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Construction & Maintenance Services » Onsite Construction Services » Solution Profiles

Innovative Header Project Solution for Power Station

Scope of Work

Header repairs can cost millions in extended outages. A major boiler construction company needed to perform the following project at a large fossil-fuel electric power generation plant in Shippingport, PA.

The project required the removal of six hundred and twenty four tube stubs (P-11, 2.25" O.D. X .534" wall, with nominal .875" through hole). The stub welds had a .562" penetration depth, a 30 degree lead-out, and were located on 28" O.D. X 5" wall P-22 outlet headers.

On similar projects, other contractors had previously utilized internally mounted equipment. That had resulted in lost time, poor overall project performance, and foreign material contamination issues from broken tooling and machine parts entering the headers.

Project Goals

For those reasons, project supervisors identified as primary project goals:

  1. Repeatable close-tolerance machining results
  2. The prevention of foreign material contamination
  3. The prevention of galling within the headers

These criteria would later serve as definitive proof of Tri Tool's improved repair concept.

Equipment Selection

The externally-mounted TRI TOOL® Header Prep Machine was selected as the perfect machine for this project. It's rigid mounting characteristics, high-torque, and quick set-up design proved ideally suited for the rapid removal of socket welds (and heat affected material) demanded by this application.

To further assure productivity and performance while meeting project objectives, a heavy duty tool holder was custom designed. This special tool holder provided maximum rigidity for increased precision, multi-position mounting for up to 4 form tool bits and a special lower pilot that rotated on a bearing.

Header Prep Machine Project specific tool holder (with 7/8 inch pilot) in use

Header Prep Machine (1st photo) and the project specific tool holder (with 7/8" pilot) in use.

This combination of the field proven TRI TOOLŪ Header Prep Machine along with the specialized tooling rapidly proved its advantages. The on-site proof-of-concept test delivered consistant cycle times in as little as 12 minutes, from station to station. On the basis of this successful demonstration, the prime contractor issued their notice to proceed, with a start date 2 weeks later. Tri Tool Inc. dispatched personnel and 5 modified Header Prep Machines to the job site. An aggressive schedule was established that specified two (10 hour) machining shifts per day. In addition, Tri Tool project management and repair & support personnel remained on duty an additional 2 hours per day to ensure readiness and a "hands on" turn over from shift to shift.

Project Success

Project completion was originally estimated at 11 shifts and was successfully accomplished in 13 due to an expansion of scope that included increasing the penetration depth, and removal of additional weld build-up from 97 tube stubs that had been previously repaired by hand.

Rely upon Tri Tool's commitment to design innovation, quality, and superior project management capabilities, all supported by an outstanding level of customer service, to complete your most challenging projects safely, on time, and within budget.