OTSG Repair – Economizer Tube & Return Bend Replacement
We received a call from a client earlier this month requesting repair services on one of their once through steam generators (OTSG). Our work began with a known quantity of repairs to be carried out, however the final inspection results revealed many more would be required. The decision was then made by our client to increase the scope of work to include all repairs that fell within the parameters of an 18-month repair option.
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- Demolish and prep for replacement of existing economizer tubes
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- Prep work for return bend weld
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- Economizer return bend replacement
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- Economizer tube return bends
Our Team Rose to the Challenge!
The scope of work included the replacement of coil tubes and return bends in the Radiant Section and the Economizer of the OTSG. Upon the first day of mobilization to site, a crew of 4 workers started on days and nights removing known pressure parts slated for replacement, per a 6-month repair option. Four days into the project, the discovery work from the inspection results drove the workload to increase.
We do what it takes! Our experienced supervision and onsite crew of skilled boilermakers came together in a combined effort to double down and efficiently carry out the increased work load, without compromising safety, and with minimal impact on the outage.
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- OTSG Economizer Tube & Return Bend Replacement
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- Confined Space Demolition and Prepping for New Radiant Tube Replacement
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- Welding new sections of inlet and outlet tubes
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- Demolish and prep for replacement of existing economizer tubes
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- Performing a difficult weld on the return bends of an economizer
From Complex Work to Successful Delivery
The repair work was very complex and challenging due to the welding positions within a confined space. We were also dealing with different types of material such as 1.25 chrome, 2.25 chrome, and carbon steel which kept our supervision on high alert so that the correct electrodes and weld procedures were utilized. Our efficient and planned approach yielded a low repair rate of 3% on 170 field welds, even while operating with varying materials and less-than-ideal work conditions!
Executing the Most Difficult Welds in the Industry
As captured in the video below, return bend welds of this type are considered the most difficult in the industry, based on the material grade, location and accessibility of the weld.
Performing welding on the return bends of this economizer had to be carried out under thorough management of change to address the limited access to the weld joints and hazards.
