Steam
Steam System
The underground steam system takes 125 psig, 353F saturated steam from the Central Energy Facility (CEF) and pipes the steam to approximately 200 campus and medical center buildings. Steam usage is metered at each building for billing to our customers; academics, athletics, housing and dining, medical school, and hospitals. At the buildings, the condensed steam is collected and returned to the CEF for reuse in the Cogen Plant and boilers, minimizing water makeup to the system.
Steam is used for space heating, hot water heating, hospital medical equipment sterilizing, dining services, pool heating, dishwashing, and other uses. The 125 psig steam is saturated steam, running at near 99% quality (very low moisture content).
Objectives for a good central steam system include high level of personnel safety, high quality of steam supply (low moisture content), high quality and quantity of condensate return to minimize water makeup at the central plant, low heat loss from steam distribution piping, accurate steam metering, and quick emergency response.
The Steam System group provides engineering, capital project management, operations, maintenance and renewal of the underground steam distribution and condensate return system.
History
Stanford has had a district steam heating system since it opened in 1881. The original boiler plant was located in Building 510 and supplied 35psi steam to the Main Quad. This plant was severely damaged by the 1906 earthquake and was replaced with a new plant on Galvez Street in 1908.
Although the chimney collapsed in the 1906 earthquake, Building 510 survived and now forms the west end of Terman Engineering (Building 500).
The Galvez Street Plant supplied 35psi steam to the campus from 1908 to 1958. This plant was located on the site now occupied by the Frances C. Arrillaga Alumni Center. During this time the underground piping system expanded beyond to the Main Quad to serve buildings such as Old Chemistry, Brown Gymnasium, the Physics Tank and Lagunita. The only remaining visible sign of this plant is a hump in the floor of the Memorial Auditorium shop area. When the Mem Aud was built in 1937, it was built over the existing buried steam main from the Galvez Street Plant to the Main Quad.
Instead of relocating the steam main, the floor of the work area was built with the hump.
In 1958, the campus steam system was converted to 125psig and 353F to provide more efficient service over longer distances. The Galvez St Plant was replaced with a new plant on Jordan Way and this site has provided 125psi steam to the campus and medical center since then. Much of the existing underground steam piping was replaced to accommodate the increased pressure and temperature but some of the original low pressure piping remains in the Main Quad and from Encina Hall to Toyon and Branner. These lines are fed with from the 125psi system through pressure reducing valves.
Steam Shop
For those of us that enjoy a hot shower in the morning, heat when it is cold outside, or a hot cooked meal, "Steam" can be a very important utility. The Steamfitters maintain and operate approximately 25 miles of steam & condensate piping on campus and 150 manholes which contain the valves for system operation. Inside the building mechanical rooms, the steamfitters provide O&M on the steam metering stations, pressure reducing stations, and condensate return systems.
Keys to good steam system performance include a good steam trap and piping insulation program, which minimize heat loss. Steam traps remove condensate from the steam piping to keep the steam quality high by minimizing water carryover to the building systems and to prevent steam induced water hammer in piping. Good insulation on the underground steam piping minimizes the heat loss to the ground and to the steam tunnel air spaces.
Steam equipment maintained and replaced by the steamfitters include: pressure reducing valves, safety relief valves, steam traps, steam meters, and expansion joints. Condensate equipment include: condensate receivers and pumps, strainers, and condensate sample stations. The condensate monitoring system is important for verifying high quality condensate return to the CEF by checking for corrosion rate of the piping systems and indentifying leaking of raw water into the system via leaking building heat exchangers.
Several of the Steamfitters are certified welders to the ASME code which is a requirement for any welding on the steam supply and condensate return carbon steel piping. A certified welder has passed a weld performance test which has been x-rayed and visually inspected for compliance to the ASME power piping code.
Safety is always an important part of the daily work. The work performed by the steam shop is almost always hot, dirty, hazardous and sometimes dangerous. The steam shop technicians receive annual training for confined space entry (manholes & tunnels), asbestos awareness, heat exposure (often well over 100 degrees) and hazard communications.
Steam Tunnels and Steam Manholes (Permit Required Confined Spaces)
Steam tunnels and manholes are used at many universities to carry the hot steam and condensate piping between the central plant and the outlying buildings. Per Cal-OSHA (Occupational Health and Safety Administration), entry into the tunnels and manholes require specific safety devices which include continuous air quality monitoring handhelds, hard hats, permit supervisor, radios, and lifelines.
These spaces are off-limits to the public. Unauthorized entry is a violation and will be addressed immediately by the local enforcement agencies.
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