100,000
Incident Summary:
The Holyrood Thermal Generating Station burns Bunker C oil as fuel in the burners. Bunker C oil is
stored in four tanks on site for its daily use. These tanks are filled by Bunker C oil brought by ocean
going tankers. These tankers berth at the plant’s marine terminal which is at a distance of 4000 feet
from tank # 1 which is the farthest tank. The oil from the tankers is pumped through 18 inch piping.
Bunker C oil being very viscous needs to be maintained at approximately 300 C by means of either
electrical or steam tracing the piping for pumping. At Holyrood the 18 inch pipe is provided with
electrical heat tracing.
Every year the plant receives between five and ten oil tankers. On 14th February a tanker arrived at
St John’s pilot station and it was ready to discharge oil on 19th February. The oil could not be
pumped for three days due the failure of the electric heat tracing on the 18 inch 4000 feet long pipe.
This resulted in a demurrage payment for three days.
Initial Conditions:
The electric heat tracing was on. It had not tripped.
Initiating Event:
When commencing to pump from the tanker the pressure was increasing indicating a block in the
discharge piping. The flow meter in the ship did not show any indication of oil flow.
Incident Description:
On 19th February, mechanics went to the dock to discharge oil from the tank. The loading arms
were connected at 1410 hrs. Mechanics commenced pumping at 1530 hrs. The pump discharge
pressure remained at 400 kpa until 1800 hrs. The flow meter at the tanker did not show any flow
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C4
except for the 137 barrels which is the volume of the empty 18 inch piping from the dock to the
block valve at dock gate. This portion of the piping is drained after discharging the oil from tankers
by means of 4 inch drain piping. It was found that the electric heat tracing had malfunctioned.
The Shift Supervisor raised an emergency work order on 20th February for electricians to attend to
the defective electric heat tracing.
The present electric heat tracing was commissioned in 2004. In 2000, Tyco, the manufacturer of the
electric heat tracing submitted a proposal to Hydro for replacement the 30 year old electric heat
tracing system. The original heat tracing cables were copper sheathed with part number R12C150.
The letter ‘C’ is for copper sheathed, the number 150 is for the length of the heating cable in feet
and the number 12 is the size of the cable in wire gauge.
Tyco’s options in 2000 were:
1. Self Regulating Heating Cables $1,122,498.00
2. Mineral Insulated Inconel Sheathed Heating Cables $879,341.00
3. Skin Effect Heat Tracing System $710,388.00
Tyco included the option of stainless steel sheathed cable heaters. However, in 2002, Hydro did not
opt for any of the above when the project for replacement of the Heat Tracing started. Hydro did
not have a budget to afford any of the above options. Hence Hydro planned to replace the defective
copper sheathed heater cables, by the plant forces over a two/four year period to preserve budget.
Tyco carried out the design calculations for copper sheathed heater cables. The sheath temperature
was calculated to be 1380 C. The watts/ft was 12. Hydro contemplated replacing the copper
sheathed mineral insulated heater cables with self regulating cables. Tyco informed Hydro that the
cost of self regulated cables would be $84,000 and that of copper sheathed mineral filled heater
cables as $18,000. Hydro opted for the copper sheathed mineral filled heater cables in view of the
lower cost as well as costs associated with new 208 V step down transformers required for the self
regulating heater cables.
The plant decided to have the copper sheathed heater cables to be jacketed with High Density
Polyethylene to protect the copper sheath from corrosion. Plant electricians began installing High
Density Polyethylene jacketed copper sheathed mineral cables during Oct 2002. The allowable
maximum temperature for High Density Polyethylene is 1100C. The maximum allowable wattage for
High Density Polyethylene jacketed heater cable is 8 watts per foot. Hydro did not change the heater
cable length to suit the lowered wattage loading.
The electric heat tracing project was completed on 12th November 2004 at a cost of $231,698. The
heat tracing began to fail from 2005. It was observed that the HDPE was cracking and melting. The
heater cable was getting overheated and grounding out due to loss of insulation. In Nov 2009, the
heat tracing system had to be modified to a two phase system from 3 phases due to excessive
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C5
grounding in one phase. There were 19 corrective maintenance work orders between Nov 2004 and
19th Feb 2011.
Immediate Corrective Action:
The electricians found that the electric heat tracing was ‘ON’ with a section halfway between the
railway crossing and the dock gate, ‘open’ circuited. The terminations of the cold leads to the
defective section had to be drilled as they had fused to their brass terminals at the terminal box. The
defective section was by-passed by energizing an unused section of a phase which had been taken
out of service in 2009.
Causes & Corrective Actions:
The decision by the Plant to go for High Density Polyethylene jacketed heater cables contributed to
the failure of the heat tracing system. As per Tyco, the HDPE jacketed cables are designed and used
as snow melting cables. These cables are used for corrosive embedded applications such as asphalt
or snow melting where the HDPE can dissipate heat over a large area. When the HDPE jacketed
heater cable is wrapped on a pipe, it has only a finite area of contact thus limiting the area for heat
transfer. The wattage loading is 8 watts per foot for the high density polyethylene jacketed cables.
The plant purchased HDPE jacketed heaters for a system which was designed for copper sheathed
cables with a load of 12 watts per foot. The tags on the cables on the 18 inch fuel oil piping show
150 feet and 1800 watts. Thus High Density Polyethylene cable heaters which were designed for a
maximum load of 8 watts/foot were subjected to a load of 12 watt/foot.
The HDPE jacketed cables have therefore been subjected to excessive overheating and broke down.
The copper core burnt out due to higher than design wattage causing the break down of the copper
sheath resulting in cable failure. The resistance measured on the system has repetitively been lower
than the allowable value of 1.6 meg ohm.
The following accelerated the breakdown of the heat tracing system.
1. The moisture ingress through defective sealing in the cladding which provided a source
for grounding.
2. Tech cables which were installed to by pass defective circuits decreased the resistance
in the heater cables and thereby increased the power in the cables resulting in
overheating.
Weekly measuring of the resistance in the circuits has been initiated as a condition monitoring
strategy.
Lessons Learned:
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C6
1. When changing the material composition of a component, thorough research has to be
done on the applicability of the new material.
2. When replacing a component in an existing system, the new component must be checked
whether it conforms to the specifications of the existing system.
3. Prior to commissioning a project, the function of the system and components in the system
should be thoroughly understood by calling for meetings and discussions with end
users/vendors.
4. When budget is not available, more Preventive Maintenance needs to be carried out to keep
the system in operation and efforts to expedite the budget approval process should be
made rather than trying to fit the project to the available budget.
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C7
Appendix 1
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C8
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C9
Appendix
2
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C10
Appendix 3
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C11
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C12
Appendix 4
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C13
Appendix 5
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C14
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C15
Appendix 6
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C16
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C17
Appendix 7
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C18
Appendix 8
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C19
Appendix 9
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C20
Appendix 10
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C21
Appendix 11
Replace Fuel Oil Heat Tracing
Appendix C
Newfoundland and Labrador Hydro C22
Appendix 12
Replace Fuel Oil Heat Tracing
Appendix D
Newfoundland and Labrador Hydro D1
Appendix D
Fossil Operations & Maintenance Information Service – Above
Ground Fuel Line Heat Tracing Cable
Replace Fuel Oil Heat Tracing
Appendix D
Newfoundland and Labrador Hydro D2
Replace Fuel Oil Heat Tracing
Appendix D
Newfoundland and Labrador Hydro D3
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E1
Appendix E
Fuel Lines Engineering, Procurement and Construction (EPC)
Services
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E2
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E3
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E4
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E5
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E6
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E7
Replace Fuel Oil Heat Tracing
Appendix E
Newfoundland and Labrador Hydro E8
Replace Fuel Oil Heat Tracing
Appendix F
Newfoundland and Labrador Hydro F1
APPENDIX F
AMEC – Condition Assessment & Life Extension Study
Replace Fuel Oil Heat Tracing
Appendix F
Newfoundland and Labrador Hydro F2