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"INTERUNIS" suggests development and commissioning of ????-?
/A-Line 32D (DDM-M)/ CDM system at the following facilities:
PIPELINES IN TUNNELS
The central problem under examination of pipeline
tunnel sections (TC) is a hindered or even impossible access,
especially at external pipeline laying, when the pipe occupies a part
of tunnel space. So, periodic examination is more often inefficient or
impossible.
CDM
System Diagram for Gas-Pipe Tunnel CrossingAn example of TP monitoring in the tunnel is a design suggested by
INTERUNIS under laying of the gas-pipe “Goluboi Potok” across the
mountain ridge “Kobyla”.
Damage of the tunnel enclosure elements
brings not smaller threat than damage of the pipeline proper. Our
company has an experience in examination of concrete structures, which
could be successfully used for complex diagnosis monitoring of the
pipeline tunnel.
PIPLEINES IN POOR CARRYING GROUNDS, AT SLIDE
HAZARDOUS AREAS, AND IN KARSTIFICATION ZONES
To the poor carrying grounds boggy and sandy grounds belong, not
ensuring the required pipe grip in a trench. A distinctive feature of
this pipeline division (TC) is a possible formation of an “arch”
resulted from the loss of TC longitudinal stability.
The area of TC egress from the ground and the “arch” upper part are
the most hazardous “arch” points. An increased level of stresses may be
seen at the “arch” edges, while the “arch” upper part is prone to
formation of corrugations that can result in pipeline break.
The diagnosis monitoring aim is as follows: a timely detection of TC
movement by measuring stresses at the pipe upper and lower generating
lines, AE testing of processes accompanying the change of pipe position
in the trench, and detection of cracks in a corrugation with a
composite geometry.
In zones of high seismicity hazard, to which a number of regions on
the way of oil pipeline belongs, the ground flash, holes,
karstification are most probable, that as a first approximation will
result at this place in formation by the pipe of a conventional
unsupported beam crossing with a typical sagging at the middle part.
Redistribution of stresses along the pipe wall can reach values
comparable with the maximum permissible ones with resulting in pipe
damage or intensive growth of cracks.
Taking into account that at the geological survey stage the places of
probable ground flashes are known, we consider that such areas belong
to potentially hazardous ones, and it makes sense to equip such areas
with the diagnosis monitoring systems.
In this case the data
parameters are the pipeline strains and AE signals typical for the
growing defects in the pipe wall.
TC laying at the areas prone to rockslide effects tends more often to
great problems during their operation.
An example of such area is the gas-pipe multi-line river crossing of
the Uzhgorod corridor across the Kama, during operation of which at
least two catastrophic pipe breakdowns occurred, and one with gas
inflammation.
INTERUNIS and VNIIGAZ has conducted a joint examination of this area
with determination of measuring stations on the basis of geological
survey by AE-testing all 9 runs at this area, and by measuring absolute
stresses over the whole pipe section.
The result of such works is the complex monitoring project for TC of
this area, which uses the special devices for measuring ground shifting
speed and direction, AE transducers and strain sensors.
An example of pipeline stress-strain state monitoring is the
diagnosis of rockslide areas of JSC “Chernomortransneft” oil pipeline
carried out jointly by INTERUNIS and VNIIST in 2006 and 2007.
Pipeline laid along the
rockslide side |
Pipeline piled overhead
section under examination |
RIVER CROSSINGS, OVERPASSES ACROSS ROADS AND RAILWAYS
“The Schedule of Technical Operation of Oil-Trunk Pipeline Crossings
over Water Obstacles” determines the basic rules of diagnosis
examination of crossings over water obstacles, the examination types,
intervals and boundaries. This document also provides for a continuous
diagnosis testing (monitoring).
Scheme of CDM System for Pipeline River CrossingWhen organizing the diagnosis monitoring, one should take into
account the distinctive features of the crossing floodplain and canal
part.
The basic types of defects in the submerged crossing are as
follows: damage of TC insulation coating, outer and inner wall
corrosion, loss of stability (sag), unbalance, pipe wall wear at pipe
headers branches, fatigue cracks, through-damages, and blue holes.
The
diagnosis monitoring technique for the floodplain part of the
submerged crossing in respect to the sensors used and their number is
similar to the monitoring technique for a TC division with poor
carrying grounds.
CDM systems of road and railway
crossings are similar by their design to the systems on river
crossings.
SHUTTERS AT LINIAR PART OF TRANSFER
PIPELINES
It is reasonable to provide for the diagnosis
monitoring of shutters at especially hazardous divisions of pipeline,
for example, water obstacles crossings. But in specific cases it may be
provided at shutters of the pipeline linear division.
The complex monitoring of sliding shutters ensures the full check in
accordance with the normative documents ??-08.00-60.30.00-???-027-1-05
and ??-08.00-29.13.00-???-012-1-05, and may be used for increasing the
overhaul life.
The complex monitoring of sliding shutters provides for the AE method
application. The continuous AE testing ensures check of basic metal
and welds; therefore, to confirm defects detected under AE testing, an
ultrasonic examination and other NDT methods stipulated by the
normative documents may be applied at mid-life repair and overhauls.
Sliding
Shutter under Inspection |
Displaying of Defective
Shutter |
The efficiency of AE monitoring of sliding shutters is confirmed by
the technique and equipment developed by INTERUNIS experts which were
applied under acceptance tests at “Tyazhmasharmatura” works in town
Aleksin.
CRYOGENIC AMMONIA TANKS
Structurally the liquid ammonia storage (LACS) is a structure
consisting of two tanks – an inner tank, wherein liquid ammonia is
stored and an outer tank. The inner tank is concentrically located
relative to the outer one. The annular space between tanks is filled
with a thermal insulation of expanded pearlite sand. For drying the
heat insulation during operation, an inert gas is supplied into the
annular space.
Pearlite-concrete blocks are used as heat insulation for bottom
plates with the joints filled with pearlite sand. The outer tank
protects the heat insulation against damage and moisture ingress.
The inner tank is practically inaccessible for periodic testing, and
its failure will result in catastrophic consequences. Therefore, it
becomes a subject of principal attention under development of CDM
system.
An
example of CDM system scheme for liquid ammonia cryogenic storage The basic defects of inner tank inadmissible according to the
conditions of operation are cracks, through corrosion, and loss of
stability.
Potentially dangerous places of the LACS inner tank are a corner weld
joint, bottom plate, erection weld (at roll assembly), welds and basic
metal of tank lower rings at the joints of inlet and outlet pipelines
and tank walls.
The factors capable to affect damaging are the failure of joints of
inner tank anchoring to a foundation plate, tank deviation from the
vertical position, increased vibration of inlet and outlet pipe
branches, heat insulation damage, and foundation deterioration.
As the basic testing method for the cryogenic tank CDM system the AE
method is used, which provides for detection of growing defects and
defects capable to grow (occurring when load varies) or a leakage, for
definition of their location and evaluation of their danger. Moreover,
temperature sensors mounted on the surfaces of inner tanks allow
evaluating the heat insulation of cryogenic tanks, while strain sensors
mounted on the anchors and foundations of the cryogenic tanks allow
checking the change in tank position and stress-strain state.
As the means for operation parameters measurement, installed are the
level meters for measuring a filling level, the pressure sensors for
checking minimum and maximum pressure, and vibration sensors for
checking a vibration level on input and output pipelines of the LACS
inner tank.
Additionally the CDM system may be equipped with a weather station
for checking wind loads and for detecting precipitations to filter the
AE signals.
The AE transducers (TAE) and other
sensors of the CDM system are fastened to a tank wall by means of
holders welded to the wall being placed in special caissons. This
allows for installing sensors on the external surface of cryogenic tank
internal shell and for excluding influence of the heat insulation
material (pearlite) on them. The sensor holders are made in such a way
that if need be to replace a sensor no hot works are required.
As per the normative documents, namely, PD ??
03-410-01 “Instructions on Technical Examination of Cryogenic Tanks for
Liquefied Gases”, it is required to check by means of the AE method
the whole surface of the test object and to ensure a uniform
distribution of TAE over the cryogenic tank casing components:
cylindrical shell and cover.
Except for the above-listed, it is proposed to equip
additionally the CDM system of the liquid ammonia cryogenic storage
with humidity sensors to be installed as recommended at the points of
AE and temperature sensors attachment. The humidity sensors make it
possible to estimate the condition and quality of the cryogenic tank
heat insulation.
BUILDINGS AND CONSTRUCTIONS
From 2002 “INTERUNIS” together with the A.F. Ioffe Physics &
Technology Institute, St.-Petersburg, the Russian Academy of Science
(FTI), and the Concrete and Steel Concrete Research & Designing
Institute has investigated the capabilities of AE method application
for diagnosis of reinforced concrete structures.
In 2004 “INTERUNIS” designed the project “Development of Monitoring
System for Long-term Supervision of Technical State of the Lomonosov
Moscow State University Library for Providing Safe Operation of this
Construction”.
Within the bounds of works as per this contract a random examination
and then analysis of the library structural layout were conducted. The
aim of such works was as follows:
- detection of available defects and damages in the main load-bearing
structures and reveal of divergences from the project;
- analysis of the data submitted by the specialists who took part in
designing and construction of the library building, and also expert
appraisal according to this analysis results;
- development of the library design scheme and determination of the
list of building structures and elements under test, and also
determination of the limiting values according to deformations of the
load-bearing structures and building stability.
CDM
System of the Central Part of the Lomonosov Moscow State University
Library (Locations of elements under test and central computing
station are designated by figures)
The result of works done is as follows:
- organization diagram for monitoring system in the building central
part (?) is developed;
- list of building structures and elements under test is determined –
one-piece reinforced concrete beams of the cantilever part (b) and
stiffening diaphragm walls (c) being adjacent to elevator shafts in
the building cantilever part;
- test methods are recommended, as well as sensor types relevant for
such methods, and points for sensors installation on the test object.
BRIDGES
The bridge construction burden is directly connected with the bridge
structural version. Tensile loads are present in structures of beam
(frame) type, while compressive loads and bend - in the portal frame
combined bridges.
The static loads can resulted in change of the design position of
structure elements and, respectively, in additional off-design loads.
Periodic operation loads will result in occurrence of fatigue cracks at
the points of geometric stress concentrators. Corrosion processes
indispensably accompanying bridge damages of all other types, as a
rule, run in hard-to-reach places and with time can cause reduction of
the structure elements bearing capacity. Presence of pores, inclusions
in concrete structures can lead to the significant reduction of the
bridge residual strength.
Scheme
of cable-beam system bridge and its basic bearing structures covered
by the CDM system
(1 – arch
pylon; 2 – cable system; 3 – bridge bearing beams in cable and beam spans;
4 – beam spans supports; 5 – arch pylon
supports)With a variety of defects types and points of their occurrence it is
impossible to provide a reliable testing of the bridge technical state
by using any single non-destructive method. This problem can be solved
on the basis of the AE method approved under different conditions and
on different structures, which allows providing for an integral
evaluation of the bridge state in combination with other
non-destructive methods. Such additional testing methods may be methods
for measuring the stress-strain state of bridge elements by the
tensometry, methods for measuring the design position changes of the
bridge structure elements by using the large linear displacement
sensors, and methods for evaluating the structure corrosive state based
on reference specimens, as well as other means for evaluating the
corrosive state.
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