be open for the performance of work. Metal caps, plugs, and covers shall
be austenitic stainless steel. Plastic items and tape shall be free of
substances that can have a harmful effect on stainless steel and other
corrosion-resistant metals in the system.
3.2.10
Cleanness Verification Flushes
After installation, check the systems for cleanness by flushing with water.
Perform flushing so that the minimum velocity through any part of the
system is not less than [1.1] [_____] meters [3.6] [_____] feet per second.
Pass flush water through a filter for cleanness evaluation. Filter
element shall be corrosion-resistant wire cloth with mesh size conforming
to ASTM E 11, No. 20 (850 micrometers), No. 25 (710 micrometers), or No. 30
(600 micrometers). Filter area shall be sufficient to limit pressure drop
so that required flushing velocity can be attained.
3.2.10.1
Flush Acceptance Criteria
**************************************************************************
NOTE: Select flush acceptance criteria based on how
critical the system is and the volume of system to
be flushed. More particles may be expected and may
be acceptable in larger systems.
**************************************************************************
The system shall be flushed until there is no more than [slight speckling]
[[0.1] [0.5] [_____] cubic centimeters] of particulates on the filter
screen. There shall be no particles larger than 0.79 by 1.59 mm 1/32 by
1/16 inch long. The flush water shall show no visual evidence of
contamination such as oil particles, discoloration, or iridescent surface
film characteristic of oil.
3.2.10.2
Recleaning of Systems
Systems which fail to meet acceptance flush criteria after flushing for
more than 4 hours shall be recleaned by the Contractor at no additional
cost to the Government. Prepare recleaning procedures and submit to the
Contracting Officer for approval. Remove instruments, components, and any
other items that may be damaged by recleaning. Perform recleaning by
flushing with hot water at not less than 60 degrees C 140 degrees F.
3.3
CLEANING SILVERBRAZED PIPING
**************************************************************************
NOTE: All silverbrazed piping, including low
pressure systems, should be cleaned to preclude
corrosion from residual brazing flux.
**************************************************************************
Clean silverbrazed piping to remove residual flux remaining in the system
after fabrication. Use one of the procedures below. The hot flush and hot
recirculating flush are preferred. Minimum flow rate through any part of
the system in liters gallons per second minute shall be 0.0037 1.5 times
the inside diameter of the pipe in mm inches. For any flushing method
used, the system shall be full of water so that joints are completely
submerged at all times.
SECTION 15212N
Page 45
Previous Page
