FIELD OF THE INVENTION

The invention relates to a conveying pipe arrangement of pneumatic conveying systems for solid materials . The invention also relates to a method for forming a conveying pipe connection . The invention also relates to a connection piece .

BACKGROUND OF THE INVENTION

In connection with pneumatic material conveying systems , metal pipes have often been used in the conveying pipework . Especially in large systems in which the material conveying distances are long, the conveying pipeworks , especially the main pipeworks , may become in length rather long, typically several kilometre long conveying pipeworks . The pipe diameters of conveying pipeworks of the known systems are rather large , of the order of 200- 800 mm, whereby the costs for a pipework formed from metal pipes are rather high .

This matter of fact has been attempted to be alleviated by forming material conveying pipeworks from plastic or a plastic composite material . The pneumatic material conveying systems often convey material placing requirements on wear resistance of the pipe parts . Especially pneumatic conveying systems for solid wastes often transport materials that place their speci fic requirements on wear resistance of the conveying pipework . Such materials include for example glass , metal , sand and corresponding materials . Pipe parts exposed to wearing often include for example pipe elbows or various connections . It has also been observed that wearing of the plastic material at the inner surface of the pipe increases when the temperature of the pipe rises for example due to friction, such as upon contact of the conveyed material with the inner surface of the pipe , or due to external conditions .

In addition, it is often necessary to provide dif ferent radiuses of curvature for the conveying pipe . In pipe parts manufactured from plastic or plastic compos ite material , thermal treatment of the pipe part is required for the pipe part to remain in the bent shape . The possibilities for thermal treatment are , especially in installation conditions , very limited or even impossible . When bending the pipe , there is also a risk that the pipe folds in such a way that the si ze or shape of the flow ori fice of the pipe will change in an undesirable manner, which especially in pneumatic conveying pipeworks intended for the transport of solid wastes may cause harm to the functionality of the system .

In conveying pipeworks formed especially from plastic pipes or plastic composite pipes , muf f connections may generally be used in order to connect separate pipe parts to each other end to end . In these connections , to a muf f , i . e . a connection sleeve part , disposed at a connection point such that the ends of the pipe parts to be connected to each other are inside the muf f and the muf f thus around the connection point , extending in a longitudinal direction of the pipes to a distance from the connection point in both directions . The connection sleeve part or the section of the pipe part to be connected has been provided with thermal resistances or the like , whereby electric current is supplied to the resistances when the connection is being formed, whereby the resistances are heated and a connection is formed between the connection sleeve part and the pipe parts . Such thermoplastic pipe connections have been described for example in publications US 2739829 , US 4530521 and US 4906313 .

Often, in the conveying pipe arrangements there is in practice a need to provide relatively small angular changes in the direction of the conveying pipe . This may be di f ficult in installation conditions with pipes that comprise reinforcements or are rigid comprising reinforcements or being entirely wear resistant material for example metal .

The obj ect of this invention is to provide a completely new solution for a conveying pipe arrangement of a pneumatic solid material conveying system, by means of which arrangement the problems o f the prior art may be avoided . One important obj ect is to provide a conveying pipe arrangement suitable for pneumatic conveying pipeworks of waste transport systems . Another obj ect is to provide , for a conveying pipework formed mainly from plastic or plastic composite material , a solution by means of which the problems of the prior art will be avoided . It is an obj ect to provide a pipe part that may be bent , even in installation conditions , to a desired shape and the connecting of which may be eas ily accomplished also to a plastic composite or plastic pipe . One obj ect is to provide a pipe part that is suited in its wear res istance properties to be used in the conveying pipeworks of pneumatic conveying systems for solid waste material .

Another obj ect is to provide a solution for connecting the pipe parts of a conveying pipework to each other, wherein the most typical connection welding methods or gluing of plastics , especially plastic pipes , may be used .

SUMMARY OF THE INVENTION

The invention i s based on an idea that a pipe part comprises a combination of a metal reinforcement part , such as a steel pipe , around which a tubular plastic composite layer or plastic layer has been arranged . The plastic pipe may be warmed and the steel pipe may be pushed into the channel of the plastic pipe . As it cools down, the plastic pipe may shrink over the steel pipe . The pipe part may be connected to another pipe part by connecting the plastic or plastic composite parts to each other directly or via a sleeve part by a plastic welding method or by gluing . The arrangement may comprise a special connection piece between the pipe parts connected to each other . By means of the connection piece , changes in the direction may be provided between the pipe parts . In one embodiment , the connection piece may be a pipe part . According to one embodiment the connection piece may be a flexible pipe part . According to one embodiment the connection piece may be flexible material . According to one embodiment the connection piece may be plastic . According to one embodiment the connection piece may be composite material . According to one embodiment the connection piece may be metal . According to one embodiment the connection piece may have been configured to be bent in a first plane , such as vertical plane , by an angle alpha (a) which i s 0-20 degrees , and/or in a second plane , such as horizontal plane , by an angle beta ( p ) which is 0-20 degrees . According to one embodiment the first plane may be a plane pass ing through a longitudinal axis of the pipe . According to one embodiment , parts limiting the bending may have been formed in the connection piece . According to one embodiment , parts protruding from the surface of the connection piece and/or recesses and protrusions therebetween may have been formed in the connection piece . According to one embodiment , the protruding parts and/or the recesses may comprise sections in a direction transverse from the longitudinal direction of the connection piece . According to one embodiment , the protruding parts and/or recesses have been arranged to a distance from each other . According to one embodiment , the protruding parts and/or the recesses may comprise annular sections . According to one embodiment, the protruding parts and/or the recesses may comprise segments arranged so as to be distributed along the circumference of the connection piece. According to one embodiment, the parts limiting the bending of the connection piece may have been arranged to limit the bending of the connection piece, for example relative to a longitudinal axis between 0-20 degrees. According to one embodiment, a distance between the adjacent protruding parts and/or recesses may have been arranged to be such that in a bent position, the sides of the adjacent protruding parts and/or recesses may have been arranged to limit the degree of the bending of the connection piece when the protruding parts and/or the walls of the recesses are in contact with each other. According to one embodiment, the wall thickness of the connection piece may be smaller in the section comprising protruding parts and/or recesses than in the side section of the connection piece. According to one embodiment, the section comprising protruding parts and/or recesses may be arranged in the connection piece in a section between a first side section and a second side section, for example in a middle section of the connection piece. According to one embodiment, the connection piece may have been arranged to allow angular changes of a different magnitude in a first longitudinal plane, such as vertical plane, than in a longitudinal plane transverse thereto, such as horizontal plane. According to one embodiment, the connection piece may be provided with limiting members enabling bending to different degrees, formed in sectors of its circumference. According to one embodiment, the limiting members allowing bending to different degrees may be different in their dimensions or shape in different sectors. According to one embodiment, the limiting members allowing bending to different degrees may be different in their dimensions or shape in different sectors in such a way that they allow the bending to different degrees in the planes of the different sectors. According to one embodiment, the section comprising protruding parts and/or recesses may be dif ferent in di fferent sectors of the circumference , whereby they may allow bending to di f ferent degrees . According to one embodiment , the connection piece may have been arranged to allow, in a vertical plane , angular changes of a dif ferent magnitude when bent upward from a hori zontal plane than when bent downward from a hori zontal plane . According to one embodiment , the connection piece may have been arranged to allow a smaller angular change upward from a hori zontal plane than downward from a hori zontal plane . According to one embodiment , the connection piece may have been arranged to allow bending upward from a hori zontal plane of between 0- 10 degrees . According to one embodiment , the connection piece may have been arranged to allow bending downward from a hori zontal plane of between 0-20 degrees . According to one embodiment , the connection piece may have been arranged to allow a smaller angular change downward from a hori zontal plane than upward from a hori zontal plane . According to one embodiment, the connection piece may have been arranged to allow bending downward from a hori zontal plane of between 0- 10 degrees . According to one embodiment , the connection piece may have been arranged to allow bending upward from a hori zontal plane of between 0-20 degrees . According to one embodiment , by rotating the connection piece there may be provided a desired angular range in the connection piece to a desired plane of bending .

According to one embodiment , the conveying pipe arrangement may comprise a first pipe section and a connecting section and a second pipe section, whereby the angle between the directions of the first and the second pipe section may be changed by means of the connecting section . According to one embodiment , the direction of the first and the second conveying pipe section may be changed by means of the connecting section from the direction of the first pipe section between fl- 20 degrees . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may be changed by means of the connecting section in a hori zontal plane by an angle of fl- 20 and in a vertical plane by an angle of 0-20 . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece , the properties of which connection piece may have been arranged to allow angular changes of a di f ferent magnitude in a hori zontal plane than in a vertical plane . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may have been arranged to allow, in a vertical plane , angular changes of a di f ferent magnitude when bent upward from a horizontal plane than when bent downward from a hori zontal plane . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may have been arranged to allow a smal ler angular change upward from a hori zontal plane than downward from a hori zontal plane . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may have been arranged to allow bending upward from a hori zontal plane of between 0- 10 degrees . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece, which connection piece may have been arranged to allow bending downward from a hori zontal plane of between 0-20 degrees . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may have been arranged to allow a smaller angular change downward from a hori zontal plane than upward from a hori zontal plane . According to one embodiment , the angle between the directions o f the f irst pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may have been arranged to allow bending downward from a hori zontal plane of between 0- 10 degrees . According to one embodiment , the angle between the directions of the first pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may have been arranged to allow bending upward from a hori zontal plane of between 0-20 degrees . According to one embodiment, by rotating the connection piece there may be provided a desired angular range in the connection piece to a desired plane of bending . According to one embodiment , the angle between the directions o f the f irst pipe section and the second pipe section may have been arranged to be changed with a connection piece , which connection piece may be provided with limiting members enabling bending to dif ferent degrees , formed in sectors of its circumference . According to one embodiment , the angle between the directions of the pipe section and the second pipe section may have been arranged to be changed with a connection piece , whereby by rotating the connection piece there may be provided a desired magnitude of the angular range of bending to a desired plane of bending, within the limits allowed by the connection piece .

According to one embodiment , the first pipe part may comprise a reinforcement or a wear resistant inner surface and the second pipe part may comprise a reinforcement or a wear resistant inner surface . According to one embodiment , the length of the connection piece and the angular change between the first and the second pipe part have been arranged according to si ze and/or speed of transported material , such that the material travels with airflow from the first to the second pipe section, such that it does not substantially contact the connection piece in a wearing manner . According to one embodiment , the length of the connection piece and the angular change between the first conveying pipe section and the second conveying pipe section have been configured according to si ze and/or speed of transported material , whereby the material travels in the conveying pipe section, in a material conveying pipe of a pneumatic material conveying system, with transport airflow from the first conveying pipe section to the second conveying pipe section without substantially contacting the connection piece in a wearing manner . Thus it is possible to apply a connection piece having preferred properties , which connection piece is not necessarily required to have an equally good wear resistance as a conveying pipe whose inner surface the transported material may substantially contact in a wearing manner .

LIST OF THE FIGURES

Fig . 1 illustrates one embodiment of a conveying pipe arrangement cut according to a vertical plane ,

Fig . 2 illustrates one embodiment of a conveying pipe arrangement cut according to a vertical plane , Fig . 3 illustrates one embodiment of a conveying pipe arrangement cut according to a hori zontal plane ,

Fig . 4 illustrates a detail of a connection area of one embodiment of a conveying pipe arrangement , Fig . 5 illustrates one embodiment of a connection piece of a conveying pipe arrangement cut in a vertical plane , and Fig. 6 illustrates one embodiment of a connection piece of a conveying pipe arrangement from the direction of arrow A of Fig. 5.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 illustrates a partial sectional view of a part of a conveying pipe arrangement of a pneumatic material conveying system according to one embodiment. The conveying pipe arrangement may comprise a first conveying pipe section 20 and a second conveying pipe section 21. The conveying pipe sections 20, 21 may have been connected to each other via a bending piece 1 and muffs 22, i.e. connection sleeve parts 22. An end 23 of the first conveying pipe part 20 may have been arranged against a first end 3 of the bending sleeve 1. The first end 3 of the bending sleeve 1 and of the first conveying pipe section 20 may have been arranged into the muff, i.e. the connection sleeve part 22. The connection sleeve part 22 may have warming means, such as thermal resistance wires, which warm up when electric current is supplied to them. The connection sleeve part 22 may have been provided with connection points 41, 42 known per se, which may have been coupled to a thermal resistance wire 43 (illustrated in Fig. 4) , and to which electric current may be connected. The resistance wire 43 may have been arranged as a coil into the connection sleeve part 22. As a result of heating of the resistance wire 43, a connection, such as a thermoplastic connection, may be formed in a manner known per se between the connection sleeve part 22 and the first conveying pipe section 20 and the bending sleeve part 1. Correspondingly an end 24 of the second conveying pipe section 21 may have been arranged against a second end 4 of the bending sleeve 1. The second end 4 of the bending sleeve 1 and of the second conveying pipe section 21 may have been arranged into another muff, i.e. connection sleeve part 22. The first conveying pipe part 20 may comprise a reinforcement part 26 and a plastic material part 25 formed or arranged over, i . e . around, the reinforcement part . The second conveying pipe part 21 may comprise a reinforcement part 28 and a plastic material part 27 formed or arranged over, i . e . around, the reinforcement part . The conveying pipe part may be formed for example by warming the tubular plastic material part 25, 27 and by inserting the tubular reinforcement part 26 , 28 in the channel space o f the plastic material part . As the tubular plastic material part 25 , 27 cool s , it may set around and against the tubular reinforcement part . The inner surface 32 of the plastic material part comes thereby against the outer surface 31 of the reinforcement part . The inner surface 30 of the reinforcement part thereby becomes the channel surface of the conveying pipe section .

The purpose of the reinforcement part may be to increase wear res istance of the conveying pipe section against internal wearing . In the embodiment according to Fig . 1 the reinforcement part 8 in a first pipe part 2 i s a pipe part forming the inner surface 9 of the f irst pipe part 2 . Over the outer surface 11 o f the reinforcement part 8 there is a plastic material part , the outer surface o f which forms the outer surface 14 of the first pipe part 2 . The f irst and/or the second conveying pipe part may have also be formed without a special reinforcement part .

In Fig . 1 the first conveying pipe part has been connected to a connection piece 1 which may in the embodiment of Fig . 1 be plastic material . The inner surface o f the wall of the connection piece 1 may form a channel 5 wall .

In the conveying pipe arrangement according to Fig . 1 , the first conveying pipe part 20 and the second conveying pipe part 21 have thus been connected to each other by means of a connection piece 1 and connection sleeve parts 22 . According to the embodiment of Fig . 1 ( and Fig . 4 ) , the inner surface of the first conveying pipe part 20 and the inner surface of the connection piece 1 may be substantially al igned, so that no step hindering material trans fer would form at the connection point . Correspondingly, the inner surfaces of the second conveying pipe part 21 and the connection piece 1 may be substantially aligned, so that no step hindering material trans fer would be formed . The outer surfaces o f the first conveying pipe part 20 and a first connection area 7 of the connection piece 1 may be substantially aligned in the connection area, so that a connection could be formed between the connection sleeve part 22 and the plastic material part of the first conveying pipe part 20 and the plastic material of the wall of the first connection area 7 of the connection piece 1 . Correspondingly, the outer surfaces of the second conveying pipe part 21 and a second connection area 8 of the connection piece 1 may be substantially aligned in the connection area, so that a connection could be formed between the connection sleeve part 22 and the plastic material part of the second conveying pipe part 21 and the plastic material of the wall o f the second connection area 8 of the connection piece 1 . The conveying pipe parts 20 , 21 and the connection piece 1 may be connected to each other by so-called electric welding . By warming the electrical resistances 43 disposed inside the parts or in the connection sleeve part 22 , a connection is formed between the first conveying pipe part 20 and the connection sleeve part 22 as well as the connection piece 1 and the connection sleeve part 22 . Correspondingly by warming the electrical resistances 43 disposed in the other connection sleeve part 22 , a connection is formed between the second conveying pipe part 21 and the connection sleeve part 22 as well as the connection piece 1 and the connection sleeve part 22 . In the embodiment of Fig. 1, the connection piece 1 may have been bent upward from a horizontal plane by an angle alpha (a) . According to one embodiment, the connection piece 1 has been configured to be bent by an angle alpha (a) in a vertical plane. According to one embodiment, the angle alpha (a) may be 0-20 degrees. According to one embodiment, the angle alpha (a) is, in a vertical plane, when bent upward from a horizontal plane, smaller than when bent downward from a horizontal plane. According to one embodiment, when bent upward the angle alpha (a) is 0.5*angle alpha (a) when bent downward. According to one embodiment, when bent upward the angle alpha (a) may be 0-10 degrees. According to one embodiment, when bent upward the angle alpha (a) may be 0-8 degrees. According to one embodiment, the angle alpha (a) is 0-20 degrees when bent downward (Fig. 2) . According to one embodiment, the angle alpha (a) is 0-16 degrees when bent downward from a horizontal plane .

Fig. 3 illustrates one embodiment of the conveying pipe arrangement. Here the connection piece has been configured to be bent in a horizontal plane (in the lateral direction) by an angle beta (p) . The angle beta (p) may be 0-20 degrees from a vertical plane. According to one embodiment, the angle beta (p) may be 0-16 degrees in the lateral direction relative to a vertical plane.

According to one embodiment, the length of the connection piece 1 and the angular change alpha (a) and/or beta (p) between a first conveying pipe section 20 and a second conveying pipe section 21 may have been configured according to size and/or speed of transported material M. According to one embodiment, the material M may travel in the conveying pipe section with transport airflow of a pneumatic material conveying system from the first conveying pipe section 20 to the second conveying pipe section 21 without substantially contacting the connection piece 1 in a wearing manner. The reinforcement part is , according to one embodiment , a pipe part , preferably a metal pipe , most preferably a steel pipe .

The thickness of the wall of the reinforcement part is smaller than the thickness of the wall of the plastic material part . According to one embodiment , the thickness of the reinforcement part is approximately less than 1 /2 of the total thickness of the wall of the pipe part , preferably 1 /20 - 1 / 4 of the total thickness of the wall of the pipe part .

The thickness of the wal l of the pipe part is in one embodiment approximately 20 - 40 mm . The thickness of the wall of the pipe part may be smaller or greater than this . The thickness of the wall of the pipe part may vary according to application .

According to one embodiment , the plastic material layer i s a pipe part separate from the reinforcement part , whereby the reinforcement part may be arranged into the channel space defined by the plastic material layer/plastic material pipe . Thus the tubular layers , plastic material layer and reinforcement part are arranged one within the other .

According to one embodiment , the conveying pipe part may have been secured by combining the plastic material pipe part and the reinforcement part with each other, for example by baking . Also other suitable manufacturing methods are applicable . The plastic material layer may be formed around the reinforcement part for example by extrusion .

The plastic material part may be or comprise wear resistant material . Thus it does not matter i f the reinforcement part should wear through at some point , because the plastic material part would ensure suf ficient wear resistance . The mechanical shape strength o f the pipe part is , however, retained .

According to one embodiment , the conveying pipe part may be bent , for example at or in proximity to the installation site . In the bending, a mandrel may be used in the flow channel of the pipe part in order to prevent buckling of the wall of the pipe part . According to one embodiment , the conveying pipe section or the connection piece 1 does not buckle in the same way as a mere plastic pipe during bending . The reinforcement part prevents deformation of the pipe part ( such as return to the shape before the bending) for example after the bending .

The reinforcement part may receive the mechanical stress in the pipe .

The reinforcement part may be , in its wall thickness , thinner than a steel pipe being used as a conveying pipe alone . According to one embodiment , the wall thickness of the reinforcement part may be for example 2- 6 mm . According to one embodiment , the strength of the wall o f the plastic material pipe may be for example 10-30 mm .

According to one embodiment , the connection piece 1 may comprise a tubular envelope 2 having a first end 3 and a second end 4 . The connection piece may comprise a channel 5 between the first end 3 and the second end 4 , the channel 5 being delimited by an inner surface 6 of the envelope o f the connection piece . The connection piece may comprise a first connection area 7 , which may extend to a distance from the first end 3 . The connection piece may comprise a second connection area 8 which may extend from the second end 4 to a distance . Limiting members 9 , 10 limiting the bending of the connection piece may have been formed in the connection piece . One connection piece 1 is illustrated in Fig . 5 . The connection piece 1 may have been formed to be in its mid area, in the area between the first connection area 7 and the second connection area 8 , at least partially, thinner in wall thickness . Thereby the connection piece 1 may have been configured to faci litate the bending thereof . The connection piece may have been configured to be bent in a first plane , such as vertical plane , by an angle alpha (a) which may be 0-20 degrees , and/or in a second plane , such as hori zontal plane , by an angle beta ( p ) which may be 0-20 degrees .

The connection piece may have been configured to be bent in a vertical plane passing through a longitudinal axis thereo f by an angle alpha (a ) and/or in a hori zontal plane passing through a longitudinal axis thereof by an angle beta ( p ) . According to one embodiment , the angle alpha ( a) may be 0-20 degrees . According to one embodiment , the angle beta ( p ) may be 0-20 degrees .

Parts 9 protruding from an outer surface of the envelope 6 of the connection piece and/or recesses 10 and protrusions 9 therebetween may have been formed in the connection piece 1 . The recesses 10 may have a base 10 ' . The protrusions/recesses may have sides 12 , 13 . The connection piece may be tubular, having an outer surface 11 and an inner surface 6 . The channel 5 may be formed within the circumference o f the inner surface 6 of the connection piece 1 ( Fig . 6 ) .

According to one embodiment , the protruding parts 9 and/or the recesses 10 may comprise sections in a direction transverse to the longitudinal direction of the connection piece . According to one embodiment , the adj acent protruding parts 9 and/or recesses 10 may have been arranged to a distance from each other . The protruding parts 9 and/or the recesses 10 may comprise annular sections . The protruding parts 9 and/or the recesses 10 may comprise segments . The protruding parts or segments may have been arranged so as to be distributed along the circumference of the connection piece 1 .

The parts 9, 10 limiting the bending of the connection piece 1 may have been arranged to limit the bending of the connection piece , for example relative to a longitudinal axis between 0-20 degrees . The longitudinal axis may have been arranged in the incoming direction of the material conveying pipe section . A distance between the adjacent protruding parts 9 and/or recesses 10 may have been arranged to be such that in a bent position, the sides 12, 13 of the adjacent protruding parts and/or recesses have been arranged to limit the degree of the bending of the connection piece. According to one embodiment, the sides of the recesses may have been arranged to limit the bending when the walls 12, 13 of the protruding parts 9 and/or the recesses 10 are in contact with each other. According to one embodiment, the wall thickness s of the connection piece 1 may be smaller in the section comprising protruding parts 9 and/or recesses 10 than in the first and/or the second connection area 7, 8 of the connection piece. According to one embodiment, the wall thickness of the connection piece may be smaller in its middle area than in the first or the second connection area .

According to one embodiment, the section comprising protruding parts 9 and/or recesses 10 may have been arranged in the connection piece 1 in a section between the first connection area 7 and the second connection area 8, for example in a middle section of the connection piece.

According to one embodiment, the connection piece 1 may have been arranged to allow angular changes of a different magnitude in a first longitudinal plane (for example vertical plane) than in a longitudinal plane transverse thereto (for example horizontal plane) .

According to one embodiment, limiting members enabling bending to different degrees may have been formed in different sectors of the circumference of the connection piece 1.

According to one embodiment, the limiting members allowing bending to different degrees may be different in their dimensions or shape in different sectors. According to one embodiment, the limiting members allowing bending to different degrees may be different in their dimensions or shape in different sectors in such a way that they allow the bending to different degrees in the planes of the different sectors. According to one embodiment, the section comprising protruding parts and/or recesses may be different in different sectors of the circumference, whereby they may allow bending to different degrees.

According to one embodiment, the connection piece 1 may have been arranged to allow, in a vertical plane, angular changes of a different magnitude when bent upward from a horizontal plane than when bent downward from a horizontal plane or plane of the incoming direction .

According to one embodiment, the connection piece 1 may have been arranged to allow a smaller angular change upward from a horizontal plane or plane of the incoming direction than downward from a horizontal plane .

According to one embodiment, the connection piece 1 may have been arranged to allow bending upward from a horizontal plane or plane of the incoming direction of between 0-10 degrees.

According to one embodiment, the connection piece 1 may have been arranged to allow bending downward from a horizontal plane or plane of the incoming direction of between 0-20 degrees.

According to one embodiment, the connection piece 1 has been arranged to allow a smaller angular change downward from a horizontal plane or plane of the incoming direction than upward from a horizontal plane.

According to one embodiment, in the stage of forming a connection of a pipe connection arrangement, by rotating the connection piece 1 there may be provided a desired angular range allowing the bending in the connection piece to a desired plane of bending.

According to one embodiment, the length of the connection piece 1 and the angular change between a first conveying pipe section 20 and a second conveying pipe section 21 may have been configured according to si ze and/or speed of transported material M . According to one embodiment , the material M may travel in the conveying pipe section with transport airflow of a pneumatic material conveying system from the first conveying pipe section 20 to the second conveying pipe section 21 without substantially contacting the connection piece 1 in a wearing manner .

According to one embodiment , a conveying pipe arrangement of a pneumatic material conveying system may comprise a first conveying pipe section 20 and a second conveying pipe section 21 and a connection piece 1 between the first conveying pipe section and the second conveying pipe section, whereby the connection piece may be a connection piece as described above or below . The connection piece 1 may have been connected from a first end 3 thereof to the first conveying pipe section 20 and from a second end 4 thereof to the second conveying pipe section 21 .

According to one embodiment , in the conveying pipe arrangement , at a connection between the first conveying pipe section 20 and/or the second conveying pipe section 21 and the connection piece 1 , a connection sleeve part 22 may have been arranged to be used, which connection sleeve part may have been arranged to enclose a connection area of the first conveying pipe section 20 and/or the second conveying pipe section 21 and the connection piece 1 disposed within the connection sleeve part 22 .

According to one embodiment , the connection sleeve part 22 may have been configured as a welding sleeve , comprising heating means , such as a resistance 43 .

According to one embodiment , the connection piece 1 may comprise plastic material or metal or has been formed from plastic or metal . According to one embodiment , the first conveying pipe section 20 and/or the second conveying pipe section 21 may be a composite-steel pipe or a composite pipe . According to one embodiment , the composite may be plastic material . According to one embodiment , the plastic material may be for example polyethylene , for example type PE100 . According to one embodiment , the steel pipe may be structural steel , for example type S235 . According to one embodiment , the steel pipe may be painted on the outside and on its inner surface .

According to one embodiment , the invention may relate to a method for forming a conveying pipe arrangement of a pneumatic material conveying system . The conveying pipe arrangement may comprise at least one first conveying pipe section 20 and one second conveying pipe section 21 , a connection sleeve part 22 , and optionally a connection piece 1 between the first conveying pipe section 20 and the second conveying pipe section 21 . In the method the first conveying pipe section 21 may be connected to the second pipe section directly or via the connection piece 1 by inserting the ends of the pipe parts 20 , 21 to be connected to each other into the connection sleeve part 22 , i . e . into the connection sleeve , and by forming a thermoplastic connection with the pipe part 20 , 21 and the connection sleeve part 22 , and/or optionally with the connection piece 1 and the connection sleeve part 22 .

According to one embodiment , in the conveying pipe arrangement the direction of the channel of the conveying pipe section may be changed by bending the connection piece 1 arranged between the first conveying pipe section 20 and the second conveying pipe section 21 in a first plane , such as vertical plane , by an angle alpha (a) and/or in a second plane , such as hori zontal plane , by an angle beta ( p ) .

According to one embodiment , the angle alpha (a) may be 0-20 degrees . According to one embodiment , the angle alpha (a) may be at most 8 degrees upward from a plane of the incoming direction . According to one embodiment , the angle alpha ( a) may be at most 7 . 5 degrees upward . According to one embodiment , the angle alpha (a) may be at most 16 degrees downward from a plane of the incoming direction . According to one embodiment , the angle alpha (a) may be at most 15 degrees downward .

According to one embodiment , the angle beta ( p ) may be 0-20 degrees . According to one embodiment , the angle beta ( p ) is at most 17 degrees relative to a vertical plane of the incoming direction . According to one embodiment , the angle beta ( p ) is at most 15 degrees in the lateral direction from a vertical plane of the incoming direction .

According to one embodiment , the direction of the channel is changed upward relative to the incoming direction by a maximum of 10 degrees , preferably by a maximum of 8 degrees , or downward relative to the incoming direction by a maximum of 20 degrees , preferably by a maximum of 17 degrees .

According to one embodiment , the direction of the channel is changed in a lateral direction relative to the incoming direction by a maximum of 20 degrees , preferably by a maximum of 17 degrees .

According to one embodiment , at least one of the conveying pipe sections 20 , 21 may be formed by arranging a plastic material pipe 25 , 27 over a reinforcement pipe 26 , 28 or a reinforcement pipe in the channel space of a plastic material pipe by heating the plastic material pipe 25 , 27 and by moving the plastic material pipe 25 , 27 and/or the reinforcement pipe 26 , 28 relative to each other, so as to form a conveying pipe section wherein the inner surface may be the inner surface 30 of the reinforcement pipe and the outer surface may be the outer surface 33 of the plastic material pipe . According to one embodiment , the outer surface 31 of the reinforcement pipe ( inner pipe ) may be disposed against the inner surface 32 of the plastic material pipe ( outer pipe ) .

The conveying pipe arrangement, the connection piece and the method according to the invention are suited particularly well to be used in the connections of a conveying pipework of pneumatic waste pipe transport systems . The pipe si zes may be rather large in diameter, for example typically 200-500 mm .