| Pipeline Cleaning | | | | that 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 reduce | | | | contract. |
| the cost of pipeline cleaning and de-scaling without | | | | Cutting is costly |
| using cutting equipment. ( as featured in World | | | | The 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 not | | | | network of pipe with acid or to cut into the pipeline |
| substantially changed, but the demands for pipeline | | | | and pressure jet. |
| cleaning and de-scaling have. Millions of dollars are at | | | | However, along with this option came environmental |
| stake in lost production time and equipment costs if | | | | implications 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 companies | | | | open at various points. |
| such as Tube Tech International, is the ability to bring | | | | Tube Tech went ahead with an environmentally |
| innovative thought to problems that have always | | | | sound solution using non-standard pigging. The volume |
| bedevilled the petrochemical industry. Indeed, the | | | | of scale built up in the pipeline was such that it |
| company's reputation is growing rapidly on the back | | | | needed to be cleaned over the whole surface area, |
| of the proposal that won it a three-year contract | | | | or the flow rate would have been compromised. The |
| with Nigeria LNG Ltd (NLNG).1 | | | | result was that more than 40 t of iron oxide and |
| Problems at the gas processing plant in the West | | | | calcium water scale was removed using a variety of |
| African state, which opened in 1999, were classified | | | | innovative 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 by | | | | aperture and inflated to match the given pipe |
| deposit, and millions of dollars in new equipment and | | | | diameter. |
| 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 and | | | | to 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 minimal | | | | nose of the pig, turning it into a pressure-jetting |
| because none of the pipelines would need to be cut | | | | nozzle. |
| * Work in Nigeria could start within two weeks | | | | • Pigs fired with a guide wire attached so |
| * Regardless of dimension ( 2 - 36 in) deposit could | | | | they could be retracted |
| be cleaned | | | | • A biodegradable pig was developed to |
| Work began immediately at the company's | | | | break down at the end of a potential dead-end run. |
| headquarters in Essex , England , focusing on the | | | | This would have negated the need to cut into the |
| logistics on getting 32 multi-disciplined operatives and | | | | pipe, as well as alleviating any risk of losing it. This |
| 46 t of cleaning and de-scaling equipment onsite at | | | | particular pigging solution had been developed prior to |
| Bonny Island as soon as possible. | | | | the project. |
| Project planning was also started, involving 12km of | | | | Once the pipeline cleaning and de-scaling work had |
| pipeline and 60,000 heat exchanger tubes. With a | | | | been completed. Tube Tech also put both closed |
| convolution of bends and 'T-offs in a maze of | | | | circuit TV and wall thickness integrity assessment |
| differing diameters of pipe work, there was no 'one | | | | inspection equipment into action. This enabled |
| size fits all' cure. In the event, the project team | | | | technicians to inspect the wall thickness of the pipes |
| came up with a combination of 12 techniques to clear | | | | electronically rather than by using expensive intelligent |
| highly stubborn scale and blockages. | | | | pigging. |
| An airborne assault was organised, and 3 cargo | | | | The competition |
| aircrafts of equipment were off- loaded in Nigeria just | | | | While there are many pipeline cleaning systems |
| 2 weeks after the initial site visit. Working continuous | | | | available from global sources, with every successful |
| day and night shifts in frequently extreme weather | | | | contract Tube Tech has frequently found the basic |
| conditions the teams completed the cleaning and | | | | equipment to be inadequate for dealing with the |
| integrity inspection three times faster than the | | | | problems specific to each contract. |
| nearest competing estimate. | | | | It is client's increased dislike of the environmentally |
| The plant was quickly restored to full production | | | | unsound chemical route and the costly cutting |
| using 12 techniques. The first cleaning system was a | | | | method that has led to the development of bespoke |
| novel 'mini pig', only 150mm in length and conforming | | | | solutions by the research team. With this 'applied |
| to the tube internal diameter. Propelled by water, the | | | | innovation' in conjunction with an in-depth study of |
| rotating blades only extended as far as the tube | | | | the system, the company has changed the rules of |
| diameter and not beyond, thereby avoiding any | | | | pigging and exchanger cleaning by inventing new pigs |
| damage. | | | | and tube cleaning processes. |
| The middle third of the dart houses a rotating bladed | | | | In the case of the Nigeria contract, the client |
| turbine, and with a water pressure of 500 psi, these | | | | approached a number of other companies, but none |
| blades (emulating the turbine blades on an aircraft | | | | were able to offer more than three cleaning |
| engine) are forced to rotate at a speed of | | | | techniques 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 blockage | | | | involvement came through the recommendation of |
| consisted of calcium and iron oxide product. The | | | | Shell Global Solutions International (SGSI). Without |
| rotating blades remove impeding scale in their path at | | | | using 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 a | | | | consistencies 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 and | | | | was why the client was looking for a fast, effective |
| manufactured by hand in materials that can be | | | | cure. |
| ferrous or non-ferrous. Tube Tech has a wide range | | | | The reward for restoring production to 100% was |
| of Darttsâ„¢ to suit diameters ranging from | | | | the 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 a | | | | prevent further scale blockages, particularly with the |
| traditional, automated high-pressure water-jetting | | | | introduction of vital measures for sound quality water |
| lance, but this was modified by Tube Tech to create | | | | treatment. |
| a new, more effective, method for the smaller pipes. | | | | While pipeline blockages are eminently treatable with |
| Its engineers adapted this system by modifying the | | | | expertise, there is a cause for a rethink on several |
| traditional high pressure jetting hose system, which | | | | fronts where prevention is better than cure. Process |
| normally reaches a maximum pipe length of 400m, so | | | | pipelines 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, thereby | | | | fabricators proven advice on how to modify them so |
| avoiding the worst case scenario of substantial | | | | that, rather than fighting fires are serious problems |
| downtime at Bonny Island and the vast financial | | | | arise, 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 work | | | | out-engineer the problem. |