| 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 can | | | | client, but it too required cleaning and |
| reduce the cost of pipeline cleaning and | | | | de-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 has | | | | The only solution option proffered by many |
| not substantially changed, but the demands | | | | experts 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 lost | | | | to cut into the pipeline and pressure jet. |
| production time and equipment costs if | | | | |
| pipelines have to be dismantled to be | | | | However, along with this option came |
| cleaned. | | | | environmental implications and costs. There |
| | | | were also considerable safety issues, as well |
| The key for pipeline cleaning and specialist | | | | as the cost of cutting the pipe open at |
| companies such as Tube Tech International, is | | | | various points. |
| the ability to bring innovative thought to | | | | |
| problems that have always bedevilled the | | | | Tube Tech went ahead with an environmentally |
| petrochemical industry. Indeed, the company's | | | | sound solution using non-standard pigging. |
| reputation is growing rapidly on the back of | | | | The volume of scale built up in the pipeline |
| the proposal that won it a three-year | | | | was such that it needed to be cleaned over |
| contract with Nigeria LNG Ltd (NLNG).1 | | | | the whole surface area, or the flow rate |
| | | | would have been compromised. The result was |
| Problems at the gas processing plant in the | | | | that 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 had | | | | including: |
| 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 system | | | | 25mm 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 be | | | | ahead, the increased water back pressure |
| minimal because none of the pipelines would | | | | would engage a solenoid in the nose of the |
| need to be cut | | | | pig, 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's | | | | run. This would have negated the need to cut |
| headquarters in Essex , England , focusing on | | | | into the pipe, as well as alleviating any |
| the logistics on getting 32 multi-disciplined | | | | risk of losing it. This particular pigging |
| operatives and 46 t of cleaning and | | | | solution had been developed prior to the |
| de-scaling equipment onsite at Bonny Island | | | | project. |
| as soon as possible. | | | | |
| | | | Once the pipeline cleaning and de-scaling |
| Project planning was also started, involving | | | | work had been completed. Tube Tech also put |
| 12km of pipeline and 60,000 heat exchanger | | | | both closed circuit TV and wall thickness |
| tubes. With a convolution of bends and | | | | integrity assessment inspection equipment |
| 'T-offs in a maze of differing diameters of | | | | into 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 up | | | | electronically rather than by using expensive |
| with a combination of 12 techniques to clear | | | | intelligent pigging. |
| highly stubborn scale and blockages. | | | | |
| | | | The competition |
| An airborne assault was organised, and 3 | | | | |
| cargo aircrafts of equipment were off- loaded | | | | While there are many pipeline cleaning |
| in Nigeria just 2 weeks after the initial | | | | systems available from global sources, with |
| site visit. Working continuous day and night | | | | every successful contract Tube Tech has |
| shifts in frequently extreme weather | | | | frequently found the basic equipment to be |
| conditions the teams completed the cleaning | | | | inadequate for dealing with the problems |
| and integrity inspection three times faster | | | | specific to each contract. |
| than the nearest competing estimate. | | | | |
| | | | It is client's increased dislike of the |
| The plant was quickly restored to full | | | | environmentally unsound chemical route and |
| production using 12 techniques. The first | | | | the costly cutting method that has led to the |
| cleaning system was a novel 'mini pig', only | | | | development of bespoke solutions by the |
| 150mm in length and conforming to the tube | | | | research team. With this 'applied innovation' |
| internal diameter. Propelled by water, the | | | | in conjunction with an in-depth study of the |
| rotating blades only extended as far as the | | | | system, the company has changed the rules of |
| tube diameter and not beyond, thereby | | | | pigging and exchanger cleaning by inventing |
| avoiding any damage. | | | | new pigs and tube cleaning processes. |
| | | | |
| The middle third of the dart houses a | | | | In the case of the Nigeria contract, the |
| rotating bladed turbine, and with a water | | | | client approached a number of other |
| pressure of 500 psi, these blades (emulating | | | | companies, but none were able to offer more |
| the turbine blades on an aircraft engine) are | | | | than three cleaning techniques involving |
| forced to rotate at a speed of approximately | | | | either 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 the | | | | recommendation of Shell Global Solutions |
| blockage consisted of calcium and iron oxide | | | | International (SGSI). Without using any of |
| product. The rotating blades remove impeding | | | | these options, Tube Tech was armed with 12 |
| scale in their path at a travel rate | | | | techniques tailored to the varying |
| averaging out at approximately 2 m/s. using | | | | consistencies and volumes facing them. The |
| this method, pipe work can be cleaned in a | | | | loss 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 materials | | | | The reward for restoring production to 100% |
| that can be ferrous or non-ferrous. Tube Tech | | | | was the three-year contract for further work. |
| has a wide range of Darttsâ„¢ to suit | | | | This 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 a | | | | introduction of vital measures for sound |
| traditional, automated high-pressure | | | | quality 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 engineers | | | | treatable with expertise, there is a cause |
| adapted this system by modifying the | | | | for a rethink on several fronts where |
| traditional high pressure jetting hose | | | | prevention is better than cure. Process |
| system, which normally reaches a maximum pipe | | | | pipelines are not often manufactured with a |
| length of 400m, so that it can extend as far | | | | view 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 of | | | | rethink at the manufacturing stage can tackle |
| substantial downtime at Bonny Island and the | | | | the root causes of scaling and blockages to |
| vast financial impact that would be implicit. | | | | out-engineer the problem. |