Pipeline Cleaning

Pipeline Cleaningthat was deemed 'un-pigable' by the client, but it too
Mike Watson of Tube Tech International, UK ,required cleaning and de-scaling as part of the
reports on how innovation and planning can reducecontract.
the cost of pipeline cleaning and de-scaling withoutCutting is costly
using cutting equipment. ( as featured in WorldThe only solution option proffered by many experts
Pipelines magazine)at that time was either to fill the entire arterial
The complexity of gas and oil pipelines has notnetwork of pipe with acid or to cut into the pipeline
substantially changed, but the demands for pipelineand pressure jet.
cleaning and de-scaling have. Millions of dollars are atHowever, along with this option came environmental
stake in lost production time and equipment costs ifimplications and costs. There were also considerable
pipelines have to be dismantled to be cleaned.safety issues, as well as the cost of cutting the pipe
The key for pipeline cleaning and specialist companiesopen at various points.
such as Tube Tech International, is the ability to bringTube Tech went ahead with an environmentally
innovative thought to problems that have alwayssound solution using non-standard pigging. The volume
bedevilled the petrochemical industry. Indeed, theof scale built up in the pipeline was such that it
company's reputation is growing rapidly on the backneeded to be cleaned over the whole surface area,
of the proposal that won it a three-year contractor the flow rate would have been compromised. The
with Nigeria LNG Ltd (NLNG).1result was that more than 40 t of iron oxide and
Problems at the gas processing plant in the Westcalcium water scale was removed using a variety of
African state, which opened in 1999, were classifiedinnovative pigging processes and types, including:
as 'uncleanable'. Condenser, heat exchanger tubes,• Pigs that could be inserted into a 25mm
and pipelines had become seriously contaminated byaperture and inflated to match the given pipe
deposit, and millions of dollars in new equipment anddiameter.
downtime were at stake if the complex system had• Bi-directional pigs adapted with pressure
to be dismantled.bypass valves so that, in the event of sticking due
Tube Tech won the initial pipeline cleaning andto the volume of deposits ahead, the increased
de-scaling contract on three grounds:water back pressure would engage a solenoid in the
* A pledge that production loss would be minimalnose of the pig, turning it into a pressure-jetting
because none of the pipelines would need to be cutnozzle.
* Work in Nigeria could start within two weeks• Pigs fired with a guide wire attached so
* Regardless of dimension ( 2 - 36 in) deposit couldthey could be retracted
be cleaned• A biodegradable pig was developed to
Work began immediately at the company'sbreak down at the end of a potential dead-end run.
headquarters in Essex , England , focusing on theThis would have negated the need to cut into the
logistics on getting 32 multi-disciplined operatives andpipe, as well as alleviating any risk of losing it. This
46 t of cleaning and de-scaling equipment onsite atparticular pigging solution had been developed prior to
Bonny Island as soon as possible.the project.
Project planning was also started, involving 12km ofOnce the pipeline cleaning and de-scaling work had
pipeline and 60,000 heat exchanger tubes. With abeen completed. Tube Tech also put both closed
convolution of bends and 'T-offs in a maze ofcircuit TV and wall thickness integrity assessment
differing diameters of pipe work, there was no 'oneinspection equipment into action. This enabled
size fits all' cure. In the event, the project teamtechnicians to inspect the wall thickness of the pipes
came up with a combination of 12 techniques to clearelectronically rather than by using expensive intelligent
highly stubborn scale and blockages.pigging.
An airborne assault was organised, and 3 cargoThe competition
aircrafts of equipment were off- loaded in Nigeria justWhile there are many pipeline cleaning systems
2 weeks after the initial site visit. Working continuousavailable from global sources, with every successful
day and night shifts in frequently extreme weathercontract Tube Tech has frequently found the basic
conditions the teams completed the cleaning andequipment to be inadequate for dealing with the
integrity inspection three times faster than theproblems specific to each contract.
nearest competing estimate.It is client's increased dislike of the environmentally
The plant was quickly restored to full productionunsound chemical route and the costly cutting
using 12 techniques. The first cleaning system was amethod that has led to the development of bespoke
novel 'mini pig', only 150mm in length and conformingsolutions by the research team. With this 'applied
to the tube internal diameter. Propelled by water, theinnovation' in conjunction with an in-depth study of
rotating blades only extended as far as the tubethe system, the company has changed the rules of
diameter and not beyond, thereby avoiding anypigging and exchanger cleaning by inventing new pigs
damage.and tube cleaning processes.
The middle third of the dart houses a rotating bladedIn the case of the Nigeria contract, the client
turbine, and with a water pressure of 500 psi, theseapproached a number of other companies, but none
blades (emulating the turbine blades on an aircraftwere able to offer more than three cleaning
engine) are forced to rotate at a speed oftechniques involving either acid cleaning, cutting into
approximately 4000rpm.the pipeline or high volume water jetting. Tube Tech's
In this instance, the scale causing the blockageinvolvement came through the recommendation of
consisted of calcium and iron oxide product. TheShell Global Solutions International (SGSI). Without
rotating blades remove impeding scale in their path atusing any of these options, Tube Tech was armed
a travel rate averaging out at approximately 2 m/s.with 12 techniques tailored to the varying
using this method, pipe work can be cleaned in aconsistencies and volumes facing them. The loss of
matter of hours rather than days.efficiency translated quickly into financial loss, which
This particular turbine blade is entirely bespoke andwas why the client was looking for a fast, effective
manufactured by hand in materials that can becure.
ferrous or non-ferrous. Tube Tech has a wide rangeThe reward for restoring production to 100% was
of Darttsâ„¢ to suit diameters ranging fromthe three-year contract for further work. This has
10mm to one metre.included advice on fouling mitigation procedures to
A second system used at Bonny Island was aprevent further scale blockages, particularly with the
traditional, automated high-pressure water-jettingintroduction of vital measures for sound quality water
lance, but this was modified by Tube Tech to createtreatment.
a new, more effective, method for the smaller pipes.While pipeline blockages are eminently treatable with
Its engineers adapted this system by modifying theexpertise, there is a cause for a rethink on several
traditional high pressure jetting hose system, whichfronts where prevention is better than cure. Process
normally reaches a maximum pipe length of 400m, sopipelines are not often manufactured with a view to
that it can extend as far as 2km.cleanability. Tube Tech can offer end users and plant
A further 10 systems were also mobilised, therebyfabricators proven advice on how to modify them so
avoiding the worst case scenario of substantialthat, rather than fighting fires are serious problems
downtime at Bonny Island and the vast financialarise, a rethink at the manufacturing stage can tackle
impact that would be implicit.the root causes of scaling and blockages to
There was also a considerable amount of pipe workout-engineer the problem.