Hydrocarbon Processing - April 2022 - 23

Special Focus Maintenance and Reliability
M. PARADIES, System Improvements Inc.,
Knoxville, Tennessee; and H. P. BLOCH,
Process Machinery Consulting, Montgomery, Texas
Use straightforward troubleshooting
and failure analysis to benefit the HPI
To operate reliably and profitably, oil
to build substandard levies and flawed
refineries, petrochemical plants and gas
processing facilities must avoid equipment
failures. In the event such failures
occur, the plant must find and remedy
the root causes of these failures. Bestin-class
facilities are reaching and maintaining
this enviable status by pursuing
repeatable failure analysis and troubleshooting
(FA/TS). Guesses are rarely
correct: they can lead to costly and even
dangerous fixes. By their very nature,
mere brainstorming sessions lack structure
and timely, tangible results.
Experience shows that troubleshooting
and failure analysis activities will terminate
in only three possibilities:
* The failure cause is determined
and removed from the inventory of
future failure possibilities
* The failure cause is not found, and
a recurrence is likely
* The failure cause is found but not
disclosed to parties interested in
doing anything about it.
Reliability professionals agree that
discovery and permanent remedial action
of the true root cause of a failure is
the only correct course of action. These
reliability-focused professionals will
readily agree that inaccurate troubleshooting
leads to incorrect conclusions
and wasted time. Because the analyst
or troubleshooter is under pressure to
do something, tinkering at the fringes of
procedural changes or design modifications
is quite common. Moreover, hiding
behind claims that a failure is an " act of
God " is common, albeit inappropriate.
The Almighty may permit that a city built
below sea level is damaged by a flood after
the levies break and the pumps fail,
but the Almighty did not ask the people
pumping equipment. The chain of events
always originates or leads to decisions
and indecisions, actions and/or inaction
by humans who, finally, are nowhere near
as perfect as they would have us believe.
Reasons to improve troubleshooting
methods. Of course, nothing devised by
man is perfect, nor will it ever be. Problems
of one kind or another will always
exist. In other words, troubles must be
identified and remedied. Regrettably,
troubleshooting is usually done after a
problem surfaces. Suppose there was a
time when the sugar cane crop failed, and
the landowner attributed the problem
to the sugar cane worm. Since pesticides
had not yet been invented, he countered
the threat with imported beetles that ate
sugar cane worms. When the beetles took
over, he imported ugly beetle-eating toads
which, unbeknownst to him, preferred
to decimate his previously profitable tobacco
leaf crop. This made him decide to
import Genovese disease-carrying rats as
the cure. These rats failed to do the job,
but by the time he considered red foxes as
the problem solvers, he realized that the
red fox recommendation came from gentrified
landowners whose ulterior motive
was nothing but hunting foxes.
While some of the above is indeed a
bit far-fetched, there is also a measure of
truth in it. It pays to consider the message:
Do not tackle serious problems with temporary
fixes. Recommend solutions that
are backed up by both data and science.
Try not to endorse remedies that have unintended
consequences or run counter to
the satisfactory experience record of others.
Therefore, investigate or pay attention
to others and try to learn from them.
A few fundamental facts are usually
recognized and accepted by the leaders
of modern industry: inadequate troubleshooting
leads to higher costs, wasted
time and makes the company's troubleshooting
team look unprofessional. Because
we, the co-authors, have made our
living as troubleshooters,
allow us to
make use of these facts in demonstrating
simple examples of solving randomly occurring
process pump problems that can
be tackled by using course content that
combines1
several proven approachesa
.
THE SEVEN ROOT-CAUSE
FAILURE ANALYSIS
Collecting a large failure mode inventory
while realizing that such an inventory
will differ for different machines and their
components makes considerable sense.
Examining this inventory and conducting
a structured review of data observed during
and after a failure makes it possible to
draw conclusions as to the failure's origin.
The reviewer or failure analyst should
concentrate on deviations from proper
design, component function, appropriate
coatings, and many other factors.
However, generalities that lead to a
so-called " shotgun approach " must be
avoided. In shotgun-style failure analysis
and troubleshooting, much time is often
wasted on debates that lack both focus
and value. There will then be a trend towards
verbalizing scenarios that are a mix
of the probable and highly improbable,
the reasonable and unreasonable, the
often observed and perhaps things that
have never happened since Leonardo
sketched a helicopter for tentative future
use by Igor Sikorsky. Do not disregard
everything that happened in the 440-yr
span between those two inventors. NevHydrocarbon
Processing | APRIL 2022 23

Hydrocarbon Processing - April 2022

Table of Contents for the Digital Edition of Hydrocarbon Processing - April 2022

Contents
Hydrocarbon Processing - April 2022 - Cover1
Hydrocarbon Processing - April 2022 - Cover2
Hydrocarbon Processing - April 2022 - Contents
Hydrocarbon Processing - April 2022 - 4
Hydrocarbon Processing - April 2022 - 5
Hydrocarbon Processing - April 2022 - 6
Hydrocarbon Processing - April 2022 - 7
Hydrocarbon Processing - April 2022 - 8
Hydrocarbon Processing - April 2022 - 9
Hydrocarbon Processing - April 2022 - 10
Hydrocarbon Processing - April 2022 - 11
Hydrocarbon Processing - April 2022 - 12
Hydrocarbon Processing - April 2022 - 13
Hydrocarbon Processing - April 2022 - 14
Hydrocarbon Processing - April 2022 - 15
Hydrocarbon Processing - April 2022 - 16
Hydrocarbon Processing - April 2022 - 17
Hydrocarbon Processing - April 2022 - 18
Hydrocarbon Processing - April 2022 - 19
Hydrocarbon Processing - April 2022 - 20
Hydrocarbon Processing - April 2022 - 21
Hydrocarbon Processing - April 2022 - 22
Hydrocarbon Processing - April 2022 - 23
Hydrocarbon Processing - April 2022 - 24
Hydrocarbon Processing - April 2022 - 25
Hydrocarbon Processing - April 2022 - 26
Hydrocarbon Processing - April 2022 - 27
Hydrocarbon Processing - April 2022 - 28
Hydrocarbon Processing - April 2022 - 29
Hydrocarbon Processing - April 2022 - 30
Hydrocarbon Processing - April 2022 - 31
Hydrocarbon Processing - April 2022 - 32
Hydrocarbon Processing - April 2022 - 33
Hydrocarbon Processing - April 2022 - 34
Hydrocarbon Processing - April 2022 - 35
Hydrocarbon Processing - April 2022 - 36
Hydrocarbon Processing - April 2022 - 37
Hydrocarbon Processing - April 2022 - 38
Hydrocarbon Processing - April 2022 - 39
Hydrocarbon Processing - April 2022 - 40
Hydrocarbon Processing - April 2022 - 41
Hydrocarbon Processing - April 2022 - 42
Hydrocarbon Processing - April 2022 - 43
Hydrocarbon Processing - April 2022 - 44
Hydrocarbon Processing - April 2022 - 45
Hydrocarbon Processing - April 2022 - 46
Hydrocarbon Processing - April 2022 - 47
Hydrocarbon Processing - April 2022 - 48
Hydrocarbon Processing - April 2022 - 49
Hydrocarbon Processing - April 2022 - 50
Hydrocarbon Processing - April 2022 - 51
Hydrocarbon Processing - April 2022 - 52
Hydrocarbon Processing - April 2022 - 53
Hydrocarbon Processing - April 2022 - 54
Hydrocarbon Processing - April 2022 - 55
Hydrocarbon Processing - April 2022 - 56
Hydrocarbon Processing - April 2022 - 57
Hydrocarbon Processing - April 2022 - 58
Hydrocarbon Processing - April 2022 - 59
Hydrocarbon Processing - April 2022 - 60
Hydrocarbon Processing - April 2022 - 61
Hydrocarbon Processing - April 2022 - 62
Hydrocarbon Processing - April 2022 - 63
Hydrocarbon Processing - April 2022 - 64
Hydrocarbon Processing - April 2022 - 65
Hydrocarbon Processing - April 2022 - 66
Hydrocarbon Processing - April 2022 - 67
Hydrocarbon Processing - April 2022 - 68
Hydrocarbon Processing - April 2022 - 69
Hydrocarbon Processing - April 2022 - 70
Hydrocarbon Processing - April 2022 - 71
Hydrocarbon Processing - April 2022 - 72
Hydrocarbon Processing - April 2022 - 73
Hydrocarbon Processing - April 2022 - 74
Hydrocarbon Processing - April 2022 - 75
Hydrocarbon Processing - April 2022 - 76
Hydrocarbon Processing - April 2022 - 77
Hydrocarbon Processing - April 2022 - 78
Hydrocarbon Processing - April 2022 - 79
Hydrocarbon Processing - April 2022 - 80
Hydrocarbon Processing - April 2022 - 81
Hydrocarbon Processing - April 2022 - 82
Hydrocarbon Processing - April 2022 - 83
Hydrocarbon Processing - April 2022 - 84
Hydrocarbon Processing - April 2022 - 85
Hydrocarbon Processing - April 2022 - 86
Hydrocarbon Processing - April 2022 - 87
Hydrocarbon Processing - April 2022 - 88
Hydrocarbon Processing - April 2022 - 88A
Hydrocarbon Processing - April 2022 - 88B
Hydrocarbon Processing - April 2022 - 89
Hydrocarbon Processing - April 2022 - 90
Hydrocarbon Processing - April 2022 - Cover3
Hydrocarbon Processing - April 2022 - Cover4
Hydrocarbon Processing - April 2022 - GP-1
Hydrocarbon Processing - April 2022 - GP-2
Hydrocarbon Processing - April 2022 - GP-3
Hydrocarbon Processing - April 2022 - GP-4
Hydrocarbon Processing - April 2022 - GP-5
Hydrocarbon Processing - April 2022 - GP-6
Hydrocarbon Processing - April 2022 - GP-7
Hydrocarbon Processing - April 2022 - GP-8
Hydrocarbon Processing - April 2022 - GP-9
Hydrocarbon Processing - April 2022 - GP-10
Hydrocarbon Processing - April 2022 - GP-11
Hydrocarbon Processing - April 2022 - GP-12
Hydrocarbon Processing - April 2022 - GP-13
Hydrocarbon Processing - April 2022 - GP-14
Hydrocarbon Processing - April 2022 - GP-15
Hydrocarbon Processing - April 2022 - GP-16
Hydrocarbon Processing - April 2022 - GP-17
Hydrocarbon Processing - April 2022 - GP-18
Hydrocarbon Processing - April 2022 - GP-19
Hydrocarbon Processing - April 2022 - GP-20
Hydrocarbon Processing - April 2022 - GP-21
Hydrocarbon Processing - April 2022 - GP-22
Hydrocarbon Processing - April 2022 - GP-23
Hydrocarbon Processing - April 2022 - GP-24
Hydrocarbon Processing - April 2022 - GP-25
Hydrocarbon Processing - April 2022 - GP-26
Hydrocarbon Processing - April 2022 - GP-27
Hydrocarbon Processing - April 2022 - GP-28
Hydrocarbon Processing - April 2022 - GP-29
Hydrocarbon Processing - April 2022 - GP-30
Hydrocarbon Processing - April 2022 - GP-31
Hydrocarbon Processing - April 2022 - GP-32
Hydrocarbon Processing - April 2022 - GP-33
Hydrocarbon Processing - April 2022 - GP-34
Hydrocarbon Processing - April 2022 - GP-35
Hydrocarbon Processing - April 2022 - GP-36
Hydrocarbon Processing - April 2022 - GP-37
Hydrocarbon Processing - April 2022 - GP-38
Hydrocarbon Processing - April 2022 - GP-39
Hydrocarbon Processing - April 2022 - GP-40
Hydrocarbon Processing - April 2022 - GP-41
Hydrocarbon Processing - April 2022 - GP-42
Hydrocarbon Processing - April 2022 - GP-43
Hydrocarbon Processing - April 2022 - GP-44
https://www.nxtbook.com/gulfenergyinfo/gulfpub/HPI-Market-Data-2023-v3
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2024-v2
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2024
https://www.nxtbook.com/gulfenergyinfo/gulfpub/gas-processes-handbook-2022_v2
https://www.nxtbook.com/gulfenergyinfo/gulfpub/gas-processes-handbook-2022
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hp_202212
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2023-v2
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hpi-market-data-2023
https://www.nxtbook.com/gulfenergyinfo/gulfpub/hp_202211
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202210
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202209
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202208
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202207_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202207
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202206_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202206
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202205_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202205
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202204_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202204
https://www.nxtbook.com/nxtbooks/gulfpub/hp_032022
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202203
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202202
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202201
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202112
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202111
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202110
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2022_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2022
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202109
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202108
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_processes_handbook_2021_v2
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_processes_handbook_2021
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202107
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202106
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202105
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202104
https://www.nxtbook.com/nxtbooks/gulfpub/hp_ebooks
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202103
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202102
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202101
https://www.nxtbook.com/nxtbooks/gulfpub/catalyst_handbook_2020_v2
https://www.nxtbook.com/nxtbooks/gulfpub/catalyst_handbook_2020
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202012
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202011
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202010
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2021
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202009
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202008
https://www.nxtbook.com/nxtbooks/gulfpub/refining_processes_handbook_2020
https://www.nxtbook.com/nxtbooks/gulfpub/refining_processes_handbook_2020_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202007
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202006
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202005
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202004
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202003
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202002
https://www.nxtbook.com/nxtbooks/gulfpub/hp_202001
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201912
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201911
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2020_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2020
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201910
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201909
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201908
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201907
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201906
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201905
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201904
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201903
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201902
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201901
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_2018_v2
https://www.nxtbook.com/nxtbooks/gulfpub/petrochemical_2018
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201812
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2019_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hpimarket_2019
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201811
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201810
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201809
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201808
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201807
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201806
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201805
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201804
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201803
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201802
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201801
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201712
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201711
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201710
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201709
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201708
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201707
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201706
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201705
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201704
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201703
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201702
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201701
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2017mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201612
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201611
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201610
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201609
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201608
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201607
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201606
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201605
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201604
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201603
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201602
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201601
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201512
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201511
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201510
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2016mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201509
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201508
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201507
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2015tmsd
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201506
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201505
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201504
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201503
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201502
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201501
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201412
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201411
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2015mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201410
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201409
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201408
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201407
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014petrochemicalprocesses_v2
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014petrochemicalprocesses
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201406
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201405
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201404
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201403
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014calendar
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201402
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201401
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201312
https://www.nxtbook.com/nxtbooks/gulfpub/hp_2014mediaplanner
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201311
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201310
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201309
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201308
https://www.nxtbook.com/nxtbooks/gulfpub/hp_srsguide2013
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201307
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201306
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201305
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201304
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201303
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201302
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201301
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201212
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201211
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201210
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201209
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201208
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201207
https://www.nxtbook.com/nxtbooks/gulfpub/hp_srsguide2012
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201206
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201205
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201204
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201203
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201202
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201201
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201112
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201111
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201110
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201109
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201108
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201107_srsguide
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201107
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201106
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201105
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201104
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201103
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201102
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201101
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201012
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201011
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201010
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201009
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201008
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201007
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201006
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201005
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201004
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201003
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201002
https://www.nxtbook.com/nxtbooks/gulfpub/hp_201001
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200912
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200911
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200910
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200909
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200908
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200907
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200906
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200905
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200904
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200903
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200902
https://www.nxtbook.com/nxtbooks/gulfpub/hp_200901
https://www.nxtbookmedia.com