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Pipeline Cleaning

Pipeline CleaningThere was also a considerable amount of
Mike Watson of Tube Tech International,pipe work that was deemed 'un-pigable'
UK , reports on how innovation andby the client, but it too required
planning can reduce the cost of pipelinecleaning and de-scaling as part of the
cleaning and de-scaling without usingcontract.
cutting equipment. ( as featured inCutting is costly
World Pipelines magazine)The only solution option proffered by
The complexity of gas and oil pipelinesmany experts at that time was either to
has not substantially changed, but thefill the entire arterial network of pipe
demands for pipeline cleaning andwith acid or to cut into the pipeline
de-scaling have. Millions of dollars areand pressure jet.
at stake in lost production time andHowever, along with this option came
equipment costs if pipelines have to beenvironmental implications and costs.
dismantled to be cleaned.There were also considerable safety
The key for pipeline cleaning andissues, as well as the cost of cutting
specialist companies such as Tube Techthe pipe open at various points.
International, is the ability to bringTube Tech went ahead with an
innovative thought to problems that haveenvironmentally sound solution using
always bedevilled the petrochemicalnon-standard pigging. The volume of
industry. Indeed, the company'sscale built up in the pipeline was such
reputation is growing rapidly on thethat it needed to be cleaned over the
back of the proposal that won it awhole surface area, or the flow rate
three-year contract with Nigeria LNG Ltdwould have been compromised. The result
(NLNG).1was that more than 40 t of iron oxide
Problems at the gas processing plant inand calcium water scale was removed
the West African state, which opened inusing a variety of innovative pigging
1999, were classified as 'uncleanable'.processes and types, including:
Condenser, heat exchanger tubes, and• Pigs that could be inserted into a
pipelines had become seriously25mm aperture and inflated to match the
contaminated by deposit, and millions ofgiven pipe diameter.
dollars in new equipment and downtime• Bi-directional pigs adapted with
were at stake if the complex system hadpressure bypass valves so that, in the
to be dismantled.event of sticking due to the volume of
Tube Tech won the initial pipelinedeposits ahead, the increased water back
cleaning and de-scaling contract onpressure would engage a solenoid in the
three grounds:nose of the pig, turning it into a
* A pledge that production loss would bepressure-jetting nozzle.
minimal because none of the pipelines• Pigs fired with a guide wire
would need to be cutattached so they could be retracted
* Work in Nigeria could start within two• A biodegradable pig was developed to
weeksbreak down at the end of a potential
* Regardless of dimension ( 2 - 36 in)dead-end run. This would have negated
deposit could be cleanedthe need to cut into the pipe, as well
Work began immediately at the company'sas alleviating any risk of losing it.
headquarters in Essex , England ,This particular pigging solution had
focusing on the logistics on getting 32been developed prior to the project.
multi-disciplined operatives and 46 t ofOnce the pipeline cleaning and
cleaning and de-scaling equipment onsitede-scaling work had been completed. Tube
at Bonny Island as soon as possible.Tech also put both closed circuit TV and
Project planning was also started,wall thickness integrity assessment
involving 12km of pipeline and 60,000inspection equipment into action. This
heat exchanger tubes. With a convolutionenabled technicians to inspect the wall
of bends and 'T-offs in a maze ofthickness of the pipes electronically
differing diameters of pipe work, thererather than by using expensive
was no 'one size fits all' cure. In theintelligent pigging.
event, the project team came up with aThe competition
combination of 12 techniques to clearWhile there are many pipeline cleaning
highly stubborn scale and blockages.systems available from global sources,
An airborne assault was organised, and 3with every successful contract Tube Tech
cargo aircrafts of equipment were off-has frequently found the basic equipment
loaded in Nigeria just 2 weeks after theto be inadequate for dealing with the
initial site visit. Working continuousproblems specific to each contract.
day and night shifts in frequentlyIt is client's increased dislike of the
extreme weather conditions the teamsenvironmentally unsound chemical route
completed the cleaning and integrityand the costly cutting method that has
inspection three times faster than theled to the development of bespoke
nearest competing estimate.solutions by the research team. With
The plant was quickly restored to fullthis 'applied innovation' in conjunction
production using 12 techniques. Thewith an in-depth study of the system,
first cleaning system was a novel 'minithe company has changed the rules of
pig', only 150mm in length andpigging and exchanger cleaning by
conforming to the tube internalinventing new pigs and tube cleaning
diameter. Propelled by water, theprocesses.
rotating blades only extended as far asIn the case of the Nigeria contract, the
the tube diameter and not beyond,client approached a number of other
thereby avoiding any damage.companies, but none were able to offer
The middle third of the dart houses amore than three cleaning techniques
rotating bladed turbine, and with ainvolving either acid cleaning, cutting
water pressure of 500 psi, these bladesinto the pipeline or high volume water
(emulating the turbine blades on anjetting. Tube Tech's involvement came
aircraft engine) are forced to rotate atthrough the recommendation of Shell
a speed of approximately 4000rpm.Global Solutions International (SGSI).
In this instance, the scale causing theWithout using any of these options, Tube
blockage consisted of calcium and ironTech was armed with 12 techniques
oxide product. The rotating bladestailored to the varying consistencies
remove impeding scale in their path at aand volumes facing them. The loss of
travel rate averaging out atefficiency translated quickly into
approximately 2 m/s. using this method,financial loss, which was why the client
pipe work can be cleaned in a matter ofwas looking for a fast, effective cure.
hours rather than days.The reward for restoring production to
This particular turbine blade is100% was the three-year contract for
entirely bespoke and manufactured byfurther work. This has included advice
hand in materials that can be ferrous oron fouling mitigation procedures to
non-ferrous. Tube Tech has a wide rangeprevent further scale blockages,
of Dartts™ to suit diameters rangingparticularly with the introduction of
from 10mm to one metre.vital measures for sound quality water
A second system used at Bonny Island wastreatment.
a traditional, automated high-pressureWhile pipeline blockages are eminently
water-jetting lance, but this wastreatable with expertise, there is a
modified by Tube Tech to create a new,cause for a rethink on several fronts
more effective, method for the smallerwhere prevention is better than cure.
pipes. Its engineers adapted this systemProcess pipelines are not often
by modifying the traditional highmanufactured with a view to
pressure jetting hose system, whichcleanability. Tube Tech can offer end
normally reaches a maximum pipe lengthusers and plant fabricators proven
of 400m, so that it can extend as far asadvice on how to modify them so that,
2km.rather than fighting fires are serious
A further 10 systems were alsoproblems arise, a rethink at the
mobilised, thereby avoiding the worstmanufacturing stage can tackle the root
case scenario of substantial downtime atcauses of scaling and blockages to
Bonny Island and the vast financialout-engineer the problem.
impact that would be implicit.



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