Title 49, § 393.45
Brake Tubing and Hose Adequacy
(a) General requirements. Brake tubing and brake hose must--
(1) Be designed and constructed in a manner that insures proper,
adequate, and continued functioning of the tubing or hose;
(2) Be installed in a manner that insures proper continued functioning
of the tubing or hose;
(3) Be long and flexible enough to accommodate without damage all
normal motions of the parts to which it is attached;
(4) Be suitably secured against chafing, kinking, or other mechanical
(5) Be installed in a manner that prevents it from contacting the
vehicle's exhaust system or any other source of high temperatures;
(6) Conform to the applicable requirements of paragraph (b) or
(c) of this section.
In addition, all hose installed on and after January 1, 1981,
must conform to those applicable subsections of FMVSS 106 (49 CFR
(b) Special requirements for metallic brake tubing, nonmetallic
brake tubing, coiled nonmetallic brake tubing and brake hose.
(1) Metallic brake tubing, nonmetallic brake tubing, coiled nonmetallic
brake tubing, and brake hose installed on a commercial motor vehicle
on and after March 7, 1989, must meet or exceed one of the following
specifications set forth in the SAE Handbook, 1985 edition:
(i) Metallic Air Brake Tubing--SAE Recommended Practice J1149--
Metallic Air Brake System Tubing and Pipe--July 76.
(ii) Nonmetallic Air Brake Tubing--SAE Recommended Practice J844--
Nonmetallic Air Brake System Type B--OCT 80.
(iii) Air Brake Hose--SAE Recommended Practice J1402--Automotive
Air Brake Hose and Hose Assemblies--JUN 85.
(iv) Hydraulic Brake Hose--SAE Recommended Practice J1401 Road
Vehicle-Hydraulic Brake Hose Assemblies for Use with Non-Petroleum
Base Hydraulic Fluid JUN 85.
(v) Vacuum Brake Hose--SAE Recommended Practice J1403 Vacuum Brake
Hose JUN 85.
(2) Except as provided in paragraph (c) of this section, brake
hose and brake tubing installed on a motor vehicle before March
7, 1989, must conform to 49 CFR 393.45 effective October 31, 1983.
(c) Nonmetallic brake tubing. Coiled nonmetallic brake tubing may
be used for connections between towed and towing vehicles or between
the frame of a towed vehicle and the unsprung subframe of an adjustable
axle of that vehicle if--
(1) The coiled tubing has a straight segment (pigtail) at each
end that is at least 2 inches in length and is encased in a spring
guard or similar device which prevents the tubing from kinking at
the fitting at which it is attached to the vehicle; and
(2) The spring guard or similar device has at least 2 inches of
closed coils or similar surface at its interface with the fitting
and extends at least 1\1/2\ inches into the coiled segment of the
tubing from its straight segment.
(d) Brake tubing and brake hose, uses. Metallic
and nonmetallic brake tubing is intended for use in areas of the
brake system where relative movement in the line is not anticipated.
Brake hose and coiled nonmetallic brake tubing is intended for use
in the brake system where substantial relative movement in the line
is anticipated or the hose/ coiled nonmetallic brake tubing is exposed
to potential tension or impact such as between the frame and axle
in a conventional type suspension system (axle attached to frame
by suspension system). Nonmetallic brake tubing may be used through
an articulation point provided movement is less than 4.5 degrees
in a vertical plane, and 7.4 degrees in a transverse horizontal
Title 49, § 393.46
Brake Tubing and Hose Connections
All connections for air, vacuum, or hydraulic braking systems shall:
(a) Be adequate in material and construction to insure proper continued
(b) Be designed, constructed, and installed so as to insure, when
properly connected, an attachment free of leaks, constrictions,
or other defects;
(c) Have suitable provision in every detachable connection to afford
reasonable assurance against accidental disconnection;
(d) Have the vacuum brake engine manifold connection at least
three- eighths inch in diameter.
(e) If installed on a vehicle on or after January 1, 1981, meet
requirements under applicable subsections of FMVSS 106 (49 CFR 571.106).
(f) Splices in tubing if installed on a vehicle after March 7,
1989, must use fittings that meet the requirements of SAE Standard
J512-OCT 80 Automotive Tube Fittings or for air brake systems SAE
J246--March 81 Spherical and Flanged Sleeve (Compression) Tube Fittings
as found in the SAE Handbook 1985 edition.