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The 4 Pass Wet Back Boiler
Available in Steam or Hot Water Versions
Ranging from 30 to 1500HP - Pressure to 250 psig.
  • Four-pass wet back design eliminates refractory baffles between flue gas passes.

  • Minimum maintenance with rugged construction for extra-long life.

  • U.L. listed boiler/burner package for firing gas, oil and combination gas/oil
    .
  • Factory tested and checked for optimum operating efficiency.

WET BACK ADVANTAGE

Dry backs are subject to deteriorating rear refractory, leaking baffles, leaking door seals, and often found with a heat-stressed rear tubesheet. Fragile refractory baffling and door seals will require continuous monitoring, maintenance, and replacement, costing thousands of dollars in materials and specialized labor cost over the life of the boiler. In addition, broken baffles and leaking seals will short-circuit boiler efficiency up until repairs can be made, and downtime during repairs can bring your production process to a halt.
All of those frustrating problems have been designed out of the CRG 4 pass wet back Wetback. It has a full wet back radiant heat transfer area that promotes superior internal water circulation and rapid heat absorption. Separate rear tubesheets allow each pass of tubes to expand and contract at its own rate without tube-to-sheet stress.Tubes are mechanically rolled, flared and beaded, making any tube service a simple matter. The only rear refractory is a 18 inch plug which allows access to the furnace for inspection.
STANDARD FEATURES :

Durability
Built in accordance with the ASME Code, the wet back design has proven to give much longer useful life cycles than dry back boilers.

Quality
Each unit is tested and inspected by Hartford and is registered with the National Board of Boiler and Pressure Vessel Inspectors.

Design
State of the art computer design techniques are used in every boiler design. This accounts for accurate calculations of construction materials and optimum utilization of the boiler's performance criteria.

Efficiency
The 4 pass wet back is designed for optimum fuel efficiency and has proven in certified tests to meet and often exceed the efficiencies of 4-pass boilers.

Low Maintenance
There is no refractory rear door, to maintain and no refractory baffles to replace. Elimination of these components results in thousands of dollars of savings.

Tube Sheets
The wet back has independent tube sheets with uniform temperatures. Three and four pass dry back boilers have tube sheets with large temperature variations and this results in premature tube failure and cracks in the tube sheets.

Easy Access
Since there is no large refractory rear door, one man can easily remove the rear cover plates for access to the tubes. Front doors can be opened without removing burner components or controls.

Compact
Computer aided design has made the wet back a space saving workhorse without sacrificing the principle of 5 sq. ft. of heating surface per BHP.

Combustion
CRG uses name brand burner components with proven reliability. Every unit is boiler/burner compatible and tested at the factory prior to shipment.
Standard Steam Trim
Standard Water Trim
  • Operating & limit pressure control
  • Modulating pressure control (when appl )
  • Water column with gauge glass combination low water cutoff& pump control
  • Probe type auxiliary low water cutoff with manual rest
  • Water column drain valve
  • Safety relief valve(s)) per ASME Code
  • Steam Gauge
  • Stack Thermometer
  • Operating & limit temperature control
  • Modulating temperature control (when appl )
  • Low water cutoff control with manual reset
  • Combination pressure, temperature gauge
  • Hot water return baffle for shock resistance
  • Safety relief valve(s)) per ASME Code
  • Stack thermometer

Boiler Specifications
(all dimensions are in inches)

BOILER HORSEPOWER     30 40 50 60 70 80  
HEATING SURFACE FIRESIDE SQ. FT. 150 200 250 300 350 400  
STEAM OUTPUT FROM & @212°F LB/HR 1035 1380 1725 2070 2415 2760  
GROSS OUTPUT MBH 1004 1339 1674 2009 2343 2678  
FIRING RATE, GAS 1,000 BTU/CF CFH 1260 1680 2100 2520 2940 3360  
FIRING RATE, LP GAS 91,500 BTU GPH 13.8 18.4 23 27.5 32 36.7  
FIRING RATE, #2 OIL 140,00O BTU GPH 9 12 15 18 21 24  
FIRING RATE, #5 & #6 OIL 150,000 BTU GPH 8.4 11.2 14 16.8 19.6 22.4  
A *NOTE: 1 STEAM OUTLET SIZE 150 PSI IN 1 ½ 2 2 1/2 2 ½ 3 3 A
A *NOTE: 2 STEAM OUTLET SIZE 15 PSI IN 4 4 4 6 6 6 A
B *NOTE: 2 SUPPLY SIZE 30 PSI IN 4 4 4 6 6 6 B
C *NOTE: 2 RETURN SIZE 30 PSI IN 4 4 4 4 4 4 C
D FEEDWATER CONNECTION IN ¾ ¾ ¾ 1 1 1 ¼ D
E BOTTOM BLOWDOWN SIZE HIGH PRESS. IN 1 1 ¼ 1 ¼ 1 ¼ 1 ¼ 1 ¼ E
E BOTTOM BLOWDOWN SIZE LOW PRESS. & HW IN 1 ¼ 1 ¼ 1 ¼ 1 ½ 1 ½ 1 ½ E
F STACK OUTLET SIZE O.D. IN 10 10 10 12 12 12 F
G FURNACE O.D. IN 14 14 16 18 18 18 G
H SHELL I.D. IN 40 40 44 48 48 48 H
I SUPPLY HEIGHT IN 60 60 64 68 68 68 I
J WIDTH WITHOUT TRIM IN 46 46 50 54 54 54 J
K WIDTH WITH TRIM IN 58 58 62 66 66 66 K
L SKID WIDTH IN 34 34 36 40 40 40 L
M END OF SKID TO FRONT PLATE IN 13 ½ 14 ¼ 15 ¼ 15 ¼ 15 ¼ 21 M
N VESSEL SHELL TO FLOOR IN 12 12 12 12 12 12 N
O SKID LENGTH IN 81 99 102 102 102 114 O
P STACK OUTLET HEIGHT IN 59 59 63 67 67 67 P
Q BLOWDOWN LOCATIONS IN 36 41 32 30 30 30 Q
R STEAM OUT LOCATION (15 PSI & UP) FROM C/L OF STACK IN 38 41 39 ½ 48 48 57 R
S SUPPLY LOCATION FROM FRONT PLATE IN 20 21 33 38 44 33 S
T RETURN LOCATION C/L TO C/L IN 39 54 45 48 48 54 T
U BURNER PROJECTION FROM FRONT PLATE IN 32 32 36 36 39 ½ 39 U
V TUBE REMOVABLE FRONT IN 61 78 81 82 82 94 V
W LENGTH FRONT TO REAR BOILER VESSEL IN 79 96 100 106 106 118 W
X APPROX. OVERALL LENGTH (WITH BURNER) STD. BURNER IN 111 128 136 142 142 158 X
APPROX. SHIPPING WEIGHT 150 PSI IN 3500 4100 4700 6000 6200 7000  
APPROX. SHIPPING WEIGHT 15 & 30 PSI LBS 3400 4000 4500 5700 5900 6200  
WATER CAPACITY @ NWL GAL 215 272 324 378 359 416  
WATER CAPACITY FLOODED GAL 252 3119 382 434 415 479  
BOILER HORSEPOWER - - 30 40 50 60 70 80  

 
BOILER HORSEPOWER 100 125 150 200 250 300 350 400
HEATING SURFACE FIRESIDE SQ. FT. 500 625 750 1000 1250 1500 1750 2000
STEAM OUTPUT FROM & @212°F LB/HR 3450 4313 5175 6900 8625 10350 12075 13800
GROSS OUTPUT MBH 3348 4184 5021 6695 8369 10043 11716 13390
FIRING RATE, GAS 1,000 BTU/CF CFH 4200 5250 6300 8400 10500 12600 14700 16800
FIRING RATE, LP GAS 91,500 BTU GPH 46 57 69 92 115 138 160 184
FIRING RATE, #2 OIL 140,00O BTU GPH 29.9 37.4 45 60 75 90 105 120
FIRING RATE, #5 & #6 OIL 150,000 BTU GPH 28 35 42 56 70 84 98 112
A *NOTE: 1 STEAM OUTLET SIZE 150 PSI IN 4 4 4 4 6 6 6 6 A
A *NOTE: 2 STEAM OUTLET SIZE 15 PSI IN 8 8 8 8 10 10 10 10 A
B *NOTE: 2 SUPPLY SIZE 30 PSI IN 8 8 8 8 10 10 10 10 B
C *NOTE: 2 RETURN SIZE 30 PSI IN 6 6 6 6 8 8 8 8 C
D FEEDWATER CONNECTION IN 1 1/4 1 1/4 1 1/4 1 1/2 1 1/2 2 2 2 D
E BOTTOM BLOWDOWN SIZE HIGH PRESS. IN 1 1/4 1 1/4 1 1/4 1 1/4 1 1/4 1 1/2 1 1/2 1 1/2 E
E BOTTOM BLOWDOWN SIZE LOW PRESS. & HW IN 1 1/2 1 1/2 2 2 2 2 2 2 E
F STACK OUTLET SIZE O.D. IN 14 14 16 16 18 20 20 24 F
G FURNACE OD IN 22 26 26 30 34 34 34 38 G
H SHELL I.D. IN 54 60 60 66 84 84 84 90 H
I SUPPLY HEIGHT IN 74 3/4 81 3/4 81 3/4 90 3/4 109 109 109 115 I
J WIDTH WITHOUT TRIM IN 60 66 1/2 66 1/2 72 1/2 90 3/4 90 3/4 90 3/4 96 1/4 J
K WIDTH WITH TRIM IN 72 79 79 84 103 103 103 106 K
L SKID WIDTH IN 44 48 48 51 64 64 64 70 L
M END OF SKID TO FRONT PLATE IN 21 3/4 25 1/8 25 1/8 21 1/4 28 5/8 28 5/8 34 5/8 30 5/8 M
N VESSEL SHELL TO FLOOR IN 14 15 15 18 18 18 18 18 N
O SKID LENGTH IN 114 132 156 168 180 180 204 198 O
P STACK OUTLET HEIGHT IN 74 3/4 81 3/4 81 3/4 90 3/4 109 109 109 115 P
Q BLOWDOWN LOCATIONS IN 29 3/4-66 32 7/8-78 32 7/8-102 33 7/8-120 35 7/8-120 35 7/8-120 41 7/8-132 47 7/8-126 Q
R STEAM OUT LOCATION (15 PSI & UP) FROM C/L OF STACK IN 56 56 75 79 1/2 70 71 84 94 1/2 R
S SUPPLY LOCATION FROM FRONT PLATE IN 32 3/4 32 32 46 1/2 54 3/4 54 3/4 56 1/4 55 7/8 S
T RETURN LOCATION C/L TO C/L IN 58 70 82 84 90 90 95 92 T
U BURNER PROJECTION FROM FRONT PLATE IN 31 3/8 34 3/4 34 3/4 34 3/4 47 1/2 47 1/2 38 1/4 52 1/4 U
V TUBE REMOVABLE FRONT IN 96 108 132 150 150 150 168 168 V
W LENGTH FRONT TO REAR BOILER VESSEL IN 116 3/8 128 3/8 152 1/4 174 1/4 177 177 195 196 1/2 W
X APPROX. OVERALL LENGTH (WITH BURNER) STD. BURNER IN 148 163 187 209 225 225 233 249 X
Y FACE OF REAR DOORS TO WATER MAKE-UP SUPPLY 15 PSI & UP IN 60 5/8 72 1/2 78 3/8 93 1/2 105 105 110 1/8 103 1/8 Y
APPROX. SHIPPING WEIGHT 150 PSI LBS 8200 10400 11800 16600 25700 27100 30200 32200
APPROX. SHIPPING WEIGHT 15 & 30 PSI LBS 7200 9400 10800 13700 24400 25800 28200 29500
WATER CAPACITY @ NWL GAL 484 676 785 1126 1890 1844 2068 2440
WATER CAPACITY FLOODED GAL 578 788 927 1350 2300 2246 2518 3000
BOILER HORSEPOWER 100 125 150 200 250 300 350 400
BOILER HORSEPOWER 500 600 700 750 800 900 1000 1200 1500
HEATING SURFACE FIRESIDE SQ. FT. 2500 3000 3500 3750 4000 4500 5000 6000 7500
STEAM OUTPUT FROM & @212°F LB/HR 17250 20700 24150 25875 27600 31050 34500 41400 51750
GROSS OUTPUT MBH 16738 200085 23432 25106 26780 30128 33475 40170 50213
FIRING RATE, GAS 1,000 BTU/CF CFH 21000 25200 29400 31500 33600 37800 42000 50400 63000
FIRING RATE, LP GAS 91,500 BTU GPH 230 275 320 344 368 413 460 550 688
FIRING RATE, #2 OIL 140,00O BTU GPH 150 180 210 225 240 270 300 360 450
FIRING RATE, #5 & #6 OIL 150,000 BTU GPH 140 168 196 210 224 252 280 336 420
A *NOTE: 1 STEAM OUTLET SIZE 150 PSI IN 6 8 8 8 8 8 8 10 10 A
A *NOTE: 2 STEAM OUTLET SIZE 15 PSI IN 10 12 12 12 12 14 14 14 14 A
B *NOTE: 2 SUPPLY SIZE 30 PSI IN 10 12 12 12 12 12 12 14 14 B
C *NOTE: 2 RETURN SIZE 30 PSI IN 8 8 10 10 10 12 12 14 14 C
D FEEDWATER CONNECTION IN 2 2 1/2 2 1/2 2 1/2 2 1/2 2 1/2 2 1/2 2 1/2 2 1/2 D
E BOTTOM BLOWDOWN SIZE HIGH PRESS. IN 1 1/2 1 1/2 2 2 2 2 2 2 2 E
E BOTTOM BLOWDOWN SIZE LOW PRESS. & HW IN 2 2 2 2 2 2 2 2 2 1/2 E
F STACK OUTLET SIZE OD IN 24 28 28 28 30 30 30 32 32 F
G FURNACE OD IN 38 44 52 52 52 52 52 56 56 G
H SHELL ID IN 96 102 112 112 112 112 112 126 136 H
I SUPPLY HEIGHT IN 121 127 1/4 138 1/4 138 1/4 138 1/4 138 1/4 138 1/4 152 1/4 162 1/2 I
J WIDTH WITHOUT TRIM IN 102 3/4 108 3/4 119 119 119 119 119 133 1/2 144 J
K WIDTH WITH TRIM IN 115 121 136 136 136 136 136 153 165 K
L SKID WIDTH IN 76 78 92 92 92 92 92 108 114 L
M END OF SKID TO FRONT PLATE IN 31 5/8 62 5/8 35 1/8 34 5/8 36 5/8 50 5/8 64 5/8 61 5/8 59 7/8 M
N VESSEL SHELL TO FLOOR IN 18 18 18 18 18 18 18 18 18 N
O SKID LENGTH IN 212 240 207 218 228 264 288 294 320 O
P STACK OUTLET HEIGHT IN 122 128 1/4 138 1/4 138 1/4 138 1/4 138 1/4 138 1/4 152 1/4 162 1/2 P
Q BLOWDOWN LOCATIONS IN 47 3/8-137 46 7/8-146 51 3/8-126 49 7/8-138 49 7/8-149 50 3/8-169 49 7/8-198 53 7/8-190 57 1/8-214 Q
R STEAM OUT LOCATION (15 PSI & UP) FROM C/L OF STACK IN 98 99 1/2 90 1/2 90 1/2 102 1/2 123 1/8 117 124 1/2 135 R
S SUPPLY LOCATION FROM FRONT PLATE IN 60 3/8 60 51 3/8 51 3/8 51 3/8 78 78 81 65 7/8 S
T RETURN LOCATION C/L TO C/L IN 102 100 89 89 102 102 122 125 180 T
U BURNER PROJECTION FROM FRONT PLATE IN 52 1/4 52 1/4 53 53 66 66 66 63 76 U
V TUBE REMOVABLE FRONT IN 184 191 171 182 193 215 237 237 262 V
W LENGTH FRONT TO REAR BOILER VESSEL IN 214 1/2 223 1/2 208 219 1/2 230 1/2 252 1/2 274 1/2 278 1/2 306 1/2 W
X APPROX. OVERALL LENGTH (WITH BURNER) STD. BURNER IN 267 276 261 273 297 319 341 345 383 X
Y FACE OF REAR DOORS TO WATER MAKE-UP SUPPLY 15 PSI & UP IN 117 5/8 127 1/8 117 5/8 129 1/8 129 1/8 130 1/2 158 5/8 156 1/8 170 5/8 Y
APPROX. SHIPPING WEIGHT 150 PSI LBS 37900 46400 48100 54100 57200 61300 66400 82000 103000
APPROX. SHIPPING WEIGHT 15 & 30 PSI LBS 34400 37400 40100 42500 44900 49700 54600 74000 93000
WATER CAPACITY @ NWL GAL 3243 3313 3092 3307 3537 4013 4401 5865 7743
WATER CAPACITY FLOODED GAL 4004 4076 3940 4204 4486 5071 5530 7295 10069
BOILER HORSEPOWER 500 600 700 750 800 900 1000 1200 1500
(NOTE: 1) 3” & ABOVE ARE 300# ANSI FLANGE
(NOTE: 2) 4” & ABOVE ARE 150# ANSI FLANGE
*NOTE: (U) & (X) dimension subject to change pending burner model
Copyright © CRG Boiler Systems a Div. of C.R.G. Electric, Inc 2002