1. Drums and Headers Make up the highest and lowest parts of the water and steam containing elements in the boiler

2. Steam Drums Function to accumulate the steam generated in the tubes and to provide a space for the separation of moisture from the steam before the steam leaves the boiler Function to provide reservoir for the water required for proper operation of the boiler Function to receive and distribute to the downcomers the feedwater required for the generation of steam

3. Water Drums Function to distribute water to the generating tubes Function to provide a receptacle for the accumulation of scale and other solid matter which may be present in or precipitate from the boiler water

4. Drums Components of the Drum  Wrapper Sheet (upper sheet of the steam drum and lower sheet of the water drum)  Tube Sheet (lower sheet of the steam drum and upper sheet of the water sheet)  Drum Heads (welded to the ends of the drum and contains manhole covers for access to the drum)

5. Drums Steam Drum Inside Diameter 54” Shell Length 10’ 8” Thickness of Tube Sheet 4 11/16” Thickness of Wrapper Sheet 1 ½” Water Drum Inside Diameter 32” Shell Length 10’ 6 1/4” Thickness of Tube Sheet 2 13/16” Thickness of Wrapper Sheet 1”

6. Drums The boiler drums are constructed from a high temperature steel alloy. The boiler drums are constructed from a high temperature steel alloy. Most drums are formed of two sheets of alloy steel which is rolled into a semi-circular shape. Most drums are formed of two sheets of alloy steel which is rolled into a semi-circular shape. The lower sheet of the steam drums and the upper sheet of the water drums are called the tube sheets. The lower sheet of the steam drums and the upper sheet of the water drums are called the tube sheets. These are rolled with an increase thickness to provide extra strength where the holes are drilled for the insertion of the generating tubes.

7. Drums The other half of the drum is called the wrapper sheet. The other half of the drum is called the wrapper sheet. The ends of the drums (drum head) and headers are formed by forging. The ends of the drums (drum head) and headers are formed by forging. The drum head has a central manhole to permit access for inspection, cleaning or repair. The drum head has a central manhole to permit access for inspection, cleaning or repair. These access openings are closed in while the boiler is in service by means of a manhole. These access openings are closed in while the boiler is in service by means of a manhole.

8. Drums The wrapper, tube and drum heads are joined together by robotic electric arc welding. The wrapper, tube and drum heads are joined together by robotic electric arc welding. Next the nozzles for the various fittings are hand welded. Next the nozzles for the various fittings are hand welded. The drum is then given a radiographic (X-ray) examination for welding defects. The drum is then given a radiographic (X-ray) examination for welding defects. The drum then treated in an annealing furnace to relieve stresses incurred during the various fabrication operations. The drum then treated in an annealing furnace to relieve stresses incurred during the various fabrication operations.

9. Drums After the annealing process is completed, a hydrostatic pressure test is made at one and one half times the design pressure of the boiler (MAWP – Mean Allowable Working Pressure). After the annealing process is completed, a hydrostatic pressure test is made at one and one half times the design pressure of the boiler (MAWP – Mean Allowable Working Pressure). If a defect in a weld appears it must be ground out and be rewelded. If a defect in a weld appears it must be ground out and be rewelded. The weld must then be X-rayed again, heat treated and pressure tested once more. The weld must then be X-rayed again, heat treated and pressure tested once more.

10. Drums The holes for the tubes are then drilled with special jig to obtain accurate alignment of holes. The holes for the tubes are then drilled with special jig to obtain accurate alignment of holes. After the holes are drilled, the is then reamed out to ensure the hole is circular as possible After the holes are drilled, the is then reamed out to ensure the hole is circular as possible

11. Drums

12. Drums Wrapper Sheet Tube Sheet Steam Drum Water Drum Wrapper Sheet Tube Sheet

13. Drums Manhole Plate Manhole Opening

14. Drums Drums Why is the steam drum a larger diameter then the water drum? Why is the steam drum a larger diameter then the water drum?

15. Drums The steam drum contains a number of drum internals where the water drum may only contain a desuperheater. The steam drum contains a number of drum internals where the water drum may only contain a desuperheater. The steam drum contains both water and steam where the water drum only contains water

16. Drums Lets look at a 600 psia boiler. Lets look at a 600 psia boiler. The specific volume of water at 600 psig is ν f = 0.02013 ft 3 /lbm The specific volume of water at 600 psig is ν f = 0.02013 ft 3 /lbm The specific volume of steam at 600 psig is ν g = 0.70843 ft 3 /lbm The specific volume of steam at 600 psig is ν g = 0.70843 ft 3 /lbm The expansion ratio is 35.19 to 1 The expansion ratio is 35.19 to 1

17. Headers In some boilers headers are used instead of water drums. The header serves the same function as the water drum. In general a drum is large enough so that it can be entered by a man thru the manhole

18. Headers A header is smaller and access is provided by means of hand holes and hand hole plates located throughout the length of the header, so that the tubes can be inspected, cleaned and maintained, as necessary

19. Type of Headers Box type headers Box type headers Sinuous type headers Sinuous type headers Circular type headers Circular type headers

20. Headers Headers are usually used with: Waterwall Tubes Waterwall Tubes Superheater Tubes Superheater Tubes Economizer Tubes Economizer Tubes

21. Headers Waterwall Tube Downcomer

22. Headers Handhole Opening Handhole Plate Gasket Seating Surface

23. Headers Dog Spiral Wound Gasket