T24
Parker Hannifin Corporation
Tube Fittings Division
Columbus, Ohio
http://www.parker.com/tfd
4300
Catalog
General Technical
Fitting and Adapter Pressure Ratings
Fitting Pressure Ratings
Pressure ratings shown on the product pages of this catalog
are for dynamic systems. A vast majority of systems where
our fittings are used fall in this category. However, there are
applications, such as hydraulic jacks, where the system
pressure is essentially static once it is pressurized.
For this type of an application the fittings can be used at
higher pressures.
The dynamic and static systems can be defined as follows:
Dynamic:
A system in which the operating pressure
fluctuates, in accordance with load, up to a maximum
pressure limited by the relief valve. In addition, the system
may also experience shocks, vibration and temperature
excursions. Example: A backhoe.
Static:
A system, once pressurized, is essentially free of
pressure fluctuations, shock, vibration and temperature
excursions, with such pressurizations not exceeding 30,000
in the life of the system. Example: A hydraulic jack.
The dynamic pressure ratings are based on a minimum
design factor of 4. In other words, the fitting is capable
of holding a pressure equal to 4 times the rated pressure
before leakage or failure. For static applications, the design
factor can be 3. Hence, the static rating can be determined
by multiplying the dynamic rating by 1.33.
Static pressure rating = 1.33 x Dynamic pressure rating
Example: Static pressure rating for a fitting rated at 6000
psi = 1.33 x 6000 = 8000 psi
Higher (dynamic) Ratings
Some parts are capable of performing at higher pressures
than those shown on the product pages. For information
on higher ratings, contact Tube Fittings Division.
Tubing Pressure Ratings
Using
Tables T20
and
T21,
determine the tube O.D. and
wall thickness 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 T20 and T21 are based
on the severity of service rating “A” (design factor of 4) in
Table T19, and temperature derating factor of 1 in
Table T7
on page T9.
If more severe operating conditions are involved, the values
in
Tables T20
an
d T21
should be multiplied by appropriate
derating factors from Tables T19 and
T7
before determining
the tube O.D. and wall thickness combination. Contact the
Tube Fittings Division when in doubt.
Pressure
Allowable design stress levels and formula used to arrive at
the design pressure values are given in the following chart.
Values i
n Table T7
are for fully annealed tubing.
The design factor is generally applied to ultimate strength of
material (or burst pressure of tubing) to provide a measure
of safety against the unknowns in material and operating
conditions. The derating factors listed here should be
applied directly to the design pressure values in
Tables T20
and
T21 t
o arrive at maximum recommended working
pressures (i.e., multiply values i
n Tables T20
an
d T21 b
y these
derating factors).
Material and Type
Allowable Design
Stress for Factor
of 4 at 72°F
Tube
Specification
Steel C1010
11,250
PSI
SAE J356, J524, J525
Steel C1021
15,000
PSI
SAE J2435, L2467
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 C4130
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
Design Pressure Formula (LAME’S)
P = S
(
d2 - d2
)
where:
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 T17 — Design Stress Values
Table T19 — Severity of Service Design and Derating Factors
Table T18 — Design Pressure Formula
*
For thin wall tubes (D/T = 10) the following formula may be
Used:
P = 2ST/D
Severity
of Service
Description
Design
Factor
Derating
Factor
A (Normal)
Moderate mechanical and
hydraulic shocks.
4.00
1.00
B (Severe)
Severe hydraulic shocks
and mechanical strain.
6.00
0.67
C (Hazardous)
Hazardous application with
severe service conditions.
8.00
0.50
P
Dimensions and pressures for reference only, subject to change.
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