B-1 · boiler
Boiler #1
Johnston packaged firetube Scotch Marine — H-3124 / NB 6456.
- Tier
- 1
- Consequence
- 4 CONFIRMED
- Probability
- —
- Risk
- —
- Scored
- 2026-10-24
- Consequence note
- B-2. Seasonal backup: 2nd boiler normally needed only below 0 F outside, depending on indoor RH. Losing one still hits the indoor environment hard, so 4 (Tier 1 floor).
Identity
- Manufacturer
- Johnston Boiler Company, Ferrysburg, MI
- Type
- Firetube Scotch Marine, packaged
- Unit tag
- 221-4C
- S.O. / serial
- 7408 #1 / H-3124
- National Board
- 6456
- Built
- 1977, ASME IV (1974)
- MAWP
- 15 psi steam / 30 psi water (15S/30W)
Pressure vessel
- Shell
- 78" dia × 100.5" long, SA285C 3/8"
- Heads / tubesheet
- SA285C 9/16"
- Furnace
- 28⅜" ID × 79½" Morrison, SA285C 5/16"
- Tubes
- 258 × SA178, 2" OD, gage 13
- Heating surface
- 1,000 ft² (≈200 BHP)
- Hydro test
- 60 psi
Water content
- Flooded (derived)
- ≈ 1,475 gal
- Normal operating
- ≈ 1,200 gal
Burner / motors
- Blower motor
- Baldor 7.5 HP, 3450 rpm, 184T
- Compressor motor
- Baldor 1.5 HP, 1725 rpm, 145T
- Blower
- Johnston R1075-40
- Compressor
- Quincy BK45
- Nozzle
- Delavan 30615-28
- Programmer
- Fireye 26CF6 / scanner 48PT2
Safety / trim
- Safety valve
- Kunkle 930, 2", set 15#
- Steam outlet
- 1×8" 150#
- Feed
- 1½" + 4" return nipple