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4300 Catalog General Technical
U15 Parker Hannifin Corporation
Tube Fittings Division
Columbus, Ohio
http://www.parker.com/tfd
Dimensions and pressures for reference only, subject to change.
Step 2: Determine Tube O.D. and Wall Thickness
UsingTablesU15 and U16,determine the tubeO.D.andwall thick-
ness combination that satisfies the following two conditions:
A. Has recommended design pressure equal to or higher
than maximum operating pressure.
B. Provides tube I.D. equal to or greater than required flow
diameter determined earlier.
Design pressure values in Tables U15 and U16 are based on the
severity of service rating “A” (design factor of 4) in Table U10,
and temperature derating factor of 1 in Table U11.
If more severe operating conditions are involved, the values in
TablesU15 and U16 s houldbemultipliedby appropriatederating
factors from Tables U10 and U11 before determining the tube
O.D. and wall thickness combination. Contact the Tube Fittings
Division when in doubt.
Allowable design stress levels and formula used to arrive at the
design pressure values are given in the following chart. Values
in Table U8 are for fully annealed tubing.
Table U8 — Design Stress Values
Design Pressure Formula (LAME’S)
D2 - d2
D2 + d2
D = Outside diameter of tube, in
d = Inside diameter of tube (D-2T), in
P = Recommended design pressure, psi
S = Allowable stress for design factor of 4, psi
T = Tube wall thickness, in.
Table U9 — Design Pressure Formula
For thin wall tubes (D/T = 10) the following formula may be
Used: P = 2ST/D
Determining Tube Size
for Hydraulic Systems
Proper tube material, type and size for a given application and
type of fitting is critical for efficient and trouble free operation of
the fluid system. Selection of proper tubing involves choosing
the right tube material, and determining the optimum tube size
(O.D. and wall thickness).
Proper sizing of the tube for various parts of a hydraulic system
results in an optimum combination of efficient and cost effective
performance.
A tube that is too small causes high fluid velocity, which has
many detrimental effects. In suction lines, it causes cavitation
which starves and damages pumps. In pressure lines, it causes
high friction losses and turbulence, both resulting in high pres-
sure drops and heat generation. High heat accelerates wear in
moving parts and rapid aging of seals and hoses, all resulting
in reduced component life. High heat generation also means
wasted energy, and hence, low efficiency.
Too large of a tube increases system cost. Thus, optimum tube
sizing is very critical. The following is a simple procedure for
sizing the tubes.
Step 1: Determine Required Flow Diameter
Use Tables U13 and U14 to determine recommended flow
diameter for the required flow rate and type of line.
The table is based on the following recommended flow veloci-
ties:
Pressure lines — 25 ft./sec. or 7.62 meters/sec.
Return lines — 10 ft./sec. or 3.05 meters/sec.
Suction lines — 4 ft./sec. or 1.22 meters/sec.
If you desire to use different velocities than the above, use one
of the following formulae todetermine the required flowdiameter.
OR
Tube I.D. (in.) = 0.64
Flow in GPM
Velocity in ft./sec.
Tube I.D. (mm) = 4.61 Flow in liters per minute
Velocity in meters/sec.
P = S ( ) where:
Material
and Type
Allowable Design
Stress fo Design
Factor of 4 at 72°F
Tube
Specification
Steel C-1010 12,500 PSI SAE J356, J524,
J525
Steel C-1021 15,000 PSI SAE J2435,
J2467
Steel, High
Strength Low Alloy
(HSLA)
18,000 PSI SAE J2613,
J2614
Stainless Steel
304 & 316 18,800 PSI ASTM A213,
A249, A269
Alloy Steel C-4130 18,800 PSI ASTM A519
Copper, K or Y 6,000 PSI SAE J528,
ASTM B75
Aluminum 6061-T6 10,500 PSI ASTM B210
Monel, 400 17,500 PSI ASTM B165