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A.Celli Evo-Lock®: the innovative solution to improve the performance and reduce the inspections of a Yankee Dryer

Yankee Dryer | Stefano Francesconi, 27 July 2021

Thanks to the continuous development and improvement of our Yankee Dryers, in A.Celli we have evolved our Yankee Dryer with forged shell, conceiving the innovative iDEAL® Evo-Lock®. 

Our new solution is able to minimize the costs related to inspection operations and is equipped with technological solutions never seen before on a Yankee Dryer. Let's find out the details of this unique engineering masterpiece.

iDEAL® Evo-Lock® Yankee Dryer

Our new Yankee Dryer EvoLock® is built with all the A.Celli technologies already known and appreciated, including the shell forged from a single steel ingot, with the novelty of a unique and highly innovative head-to-shell connection system, which does not require the use of structural welds or bolts.

This solution allows, from an engineering point of view, to minimize the deformation of the shell edges induced by the deformation of the heads, which in itself is caused by the internal steam pressure. This important feature improves the runnability on sheet edges, and consequently the efficiency of the machine.

The special design also allows to reduce the overall width of the shell, giving you the capability of drying a larger format sheet with the same existing machine gauge, and, as we will analyze in the next paragraphs, to reduce the necessary inspection interventions.

Required inspections: comparison between Evo-Lock® and other Steel Yankee Dryers

For our analysis, we will consider three types of steel Yankee Dryer on the market::

  • A traditional Yankee Dryer with welded shell and shell connected to the heads by means of full penetration structural welds;
  • A.Celli iDEAL® Forged YD, with forged shell and head-to-shell connection by means of bolts;
  • The new A.Celli iDEAL® Evo-Lock® solution, with forged shell and a new head-to-shell connection system who does not require bolts nor welds.

The following table compares the timings and types of the required checks for the aforementioned types of Yankee Dryers during the first 12 years of life:

Year

Welded shell and head/shell connection with structural welds

A.Celli iDEAL® Forged YD 

New  A.Celli iDEAL® Evo-Lock® 

1

Visual Inspection (Welds) 

   

2

Internal + Internal/External Ultrasonic Testing Inspections

Internal Inspection

Internal Inspection

3

Visual Inspection (Welds) 

   

4

Internal + Visual 

Inspection (Weld) 

Internal Inspection

Internal Inspection

5

Visual (Weld) + Bolt Ultrasonic Testing Inspection

Bolt Ultrasonic Testing Inspection

Bolt Ultrasonic Testing Inspection

6

Internal + Visual Inspection (Welds)

Internal Inspection

Internal Inspection

7

Internal/External Ultrasonic Testing Inspection

   

8

Internal + Visual Inspections (Welds)

Internal Inspection

Internal Inspection

9

Visual Inspection (Welds) 

   

10

Internal + Visual (Weld) + Bolt Ultrasonic Testing Inspections

Internal + Bolt Ultrasonic Testing Inspections

Internal + Bolt Ultrasonic Testing Inspections

11

Visual Inspection (Welds)  

   

12

Internal + Internal/External Ultrasonic Testing Inspections

Internal Inspection

Internal Inspection

 

From the table we can see how, for typical welded Yankees, the combination of periodic weld inspections and regular internal inspections recommended every 2 years leads to a tight schedule of invasive, expensive and prolonged checks compared to those required for the A.Celli iDEAL® Forged Yankee Dryers. The greatest impact of these interventions is due to the need to completely cool the cylinders for the inspection of the internal welds.

As for the Yankee Dryers of the iDEAL® product family, the staff will have to access them only for the biennial visual inspections typical of all Yankees, while the ultrasound tests are prescribed only for the structural screws which are all located on the outside, and therefore do not require the complete cooling of the cylinder.

Starting from these premises, A.Celli has developed the new generation of iDEAL® Evo-Lock® Yankee Dryers to take a further important evolutionary step also from the point of view of reducing periodic inspections.

In the following table we will associate the different types of inspection and their respective intervals with the typical times necessary for their execution to calculate the total downtime of the Yankee cylinders during the first 12 years of life.


Additional downtime over 12 years

Welded shell and head/shell coupling with structural welds

A.Celli iDEAL® Forged YD 

New A.Celli iDEAL®  Evo-Lock® 

No. of internal inspections

6

6

6

No. of Internal visual weld inspections

9

-

-

No. of Internal / external UT weld inspections

3

-

-

No. of external UT weld inspections (head/shell)

-

-

1

No. of external UT bolt inspections

2

2

2

No. of Yankee Dryer cool downs

12

6

6

       

Time for internal inspections

6 hours

6 hours

6 hours

Time for internal visual welds inspections

4 hours

-

-

Time for internal / external UT welds inspections 

48 hours

-

-

Time for UT bolts inspections

2 hours

6 hours

2 hours

Time to cool / heat the Yankee Dryer

18 hours

18 hours

18 hours

       

Required time for internal inspections in 12 years

6 hours x 6 = 36 hours

6 hours x 6 = 36 hours

6 hours x 6 = 36 hours

Required time for internal visual weld inspections in 12 years

4 hours x 9 = 36

-

-

Required time for internal / external UT welds inspections in 12 years

48 hours x 3 = 144

-

-

Required time for UT bolts inspections in 12 years

2 hours x 2 = 4 hours

6 hours x 2 = 12

2 hours x 2 = 4 hours

Required time for YD cooling in 12 years

18 hours x 12 = 216 hours

18 hours x 6 = 108 hours

18 hours x 6 = 108 hours

Total time required for inspections in 12 years

436 hours

156 hours

148 hours

 

The results clearly show the advantage of A.Celli's Yankee Dryers, in particular the new Evo-Lock® version which, compared to conventional Yankees and the iDEAL® Forged YD, is unmatched in terms of time and costs saved on periodic inspections.

Contact us for more information

If you are looking for a new Yankee Dryer contact us: you will find trained technicians at your disposal to help you choose the best solution for your needs.

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