Hydrocarbon Processing - March 2022 - 65

Plant Design,
Engineering,
Construction and
Commissioning
M. AL-HAMAIDI and M. MULLA,
Saudi Aramco, Dhahran, Saudi Arabia
Utilize heavy-duty cable tray systems
to improve cable tray designs
This article presents a novel design
concept that utilizes a heavy-duty cable
tray system to optimize cable tray design,
procurement and construction. Typically,
cable tray designs follow the examples
mentioned in National Electrical Manufacturers
Association (NEMA) standards.
In Saudi Aramco's Tanajib Gas Plant project,
a full report for the cable tray and
structural steel design-containing detailed
design calculations, shop tests witnessed
by an outside inspection agency
and simulations prepared by Wescosa-
was conducted to prove the compliance of
the heavy-duty cable tray system with all
applicable standard requirements.
One of the difficulties that many oil
and gas projects face is the demand for
power, which leads to a significant number
of cables. In Saudi Aramco projects,
the preferred installation method for cables
is utilizing aboveground cable trays to
enhance the safety, reliability and maintenance
requirements. Therefore, aluminum
cable trays are the ideal option for
projects that require properly designed
pipe rack and cable tray supports.
Utilizing heavy-duty cable tray systems
will significantly optimize the
quantity of supports
required for the
cable tray without affecting the quality,
reliability and safety of the facility. This
will also eliminate the difficulties of the
design and installation, especially in
congested areas where multiple curves
and levels coincide. Moreover, this will
improve the project schedule related to
material delivery and installation.
TABLE 1. Horizontal bend fitting-Nominal data
Safe working
load (SWL)
149 kg/m
Total length of
mid-line fitting, Lm
3,571.8 mm (3.5718 m)
Width of cable
tray fitting, w
900 mm (0.9 m)
TABLE 2. Horizontal bend fitting-Mid-span deflection results
Mid-span deflection
Point R
At Load Q
At Load Q1.7
13.63 mm 41.99 mm
15.78 mm 52.62 mm
Point T Average, (R+T)/2 Required, (Lm/100)
27.81 mm
34.2 mm
Remarks
≤ 35.7 mm (no damage) Passed
No collapse
Passed
TABLE 3. Horizontal bend fitting-Transverse deflection results
Transverse deflection
Point S
At Load Q
At Load Q1.7
28.48 mm
35.52 mm
Transverse, S-average Required, (w)/20
≤ 45 mm (no damage)
No collapse
0.67 mm
1.32 mm
The NEMA VE 2 standard addresses
the shipping, handling, storing and
installation of cable tray systems. This
article will demonstrate the comparison
between the typical NEMA VE 2
design and the improved design according
to the manufacturer's recommendation,
which utilizes the application of a
heavy-duty cable tray system based on
horizontal 6-m cable trays with heavyduty
joint connectors and heavy-duty
expansion joint connectors. In addition,
the system includes heavy-duty horizontal
bend fittings, heavy-duty horizontal
tee fittings and heavy-duty horizontal
cross fittings.
Remarks
Passed
Passed
NEMA VE 2 design. The following details
NEMA VE 2 requirements:
* The expansion joint connector
should have two supports located
within 600 mm (2 ft) on each side.
* The horizontal bend fitting should
have one support located in the
center of the fitting and two
supports within 600 mm (2 ft)
of each fitting's edge.
* The horizontal cross fitting should
have four supports under each
side rail and four supports within
600 mm (2 ft) of each fitting's edge.
* The horizontal tee fitting should
have three supports under each
Hydrocarbon Processing | MARCH 2022 65
Load Q
532.2 kg
Load Q1.7
907.74 kg
Hydrocarbon Processing - March 2022

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