(4) Check completed brazed joint for a complete ring of brazing
alloy between the outside surface of the pipe and the face of the
fitting, and for a visible fillet.
(5) Check stainless steel and other susceptible material for
evidence of stress cracks. Check inside of joint if possible with
borescope or other aids.
b.
Nondestructive Examination
For high pressure compressed air systems, any fitting, copper-nickel pipe,
or stainless steel tubing which is reused after unsweating a brazed joint
shall be liquid penetrant examined for cracks. Any crack detected shall be
cause for rejection of the fitting or pipe. Liquid penetrant examination
shall be performed by qualified personnel.
c.
Repair of Brazed Joints
Defective joints may be repaired. However, no more than two attempts to
repair by reheating and additional face feeding of brazing filler metal
will be permitted, after which the defective joint shall be unsweated,
reprepared as a new joint, examined for defects on pipe and fittings, and
rebrazed. Perform required NDE.
3.4.2
Testing
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NOTE: If air (pressure) drop tests are used for
system acceptance, assure that leakages at
acceptable rates through valves (or other
components) are not causing pressure drop. Most
hard-seated valves have some allowable leakage rate
(about 10 cubic centimeters 0.0026 gal per hour of
water per 25 mm one inch valve size or 3 liters per
hour 0.1 cubic feet per hourof gas per 25 mm one inch
of valve size). Delete check for cross-connection
if only one type of system is involved in project.
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3.4.2.1
General Requirements, Testing
Perform testing after cleaning and acceptance of cleanness. Contractor
shall provide everything required for tests. Tests shall be subject to the
approval of the Contracting Officer. Calibrate the test pressure gage with
a dead weight tester within [15] [_____] days before use and certify by
initial and date on a sticker applied to dial face. [Pressurize each
piping system individually and check to assure that there are no
cross-connections between different systems prior to hydrostatic and
a.
Supervision of Testing
For [high] [and] [medium] pressure system, an experienced registered
professional engineer responsible for safety and employed by the Contractor
shall be present during testing.
3.4.2.2
Hydrostatic and Leak Tightness Tests
a.
Preliminary Preparation
SECTION 15212N
Page 48
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