S9407-AB-HBK-010 Datasheet, PDF (42/276 Pages) Glenair, Inc. – HANDBOOK OF SHIPBOARD ELECTROMAGNETIC SHIELDING PRACTICES

S9407-AB-HBK-010, Rev. 2
b. Prior to cutting Type 2 conduit, cut through the rubber jacket around the conduit with an
appropriate knife at the point where the final cut through the metal is to be made. Peel
back the jacket away from each side of the location of the cut as much as practicable
to avoid damage to the jacket caused by heat from silver-soldering or brazing. Silver-
solder or braze as in step a above. Where brazing is not feasible, the rubber jacket at
the area of the cut should be covered tightly with an appropriate tape during cutting.
c. Cut the conduit squarely with a high speed knife-edge saw or with a hacksaw having a
fine-toothed blade.
d. Snip off any loose strands from the braid, and remove all burrs and sharp edges from
the inner core of the conduit.
3.5.4 Silver Brazing Fittings to Conduit
Flexible metal conduit can be terminated or coupled by certain steel fittings (listed in this
handbook) which are best attached by silver brazing. A silver-base brazing alloy (having 34-36
percent silver), in accordance with Federal Specification WW-B-654, Grade VIII, or equivalent, is
recommended. Either a 1/16-inch or a 1/8-inch diameter rod, determined by conduit size, should be
adequate for all joints. The brazing flux (a white, water-soluble paste), in accordance with Federal
Specification 0-F-499, Type B, or equivalent, is recommended for use with the above-mentioned
brazing rod.
WARNING
Silver-brazing alloy contains cadmium, and poisonous fumes may be
formed on heating. Do not breathe fumes. Use only with an adequate
ventilation device, such as a fume collector, exhaust ventilator, or air-
supplied respirator.
Before silver-brazing, all surfaces to be joined must be cleaned. Wash off all grease and oil
with a good solvent. The flux should be applied evenly with a brush to the contact surfaces of both
the conduit and the fitting.
The oxyacetylene process is preferred for the manual brazing operation, using a neutral to
reducing flame. Apply heat to the fitting, never to the braid, until the flux boils, turns a powdery white,
and then becomes transparent. Filler rod, which can be prefluxed, is then added starting at the
hottest point with the tip of the flame always on the rod or fitting and working around the
circumference. Fitting and conduit should be brazed in a vertical position, where practicable, with the
fitting below the conduit. After a fillet has been made, the torch flame is played on the fitting uniformly
so that the silver braze is drawn into the joint.
After brazing, while the parts are still hot, the flux should be removed by washing in hot water
greater than 125°F (the hotter, the better), wiping with a wet swab, brushing with a wet brush, or
brushing with a wire brush. Thorough drying after flux removal is required.
It should be noted that while silver-brazing is an approved method for flexible metal conduit to
be terminated or coupled, it is not the only method that can be utilized to perform these functions.
Low temperature tin lead soldering is an example of another acceptable method that can be used.
CHANGE 2 of Revision 2
3-10