GB2568045A

GB2568045A - Formulation

Info

Publication number: GB2568045A
Application number: GB1718046.4A
Authority: GB
Inventors: Fairley Gary; Ridge Martin
Original assignee: Sanccus Ltd
Current assignee: Sanccus Ltd
Priority date: 2017-11-01
Filing date: 2017-11-01
Publication date: 2019-05-08
Anticipated expiration: 2037-11-01
Also published as: GB2568045B; GB201718046D0

Abstract

The invention relates to a water-soluble pig comprising from 50 to 100 wt % of one or more polyethylene glycols (PEGs or PEOs), wherein each of the one or more polyethylene glycols has an average molar mass of 400 g/mol or above, preferably 4000 g/mol. The pig may also comprise a plasticizer, a surfactant, dyes and biocides and have a melting point of not less than 45ºC. The pig may be spherical and have a diameter from 5.08 to 60.96 cm. The pig may have a protective covering or mold. A possible method of preparation is supplied along with a possible method of displacing gas from a pipeline comprising inserting the pig in a length of 50 to 250 m pipeline before pushing the pig through with an aqueous liquid - water with or without added glycol or glycol ether. The liquid pushes the pig through the pipeline and displaces the gas, which exits through a vent port at the far end of the pipeline.

Description

The invention relates to a water-soluble pig which comprises 50 to 100 wt % of one or more polyethylene glycols. The invention extends to the preparation of the pig and to the use of same in a pipe or pipeline. In particular, the water-soluble pig of the invention finds use in the onshore removal of air from short sections of pipeline as they are being filled with liquid, before being sealed and transported offshore for connection to a subsea pipeline.

BACKGROUND OF THE INVENTION

Mechanical pipeline pigs typically comprise a few (maybe 3-5) hard polyurethane discs or cups fixed at regular intervals along a metal bar. They are usually inserted into a pipeline under pneumatic or hydraulic pressure using a pre-installed pig launcher. Their primary purpose is to clean and they do this by pushing out bulk gas, liquid hydrocarbon or water. If they have brushes attached, they also scrape the pipe walls to remove wax, scale or other debris. Often mechanical pipeline pigs are used in conjunction with chemicals such as gels and solvents. Typically, the chemicals are pumped into the pipelines prior to the launching of a pig to enhance cleaning or the lifting and transport of debris.

Mechanical pipeline pigs have to be recovered at the end of the cleaning operation which means a pig catcher must be installed at their destination point. The pigs can get stuck in lines if there is an unexpected deposit of debris, if the line is distorted by damage or by loss of drive pressure caused by abrasion and they can get stuck at tight bends. Also, sometimes during the life of a pipeline, the launcher and catcher in a pipeline are removed, for example if a field is redesigned or there is a change in ownership. Further, mechanical pigs cannot be used if the diameter of the pipeline changes. In these instances other pigging methods need to be deployed, such as using foam or gel pigs which are flexible though not as abrasive.

Gel pigs are also used to evacuate the air and allow the filling of short (100-200m) pipeline connectors also known as spools. These are usually filled with a glycol or a glycol/water mix before being sealed, transported offshore and used to connect a new or rerouted subsea pipeline. Gel pigs are an option as they can be ejected out of the spools by shearing through the vent port using the filling liquid, but there is a risk of some sheared pieces of the gel pig material being left behind. Further, filling liquid must be spilled in order to make sure the gel pig is ejected. It would be desirable to avoid the costs associated with wasting the liquid, including the costs of disposing of it. It would also be desirable to avoid leaving gel pig material in the spool which, if left in the spool, would be flushed through the production system when production starts. There is a need for an improved way to prepare spools for transport offshore which overcomes one or more of these problems.

The present invention seeks to solve one or more of the aforementioned problems or meet one or more of the aforementioned objectives.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides a water-soluble pig comprising from 50 to 100 wt % of one or more polyethylene glycols. It has been found that the pig of the invention is especially useful in removing air from sections of a pipeline while the sections of pipeline are being filled with a liquid before they are sealed, transported to the site of a subsea pipeline and connected to the subsea pipeline. The liquid is aqueous, i.e. it comprises water and can be 100 wt % water or a mixture of a watersoluble or water-miscible solvent and water. Once the pig has displaced the air in the section of pipeline and the pipeline is sealed, the pig will dissolve and thus the problems associated liquid spillage and disposal caused by a pig ejection process are avoided.

In a second aspect, the invention provides a method of preparing the water-soluble pig of the invention. In particular, the method involves: melting the one or more polyethylene glycols to form molten polyethylene glycol or a molten mixture of polyethylene glycols; optionally mixing one or more additional components into the molten polyethylene glycol or molten mixture of polyethylene glycols to form a molten composition; casting the molten polyethylene glycol, molten mixture of polyethylene glycols or molten composition into a mold; and allowing the molten polyethylene glycol, molten mixture of polyethylene glycols or molten composition to solidify by cooling.

In a third aspect, the invention provides a method of displacing gas from a pipe using the water-soluble pig of the invention. The method comprises inserting the pig of the invention into an open end of a pipe, introducing an aqueous liquid into the pipe behind the pig so that the liquid pushes the pig through the pipe and displaces the gas in the section of pipe in front of the pig; allowing the gas to exit through, for example, a vent port in the far end of the pipe; and sealing the pig into the pipe once the pig has reached the end of the pipeline. The pipe has two ends, one of which is an open end or pig entry end and, the other, a far end or gas exit end. The far end is also open to allow the gas to exit. In the method of the third aspect of the invention, the pig travels from the open end to the far end. The pig is sealed into the pipe by sealing the open end and the far end/any vent ports. Thus the pig of the invention can be used to purge gas from a pipe. It is particularly useful in the purging of air from a section of pipeline while the section of pipeline is being filled with liquid comprising water before being sealed, transported to the site of a subsea pipeline and connected to the subsea pipeline. The aqueous liquid can be 100 wt % water or a mixture of a water-soluble or water-miscible solvent and water.

In a fourth aspect, the invention provides a method of cleaning a pipe using the watersoluble pig of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

A pipeline is a conduit comprising pipes connected end to end generally used for long distance fluid, i.e. liquid or gas, transport. Pipelines can, for example, be onshore or they can be offshore and/or subsea. The terms “pipe” and pipeline” are used interchangeably herein.

A spool is a pipe, or a “short” section of a pipeline, typically 100 m to 200 m in length which is used, for example, in subsea pipelines. For example, spools can be used as a temporary fix to a subsea pipeline after a valve has been removed for repair. Generally, spools are assembled offsite and then transported to the site of the pipeline to be connected to the pipeline.

A pig is a device that is usually cylindrical, spherical or barrel-shaped and, in use, is inserted into a pipeline and propelled through the pipeline by the pressure of flow of gas, air or liquid introduced behind it. The pig of this invention can be used to clean a pipeline and/or purge a pipeline of gas, such as air. In the context of this invention, purging a pipeline of gas means removing the gas from the pipeline by displacing it with liquid.

As used herein, the term “comprising” is intended also to encompass as alternative embodiments “consisting essentially of” and “consisting of.” “Consisting essentially of” permits the inclusion of substances that do not materially affect the basic and novel characteristics of the composition (pig) under consideration.

In a first aspect, the invention provides a water-soluble pig which comprises from 50 to 100 wt % of one or more polyethylene glycols. This wt % is based on the total weight of the pig. One or more polyethylene glycols constitute from 50 to 100 wt % of the pig and these represent all of the polyethylene glycol(s) in the pig. That is, the one or more polyethylene glycols as defined herein accounts for all of the polyethylene glycol(s) in the pig.

Polyethylene glycol has the general empirical formula H(O CH₂CH₂)_nOH, where n is the degree of polymerization. The one or more polyethylene glycols are each independently chosen from polyethylene glycols having an average molar mass of 400 g/mol or above, or of from 400 g/mol to 8000 or of from 400 g/mol to 6000 g/mol. For example, the one or more polyethylene glycols can be each independently chosen from polyethylene glycols having an average molar mass of from 3000 to 6000 g/mol. The average molar mass is calculated from the OH number according to DIN 53240. Suitable polyethylene glycols include those in the Pluriol E™ range supplied by BASF, for example, Pluriol E™ 600, Pluirol E™ 1500, Pluriol E™ 4000 and Pluriol E™ 6000.

In one embodiment, the one or more polyethylene glycols is one polyethylene glycol, i.e. the water-soluble pig comprises from 50 to 100 wt % or 65 to 97 wt % or 90 to 97 wt % or 95 wt % of one polyethylene glycol chosen from polyethylene glycols having an average molar mass of 400 g/mol or above, or of from 400 g/mol to 8000 or of from 400 g/mol to 6000 g/mol. The polyethylene glycol can be a polyethylene glycol which has an average molar mass of from 3000 to 6000 g/mol, or of from 3000 to 5000 g/mol. In one embodiment, the one or more polyethylene glycols is a polyethylene glycol having an average molar mass of 4000 g/mol and the water-soluble pig comprises from 50 to 100 wt % or 65 to 97 wt % or 90 to 97 wt % or 95 wt % of a polyethylene glycol having an average molar mass of 4000 g/mol.

In one embodiment, the one or more polyethylene glycols is two or more (at least two) polyethylene glycols, i.e. the water-soluble pig comprises from 50 to 100 wt % or 65 to 97 wt % or 90 to 97 wt % of two or more polyethylene glycols, where each polyethylene glycol independently has an average molar mass of 400 g/mol or above or of from 400g/mol to 8000 or 6000 g/mol.

In one embodiment, the two or more polyethylene glycols comprises a polyethylene glycol which has an average molar mass of from 3000 to 6000 g/mol, or a polyethylene glycol which has an average molar mass of from 3000 to 5000 g/mol, or a polyethylene glycol which has an average molar mass an average molar mass of 4000 g/mol. In one embodiment, the blend of two or more polyethylene glycols comprises a polyethylene glycol which has an average molar mass of from 3000 to 6000 g/mol, or a polyethylene glycol which has an average molar mass of from 3000 to 5000 g/mol, or a polyethylene glycol which has an average molar mass of 4000 g/mol and this polyethylene glycol is present in an amount of from 60 to 80 wt % of the pig.

In one embodiment, the two or more polyethylene glycols are: a polyethylene glycol having an average molar mass of from 3000 to 5000 g/mol, wherein said polyethylene glycol is present in an amount of from 60 to 80 wt % of the pig; a polyethylene glycol having an average molar mass of 7000 to 9000 g/mol, wherein said polyethylene glycol is present in an amount of from 10 to 30 wt % of the pig; and a polyethylene glycol having an average molar mass of 500 to 700 g/mol, wherein said polyethylene glycol is present in an amount of from 5 to 15 wt % of the pig. Thus the two or more polyethylene glycols are or consists of three different polyethylene glycols. In this embodiment, the two or more polyethylene glycols can be: a polyethylene glycol having an average molar mass of 4000 g/mol, wherein said polyethylene glycol is present in an amount of from 60 to 80 wt % of the pig; a polyethylene glycol having an average molar mass of 8000 g/mol, wherein said polyethylene glycol is present in an amount of from 10 to 30 wt % of the pig; and a polyethylene glycol having an average molar mass of 600 g/mol, wherein said polyethylene glycol is present in an amount of from 5 to 15 wt % of the pig. Further, in this embodiment, the two or more polyethylene glycols can be: a polyethylene glycol having an average molar mass of 4000 g/mol, wherein said polyethylene glycol is present in an amount of from 70 wt % of the pig; a polyethylene glycol having an average molar mass of 8000 g/mol, wherein said polyethylene glycol is present in an amount of from 20 wt % of the pig; and a polyethylene glycol having an average molar mass of 600 g/mol, wherein said polyethylene glycol is present in an amount of 10 wt % of the pig. In one embodiment, the water-soluble pig comprises 100 wt % of the two or more polyethylene glycols, i.e. the total amount of the two or more polyethylene glycols is 100 wt %, based on the weight of the pig.

The pig can comprise components other than the one or more polyethylene glycols. The pig can comprise a plasticiser. The function of the plasticizer is to control or reduce the brittleness of the composition. Suitable plasticizers include long chain surfactants such as alcohol ethoxylates with a minimum of 9 moles of ethoxylation and a maximum of 15 moles of ethoxylation, alcohol ethoxylates obtainable by reacting one mole of alcohol to 9-15 moles of ethylene oxide. Examples of these surfactants include Surfac UN 90 which is a C9-11 alcohol reacted with 9 moles of ethylene oxide, polyglycerides and low molecular weight (e.g. 400-600 g/mol) polyethylene glycol. Suitable plasticizers do not include those that are incompatible with polyethylene glycol such as polyvinyl acetate and ethylene vinyl acetate. The plasticisers are water soluble. The pig can comprise, for example, from 0 to 15 wt % or 1 to 10 wt % or 3 to 10 wt % of plasticizer, based on the total weight of the pig.

The pig can include other additives such as corrosion inhibitors, surfactants, dyes and biocides. These additives are soluble in water and compatible with polyethylene glycol in that they will mix with polyethylene glycol without forming incompatible “lumps”. The other additives can include sodium benzoate, sodium thiosulfate, sodium metasilicate; these can provide preservative properties/act as corrosion inhibitors once dissolved.

In one embodiment, the invention provides a water-soluble pig comprising:

(a) from 50 to 100 wt % of one or more polyethylene glycols;

(b) from 0 to 15 wt % of a plasticizer; and (c) from 0 to 1 wt % of other additives such as corrosion inhibitors, surfactants, dyes and biocides.

The sum of wt % of the one or more polyethylene glycols of (a), the plasticizer of (b) and the other additives of (c) is 100 wt %.

Each of the one or more polyethylene glycols employed in the first aspect of the invention is soluble in water. Generally each of the one or more polyethylene glycols is solid at the temperature that the pipeline pig is intended for use in, for example at a temperature of up to 45 °C. However, providing the pig is solid at the temperature that the pipeline pig is intended for use in, a proportion of the one or more polyethylene glycols can be liquid with the remainder being solid at the temperature that the pipeline pig is intended for use in.

The pig is soluble in water at a temperature of below 25 °C and/or a temperature of below 45 °C and/or at any temperature. The time that the pig takes to dissolve is related to the specific purpose of the pig. For example, in the purging of gas from spools the maximum time it takes from inserting the pig into a spool to the spool being filled with, for example, water or a glycol/water mix is usually only about 1 hour under normal conditions (for example, without delays due to equipment failure). The pig needs to stay intact while the pipe is being filled. The minimum time it might then take to transport the pipe and connect it to a subsea pipeline is 48 hours. The pig needs to be dissolved completely when the spool becomes part of an operational pipeline so as, for example, not to cause any blockage of that pipeline. Thus, when used to purge gas from spools, preferably the pig will start dissolving after 2 hours and will be completely dissolved within 48 hours. The time that it takes the pig to dissolve completely in water will depend on factors such as the composition of the pig, the size of the pig and the temperature of the water.

The pig can be water-soluble such that a pig of diameter 50.08 ± 0.04 cm (2 ± 0.016 inches) will dissolve in water within, i.e. in less than, 24 hours, when the water is at a temperature of 10 °C and the total weight of the pig and the water is 1 kg. This watersolubility test is static, i.e. no stirring is involved. In one embodiment, over 50 % by weight of the pig of diameter 50.08 ± 0.04 cm (2 ± 0.016 inches) will dissolve in the water within 4 hours, under these test conditions. In one embodiment, over 55 % by weight of the pig of diameter 50.08 ± 0.04 cm (2 ± 0.016 inches) will dissolve in the water within 4 hours, under these test conditions. In one embodiment, over 60 % by weight of the pig of diameter 50.08 ± 0.04 cm (2 ± 0.016 inches) will dissolve in the water within 4 hours, under these test conditions. In one embodiment, over 65 % by weight of the pig of diameter 50.08 ± 0.04 cm (2 ± 0.016 inches) will dissolve in the water within 4 hours, under these test conditions. In one embodiment, over 70 % by weight of the pig of diameter 50.08 ± 0.04 cm (2 ± 0.016 inches) will dissolve in the water within 4 hours, under these test conditions.

Pigs of the invention with the afore-mentioned water-solubilities are particularly suitable for use in spools, i.e. sections of pipeline that are about 100 to 200 m long, which are filled with an aqueous liquid. The aqueous liquid is a liquid comprising water and can be 100 wt % water or be a mixture of a water-soluble or water-miscible solvent and water. The water-soluble or water miscible solvent can be a glycol or a glycol ether. A glycol is a dihydric alcohol which has an aliphatic carbon chain. The general formula (1) for glycols is HOCH₂CH2(OCH2CH₂)nOH. Preferably n= 0 to 3, i.e., the glycol is ethylene glycol (n = 0 in formula (1)), diethylene glycol (n = 1 in formula (1)), triethylene glycol (n = 2 in formula (1)) or a combination of same. The glycol ether can be an alkyl glycol ether such as butyl glycol, also known as 2-butoxyethanol (ΟΗ3θΗ₂ΟΗ₂ΟΗ₂ΟΟΗ₂ΟΗ₂ΟΗ). In the mixture of the water-soluble or water-miscible solvent and water, preferably the water is present in an amount of at least 10 wt % or of at least 20 wt %. The water can be present in an amount of from 10 to 20 wt %.

The pig must be solid at the temperatures at which it is used. Typically the pig will have a melting point of greater than 45 °C enabling its use in hot climates. The inventors have recognised that there is a need to provide non-mechanical pigs that function effectively over a wide temperature range and thus are suitable for use, in particular, in hot climates.

The pig has a Shore A hardness value of at least 30 (Shore A units) as measured using a durometer (made by Sauter GMBH, model HBA 100-0). If the pig is too soft (for example, having a Shore A hardness of less than about 15), it may not hold its shape and will allow liquid bypass in the pipeline.

In order to function, e.g. to be able to push gas out of the pipeline in front of it, the pig must maintain its form in the pipeline for a period of time. Slump occurs when the pig, over time, starts to flatten under its own weight on the top and bottom. When the pig is in the shape of a sphere, slump causes the shape to change to an oblate spheroid. The pig has a circular cross section and slump is indicated by a decrease in the diameter of the cross section measured from the top to the bottom of the pig. Slump can be observed with the eye and can also be measured using callipers. Typically, the pig can maintain zero slump for up to 24 hours. Typically this is the maximum time it takes from removing the pig from its mold to completing the filling of the spool. Preferably, the pig can maintain zero slump for up to 24 hours at room temperature (20 °C) or up to 2 hours at temperatures of up to 45 °C.

Preferably the pig is resilient to impact it might be subjected to in use. The impact it might be subjected to will depend on how the pig is transported; for example, whether or not it is contained in a protective covering, such as the mold it was formed in. Impact resistance can be measured using a drop test. A suitable drop test involves dropping a pig in the shape of a sphere having a diameter of 5.08 cm (2 inches) for a height of 1.5 m onto a concrete floor. If the pig breaks or shows any cracks or splinters then it has failed the test. If the pig remains intact without any cracks or splinters then it has passed the test. This test assesses impact resistance. If the pig can withstand the impact of being dropped into a concrete floor from 1.5 metres, then it is considered less likely to shatter in use, e.g. if dropped suddenly during transportation. In one embodiment, the pig of the invention passes this drop test.

The pig has a circular cross-section or substantially circular cross-section with a diameter that is equal or substantially equal to the internal diameter of the pipe which it is intended to be used in. The pig may be cylindrical or substantially cylindrical. In this form, the pig is particularly suited to use in straight pipeline or pipelines with gentle bends. The composition may be spherical, i.e. shaped like a ball, or substantially spherical. Spherical pigs are suitable for use in cleaning pipelines with tight bends in them; they have the advantage of being able to travel around bends including 90° bends in a pipeline relatively easily. Typically, the pig will have a circular cross-section with an internal diameter of from 5.08 cm to 60.96 cm (i.e. 2 inches to 24 inches) or an internal diameter of from 10.16 cm to 40.64 cm (i.e. 4 inches to 16 inches).

The pig should be kept in a protective covering prior to its insertion into a pipeline or section of pipeline. The protective covering can be made of nylon, HDPE (high density polyethylene) or a similar elastomer and can be the mold in which the pig was cast. The protective covering serves to prevent premature slumping and dissolution of the pig. The invention also extends to the pig covered by or protected by a protective covering such as the mold in which it was cast.

In a second aspect, the invention provides a method of making the water-soluble pig of the invention. The method involves the steps of (i) melting the one or more polyethylene glycols to form molten polyethylene glycol or a molten mixture of polyethylene glycols; (ii) optionally mixing one or more additional components into the molten polyethylene glycol or molten mixture of polyethylene glycols to form a molten composition; (iii) casting the molten polyethylene glycol, molten mixture of polyethylene glycols or molten composition into a mold; and (iv) allowing the composition to solidify by cooling to room temperature (20 °C). The pig may be kept in the mold just prior to its insertion into the pipe. In one embodiment, the method of the invention includes a step of removing the pig from the mold.

The one or more polyethylene glycols can be heated to a temperature of about 70 °C until the polyethylene glycol or the blend of polyethylene glycols has melted. The polyethylene glycol can be stirred during this step. The plasticizer, if used, is added and the stirring is continued for a short period of time. The mold is typically in two parts and is prepared by applying a thin layer of grease to the inner surface of each of the parts and then bolting the parts together. The molten polyethylene glycol, molten mixture of polyethylene glycols or molten composition is poured into the mold (usually via a hole in the top) and allowed to set by cooling. The setting may take up to 24 hours or longer.

The pig is obtainable or obtained by the methods described herein and the invention extends to a pig in a mold obtainable or obtained by the methods described herein.

In a third aspect, the invention provides a method of cleaning a pipeline using the pig of the invention. In one embodiment, cleaning involves displacing a gas such as air from a pipeline. The pig of the invention is particularly suited to displacing air from spools as they are being filled with a liquid before being sealed, transported to the site of a pipeline (usually subsea) and connected to the pipeline. The liquid is an aqueous liquid, i.e. it comprises water and can be 100 wt % water or be a mixture of a watersoluble or water-miscible solvent and water as described above. The method involves manually placing the pig in an open end of a spool. This end is referred to herein as the pig entry end. The end flange at the pig entry end of the spool is then attached and liquid is introduced into the spool behind the pig so as to propel the pig to the other end of the spool, causing the pig to displace any air in the spool to the section of the spool in front of the pig. The displaced air will exit the spool through a vent port on the flange at the other end of the spool. This end is referred to herein as the gas exit end.

The pig will be pushed by the liquid to the gas exit end of the spool and will partially or completely block the vent port allowing for a complete liquid fill with the minimum spillage. The spool is then closed off at the pig exit end. The pig will then dissolve so there is no solid waste due to the pig or pieces of it being left in the spool. Thus the pig will not contribute to any jamming or plugging of the pipeline or any auxiliary lines connected to it when the spool is connected and production is started.

The following examples provide illustrations of the disclosed technology. The examples are non-exhaustive and are not intended to limit the scope of the disclosed technology.

A procedure for making the pig of the invention is set out below.

1. The PEG (usually in the form of flakes or powder) is weighed out and put in an open top metal drum or similar container

2. The drum is put in a drum heater at around 70 degrees Celsius until the PEG has melted. The PEG is mixed during the melting period.

3. The plasticiser, if required, and any other additives being used, are added. Mixing continues for around 10 minutes.

4. A thin layer of grease is applied to the inner surface of the spherical mold and the parts of the mold are bolted together.

5. The molten composition is poured into the mold via a hole on the top.

6. A Quality Control (QC) sample is taken

7. The pig is left to cool and set for 24 hours.

QC testing is done and if it passes the pig is dispatched. QC tests include a dissolution test, a drop test and Shore A hardness measurement.

Example 1

A pig comprising: 10 wt % of polyethylene glycol having a molar mass of 600 g/mol (PEG 600); 70 wt % of polyethylene glycol having a molar mass of 4000 g/mol (PEG 4000); and 20 wt % of polyethylene glycol having a molar mass of 8000 g/mol (PEG 8000) was prepared. The polyethylene glycols were premelted in an oven, mixed in a glass beaker, poured into a mold and allowed to cool. The mold was of a sphere having a diameter of 5.08 cm (2 inches).

Example 2

Using the procedure outlined for Example 1, a pig comprising: 95 wt % of polyethylene glycol having a molar mass of 4000 g/mol (PEG 4000) and 5 wt % of the surfactant UN 90 was prepared. The mold was of a sphere having a diameter of 5.08 cm (2 inches).

Dissolution test

A pig in the shape of a sphere having a diameter of 5.08 cm (2 inches) was placed in a clear container of water. The sum of the weight of the pig and the weight of the water is 1 kg. The temperature of the water was 10 °C. The appearance of the pig was observed over time. Periodically the pig was removed from water, patted dry with a paper towel and, after its diameter and weight were measured, it was returned to the water. 100 % dissolution occurs when the solution is clear with no solid or colloidal material visible. The results of the dissolution test for the pigs of Example 1 and 2 are shown in Table 1.

Drop test

The drop test involves dropping a pig in the shape of a sphere having a diameter of 5.08 cm (2 inches) for a height of 1.5 m onto a concrete floor. If the pig breaks or shows any cracks or splinters then it has failed the test. If the pig remains intact without any cracks or splinters then it has passed the test. The results of the drop test for the pigs of Example 1 and 2 are shown in Table 1. This test assesses impact resistance. If the pig can withstand the impact of being dropped into a concrete floor from 1.5 metres, then the pig is considered less likely to shatter in use, e.g. if dropped suddenly during transportation.

Shore A hardness

Shore A hardness is measured using a durometer such as that made by Sauter GMBH. The Shore A hardness for the pigs of Example 1 and 2 are shown in Table 1.

Table 1

	Example 1	Example 2
Drop Test ~150cm*	Pass	Pass
Durometer**	~95	~90
Example 2
Time/ Hrs	Diameter	Weig	ht
	mm	%loss	g	% loss
0	51.42	0	84.41	0
2ⁿ	42.53	17.29	48.99	41.96
	37.52	25.13	25.13	70.22

5	33.22	35.39	17.12	79.72
24	0	100	0	100
Example 1
Time/hrs	Diameter	Weig	ht
	mm	% loss	G	% loss
0	51.27		81.94	0
2	44.46	13.2	46.75	42.9
4	35.64	30.4	21.92	73.2
5	31.92	37.7	14.03	82.9
24	0	100	0	100

* Did not break or deform on impact with	the ground

**Shore A * Hole developed in side of Pig ^## No longer spherical

Claims

1. A water-soluble pig comprising from 50 to 100 wt % of one or more polyethylene glycols, wherein each of the one or more polyethylene glycols is chosen independently from polyethylene glycols having an average molar mass of 400 g/mol or above, or from polyethylene glycols having an average molar mass of from 400 g/mol to 8000 or 6000 g/mol.

2. A water-soluble pig according to claim 1, comprising:

(a) from 50 to 100 wt % of the one or more polyethylene glycols;

(b) from 0 to 15 wt % of a plasticizer; and (c) from 0 to 1 wt % of one or more additives chosen from surfactants, dyes and biocides.

3. A water-soluble pig according to claim 1 or claim 2, wherein the one or more polyethylene glycols is a polyethylene glycol having an average molar mass of from 3000 to 6000 g/mol or is a polyethylene glycol having an average molar mass of 4000 g/mol.

4. A water-soluble pig according to claim 3, wherein the one or more polyethylene glycols is a polyethylene glycol having an average molar mass of from 3000 to 5000 g/mol or is a polyethylene glycol having an average molar mass of 4000 g/mol and the water-soluble pig comprises from 90 or 93 to 97 wt % of one or more polyethylene glycols.

5. A water-soluble pig according to claim 1 or claim 2, wherein the one or more polyethylene glycols is two or more polyethylene glycols which comprise a polyethylene glycol having an average molar mass of 3000 to 6000 g/mol or a polyethylene glycol having an average molar mass of 4000 g/mol, and which polyethylene glycol is present in an amount of 60 to 80 wt % of the pig.

6. A water-soluble pig according to any one of claims 1, 2 or 5, wherein the one or more polyethylene glycols are: a polyethylene glycol having an average molar mass of 3000 to 5000 g/mol present in amount of 60 to 80 wt %; a polyethylene glycol having an average molar mass of 7000 to 9000 g/mol present in amount of

10 to 30 wt %; and a polyethylene glycol having an average molar mass of 500 to 700 g/mol present in amount of 10 to 15 wt %.

7. A water-soluble pig according to any one of the preceding claims, wherein the pig has a melting point of not less than 45 °C.

8. A water-soluble pig according to any one of the preceding claims, wherein the pig is spherical or substantially spherical in shape.

9. A water-soluble pig according to any one of the preceding claims, wherein the pig has a circular cross-section having an internal diameter of from 5.08 cm to 60.96 cm (2 inches to 24 inches).

10. A water-soluble pig according to any one of the preceding claims, wherein the pig has a protective covering or mold.

11. A method of preparing a water-soluble pig according to any one of claims 1 to 10, comprising (i) melting the one or more polyethylene glycols to form molten polyethylene glycol or a molten mixture of polyethylene glycols; (ii) optionally mixing one or more additional components into the molten polyethylene glycol or a molten mixture of polyethylene glycols to form a molten composition; (iii) casting the molten polyethylene glycol, molten mixture of polyethylene glycols or molten composition into a mold; and (iv) allowing the molten polyethylene glycol, molten mixture of polyethylene glycols or molten composition to solidify by cooling.

12. A method according to claim 11, including the step of removing the pig from the mold.

13. A method of displacing gas from a pipeline which is open at one end comprising inserting a pig according to any one of claims 1 to 12 or obtainable by the method of claims 13, into the open end of the pipeline; introducing an aqueous liquid into the pipeline so that the liquid pushes the pig through the pipeline and displaces the gas in the section pipeline in front of the pig; allowing the gas to exit through a vent port in the far end pipeline; and sealing the pig into the pipeline once the pig has reached the far end of the pipeline.

14. A method according to claim 13, wherein the aqueous liquid is water or a mixture of water and at least one glycol or glycol ether.

15. A method according to claim 13 or 14, wherein the section of the pipeline is from

5 50 m to 250 m in length.

16. Use of the water-soluble pig of any one of claims 1 to 15 or obtainable by the method of claim 11 to clean a pipeline.

Intellectual Property Office

Application No: GB1718046.4

Claims searched: 1-16

Examiner: Dr Kathryn Willett

Date of search: 26 April 2018

Patents Act 1977: Search Report under Section 17

Documents considered to be relevant:

Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-15 GB2313644 A (COPIPE SYSTEMS) See whole document, especially figure 1 and page 6 lines 28 to 36. A US 6802909 Bl (CRENSHAW) See whole document. A CN 206262942 U (SICHUAN ZHANQI TECH) See whole document.

Categories:

X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention. same category. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.

Field of Search:

Search of GB, EP, WO & US patent documents classified in the following areas of the UKCX :

Worldwide search of patent documents classified in the following areas of the IPC____________