GB2092490A

GB2092490A - Improvements in pipe surface treatment

Info

Publication number: GB2092490A
Application number: GB8104252A
Authority: GB
Original assignee: Pipeline Induction Heat Ltd
Current assignee: Pipeline Induction Heat Ltd
Priority date: 1981-02-11
Filing date: 1981-02-11
Publication date: 1982-08-18
Also published as: AU8068482A

Abstract

Apparatus for blast cleaning of the surface of a pipe comprises a yoke 1 received circumferentially about the pipe and secured in contact therewith. Cogs 3 of the yoke 1 engage teeth of a rack 5 mounted to the yoke and a driving chain 4 connects together the cogs 3. A motor (not shown) connects drive to cogs 3 and chain 4 causing movement of rack 5 in circumvention of the pipe 2 in operation of the apparatus. A blast cleaning head 6 is mounted to rack 5 and comprises passageways terminating at the work surface of pipe 2, one for directing a stream of blasting particles to the surface and the other for recovering particles after impact and returning them to the source of particles. <IMAGE>

Description

SPECIFICATION Improvements in pipe surface treatment The invention relates to apparatus for particle bombardment (eg. grit blasing) of a pipe external surface.

The invention provides an apparatus for particle bombardment of a pipe external circumferential surface, which apparatus comprises a member receivable about said said surface and having at least part rotatable in relation thereto and means carried by said part for directing a particle stream onto said surface.

In a particular embodiment of the invention, the carrying member is a yoke including power means operable to cause said rotation upon actuation.

The yoke will conveniently comprise a first portion which in use is secured to the pipe circumference and a second portion movable relative thereto in rotation about the pipe, said means for directing the particle stream being mounted to the second portion. Conveniently, the second portion comprises a rack carrying said directing means and engaged with at least one pinion, or similar toothed drive transmission wheel, connected drivably to the power means and mounted to the first portion of the yoke.

Preferably, the rack will extend parallel to the pipe circumference around only a portion thereof, a plurality of pinions or the like being provided in spaced relationship so that drive is, in use, permanently connected to the rack to maintain permanent and preferably uniform movement of the stream directing means around the pipe.

In preferred embodiments of the invention, the apparatus includes as the stream-directing means a blast cleaning head for directing a stream of particles such as sand or shot onto the pipe surface to effect cleaning thereof and in particularto remove therefrom grease, corrosion products or weld debris so that an epoxy resin coating or coating of other protective plastics material may be applied to the pipe surface.

The blast cleaning head may conveniently comprise a passageway for a blasting particle-laden stream terminating at an orifice which opens to the work face of the head and is surrounded by a skirt which in use contacts the surface of the pipe to be blasted to prevent or reduce projection of blasting particles into the atmosphere. Preferably, the passageway is defined by means which defines with further means a return passage for used particles; the work face of the head may accordingly include an inner orifice from which to direct onto the pipe surface the stream of blasting particles and outer annular orifice connected in a return circuit for expended particles.

The skirt will preferably be flexible to facilitate such contact with the pipe surface as essentially to prevent escape of projectile particles. The skirt will most preferably comprise a plurality of bristles, for example perlon bristles.

The stream-directing means may in the alternative be a head for conveyance onto a preheated pipe surface of a stream of particles of plastics material (eg. an epoxy resin).

The following is a description, by way of example only, of one embodiment of the invention, reference being made to the accompanying drawings in which Figure 1 is a perspective view of apparatus in position about a pipe circumference, the apparatus being different to apparatus according to the invention but modifiable to the form of an apparatus according to the invention by replacement of the bevel cutting tool by a blast cleaning head as shown in Figure 2; and Figure 2 shows diagrammatically and in crosssection a blast cleaning head for use with the apparatus shown in Figure 1.

The apparatus shown in Figure 1 comprises a yoke 1 received circumferentially about a pipe 2. The yoke 1 is in contact with the circumferential surface of the pipe 2 and is secured over the circumferential surface by means not shown in the figure. A motor (not shown) is mounted to the yoke 1 in driving relationship to cogs 3 (of which two only are shown in the figure). The cogs are connected by means of a driving chain 4. The cogs 3 engage with teeth on a rack 5 mounted to the yoke 1 and movable relative thereto in rotation about the circumference of the pipe 2.

A blast cleaning head 6 (Figure 2) is mounted to the rack 5 and circumvents the pipe 2 with rotation of the rack.

The blast cleaning head 6 shown in Figure 2 comprises a passageway 7 for conveying a stream of particie-laden air to the surface of the pipe 2, the passageway 7 including a portion 8 for connection to a supply line (not shown) between the head and a source (not shown) of particle-laden air under pressure and a portion of wider cross section 9 terminating in an orifice 10 from which the particle-laden stream leaves the passageway 7 and is directed onto the surface of the pipe.

The head 6 also comprises a passage 11 which is use is connected to a return line (not shown) forming part of a return circuit to the source of the laden stream by means of which expended blast particles can be conveyed away from the work surface. As will be seen from the figure, the passage 11 includes an upstream portion 13 of annularform defined between walls 12 of the head 6 and the portion 14 of the supply passageway 7.

A skirt 15 of bristles made of perlon is provided at the base of the head and in used the skirt engages the surface of the pipe to prevent projection of blast particles from the work surface into the atmosphere.

The invention as described earlier without reference to the drawings may include any one or more of the features described above with reference to the drawings.

1. An apparatus for particle bombardment of a pipe external circumferential surface, which apparatus comprises a member receivable about said surface and having at least part rotatable in relation thereto and means carried by said part for directing a particle stream onto said surface.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in pipe surface treatment The invention relates to apparatus for particle bombardment (eg. grit blasing) of a pipe external surface. The invention provides an apparatus for particle bombardment of a pipe external circumferential surface, which apparatus comprises a member receivable about said said surface and having at least part rotatable in relation thereto and means carried by said part for directing a particle stream onto said surface. In a particular embodiment of the invention, the carrying member is a yoke including power means operable to cause said rotation upon actuation. The yoke will conveniently comprise a first portion which in use is secured to the pipe circumference and a second portion movable relative thereto in rotation about the pipe, said means for directing the particle stream being mounted to the second portion. Conveniently, the second portion comprises a rack carrying said directing means and engaged with at least one pinion, or similar toothed drive transmission wheel, connected drivably to the power means and mounted to the first portion of the yoke. Preferably, the rack will extend parallel to the pipe circumference around only a portion thereof, a plurality of pinions or the like being provided in spaced relationship so that drive is, in use, permanently connected to the rack to maintain permanent and preferably uniform movement of the stream directing means around the pipe. In preferred embodiments of the invention, the apparatus includes as the stream-directing means a blast cleaning head for directing a stream of particles such as sand or shot onto the pipe surface to effect cleaning thereof and in particularto remove therefrom grease, corrosion products or weld debris so that an epoxy resin coating or coating of other protective plastics material may be applied to the pipe surface. The blast cleaning head may conveniently comprise a passageway for a blasting particle-laden stream terminating at an orifice which opens to the work face of the head and is surrounded by a skirt which in use contacts the surface of the pipe to be blasted to prevent or reduce projection of blasting particles into the atmosphere. Preferably, the passageway is defined by means which defines with further means a return passage for used particles; the work face of the head may accordingly include an inner orifice from which to direct onto the pipe surface the stream of blasting particles and outer annular orifice connected in a return circuit for expended particles. The skirt will preferably be flexible to facilitate such contact with the pipe surface as essentially to prevent escape of projectile particles. The skirt will most preferably comprise a plurality of bristles, for example perlon bristles. The stream-directing means may in the alternative be a head for conveyance onto a preheated pipe surface of a stream of particles of plastics material (eg. an epoxy resin). The following is a description, by way of example only, of one embodiment of the invention, reference being made to the accompanying drawings in which Figure 1 is a perspective view of apparatus in position about a pipe circumference, the apparatus being different to apparatus according to the invention but modifiable to the form of an apparatus according to the invention by replacement of the bevel cutting tool by a blast cleaning head as shown in Figure 2; and Figure 2 shows diagrammatically and in crosssection a blast cleaning head for use with the apparatus shown in Figure 1. The apparatus shown in Figure 1 comprises a yoke 1 received circumferentially about a pipe 2. The yoke 1 is in contact with the circumferential surface of the pipe 2 and is secured over the circumferential surface by means not shown in the figure. A motor (not shown) is mounted to the yoke 1 in driving relationship to cogs 3 (of which two only are shown in the figure). The cogs are connected by means of a driving chain 4. The cogs 3 engage with teeth on a rack 5 mounted to the yoke 1 and movable relative thereto in rotation about the circumference of the pipe 2. A blast cleaning head 6 (Figure 2) is mounted to the rack 5 and circumvents the pipe 2 with rotation of the rack. The blast cleaning head 6 shown in Figure 2 comprises a passageway 7 for conveying a stream of particie-laden air to the surface of the pipe 2, the passageway 7 including a portion 8 for connection to a supply line (not shown) between the head and a source (not shown) of particle-laden air under pressure and a portion of wider cross section 9 terminating in an orifice 10 from which the particle-laden stream leaves the passageway 7 and is directed onto the surface of the pipe. The head 6 also comprises a passage 11 which is use is connected to a return line (not shown) forming part of a return circuit to the source of the laden stream by means of which expended blast particles can be conveyed away from the work surface. As will be seen from the figure, the passage 11 includes an upstream portion 13 of annularform defined between walls 12 of the head 6 and the portion 14 of the supply passageway 7. A skirt 15 of bristles made of perlon is provided at the base of the head and in used the skirt engages the surface of the pipe to prevent projection of blast particles from the work surface into the atmosphere. The invention as described earlier without reference to the drawings may include any one or more of the features described above with reference to the drawings. CLAIMS

2. An apparatus as claimed in Claim 1 wherein said particle directing means comprises a member defining an exit orifice for said particle stream, said orifice opening to a work surface in use of the apparatus and being surounded by a skirt which in use contacts the work surface to reduce or prevent projection of particles of said stream into the atmosphere.

3. An apparatus as claimed in Claim 2 wherein said skirt is defined by bristles extending from said orifice defining member and forming a generally continuous barrier to particles of said particle stream.

4. An apparatus as claimed in any preceding claim wherein the carrying member is a yoke including power means operable to cause rotation in circumvention of the pipe of said particle-directing means.

5. An apparatus as claimed in Claim 4wherein the yoke comprises a first portion which in use is secured to the pipe circumference and a second portion moveable relative thereto in rotation about the pipe, said means for directing the particle stream being mounted to the second portion.

6. An apparatus as claimed in Claim 5 wherein the second portion comprises a rack carrying said directing means and engaged with at least one pinion, or similar toothed drive transmission wheel, connected driveably to the power means and mounted to the first portion of the yoke.

7. An apparatus as claimed in Claim 6 wherein the rack extends parallel to the pipe circumference around only a portion thereof, a plurality of pinions or the like being provided in spaced relationship so that drive is, in use, permanently connected to the rack to maintain permanent and preferably uniform movement of the stream directing means around the pipe.

8. An apparatus as claimed in Claim 1 and substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.