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Pipeline Cleaning

Pipeline  Cleaning
There was also a considerable amount of pipe
Mike Watson of Tube Tech International, UK ,work that was deemed 'un-pigable' by the
reports on how innovation and planning canclient, but it too required cleaning and
reduce the cost of pipeline cleaning andde-scaling  as  part  of  the  contract.
de-scaling without using cutting equipment. (
as  featured  in  World  Pipelines  magazine)Cutting  is  costly
The complexity of gas and oil pipelines hasThe only solution option proffered by many
not substantially changed, but the demandsexperts at that time was either to fill the
for pipeline cleaning and de-scaling have.entire arterial network of pipe with acid or
Millions of dollars are at stake in lostto  cut  into  the pipeline and pressure jet.
production time and equipment costs if
pipelines have to be dismantled to beHowever, along with this option came
cleaned.environmental implications and costs. There
were also considerable safety issues, as well
The key for pipeline cleaning and specialistas the cost of cutting the pipe open at
companies such as Tube Tech International, isvarious  points.
the ability to bring innovative thought to
problems that have always bedevilled theTube Tech went ahead with an environmentally
petrochemical industry. Indeed, the company'ssound solution using non-standard pigging.
reputation is growing rapidly on the back ofThe volume of scale built up in the pipeline
the proposal that won it a three-yearwas such that it needed to be cleaned over
contract  with  Nigeria  LNG  Ltd  (NLNG).1the whole surface area, or the flow rate
would have been compromised. The result was
Problems at the gas processing plant in thethat more than 40 t of iron oxide and calcium
West African state, which opened in 1999,water scale was removed using a variety of
were classified as 'uncleanable'. Condenser,innovative pigging processes and types,
heat exchanger tubes, and pipelines hadincluding:
become seriously contaminated by deposit, and
millions of dollars in new equipment and• Pigs that could be inserted into a
downtime were at stake if the complex system25mm aperture and inflated to match the given
had  to  be  dismantled.pipe  diameter.
Tube Tech won the initial pipeline cleaning• Bi-directional pigs adapted with
and  de-scaling  contract  on  three grounds:pressure bypass valves so that, in the event
of sticking due to the volume of deposits
* A pledge that production loss would beahead, the increased water back pressure
minimal because none of the pipelines wouldwould engage a solenoid in the nose of the
need  to  be  cutpig, turning it into a pressure-jetting
nozzle.
* Work in Nigeria could start within two
weeks• Pigs fired with a guide wire attached
so  they  could  be  retracted
* Regardless of dimension ( 2 - 36 in)
deposit  could  be  cleaned• A biodegradable pig was developed to
break down at the end of a potential dead-end
Work began immediately at the company'srun. This would have negated the need to cut
headquarters in Essex , England , focusing oninto the pipe, as well as alleviating any
the logistics on getting 32 multi-disciplinedrisk of losing it. This particular pigging
operatives and 46 t of cleaning andsolution had been developed prior to the
de-scaling equipment onsite at Bonny Islandproject.
as  soon  as  possible.
Once the pipeline cleaning and de-scaling
Project planning was also started, involvingwork had been completed. Tube Tech also put
12km of pipeline and 60,000 heat exchangerboth closed circuit TV and wall thickness
tubes. With a convolution of bends andintegrity assessment inspection equipment
'T-offs in a maze of differing diameters ofinto action. This enabled technicians to
pipe work, there was no 'one size fits all'inspect the wall thickness of the pipes
cure. In the event, the project team came upelectronically rather than by using expensive
with a combination of 12 techniques to clearintelligent  pigging.
highly  stubborn  scale  and  blockages.
The  competition
An airborne assault was organised, and 3
cargo aircrafts of equipment were off- loadedWhile there are many pipeline cleaning
in Nigeria just 2 weeks after the initialsystems available from global sources, with
site visit. Working continuous day and nightevery successful contract Tube Tech has
shifts in frequently extreme weatherfrequently found the basic equipment to be
conditions the teams completed the cleaninginadequate for dealing with the problems
and integrity inspection three times fasterspecific  to  each  contract.
than  the  nearest  competing  estimate.
It is client's increased dislike of the
The plant was quickly restored to fullenvironmentally unsound chemical route and
production using 12 techniques. The firstthe costly cutting method that has led to the
cleaning system was a novel 'mini pig', onlydevelopment of bespoke solutions by the
150mm in length and conforming to the tuberesearch team. With this 'applied innovation'
internal diameter. Propelled by water, thein conjunction with an in-depth study of the
rotating blades only extended as far as thesystem, the company has changed the rules of
tube diameter and not beyond, therebypigging and exchanger cleaning by inventing
avoiding  any  damage.new  pigs  and  tube  cleaning  processes.
The middle third of the dart houses aIn the case of the Nigeria contract, the
rotating bladed turbine, and with a waterclient approached a number of other
pressure of 500 psi, these blades (emulatingcompanies, but none were able to offer more
the turbine blades on an aircraft engine) arethan three cleaning techniques involving
forced to rotate at a speed of approximatelyeither acid cleaning, cutting into the
4000rpm.pipeline or high volume water jetting. Tube
Tech's involvement came through the
In this instance, the scale causing therecommendation of Shell Global Solutions
blockage consisted of calcium and iron oxideInternational (SGSI). Without using any of
product. The rotating blades remove impedingthese options, Tube Tech was armed with 12
scale in their path at a travel ratetechniques tailored to the varying
averaging out at approximately 2 m/s. usingconsistencies and volumes facing them. The
this method, pipe work can be cleaned in aloss of efficiency translated quickly into
matter  of  hours  rather  than  days.financial loss, which was why the client was
looking  for  a  fast,  effective  cure.
This particular turbine blade is entirely
bespoke and manufactured by hand in materialsThe reward for restoring production to 100%
that can be ferrous or non-ferrous. Tube Techwas the three-year contract for further work.
has a wide range of Darttsâ„¢ to suitThis has included advice on fouling
diameters  ranging  from  10mm  to one metre.mitigation procedures to prevent further
scale blockages, particularly with the
A second system used at Bonny Island was aintroduction of vital measures for sound
traditional, automated high-pressurequality  water  treatment.
water-jetting lance, but this was modified by
Tube Tech to create a new, more effective,While pipeline blockages are eminently
method for the smaller pipes. Its engineerstreatable with expertise, there is a cause
adapted this system by modifying thefor a rethink on several fronts where
traditional high pressure jetting hoseprevention is better than cure. Process
system, which normally reaches a maximum pipepipelines are not often manufactured with a
length of 400m, so that it can extend as farview to cleanability. Tube Tech can offer end
as  2km.users and plant fabricators proven advice on
how to modify them so that, rather than
A further 10 systems were also mobilised,fighting fires are serious problems arise, a
thereby avoiding the worst case scenario ofrethink at the manufacturing stage can tackle
substantial downtime at Bonny Island and thethe root causes of scaling and blockages to
vast financial impact that would be implicit.out-engineer the problem.



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