Page 401 - Reciprocating Compressors Operation Maintenance

386 Reciprocating Compressors: Operation and Maintenance

TEMPERATURE EFFECT ON PRESSURE RATING

OL
UJ

20 40 60 80 100

RATED WORKING PRESSURE, PERCENT
FIGURE 7-3. The effect of temperature on pressure rating of plastic piping.

"Plastic polyvinyl chloride (PVC) cannot be used in compressed air
piping systems without the risk of explosion," warns the Washington
State Department of Labor & Industries (L&I) in a Hazard Alert bulletin
issued several years ago.
The bulletin states that when PVC piping explodes, plastic shrapnel is
thrown in all directions. Paul Merrill, senior safety inspector in L&Fs
Spokane office, is quoted: "We're seeing more incidents of explosive
failure, and we're citing more employers for using PVC air system pip-
ing. It's probably just a matter of time before someone gets seriously
injured in one of these explosions unless everyone pays more attention to
the manufacturer's warnings."
In Washington, according to the bulletin, a section of PVC pipe being
used for compressed air exploded 27 ft above a warehouse floor. A frag-
ment of the pipe flew 60 ft and embedded itself in a roll of paper. Fortu-
nately, nobody was in the area at the time. In another incident, a PVC
pipe explosion in a new plant in Selah, WA, broke an employee's nose
and cut his face. In a Yakima, WA, incident, PVC piping buried 3 ft
underground exploded, opening up a crater 4 ft by 3 ft.