| Pipeline Cleaning | | | | There was also a considerable amount of |
| Mike Watson of Tube Tech International, | | | | pipe work that was deemed 'un-pigable' |
| UK , reports on how innovation and | | | | by the client, but it too required |
| planning can reduce the cost of pipeline | | | | cleaning and de-scaling as part of the |
| cleaning and de-scaling without using | | | | contract. |
| cutting equipment. ( as featured in | | | | Cutting is costly |
| World Pipelines magazine) | | | | The only solution option proffered by |
| The complexity of gas and oil pipelines | | | | many experts at that time was either to |
| has not substantially changed, but the | | | | fill the entire arterial network of pipe |
| demands for pipeline cleaning and | | | | with acid or to cut into the pipeline |
| de-scaling have. Millions of dollars are | | | | and pressure jet. |
| at stake in lost production time and | | | | However, along with this option came |
| equipment costs if pipelines have to be | | | | environmental implications and costs. |
| dismantled to be cleaned. | | | | There were also considerable safety |
| The key for pipeline cleaning and | | | | issues, as well as the cost of cutting |
| specialist companies such as Tube Tech | | | | the pipe open at various points. |
| International, is the ability to bring | | | | Tube Tech went ahead with an |
| innovative thought to problems that have | | | | environmentally sound solution using |
| always bedevilled the petrochemical | | | | non-standard pigging. The volume of |
| industry. Indeed, the company's | | | | scale built up in the pipeline was such |
| reputation is growing rapidly on the | | | | that it needed to be cleaned over the |
| back of the proposal that won it a | | | | whole surface area, or the flow rate |
| three-year contract with Nigeria LNG Ltd | | | | would have been compromised. The result |
| (NLNG).1 | | | | was that more than 40 t of iron oxide |
| Problems at the gas processing plant in | | | | and calcium water scale was removed |
| the West African state, which opened in | | | | using 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 seriously | | | | 25mm aperture and inflated to match the |
| contaminated by deposit, and millions of | | | | given pipe diameter. |
| dollars in new equipment and downtime | | | | • Bi-directional pigs adapted with |
| were at stake if the complex system had | | | | pressure bypass valves so that, in the |
| to be dismantled. | | | | event of sticking due to the volume of |
| Tube Tech won the initial pipeline | | | | deposits ahead, the increased water back |
| cleaning and de-scaling contract on | | | | pressure would engage a solenoid in the |
| three grounds: | | | | nose of the pig, turning it into a |
| * A pledge that production loss would be | | | | pressure-jetting nozzle. |
| minimal because none of the pipelines | | | | • Pigs fired with a guide wire |
| would need to be cut | | | | attached so they could be retracted |
| * Work in Nigeria could start within two | | | | • A biodegradable pig was developed to |
| weeks | | | | break down at the end of a potential |
| * Regardless of dimension ( 2 - 36 in) | | | | dead-end run. This would have negated |
| deposit could be cleaned | | | | the need to cut into the pipe, as well |
| Work began immediately at the company's | | | | as alleviating any risk of losing it. |
| headquarters in Essex , England , | | | | This particular pigging solution had |
| focusing on the logistics on getting 32 | | | | been developed prior to the project. |
| multi-disciplined operatives and 46 t of | | | | Once the pipeline cleaning and |
| cleaning and de-scaling equipment onsite | | | | de-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 60,000 | | | | inspection equipment into action. This |
| heat exchanger tubes. With a convolution | | | | enabled technicians to inspect the wall |
| of bends and 'T-offs in a maze of | | | | thickness of the pipes electronically |
| differing diameters of pipe work, there | | | | rather than by using expensive |
| was no 'one size fits all' cure. In the | | | | intelligent pigging. |
| event, the project team came up with a | | | | The competition |
| combination of 12 techniques to clear | | | | While there are many pipeline cleaning |
| highly stubborn scale and blockages. | | | | systems available from global sources, |
| An airborne assault was organised, and 3 | | | | with every successful contract Tube Tech |
| cargo aircrafts of equipment were off- | | | | has frequently found the basic equipment |
| loaded in Nigeria just 2 weeks after the | | | | to be inadequate for dealing with the |
| initial site visit. Working continuous | | | | problems specific to each contract. |
| day and night shifts in frequently | | | | It is client's increased dislike of the |
| extreme weather conditions the teams | | | | environmentally unsound chemical route |
| completed the cleaning and integrity | | | | and the costly cutting method that has |
| inspection three times faster than the | | | | led to the development of bespoke |
| nearest competing estimate. | | | | solutions by the research team. With |
| The plant was quickly restored to full | | | | this 'applied innovation' in conjunction |
| production using 12 techniques. The | | | | with an in-depth study of the system, |
| first cleaning system was a novel 'mini | | | | the company has changed the rules of |
| pig', only 150mm in length and | | | | pigging and exchanger cleaning by |
| conforming to the tube internal | | | | inventing new pigs and tube cleaning |
| diameter. Propelled by water, the | | | | processes. |
| rotating blades only extended as far as | | | | In 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 a | | | | more than three cleaning techniques |
| rotating bladed turbine, and with a | | | | involving either acid cleaning, cutting |
| water pressure of 500 psi, these blades | | | | into the pipeline or high volume water |
| (emulating the turbine blades on an | | | | jetting. Tube Tech's involvement came |
| aircraft engine) are forced to rotate at | | | | through the recommendation of Shell |
| a speed of approximately 4000rpm. | | | | Global Solutions International (SGSI). |
| In this instance, the scale causing the | | | | Without using any of these options, Tube |
| blockage consisted of calcium and iron | | | | Tech was armed with 12 techniques |
| oxide product. The rotating blades | | | | tailored to the varying consistencies |
| remove impeding scale in their path at a | | | | and volumes facing them. The loss of |
| travel rate averaging out at | | | | efficiency 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 of | | | | was looking for a fast, effective cure. |
| hours rather than days. | | | | The reward for restoring production to |
| This particular turbine blade is | | | | 100% was the three-year contract for |
| entirely bespoke and manufactured by | | | | further work. This has included advice |
| hand in materials that can be ferrous or | | | | on fouling mitigation procedures to |
| non-ferrous. Tube Tech has a wide range | | | | prevent further scale blockages, |
| of Dartts™ to suit diameters ranging | | | | particularly with the introduction of |
| from 10mm to one metre. | | | | vital measures for sound quality water |
| A second system used at Bonny Island was | | | | treatment. |
| a traditional, automated high-pressure | | | | While pipeline blockages are eminently |
| water-jetting lance, but this was | | | | treatable 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 smaller | | | | where prevention is better than cure. |
| pipes. Its engineers adapted this system | | | | Process pipelines are not often |
| by modifying the traditional high | | | | manufactured with a view to |
| pressure jetting hose system, which | | | | cleanability. Tube Tech can offer end |
| normally reaches a maximum pipe length | | | | users and plant fabricators proven |
| of 400m, so that it can extend as far as | | | | advice on how to modify them so that, |
| 2km. | | | | rather than fighting fires are serious |
| A further 10 systems were also | | | | problems arise, a rethink at the |
| mobilised, thereby avoiding the worst | | | | manufacturing stage can tackle the root |
| case scenario of substantial downtime at | | | | causes of scaling and blockages to |
| Bonny Island and the vast financial | | | | out-engineer the problem. |
| impact that would be implicit. | | | | |