Chemical Engineering September 2015 - 71

equation for achieving successful
and superior results.
n
Edited by Gerald Ondrey
References
1. American Petroleum Institute, " Pressure-relieving and Depressuring
Systems, " ANSI/API Standard 521, 5th ed.,
January 2007.
2. Kim, J. S., Dunsheath, H. J., and Singh, N. R., " Sizing
Calculations for Pressure-Relief Valves, " Chem. Eng. February
2013, pp. 35-39.
3. Center for Chemical Process Safety (CCPS), " Guidelines
for Pressure Relief and Effluent Handling Systems, " AIChE,
New York, N.Y., 1998.
4. Darby, R., Size Safety-Relief Valves for Any Conditions,
Chem. Eng., September 2005, pp. 42-50.
Final remarks
The universal equation for pipe
flows, Equation (8), which is based
on a homogenous equilibrium model
and a Newtonian flow behavior, is
simple and useful for designing piping
systems as demonstrated in the
example calculations. However, as
with other general pipe-flow equations,
the universal equation cannot
be applied to non-equilibrium situations
and sub-cooled flashing flow
and special handling fluids, such as
slurries and non-Newtonian fluids.
" The universal equation for
pipe flows presented here
is simple and useful for
designing piping systems
as demonstrated in the
example calculations. "
This article also examined the
existing calculation procedures to
develop a new procedure that is
convenient and easy to follow as
demonstrated in the example calculations.
In those cases with significant
velocity changes, it is possible
that the universal equation based on
isenthalpic flash may deviate from
the actual flow path. It is well known
that the actual pipe flow path is
somewhere between isentropic and
isenthalpic flow paths. Therefore, the
authors are currently developing the
calculation procedure for the actual
flow path. In the meantime, the universal
equation for pipe flows presented
in this article can help design
engineers complete their assigned
tasks with a better understanding
of the key parameters in pipe-flow
equations, and even manipulate the
5. Simpson, L. L., Navigating the Two-Phase Maze, International
Symposium on Runaway Reactions and Pressure
Relief Design, A. Melhem and H. G. Fisher, eds., Design
Institute for Emergency Relief Systems (DIERS), AIChE,
New York, meeting held in Boston, Mass., August 1995,
pp. 394-417.
6. Leung, J. C., Easily Size Relief Devices and Piping for
Two-Phase Flow, Chem. Eng. Progress, December 1996,
pp. 28-50.
7. Crowl, D. A. and Louvar, J. F., " Chemical Process Safety:
Fundamentals with Applications, " Prentice Hall, Englewood
Cliffs, NJ (1990).
8. Kim, J. S. and Singh, N. R., A Novel Adiabatic Pipe Flow
Equation for Ideal Gases, ASME Trans. J. of Fluids Engineering,
January 2012.
9. Kim, J. S. and Singh, N. R., A Novel Equation for Isothermal
Pipe Flow, " Chem. Eng., June 2012, pp. 66-70.
Authors
Jung Seob Kim is a principal process
engineer at SK E&C USA Inc.
(1430 Enclave Parkway Suite 150,
Houston, TX 77077; Phone: 281258-2619;
Email: jkim3@sk.com)
where he is responsible for designing
petrochemical and petroleumrefinery
plants. He has more than
30 years of experience in different
roles with the petrochemical process industry including
with Bayer Technology Services, Samsung BP Chemicals
and Samsung Engineering. He holds a B.S.Ch.E. from the
University of Seoul, is a member of AIChE, and is a registered
professional engineer in the state of Texas.
Heather Jean Dunsheath is a
process safety specialist at Covestro
LLC (8500 West Bay Road MS
21, Baytown, TX 77523; Phone:
281-383-6879; Email: heather.
dunsheath@covestro.com) where
she has more than nine years of
experience designing emergency
relief systems and facilitating process
hazard analysis studies. She
holds a B.S.Ch.E. from Rice University.
Taek Kyoung Oh is a junior process
engineer at SK E&C (SK G.Plant,
100 Euljiro Jugn-gu, Seoul 100847,
South Korea; Phone: +82-23771-5431;
email: Asha@sk.com)
where he has experience with process
design, process modeling, utility
services and emergency relief
system design. He holds a B.S.Ch.E.
from Chung-Ang University.
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