TTT Header Integrity Program
A new approach to HRSG header replacement
Header replacement can be one of the most labor-intensive and outage-critical repairs performed within an HRSG.
The TTT Header Integrity Program combines patented Tuff Tube Transition connection technology with engineering, fabrication and installation strategies designed to improve the integrity of the replacement assembly while dramatically simplifying field installation.
TTT-lined headers utilize the Tuff Tube Header Connection (TTHC) within the fabricated header assembly, with Tuff Tube Purgeless Sleeves (TTPS) available to simplify tube-to-tube field connections during full header replacement.
The result is a replacement strategy designed around quality, installation efficiency and long-term connection integrity.
The real failure location
When the header isn't the real problem
After repeated tube failures, a plant may eventually decide to remove and replace an entire header section with a conventional prefabricated stubbed header.
But in recurring tube-to-header failure scenarios, the header itself may not be the component driving the replacement. The vulnerable area can instead be associated with the tube-to-header connection and the Heat Affected Zone created where relatively thin-walled tube material is welded to the substantially heavier header.
The Header Integrity Program approaches the replacement differently: rather than simply reproducing the conventional connection configuration, TTT technology is incorporated into the replacement strategy to address the connection itself.
Reengineering the connection
Move the weld away from the thin tube wall.
One of the most challenging areas of a conventional header assembly is the transition between the relatively thin tube wall and the substantially heavier header.
Conventional configurations can place significant welding and thermal effects directly onto the thin tube material.
The Tuff Tube Header Connection changes that geometry.
The TTHC is designed to reduce the thermal fatigue difference at the tube-to-header connection and move the welding interface away from the vulnerable conventional configuration.
When incorporated into a new replacement header, TTHCs can be fabricated into the assembly under controlled shop conditions before the completed header is delivered to the plant.
From engineering to installation
One engineered sequence.
Engineering & project review
The existing header configuration, materials, dimensions and operating requirements are reviewed to determine the appropriate TTT-lined replacement configuration.
Engineered TTHC connections
TTHCs are designed and manufactured for the specific tube-to-header application.
Header fabrication
The TTHCs are integrated into the replacement header assembly during fabrication, allowing critical work to be completed before the outage installation begins.
Engineering validation
Where appropriate, Finite Element Analysis can be used to compare the proposed TTT-lined configuration against the conventional design and evaluate stresses at the connection.
Field installation
The completed assembly is installed during the outage. TTPS connections can also be incorporated where appropriate for tube-to-tube field tie-ins, reducing the complexity associated with conventional open-root butt welds.
Program in action
See the Header Integrity Program in Action
Follow the Wise County replacement headers through controlled shop fabrication before field installation.
Real-world case study — Wise County, Texas, USA
Replacement of three RH1 lower reheat headers
- Material
- Grade 22 / 2¼ Chrome
- Installation
- Completed in 5 days
- Scope
- Engineering, fabrication and installation of three replacement reheat headers using TTT connection technology
For this project, conventional proposals estimated an installation duration of approximately 6–8 weeks. Viking Vessel Services engineered, constructed and installed the replacement headers using TTT technology.
“We received proposals from competitors with conventional installation methods that averaged installation times for 6–8 weeks. The Viking team was able to install these headers in 5 days.”
The result
5 DAYS
to install the new headers.
Field installation
Watch the Wise County Field Installation
Field installation and replacement of the Wise County reheat headers using TTT connection technology.
Engineered — not just faster
Speed was only part of the objective.
Finite Element Analysis was performed as part of the Wise County project to evaluate the TTT tube-to-header connection against the conventional/OEM configuration.
According to the plant’s written testimony, the analysis showed the Viking-designed tube-to-header connection to be:
53% STRONGER
than the OEM connection evaluated for the project.
Per the customer’s written testimony
This is important because the Header Integrity Program isn't simply about finding a faster way to replace a header. It is about using the outage as an opportunity to address the connection itself.
Performance after installation
Operating history, not just installation time.
150+
Starts
Accumulated at the time of the customer’s written testimony, plus a significant amount of baseload operation.
TWO
Inspections
Completed by the customer since installation at the time of the written testimony.
NO
Reported failure
No signs of premature failure or unanticipated wear or stress reported at the time of the written testimony.
“I look forward to using Viking for additional repairs, and replacements in the future.”
— Vistra Energy, Wise County Plant, Texas, USA
One program
One program. Multiple capabilities.
Where installation is required, Viking Vessel Services provides the field-service capability behind the TTT technology.
- Engineering Review
- TTT Connection Design
- TTHC Integration
- Replacement Header Fabrication
- Finite Element Analysis
- TTPS Field Tie-Ins
- Quality Control
- Field Installation Support
A complete connection strategy
TTHC + TTPS.
The Header Integrity Program brings together two core TTT technologies. TTHCs can be integrated into the fabricated header assembly for the tube-to-header connections, while TTPS components can be used where appropriate for tube-to-tube field tie-ins during installation.
TTHC
Tube-to-Header
TTPS
Tube-to-Tube
Final call to action
When your header has to come out, replace more than the header.
Replace the conventional connection strategy with a system engineered around installation efficiency and connection integrity. Talk to us before your next planned header replacement.