Method of determining fouling

Abstract

A method of determining fouling of a segment (fig.3, 301) of a pipe (fig.3, 300) comprising receiving first measured segment data 201 indicative of a measured internal radius of a first segment of pip

Description

The present disclosure relates to a method of determining fouling. More particularly, the present disclosure relates to: a method of determining fouling of a pipe, of a segment of a pipe or of a plurality of segments of pipe; a computer program product; and a system comprising the computer program product and an inspection pig. Tubing systems in refining furnaces, boilers, fired heaters and other fixed industrial processing apparatuses typically have a sinusoidal path to optimise the exposure of the contents of the tubing systems to heat. Such a sinusoidal path is frequently referred to as being serpentine. Other connecting pipelines, which may be above ground, below ground or under water, can be treated in a similar way for both cleaning and testing using controlled pigs. In a typical tubing system, a product to be treated usually passes through the tubing system that has horizontally and / or vertically set tubes, and the passage of the product through the tubing system may be in a horizontal direction, a downward direction, an upward direction, or a combination thereof. Some tubing systems may include a section of closely packed tubes that may be used to, for example, raise a temperature of the product to be treated by way of convection heating. The pre-heated product may then be passed to a subsequent section of the tubing system in which there is more space between the tubes, and such tubes may be heated by way of radiant heating. Typically, in both sections, the tubing system includes straight tube sections joined by bent tube sections, which may be semi-circular (also known as U-bends) or may be box headers with sharp bends in the form of 90 degree turns, sometimes referred to as "horseshoes" and / or "mule ears". Other tubing systems may include at least one helical coiled tube or at least one arbour coiled tube. The term "p:g" (or otherwise known as pipeline inspection gauge) is used to refer to devices that are passed through a pipe or tubing whether for cleaning purposes or for monitoring the condition of the pipe or tubing. Pigs may be used for aiding separation of product from the pipe or tubing, in particular identifying materiai build-up on interior walls of the pipe or tubing, for fluid transport separation, etc. Pigs may be used to inspect, detect and record conditions of a pipe or tubing from the inside to check the surface conditions of the interior and / or exterior of the pipe or tubing, to check for material deposits on the interior and / or exterior wails of the pipe or tubing and to check for degradation and irregularities in the pipe or tubing. This is important because, if a pipe or tubing is blocked, breached or has a compromised structural integrity during its operation, it could not only lead to costly and disruptive unscheduled downtime but also result in life threatening conditions for nearby people. In addition, it is known to wrap or encase pipelines in insulation material. Carrying out inspection of such pipelines from the inside may avoid costly time and effort in removing the insulation material for the purpose of exposing the pipeline's outer surface. In order for efficient and safe operation of a tubing system, it is important that the tubing system is not only periodically cleaned and free from deposits, but also inspected to ensure the walls of the tubing system are free from undesirable deposits, tube material condition anomalies, wall thinning and / or various forms of metallurgical degradation. Inspection of a pipe or tubing may be performed to assess the need for cleaning and / or repair or to assess the effectiveness of previous cleaning and / or repair. Conventionally, inspections of a pipe or tubing have been performed online through viewing windows and / or by inspecting the pipe manually during shutdown of the pipe or tubing. Monitoring of the condition of a pipe or tubing has also been conventionally carried out by radiography, precision monitoring of flow and pressure, thermal imaging, and hand-held non-destructive testing (NDT) such as ultrasonic testing (UT). However, each of these techniques is limited in its usefulness and has its disadvantages. Manual NDT can be time consuming, for example taking 6-7 days fully to inspect an entire furnace, and also requires abrasive cleaning of the outer wall of the tubing system of the furnace in order to enable successful inspection. Furthermore, a furnace would normally need internal scaffolding to enable the inspection to be carried out, thus costing considerable time. Thermal imaging usually involves searching for hotspots as an indication of contamination, but is not suitable for inspecting closely packed tubes such as seen in convection heating sections. When monitoring is carried out whilst the furnace is in operation, some areas of the tubing system may not be visible through the viewing windows. Furthermore, the far side of the tubing system is either difficult or impossible to monitor using the conventional monitoring techniques. Accordingly, it may be necessary to replace one or more sections of the tubing system according to a supplier-provided lifetime warranty, which can result in not only unnecessary replacement of tube sections but also unnecessary and costly downtime of the tubing system. In subsea situations and where accessibility is prevented by normal means, use of controlled pigging can present a unique option for cleaning and material inspection. Alternatives, such as use of skilled / qualified divers or submersible remote operated equipment, can introduce additional dangers and restrictive or prohibitively high costs. It is known to provide a tethered pig with monitoring equipment and to send it through a pipe. Operation of the equipment is controlled from outside the pipe via a cable. Responses detected by the on-board monitoring equipment are transmitted back along the cable to an external monitoring unit. According to a first aspect of the present disclosure, there is provided a method of determining fouling comprising determining fouling of a segment of pipe by: receiving first measured segment data indicative of a measured internal radius of a first segment of pipe; calculating a fouling thickness wherein the fouling thickness is a difference between the measured internal radius of the first segment of pipe and a first expected radius wherein the first expected radius is an expected unfouled internal radius of the first segment of pipe; determining a fouling parameter wherein the fouling parameter is based on the fouling thickness; and obtaining an indication of fouling by comparing the fouling parameter to a predetermined fouling threshold value wherein the fouling parameter exceeding the predetermined fouling threshold is indicative of fouling of the first segment of pipe. In one or more embodiments, the first measured segment data may further be indicative of the presence or absence of scattering of a measurement signal; and wherein the step of obtaining an indication of fouling further comprises identifying an indication of scattering of the measurement signal in the first measured segment data. In one or more embodiments, the fouling parameter may be the fouling thickness and wherein the predetermined fouiing threshold value is a predetermined fouling threshold thickness. In one or more embodiments, the fouling parameter may be a fouling volume calculated as a product of the fouling thickness and a surface area of the internal surface of the first segment of pipe and wherein the predetermined fouling threshold value is a predetermined fouling threshold volume. In one or more embodiments, the method may further comprise the steps of: defining a plurality of segments of the internal surface of the pipe and receiving a plurality of measured segment data each indicative of a measured internal radius of the corresponding segment of pipe wherein the first measured segment data comprises one of the plurality of measured segment data; and determining fouling of each segment of pipe represented by the plurality of measured segment data by, for each segment of pipe: receiving the measured segment data indicative of a measured internal radius of the corresponding segment of pipe; calculating a fouling thickness wherein the fouling thickness is a difference between the measured internal radius of the segment of pipe and a corresponding expected radius wherein the corresponding expected radius is an expected unfouled internal radius of the segment of pipe; determining a fouling parameter for the segment of pipe wherein the fouling parameter is based on the fouling thickness of the segment of pipe; obtaining an indication of fouling of the segment of pipe by comparing the fouling parameter to the predetermined fouling threshold value wherein the fouling parameter exceeding the predetermined fouling threshold is indicative of fouling of the segment of pipe. In one or more embodiments, the method may further comprise classifying the pipe as fouled if more than a predetermined acceptable number of segments are identified as being fouled. In one or more embodiments, the method may further comprise, prior to determining fouling of each segment of pipe, comparing the measured internal radius of two segments of the pipe which are located adjacent to one-another on the pipe and, if a difference between the radii of the two segments is greater than a predetermined difference threshold, the method comprises excluding the measured segment data associated with the two compared segments from the determination of fouling. In one or more embodiments, the method may further comprise, prior to determining fouling of each segment of pipe represented by the plurality of measured segment data, for each segment of pipe of the plurality of segments of pipe, comparing the measured internal radius of the segment of pipe to the measured internal radii of at least two adjacent segments of pipe and, if the difference between the radius of the segment of pipe differs from both of the two adjacent segments by more than a predetermined difference threshold, the method comprises excluding the measured segment data associated with the segment of pipe from the determination of fouling. In one or more embodiments, the method may further comprise the step of presenting the information indicative of which of the segments of the pipe are fouled to the user based on the determination of fouling of each segment of pipe. In one or more embodiments, the method may further comprise the step of providing instructions to a cleaning pipeline inspection gauge (PIG) to dean the fouled segment or segments. In one or more embodiments, the method may further comprise the step of providing instructions to a cleaning PIG to clean the whole pipe based on the pipe being classified as fouled. In one or more embodiments, the method may further comprise receiving the measured segment data from an inspection PIG that comprises at least one sensor configured to collect the measured segment data. In one or more embodiments, the inspection PIG from which the measured segment data are received may comprises a plurality of sensor elements configured to collect the measured segment data corresponding to a plurality of different circumferential segments of the pipe such that circumferential segmentation of the pipe is defined by the number of sensor elements mounted on the PIG. In one or more embodiments, the PIG may be configured to travel longitudinally through the pipe and, while travelling through the pipe, the PIG is configured to record a plurality of segment data measurements along the length of the pipe wherein the surface area of the plurality of segments of the internal surface of the pipe are defined by the product of the number of measurements taken over the length of the pipe by the circumferential length of each circumferential segment defined by the sensor elements of the PIG. According to a second aspect of the present disclosure, there is provided a computer program product comprising computer program code configured to cause a computing system comprising a processor and a memory to perform the method of any of claims 1-14 when the computer program code is executed on the computing system. According to a third aspect of the present disclosure, there is provided a system comprising the computer program product of claim 15 and an inspection PIG configured to record the measured segment data. It will be appreciated that the use of the terms "first" and "second", and the like, in this patent specification is merely intended to help distinguish between similar features, and is not intended to indicate the relative importance of one feature over another feature, unless otherwise specified. Within the scope of this patent application, it is expressly intended that the various aspects, embodiments, exampies and aiternatives set out in the preceding paragraphs, and the ciaims and / or the foliowing description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and all features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that other embodiments, beyond the particular embodiments described, are possible as well. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are covered as well. The above discussion Is not intended to represent every example embodiment or every implementation within the scope of the current or future Claim sets. The figures and Detailed Description that follow also exemplify various example embodiments. Various example embodiments may be more completely understood in consideration of the following Detailed Description in connection with the accompanying Drawings. Brief Description of the Drawings One or more embodiments will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows an example inspection pig comprising a plurality of sensor elements located in a pipe; Figure 2 shows an example method of determining fouling according to one or more embodiments of the present disclosure; Figure 3 shows an exampie of a pipe, the internai surface of which has been separated into a plurality of segments; Figure 4 shows a computer readable medium comprising computer program code; and Figure 5 shows an example system comprising the computer program product and an inspection pig. Detailed Description A pig for one or both of inspecting and cleaning a tubular object, such as a pipe, is shown in Figure 1 and is designated generally by the reference numeral 30. The pig 30 of the depicted embodiment comprises a body 32 that comprises an intermediate portion 34 arranged between two end portions 36 so that the intermediate portion 34 and the end portions 36 are co-axially aligned along the length of the pig 30. The cross-section of each of the intermediate portion 34 and end portions 36 is substantially circular but may vary in shape in other embodiments. The intermediate portion 34 Is in the form of a sensor ring onto which a sensor comprising a plurality of sensor elements 38 is mounted. In one or more embodiments, the sensor ring may be a transducer ring onto which a transducer comprising a plurality of transducer elements 38 is mounted. The present disclosure will generally discuss a pig equipped with transducers for acquiring measured segment data indicative of a measured internal radius of a first segment of a pipe through which the pig travels. It will be appreciated, however, that other types of sensors could be used to measure the internal radius of segments of pipes through which the pig travels and, as such, the present disclosure should not be considered to be limited only to transducers. The transducer elements 38 are arranged in a single row about the entire circumference of the body 32 at a predetermined pitch Y and diameter. Preferably, the transducer elements 38 have the same length X and the same width Z. The transducer elements 38 may be encapsulated by an epoxy resin (not shown), which not only mechanically holds the transducer elements 38 in place but also acts as a matching layer. The intermediate and end portions 34,36 together define a single body 32 of the pig 30, i.e. a single-bodied pig 30. Each end portion 36 may be covered by a respective end cap on which an alignment implement is mounted. The alignment implements are configured to, in use, engage an interior wall of the tubular object so as to align the pig 30 relative to the tubular object. Each alignment implement may comprise a plurality of radially extending resilient brushes or a resilient flange. In the embodiment shown, the plurality of transducer elements 38 is a plurality of ultrasonic transducer elements that are operable to both transmit and receive an ultrasonic signal (or signals). Each transducer element 38 includes a piezocomposite crystal, which functions as a transmitter to convert an electrical signal supplied by an electronic component into a transmitted ultrasonic signal. The transmitted ultrasonic signa! is transmitted towards the wall of the tubular object and is then reflected off an internal or external surface of the wall of the tubular object, or off material build-up on an interior or exterior wall of the tubular object, back towards the piezocomposite crystal. In this way, the piezocomposite crystal is able to receive a first reflected ultrasonic signal from the internal wall surface of the tubular object, and also receive a second reflected ultrasonic signal from the external wall surface of the tubular object. The piezocomposite crystal then functions as a sensor that converts the received (reflected) ultrasonic signai(s) into an electrical signal (or electrical signals) for analysis. In other embodiments, the plurality of transducer elements may instead be a plurality of sensor elements configured to transmit other types of acoustic signals or electromagnetic radiation signals. For example, each transmitter may be a laser or radio transmitter. It will also be appreciated that, in other embodiments of the invention, each sensor element may include a transmitter and receiver that are separate from each other. Each of the intermediate and end portions 34,36 defines a bore therein along its length. A bore of each end portion 36 is connected to a respective end of a bore of the intermediate portion 34 so that the bores of the end portions 36 combine with the bore of the intermediate portion 34 to define an overall bore of the pig 30. The pig 30 includes a controller 40 and a power supply device (e.g, a battery) that is stored inside the bore of the pig. The controller 40 may be, for example, a computer or a processor. The pig 30 further includes a printed circuit board that is stored inside the bore of the pig 30. The controller 40 and the power supply device are preferably mounted onto the printed circuit board. Flexible electrical connections (e.g. electrical wires) are used to connect the sensor elements 38 to the printed circuit board. This is so that the controller 30 can send control signals for operating the transducer elements 38 and receive information collected by the transducer elements 38. The pig 30 preferably comprises a storage media device, such as a memory card, configured to store the information collected by the plurality of transducer elements 38. The storage media device is preferably stored inside the bore. A pig may be an inspection pig which is configured to inspect the conditions within the pipe. Such a pig may make use of the sensor elements to measure the internal radius of the pipe as it travels therethrough. A pig may be a cleaning pig which is configured to clean the interior of the pipe. Such a pig may make use of, for example, brushes, resilient flanges and other cleaning implements in order to provide for the cleaning functionality. In other embodiments, the pig may be both an inspection pig and a cleaning pig configured to provide both sets of functionality. Figure 2 shows an example embodiment of a method of determining fouling according to the present disclosure. The method comprises determining fouling of at least a segment of a pipe. It will be appreciated that, in the context of the present disclosure, the reference to a pipe may be a reference to any hollow tube through which a pig can travel and perform either inspection or cleaning of. For the purposes of analysis, a pipe may be divided into a single segment or a plurality of segments which, in the present disclosure, can be analysed to determine the presence or absence of fouling. The segments define a portion or portions of the pipe which can be separately analysed. Smaller segments may provide for a higher resolution indication of the presence of fouling while larger segments (including defining the pipe as having a single iarge segment) may provide for a coarse determination of the presence of fouling. The disclosed method is effective whether used as a coarse or fine measure of fouling of a pipe. In one or more embodiments, both the fouling of small segments and larger segments will be calculated. Calculating the degree of fouling of both small segments and large segments may allow for comparisons between levels of fouling to be made. For example, a degree of fouling of the whole pipe may be calculated and the average fouling of one or more segments of the whole pipe may calculated. Using all of this data, a relative degree of fouling of small segments may be calculated as a comparison to the average fouling of the whole pipe. The method comprises receiving 201 first measured segment data indicative of a measured internal radius of a first segment of pipe. The data may be received in any suitable form and may be received from an inspection pig. For example, the first measured segment data may be received via a data cable coupled to the pig. Alternatively, in embodiments where the attenuation provided by the pipe through which the pig is travelling is not a problem, the first measured segment data may be transmitted wirelessly to a receiver of a computing system. The measured internal radius of the first segment of pipe, or any measured segment of pipe, will not represent the radius of the pipe itself in the presence of fouling but will. Instead, be an apparent Internal radius of the pipe where the apparent internal radius is smaller than the true internal radius of the pipe due to the presence of fouling. That is, fouling will reduce the empty space within the pipe leading to a lower measured radius compared to the radius of the pipe itself. Where no fouling is present, the measured internal radius will be representative of a true radius of the pipe. The method further comprises calculating 202 a fouling thickness wherein the fouling thickness is a difference between the measured internal radius of the first segment of pipe and a first expected radius. The first expected radius may be the expected unfouled internal radius of the first segment of pipe. Thus, calculating the difference between the measured internal radius of the first segment and the first expected radius, one is left with the thickness of fouling material deposited on the interior pipe. The method further comprises determining 203 a fouling parameter wherein the fouling parameter is based on the fouling thickness. The fouling parameter may be any of a plurality of possible fouling parameters which provides an indication of the degree of fouling of the first segment of pipe. The fouling parameter may be the fouling thickness itself. In such an embodiment, no additional steps may be required to determine the fouling parameter since this has already been determined. In other embodiments, however, the fouling parameter may be, for example, a fouling volume. The fouling volume may be calculated as a product of the fouling thickness and a surface area of the internal surface of the first segment of pipe. The internal surface area of the pipe may be calculated as a product of the longitudinal length of the segment multiplied by the circumferential length of the unfouled segment which itself may be calculated as RD where: n is the constant otherwise written as "pi"; and D is the unfouled diameter of the pipe. It will be appreciated that such a calculation of the fouling volume may be an estimate of the true fouling volume since the average circumferential length of the fouling material which makes up the fouling volume will be slightly lower than the circumferential diameter of the unfouled pipe. In other embodiments, a more accurate estimate of the fouling volume may be calculated by calculating an average circumferential length of the fouling material by using an average estimated radius of the fouling material. It will be appreciated that other approaches to estimating the fouling volume may also be used. Alternative fouling parameters indicative of the amount of fouling that are based on the fouling thickness may also be used. It will be appreciated that the skilled person may calculate any of a number of possible parameters based on the fouling thickness. The fouling thickness may not be a completely accurate measure of the degree of fouling of the segment of pipe in question (such as the first segment) since the true internal radius of the pipe may differ from the expected radius for reasons other than fouling. For example, the thickness of the pipe may not be uniform throughout its length and the expected internal radius may only be an estimate or average of the internal radius of the pipe across a whole or part of its length. For this reason, the use of the predetermined fouling threshold value allows for both: differences between the true internal radius of the pipe and the expected radius of the pipe; and an acceptable level of fouling to be tolerated. In one or more embodiments, the pig may be configured to enter a measurement mode in which it is configured to measure the internal radius of the pipe across one or more segments. Where the measured internal radius of the pipe is consistent, the pig may be configured to register the measured consistent internal radius as the expected radius of the pipe or as the internal radius of one or more segments of the pipe, such as the expected radius of the first segment of pipe. The method further obtaining 204 an indication of fouling by comparing the fouling parameter to a predetermined fouling threshold value. If the fouling parameter exceeds the predetermined fouling threshold value, this is considered to be an indication that the first segment is fouled. The fouling threshold value may be a value which indicates a maximum allowable value of the fouling parameter before the segment of pipe is determined to be fouled or, at least, unacceptably fouled. The fouling threshold value may be a set value or it may be a value which can be defined by a user based on a user input. The fouling threshold value may be a value that has the same dimensions as the fouling parameter. For example, If the fouling parameter is a distance (such as a radius), then the fouling threshold value may be the maximum acceptable distance (such as radius) before which the pipe segment is considered to be fouled. In other embodiments, if the fouling parameter is a fouling volume (i.e., an estimated volume of fouling material built up on the segment), then the fouling threshold value may be a maximum acceptable fouling volume before which the pipe segment is considered to be fouled. In further embodiments, there may be provided a plurality of threshold values that define one or more threshold bounds. Depending on which threshold bound within which the fouling parameter falls, different actions may be taken, planned or recommended. The actions which may be taken will be described in further detail below. It will be appreciated that any suitable actions or combination of actions may be taken. The first measured segment data may further be indicative of the presence or absence of scattering of a measurement signal. That is, during the measurement of the internal radius of the pipe, the measurement signal (which may, for example, be an ultrasonic signal) may be scattered by the feature from which it is reflected. The feature from which the signal is reflected may be referred to as the reflector. Where the pipe is not fouled, the measurement signal is more likely to be reflected without substantia! scattering and, as such, the corresponding measured segment data will be indicative of the absence of scattering of the measurement signal. In contrast, where the pipe is fouled, the fouling is unlikely to have a uniform surface and, as such, the measurement signal is more likely to be reflected with scattering and, as such, the corresponding measured segment data will be indicative of the presence of scattering of the measurement signal. The indication of fouling may be further defined by the presence of an indication of scattering in the measurement signal. That is, method may comprise validating the indication of fouling by identifying the presence of scattering of the measurement signal in the measured segment data. Figure 3 shows an example of a pipe 300, the internal surface of which has been split into a plurality of segments 301, as will be described. The method may further comprise a step of defining a plurality of segments 301 of the internal surface of the pipe 300, as depicted in Figure 3. The segments 301 of the internal surface of the pipe 300 may be defined by a pig which is performing the data collection. The number of sensor elements which are mounted to the pig may define the number of segments 301 that the circumference of the pipe 300 is separated into. For example, in an embodiment where the pig has four sensor elements located around its sensor ring, the circumference of the internal surface of the pipe may be split into four sections, thereby defining the circumferential segmentation of each segment which defines the circumferential resolution of the measurements. The longitudinal segmentation may be defined by the pig as it travels longitudinally through the pipe and records a plurality of segment data measurements. The longitudinal length of each segment 301 may be defined by the number of measurements taken over the length of the pipe, i.e., the regularity with which measurements are recorded per unit length which thereby defines the longitudinal resolution of the measurements. The longitudinal resolution may also be referred to as an axial resolution. The surface area of each segment 301 may then be defined as the product of the number of measurements taken over the length of the pipe 300 by the circumferential length of each circumferential segment. It will be appreciated that this may provide one way of defining the segments 301 of the internal surface of the pipe 300, however, different methods may be used to define the size of the segments 301. The method may further comprise receiving a plurality of measured segment data each indicative of a measured internal radius of the corresponding segment of pipe. The plurality of measured segment data may be received directly from a pig which performed the measurements or the measured segment data may be received from an intermediate device which itself received the measured segment data from the pig. In still other embodiments, the data may not necessarily be received from a pig and, instead, may directly or indirectly be received from another device which is capable of obtaining the measured segment data. It will be appreciated that, herein, the word "corresponding" is used to indicate that the measured segment data is data indicative of the internal radius of the referred-to segment of pipe and not a different segment. The method may then, based on the received plurality of measured segment data, determine fouling of each segment of pipe of the plurality of defined segments of the internal surface of the pipe. The first measured segment data comprises one of the plurality of measured segment data. This determination of fouling may be performed in the same way as depicted in figure 1 and as described above for the first segment. That is, determining fouling of each segment of pipe represented by the plurality of measured segment data may comprise, for each segment of pipe: receiving the measured segment data indicative of a measured internal radius of the corresponding segment of pipe, calculating a fouling thickness wherein the fouling thickness is a difference between the measured internal radius of the segment of pipe and a corresponding expected radius wherein the corresponding expected radius is indicative of an expected unfouled internal radius of the segment of pipe; determining a fouling parameter for the segment of pipe wherein the fouling parameter is based on the fouling thickness of the segment of pipe; and obtaining an indication of fouling of the segment of pipe by comparing the fouling parameter to the predetermined fouling threshold value wherein the fouling parameter exceeding the predetermined fouling threshold is indicative of fouling of the segment of pipe. It will be appreciated that any optional steps, alternatives or other features described in relation to the method of determining fouling of the first segment may equally be applied to the determination of fouling of each or any segments of pipe. The method may include classifying the pipe as a whole as fouled if more than a predetermined number of segments are identified as being fouled. For example, if seven of twenty segments are identified as being fouled, then the whole pipe may be classified as fouled. The predetermined number of segments may be a fixed number of segments or percentage of segments, such as 30%, 40% or 50% or another percentage of segments. In other embodiments, the pipe may be separated into macro-segments where each macro-segment is comprised of a plurality of the segments of pipe. In such an embodiment, a macro-segment may be defined as fouled if more than a predetermined number of segments of the macro-segment are identified as being fouled. This may be helpful for particularly long pipes where it is more advantageous to be able to define particular macro-segments of a pipe as fouled as opposed to the whole pipe. Defining a whole pipe, a macro-segment or one or more individual segments of pipe as fouled may be particularly useful, as these classifications may be used to inform further actions. One action which may be taken as part of the method is presenting the information indicative of which of the segments of pipe are fouled to a user based on the determination of fouling of each segment of pipe. The information regarding fouling, or non-fouling, may be presented to the user in any suitable form such as a report, a graph, a dashboard, an audio output or in another form. A user of a computing device on which the report is displayed, or another computing device, may be able to initiate additional actions in response to receipt of the presentation of the information. A further action which may be additionally or alternatively be taken as part of the method may be a step of providing instructions to a cleaning pipeline inspection gauge (pig) to clean the fouled segment or segments. The provision of instructions to the pig may be an automatic action based on one of several indications of fouling. In other examples, the provision of instructions to the pig to perform cleaning may be based on a user input indicative that cleaning should be performed. The pig may be instructed to clean one or more fouled segments of pipe based on the identification of one or more fouled segments of pipe. The pig may be instructed to clean only fouled segments of pipe, fouled segments and segments adjacent to the segments identified as fouled or to clean the whole pipe based on the identification of any fouled segments. In other embodiments, the pig may be instructed to perform cleaning only if the whole pipe or a macro-segment of pipe has been designated as fouled based on more than a predetermined number of acceptable segments being identified as fouled. One or more of the optional follow-up actions approaches may allow for efficient cleaning of a pipe without requiring cleaning the entire pipe based on an indication of only one or two fouled segments or macro-segments. In other embodiments, an identification of more than a predetermined number of acceptable fouled segments or macro segments may be enough to Instruct cleaning of the whole pipe, thereby spending less time on inspection than may be performed if the entire pipe is inspected. In embodiments wherein a plurality of threshold values is used to define one or more threshold bounds, different actions may be taken based on the bound in which the fouling parameter falls. For example, where: a first threshold bound is defined between a first threshold value and a second threshold value; and a second threshold bound is defined between the second threshold value and a third threshold value, the method may comprise presenting the information indicative of the identification of a fouled segment if the fouling parameter falls within the first threshold bound. If the fouling parameter falls within the second threshold bound, the method may comprise both presenting the information to a user and automatically instructing cleaning of the identified fouled segment, macro-segment or pipe. It will be appreciated that, in this example, the second threshold value would be larger than the first threshold value and the third threshold value would be larger than the second threshold value. Different levels of cleaning may also be defined and instructed, depending on the level of fouling that is identified by way of the use of threshold bounds. The method may further comprise one or more steps performed prior to the steps for determining fouling of the plurality of segments of pipe. For example, there may be provided one or more validation steps which are performed in order to remove outlier measured segment data. Outlier segment data may result from errors made during measurement which may occur for any number of reasons. The validation steps comprise comparing the measured internal radius of each segment to the measured internal radius of at least a second, adjacent, segment. Herein, an adjacent segment is defined as a segment which physically borders another segment in the pipe. If the difference in the radii of adjacent segments is greater than a predetermined difference threshold, this may be an indication that one of the measurements is an outlier resulting from an error during measurement. This validation step can be performed because it is not expected that the internal radii of the pipes will change suddenly but that, instead, there wiil be steady changes in any fouiing within the pipes. In one or more embodiments, the method comprises comparing the measured internal radius of two segments of the pipe which are located adjacent to one-another on the pipe. If a difference between the radii of the two segments is greater than the predetermined difference threshold, the method may comprise excluding the measured segment data associated with the two compared segments from the determination of fouiing. In this embodiment, since only two segments are compared, it may not be possible to tell which of the segments is the outlier measurement and, as such, it may be preferable to disregard both segments. In one or more alternative embodiments, the method may comprise, prior to determining fouiing of each segment of pipe represented by the plurality of measured segment data, for each segment of pipe of the plurality of segments of pipe, comparing the measured internal radius of the segment of pipe to the measured internal radii of at least two adjacent segments of pipe. If the difference between the radius of the segment of pipe differs from both of the two adjacent segments by more than a predetermined difference threshold, the method comprises excluding the measured segment data associated with the segment of pipe from the determination of fouling. In order to further differentiate these segments, one might refer to the segment of pipe of interest that is being compared to the two other segments of pipe as the target segment of pipe. The two segments which are being used for the comparison may be referred to as validation segments. In this embodiment, the target segment can be excluded without excluding the validation segments. It will be appreciated that more than two validation segments may be used. In yet other embodiments, an average of the measured internal radii of a set of validation segments comprising two or more segments may be compared to the target segment. Figure 4 shows an example of a computer program product 400 comprising computer program code configured to cause a computing system comprising a processor and a memory to perform the method described with reference to figure 2. The computer program product 400 may be any suitable computer readable medium since as a hard drive, a CD, a USB stick drive or any other medium suitable for comprising the computer program code. Thus, the described method may be a computer implemented method. Figure 5 shows an example system 500 comprising the computer program product 501 described with reference to Figure 4 and an inspection pig 502 configured to record the measured segment data. The system 500 may further comprise a computing system comprising a memory and a processor configured to execute the computer program product of the system. In areas of dean pipe, one measurement is typically sufficient to get an accurate wall measurement. In corroded or otherwise damaged / unclean areas, averaged measurements would be useful for obtaining accurate wall measurements. Accordingly multiple measurements of the corroded or otherwise damaged / unclean areas can be dynamically averaged. It will be appreciated that the above numerical values are merely intended to help illustrate the working of the invention and are not necessarily limiting on the scope of the invention. The listing or discussion of an apparently prior-published document or apparently prior-published information in this specification should not necessarily be taken as an acknowledgement that the document or information is part of the state of the art or is common general knowledge. Preferences and options for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features and parameters of the invention.

Claims

1. A method of determining fouling comprising determining fouling of a segment of pipe by:receiving first measured segment data indicative of a measured internal radius of a first segment of pipe;calculating a fouling thickness wherein the fouling thickness is a difference between the measured internal radius of the first segment of pipe and a first expected radius wherein the first expected radius is an expected unfouled internal radius of the first segment of pipe;determining a fouling parameter wherein the fouling parameter is based on the fouling thickness; andobtaining an indication of fouling by comparing the fouling parameter to a predetermined fouling threshold value wherein the fouling parameter exceeding the predetermined fouling threshold is indicative of fouling of the first segment of pipe.

2. The method of claim 1 wherein the first measured segment data is further indicative of the presence or absence of scattering of a measurement signal; andwherein the step of obtaining an indication of fouling further comprises identifying an indication of scattering of the measurement signal in the first measured segment data.

3. The method of claim 1 or claim 2 wherein the fouling parameter is the fouling thickness and wherein the predetermined fouling threshold value is a predetermined fouling threshold thickness.

4. The method of claim 1 or claim 2 wherein the fouling parameter is a fouling volume calculated as a product of the fouling thickness and a surface area of the internal surface of the first segment of pipe and wherein the predetermined fouling threshold value is a predetermined fouling threshold volume.

5. The method of any preceding claim further comprising the steps of:defining a plurality of segments of the interna! surface of the pipe and receiving a plurality of measured segment data each indicative of a measured internal radius of the corresponding segment of pipe wherein the first measured segment data comprises one of the plurality of measured segment data; anddetermining fouling of each segment of pipe represented by the plurality of measured segment data by, for each segment of pipe:receiving the measured segment data indicative of a measured internal radius of the corresponding segment of pipe;calculating a fouling thickness wherein the fouling thickness is a difference between the measured internal radius of the segment of pipe and a corresponding expected radius wherein the corresponding expected radius is an expected unfouled internal radius of the segment of pipe;determining a fouling parameter for the segment of pipe wherein the fouling parameter is based on the fouling thickness of the segment of pipe;obtaining an indication of fouling of the segment of pipe by-comparing the fouling parameter to the predetermined fouling threshold value wherein the fouling parameter exceeding the predetermined fouling threshold is indicative of fouling of the segment of pipe.

6. The method of claim 5 further comprising classifying the pipe as fouled if more than a predetermined acceptable number of segments are identified as being fouled.

7. The method of claim 5 or claim 6 further comprising, prior to determining fouling of each segment of pipe, comparing the measured internal radius of two segments of the pipe which are located adjacent to one-another on the pipe and, if a difference between the radii of the two segments is greater than a predetermined difference threshold, the method comprises excluding the measured segment data associated with the two compared segments from the determination of fouling.OQ sZ-KS8. The method of any one of claims 5 to 7 further comprising, prior to determining fouling of each segment of pipe represented by the plurality of measured segment data, for each segment of pipe of the plurality of segments of pipe, comparing the measured internal radius of the segment of pipe to the measured internal radii of at least two adjacent segments of pipe and, if the difference between the radius of the segment of pipe differs from both of the two adjacent segments by more than a predetermined difference threshold, the method comprises excluding the measured segment data associated with the segment of pipe from the determination of fouling.

9. The method of any one of claims 5 to 8 further comprising the step of presenting the information indicative of which of the segments of the pipe are fouled to the user based on the determination of fouling of each segment of pipe.

10. The method of any preceding claim further comprising the step of providing instructions to a cleaning pipeline inspection gauge (PIG) to dean the fouled segment or segments.

11. The method of any one of claims 6 to 10 further comprising the step of providing instructions to a cleaning PIG to clean the whole pipe based on the pipe being classified as fouled.

12. The method of any preceding claim wherein the method comprises receiving the measured segment data from an inspection PIG that comprises at least one sensor configured to collect the measured segment data.

13. The method of claim 12 wherein the inspection PIG from which the measured segment data are received comprises a plurality of sensor elements configured to collect the measured segment data corresponding to a plurality of different circumferential segments of the pipe such that circumferential segmentation of the pipe is defined by the number of sensor elements mounted on the PIG.14, The method of claim 13 wherein the PIG is configured to travel longitudinally through the pipe and, while travelling through the pipe, the PIG is configured to record a plurality of segment data measurements along the length of the pipe wherein the surface area of the plurality of segments of the5 internal surface of the pipe are defined by the product of the number of measurements taken over the length of the pipe by the circumferential length of each circumferential segment defined by the sensor elements of the PIG,15. A computer program product comprising computer program code io configured to cause a computing system comprising a processor and a memory to perform the method of any one of claims 1 to 14 when the computer program code is executed on the computing system.

16. A system comprising the computer program product of claim 15 and an 15 inspection PIG configured to record the measured segment data.

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