Case Studies - Equipment

Proactive CFB Boiler Maintenance Saves $ Millions and Triples Run Cycles

CFB Boiler This coal-burning boiler was commissioned in 1998 with an 11,450 sqft (1064 sq.m.) heating surface and 1.2 million pounds per hour (544 t/h) steaming cap. IGS first applied HVTS in 2020 and monitored the condition of the boiler...
PROBLEM: The annual cost from forced outages, RIK, general maintenance and electrical cost associated with each unit could reach an average of 8-12 Million dollars. SOLUTION: IGS HVTS addressed the problems and increased the run cycles from 4-6 months to...
1. Before IGS HVTS See the bare tube condition prior to the IGS HVTS application. Notice hard edges around discontinuity from erosion damage where ash build-up has deviated material flow into the unprotected substrate.  
2. IGS HVTS Applied In order to prevent further substrate wastage IGS has cladded the area with HVTS as opposed to having to cut and replace tubes. Pictured is the area of low tube thickness now protected by IGS cladding....
3. Ceramic Top Coat Once the cladding process has been completed, IGS applies a proprietary ceramic top coat as a wear indicator during future outage inspections to help navigate future coating plans.  
4. After a 14-Month Run Cycle The coated area after a 14-month run cycle appears on the right. The presence of ceramic top coat (Green) can still be identified meaning underlying thermal spray cladding is still at 100% as-applied condition....
The Benefits of HVTS HVTS cladding reduces tube wear and increases overall production. This reduces costs associated with maintenance from both planned maintenance and forced outages. Reducing the need for welding and eliminating the requirement for refractory in some areas...

Weld Overlay Alternative for Boiler Pressure Parts

A waste-to-energy plant in Turin, Italy, was preparing for an outage on one of their lines. They were waiting for approval from the notified body to carry out the weld overlay. The outage was nearing, and the approval was yet...
Power Plant
Corrosion of the Boiler Pressure Parts The plant, built by CNIM, was commissioned in 2014. Following several years in operation, they noticed corrosion in the second pass of the boiler. Alloy 625 weld overlay has already been installed in the...
Selecting a Suitable Solution IGS HVTS was selected for several reasons. Strong global references in similar applications supported by laboratory testing. HVTS is not a welding process – the pressure part temperature stays below 150C during the application, therefore, unlike...

Plant Replaces Weld Overlay in their CFB Boiler

This CFB boiler built in the mid-1990s is designed to burn anthracite coal, hazardous waste coal piles located throughout Pennsylvania. The plant observed severe erosion and metal wastage on the boiler tube due to how these combustors operate. Over the...

Thermal Spray Stops Alloy T24 Fireside Corrosion in Supercritical Boiler

This Power Plant provides steam to nearby industrial facilities using sustainable biomass (such as SBP, GGL, FSC, and PEFC) and industrial by-products (such as bio-propane) to generate power and heat.
SUPERCRITICAL BOILER The boiler has five rows of six burners on two sides. These burners are fed with coal, bio-propane, wood, and MBM (Meat and Bone Meal) – animal residue foam injected into the boiler. MBM is very erosive, so...
A SUPER ALLOY T24 BOILER The unique feature of this boiler is that it is one of the first boilers manufactured with alloy T24. T24 material is a novel superalloy, designed for strength at high temperatures that does not require...
ALLOY T24 WELDING ISSUES Welding this superalloy is difficult, especially without annealing or post-weld heat treatment. Non-alloy steel, a material used to produce typical boiler tubes, PH 265GH, is the easiest material to weld. The superheater material, 10CrMo9-10, is known...
As a result, these first boilers manufactured with T24 suffered many leaks after just a few hundred hours of operation. Welding experts from VGA and other parties involved helped them find the solution, enabling them to erect such supercritical boilers...
TESTING HVTS SUPERALLOY PROTECTION As the plant continued having multiple stoppages due to tube leaks, in 2019, they decided to apply a protective cladding onto a test area to evaluate its performance. IGS HVTS was chosen for this on-site job....
IGS HVTS – High-Velocity Thermal Spray HVTS cladding was also applied onto superheater hanging tubes facing soot blowers. Test areas were installed onto various locations of tube bundles as an alternative to thick metal protection shields.
A LEAK OCCURRED DURING HVTS TESTING After installing the trial HVTS application in August 2019, another forced unexpected shutdown due to a tube leak occurred in December that year. Although initially it was suspected to be in the IGS clad...
QUALITY INSPECTION PROGRAMME UT Quality inspected HVTS cladding and unprotected tubes. They performed tube scanning using a PEC Scan, Pulsed Eddy Current scanning, that delivers specific tube thickness mapping. This inspection was conducted in 2019 and again in 2021. By...
INSPECTION DISCREPANCIES AND RESULTS When comparing inspection results between 2019 and 2021, the inspection company immediately noticed that some areas appeared to have gained thickness. Cyril Narjoz, IGS Boiler Reliability Expert, commented:
“You need to keep in mind that first of all, you never read the same point two years later, it’s impossible. Even when you do the reading on the same spot, during the same inspection or the day later, you...
The inspection results were matched with the positioning of the HVTS cladded area. It was a challenge because it didn’t match the red area or the colored area of the thinning. Moreover, to make it a little more complicated, in...
“Nevertheless, what we can see in the area where we applied the HVTS the cladding, there’s much less thinning. And above the area, we have this red zone where we can notice up to nearly one millimeter per year loss...
FUTURE-PROOFING THE BOILER Initially, prior to evaluating the readings, the plant had commissioned IGS to expand their HVTS cladding scope to protect a 35 m² surface area finishing the band and protecting a band below. However, after evaluating the readings...
HVTS APPLICATION IN 2021 The expanded scope was completed in record time by IGS utilizing additional operational resources to speed up the process, with work proceeding simultaneously on several levels. Plant representative said: “We really appreciated IGS’ flexibility during the...
SUPERHEATER TUBES This project’s second exciting part included the hanging superheater tube bundle with steam at 320 bar / 5400C. These tubes face the soot blowers that are operated at regular intervals to clean deposits of the tube surfaces. Welded...
Cyril Narjoz commented: “Cladding supplied by a different vendor was also applied and tested in a similar area and performed well.  The key difference is – these other tests were sprayed in the workshop before being installed in the boiler....
CONCLUSION As T24 material is extremely challenging to weld. One of the major benefits of the IGS HVTS solution is that no welding is involved in its application. Since HVTS is not welded, it does not generate any alteration to...

Twice as Good and Twice as Fast: Reliable Boiler Tube Protection

Most Modern Power Plant The plant was completed and commissioned in 2010. The power plant’s production capacity is 180,000,000 kWh per year. The heat and energy produced is mainly used by a paper mill and the local municipality’s district heating...
PROBLEM After discovering metal wastage in 2014 and having to replace a panel section in 2016, engineers decided to protect new panels with thermal spray cladding. SOLUTION Integrated Global Services (IGS) proposed a high velocity thermal spray (HVTS) alloy cladding...
Boiler Metal Wastage In summer 2014 corrosion was identified on the unprotected boiler tubes, above the weld overlay section. New panels were installed to replace corroded sections, needing cost-effective protection, which would also be faster to apply than weld overlay....
2020 Inspection Spot check inspection of the boiler in 2020 on both HVTS alloy cladding applications showed no reduction of metal thickness. The Power Plant’s boiler engineer, commented: “We are pleased with the service provided by IGS. Reliability and efficiency...
Routine Boiler Inspections IGS have certified inspectors who are able to evaluate the performance of any boiler tube protection, highlighting areas of improvement and advising on a suitable solution for erosion and corrosion issues.

Reliable Boiler Protection Supported By Long-Term EPRI Study

EPRI Study In the mid 2000s, a US power utility owner and EPRI performed a long-term study to determine if thermal spray technology would protect the sidewall tubes (adjacent to burner levels) from thinning caused by reduced sulfidizing atmospheres. A...
PROBLEM The boiler was experiencing tube wall thickness wastage caused by operating the boiler in a reducing atmosphere (low NOₓ burners)which results in sulfidation corrosion. This boiler is the newest of the 1300 mw units but experienced very similar corrosion...
SOLUTION During the Fall of 2019, the plant was in a major planned outage. A full furnace scaffold was installed for boiler maintenance and a tube assessment was performed. During the inspection, new wastage was discovered on the upper front...

Rapid Response To Address The Boiler Damage Zone

Scheduled Shutdown

The unit was in a scheduled outage in October 2019, at which time the fireside of the tubes in the boiler were inspected by robotic UT. Wastage was discovered on both sidewalls above the existing field applied overlay, rear wall slope and burners, and front wall slope and burners. The type of damage is typical for opposed wall fired pulverized coal boilers operating in a reducing atmosphere with low NOₓ burners.

Rapid Response

IGS was contracted to install 5450 EPRI Proven HVTS Alloy Cladding over the damage zones. IGS offered a rapid response and addressed the areas during the week of November 4, 2019. The IGS solution is a rather fast application – a total of 2,000 square foot of boiler tubing was protected with HVTS in 5 short days.

Safety First

The project was executed in accordance with the IGS Safety Program. Safety is, and always will be Integrated Global Services’ first and highest priority. Our Management Team is dedicated to becoming the industry leader in Health and Safety while our excellent safety record bears witness to this fact. A continuous improvement process is utilized that enables all levels of personnel to take part in identifying and fixing hazards associated within the workplace. This is marked by our Safety Committee that involves members of all areas and levels of IGS.

Quality

IGS Thermal Spray projects are performed in accordance with the IGS quality control standards which have been developed in to meet customer requirements. All site work will be executed in accordance to the accepted Quality Control Plan (ITP/QCP) and accompanying method statement. The final project QC package will be issued along with this report.

HVTS Stops Alloy 625 Weld Overlay Corrosion in a WtE Boiler

Stopping Fireside Corrosion in WtE Boiler A waste to energy boiler was experiencing fireside corrosion. Shop applied Alloy 625 weld overlay was showing signs of premature accelerated degradation. IGS was contracted to apply an HVTS cladding on top of the weld overlay...
Renergia Perlen The Renergia waste incineration plant is a joint effort of all waste disposal associations from Central Switzerland and Perlen Papier AG. Renergia Zentralschweiz AG is responsible for more than just recycling waste from Central Switzerland. It supplies Perlen...

WTE Boiler Fireside Corrosion of Alloy 625 Weld Overlay Cladding

The Hitachi Zosen Inova (HZI) furnace installed at Renergia is an inclined moving grate four-pass waste to energy boiler with an external economizer. The boiler’s thermal capacity is 47MW with the steam flow of 58 t/h and steam pressure of 41 Bar at 410°C.

Alloy 625 weld overlay was shop-applied on the fireside water wall panels to protect the WtE boiler tubes from fireside corrosion. After months of operation, an inspection revealed accelerated degradation of the Alloy 625 just above the grate.

Several solutions were considered to manage the boiler tube metal wastage and improve reliability and lifetime of the water walls, including replacement, field applied weld overlay and thermal spray.

Evaluation of Alternatives The replacement of affected water wall sections with new tubes would have been time-consuming and expensive, considering the estimated frequency of replacement of 5 years or less. Like-for-like weld overlay repair is an intensive and time-consuming solution....
HVTS Application IGS HVTS application took place in 2017 on a 20m2 area located on the left membrane wall at the very low furnace of the moving grate WtE boiler above the refractory. The plant also had a thermal spray (TS)...
Weld Overlay Protection: Inspection and Results Markus Benz, head of maintenance at Renergia Zentralschweiz AG, commented: “IGS has been selected in November 2017 to apply ~20m² of their IGS material using their HVTS technology. They mobilized efficiently and performed within the...
2020 Inspection and Results The latest inspection in 2020 has confirmed that HVTS IGS5470 is performing in line with expectations and is protecting weld overlay areas from further corrosion.

How A Plant Stopped CFB Boiler Tube Repairs From 500 To 0

Boiler Units and Wastage Mechanisms This US City Hybrid Energy Center operates two 300-MW CFB boilers that burn a combination of coal mixed with up to 20% biomass. The cladding along the water walls, as with any CFB, requires regular...
PROBLEM Thermal Spray Cladding applied by a previous vendor was unable to prevent metal wastage. After one year in service, 500 tube repairs were carried out due to insuffient erosion-corrosion protection. SOLUTION IGS was invited to remedy the problem areas...

Gee… not a Lucky Star

Inspection of a previously applied protection is a critical part of any project. During the inspection, IGS utilized both visual and magnetic lift-off (MLO) techniques to record any low readings.

Areas that were below the minimum specification were noted and recorded. A considerable amount of the existing coating was significantly eroded. In many cases, it had worn through to the substrate and in the worst cases had allowed significant tube gouging to occur. The amount of defects observed was significantly greater than expected, with 500 tube repairs performed.

Working in Partnership The asset owner and IGS worked closely to mitigate problems during 2016. IGS laid out a 2-year plan to stabilize the existing problems, proactively protect future problem areas, and forecast maintenance spend. The plant made investments in...
Rehabilitation Process in 2016 1.  IGS surveyed and mapped the problem areas. 2.  IGS, Client, and the 3rd Party agreed on a repair procedure to include: removal of failed cladding, repeat inspection to determine severity of tube damage, mechanical tube...

IGS HVTS Stopped Erosion Corrosion In Waste Fueled CFB Boiler

Problem Areas and Custom Solution The unit was commissioned in 2008 and protective cladding was installed that same year. After several years in service, low tube thickness values were observed requiring expansion of the cladding coverage. In addition, previously utilized...
PROBLEM Corrosion and erosion mechanisms were both major contributors to tube wastage in this biomass CFB Boiler, burning waste/biomass. SOLUTION The plant has implemented customized HVTS (High Velocity Thermal Spray) cladding to avoid imminent large scale boiler tube panel replacement....

Inspection in 2017

The inspection was carried out together with the 3rd party CFB Expert and Plant Manager. Cladding was observed to be in a flawless condition. This mini-outage verified the reliability of the IGS HVTS cladding. Extensive inspection was completed throughout the entirety of the cladding scope. With the top coat completely intact, the cladding system was confirmed to be in ‘as-sprayed’ condition.

Fouling was virtually eliminated in the cladded locations and any adhered fouling was no longer tenacious and was easily brushed away.

Plant Manager, Pete Kline Said: “During operation, we had fouling, we had buildup, we had erosion that was eroding that off and refouling. There were some mechanisms going on there that I wasn’t expecting and didn’t understand, and we were...
Pete Kline Continued… “What that required us to do was to develop a long-term approach of identifying the high-risk areas, the critical areas and prioritizing the application over time. Identify what areas we were going to go after, where we...