HomeMy WebLinkAboutA019 - Resolution awarding a contract to Helfrich Brothers Boiler Works, Inc., of Lawrence, MA, for Inconel overlaid Boiler Tubes for the Power Plant in the amount of $56,000ITEM #:22
DATE:09-23-25
DEPT:ELEC
SUBJECT:INCONEL OVERLAID REPLACEMENT BOILER TUBES FOR POWER
PLANT
COUNCIL ACTION FORM
BACKGROUND:
The City's Power Plant operates two high-pressure steam units to generate electricity. These
units are referred to as Unit 7 and Unit 8. Until 2016, the primary fuel for these units was coal,
with the secondary fuel being Refuse Derived Fuel (RDF) produced by the Resource
Recovery Plant. The combusting coal created ash, which neutralized the corrosive properties
from burning RDF.
In 2016, both Units 7 and 8 were converted from coal to natural gas and continued to co-fire
RDF. Because natural gas does not produce ash, the corrosive environment created by
combusting RDF is not neutralized, and accelerated boiler tube corrosion occurs. The tube
corrosion is especially apparent in the superheat section of the boiler in both units. The
superheat section is located in the upper portion of each boiler where the steam is dried and
subjected to the highest temperatures and pressures.
Boiler tube failures result in forced outages of the unit, resulting in several days of reduced
power plant capacity (and potential financial penalties), along with an interruption in the ability
to dispose of the RDF from the community's solid waste.
When it became apparent that accelerated tube corrosion was beginning to occur in both
boilers, staff performed extensive research and found that applying a hardened metal called
Inconel over the tubes dramatically slows the corrosion of the tube base metal. The superheat
section of tubes was replaced with Inconel coated tubes in Unit 7 in 2019. Unit 8's superheat
tubes were replaced in 2020 with Inconel tubes.
It was recently discovered that some of these superheat tubes in both units have had
their Inconel overlay compromised and are now failing. It appears the failures are due to
pinhole size areas where the coating was not fully covering the tube. This allowed a path for
corrosion of the base metal, weakening the tube.
Unit 8 recently suffered a tube rupture because of a weak tube caused by this kind of
corrosion. After thoroughly cleaning Unit 8 boiler and then performing an inspection of
each superheater tube, 18 tubes were found to have been compromised with corrosion
and need to be fully replaced.
Due to the specialized process for overlaying the boiler tubes with Inconel, few companies are
able to perform the overlay process with the high-quality procedures required. Therefore,
staff solicited quotes from the two known qualified providers of this type of specialized
work which are shown below.
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VENDOR COST
Helfrich Brothers Boiler Works Inc.
Lawrence, MA $56,000
Boiler Tubes of America
Lyman, SC $88,443
After evaluating the quotes, staff determined the low quote from Helfrich Brothers
Boiler Works, Inc, of Lawrence, MA, is acceptable. Funding for the purchase of the tubes
will come from the Unit 8 operating budget where there is $100,000 budgeted for replacement
parts and supplies.
Once the tubes are manufactured and delivered, the installation for the Unit 8 tubes will occur
through an existing agreement with a contractor for Power Plant boiler maintenance.
Installation is expected to cost $130,000. The existing contract for boiler maintenance with this
company in FY 2025/26 is for an amount not-to-exceed $350,000, of which $295,000 remains
unspent.
FUTURE BOILER OPERATIONS:
Installing Inconel-overlaid tubes is an established approach to reduce corrosion in a waste-to-
energy boiler. Therefore, the appearance of corrosion in this section of the boiler tubes gives
staff pause about whether the corrosion observed is an isolated occurrence or whether
corrosion may continue to appear throughout the boiler. Although staff performed a thorough
inspection of the Unit 8 superheat section and identified these 18 tubes in need of
replacement, the tight spacing of the tubes in this section makes it difficult to inspect every
surface adequately.
The use of the Power Plant boilers for waste-to energy is expected to continue until summer
2027. Soon after, the Electric Department's New Thermal Generation project is expected to be
in service to replace the capacity of Unit 7, which will be retired. Unit 8, however, is planned to
continue operating for at least ten years longer. If Unit 8 experiences major boiler tube
reliability issues, the utility is at risk of significant expenses to perform a major boiler overhaul
(on aging and soon-to-be retired equipment) or paying major financial penalties for lost
generating capacity.
The 18-tube replacement for Unit 8 described in this Council Action Form is expected to be
completed in November. Meanwhile, Unit 7 is combusting natural gas and RDF. When Unit 7
is brought down to address known leaks, it is expected to require an outage of approximately
two months. It is staff's expectation that, in the probable case, Unit 7 can be utilized through
2027 for RDF combustion, handling approximately 30-40% of the RDF produced. Unit 8 is
large enough to dispose of the entire amount of RDF produced. However, the question for
staff is the level of confidence in operating Unit 8 to combust RDF, and whether doing
so will cause further deterioration leading to reliability issues.
In light of these concerns, staff is discussing how to best approach the next 20 months
of Power Plant operation, balancing: 1) the need to dispose of the community's solid
waste during that time, 2) the preservation of the lifespan of Unit 8 for at least ten years
beyond the conclusion of waste-to-energy, and 3) the burden of alternative approaches
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to waste-to-energy (e.g., landfilling and transportation of solid waste) on partners, such
as Resource Recovery, garbage haulers, and the landfill.
The best approach to address all three of these areas of concern is to reduce the
amount of waste entering the solid waste system and eventually becoming refuse-
derived fuel. This is particularly important for plastic waste, which staff believes is the
largest contributor to the boiler tube corrosion concerns. Staff is anticipating returning
to the City Council in October with additional information about a curbside recycling
program, which would address a significant amount of the plastic waste disposed in
the Power Plant boilers.
ALTERNATIVES:
1. Award a contract to Helfrich Brothers Boiler Works, Inc., Lawrence, MA, for Boiler Tubes
for the Power Plant in the amount of $56,000.
2. Award a contract to the other company that submitted a quote.
3. Do not approve the contract and direct staff to solicit formal bids in an effort to obtain
more competitive pricing.
However, staff is uncertain that other companies exist that are qualified to accomplish
this work, and delays will increase costs.
CITY MANAGER'S RECOMMENDED ACTION:
The purchase of the Inconel overlaid tubes is critical for the longevity and reliability of
Unit 8 boiler. Without specialized overlaid tubes, tube failures will increase causing
significant unit downtime. The installation of these tubes will be completed under a
separate, existing contract for Power Plant boiler maintenance. Therefore, it is the
recommendation of the City Manager that the City Council adopt Alternative No. 1.
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