GB2069374A

GB2069374A - Spray-painting an oil tank exterior

Info

Publication number: GB2069374A
Application number: GB8004370A
Authority: GB
Original assignee: Port of Singapore Authority
Current assignee: Port of Singapore Authority
Priority date: 1980-02-08
Filing date: 1980-02-08
Publication date: 1981-08-26

Abstract

The surface 32 of a large cylindrical oil tank 33 is painted by positioning an upper support 4 at the top of the tank and slowly lowering a spraying unit 2 on guide ropes 3 suspended from the support 4, the lowering of the spraying unit being controlled by a rope 6 and the unit being switched on by the person on the ground through a power cable 12. When the unit 2 reaches the ground upon completing the painting of a vertical strip, the person switches it off. Then another person on top of the tank moves the support 4 round the tank to a new position, and the first person hoists the unit 2 up to the support 4, switches it on again, and paints another vertical strip by lowering the unit slowly to the ground again. The bottom ends of the guide ropes 3 are weighted down by a tensioning frame 5 which hangs on the guide ropes just above the ground. <IMAGE>

Description

SPECIFICATION Method of and apparatus for spraying a surface with fluid by means of a spraying unit This invention relates to a method of and apparatus for spraying a surface with fluid by means of a spraying unit.

According to a first aspect of the invention there is provided a method of spraying a surface with fluid by means of a spraying unit, comprising the steps of spraying the surface with the fluid in a series of strips one after another by means of said unit, the unit being moved in a controlled manner along an elongate guide during the spraying of each strip, the guide being held substantially stationary during the spraying and being moved from one position to another in intervals between the spraying of successive strips.

According to a second aspect of the invention there is provided apparatus for spraying a surface with fluid, comprising a spraying unit, an elongate guide along which said unit can be guidedly moved, means for holding the guide substantially stationary during spraying and for enabling the guide to be moved from position to position in intervals between spraying, and means for controlling the movement of said unit along said guide.

A preferred application of the invention is to the painting of the surfaces of large cylindrical oil storage tanks such as do not require much pretreatment before painting.

The invention will be described by way of example with reference to the accompanying drawings, wherein: Figure 1 illustrates the painting of the exterior surface of a large cylindrical oil storage tank by a method and apparatus in accordance with the invention; Figures 2, 3 and 4 are a plan view, front elevation and side elevation respectively of a paint-spraying unit of the apparatus of Figure 1; Figures 5, 6 and 7 are a plan view, side elevation and front elevation of a support of the apparatus of Figure 1; and Figures 8, 9 and 10 are a plan view, a front elevation and a side elevation of a lower tensioning frame forming a weight of the apparatus of Figure 1.

Referring to the drawings, the illustrated apparatus 1 comprises a spraying unit 2, an elongate guide 3 along which the unit 2 can be guidedly moved, a support 4 for suspending the guide 3 substantially vertically, a weight 5 for weighting down the bottom end of the guide 3, and a rope 6 for controlling the movement of the spraying unit 2 along the guide 3.

Referring to Figs. 2, 3 and 4, the spraying unit 2 comprises a simple frame 7 on which a readily available commercial electric sprayer 8 is mounted. A funnel-shaped wind shield 9 is fitted to the spray nozzle 10 of the sprayer 8, not only to prevent wind from affecting the spray but also to concentrate the spray such that it is even and regular on the surface to be painted. A simple hook 11 is provided on the top of the spraying unit 2 through which the rope 6, which is a nylon rope, is attached. A long and flexible power cable 1 2 (not shown in Figs. 2, 3 and 4) extends from the electric sprayer 9 to a control unit (not shown) for control of the electric sprayer 8 by the person (the "operator") 13 (see Fig. 1) operating the apparatus 1.The spraying unit frame 7 includes two vertical tubes 14 for slidably receiving two nylon ropes forming the elongate guide 3. The tubes 14 are long enough for the spraying unit 2 to be held substantially vertical when sliding along the ropes 3 when the ropes 3 are substantially vertical and are under tension.

Referring now to Figs. 5, 6 and 7, the support 4 comprises a frame 15, three pairs of castors 16, 17 and 18 and a pulley 19. The frame 15 comprises two substantially vertical side members 20, one at each side, two substantially horizontal intermediate side members 21, two relatively short, substantially horizontal lower side members 22, one at each side and two diagonal members 23, one at each side. The castors 1 6 and 17 are mounted on members 21 , which are pivoted at 24 on members 20.The angle between substantially vertical members 20 and substantially horizontal members 21 can be selectively adjusted by virtue of the fact that the diagonal members 23 are pivoted, for example at 25, in any selected one of a plurality of holes along member 21 and are secured at their other ends by tightened nuts and bolts 26 engaging in slots 27 in members 23, the positions of the nuts and bolts 26 along the slots 27 being adjustable before the nuts and bolts are tightened.

The other castors 1 8 are mounted at the ends of the lower side members 22, which are welded perpendicularly to members 20. The spacing between castors 1 8 and members 20 is adjustable by means of a horizontal slot 28 in each of members 22, and a nut and bolt device 29 for fixing the positions of the castors 1 8 relative to members 22.

The pulley 19 is mounted in the middle of an upper cross member 30 of the frame 1 5.

Referring briefly to Figures 8, 9 and 10, the weight 5 is constructed in the form of a substantially rigid frame comprising two guide tubes 31.

Before proceeding with a description of how the apparatus 1 is used, it should be mentioned that the guide 3 is in the form of two further nylon ropes, not individually shown.

In order to use the apparatus 1 for the purpose of painting the outside surface 32 of a large cylindrical oil tank 33 (Fig. 1), the support 4 is first positioned as shown in Fig. 1 on the edge of the tank top so that the castors 1 6 and 1 7 rest on top of the tank and the castors 1 8 engage the side of the tank and the support 4 is secured in position by two ropes (not shown) tied to any suitable protrusion (not shown) in the centre of the tank roof 34. The support 4 may be held in position additionally either by friction or by additional fixing means, not shown. The two guide ropes (not individually shown) are then released from the support 4 to the ground.On the ground, the guide ropes are threaded through the two guide tubes 14 of the spraying unit frame 7 and then throug'n the two guide tubes 31 of the weight 5. The lengths of the guide ropes are then adjusted according to the height of the tank 33, after which the guide ropes are properly secured to the frame forming the weight 5, in such a way that the weight 5 hangs just above ground level and tensions the two guide ropes 3 for the vertical movement of the spraying unit 2. Suitable weights (not shown), for example, bricks or similar objects, could be placed on the frame forming the weight 5 if more tension is required in the guide ropes 3.

The rope 6 is threaded over the pulley 19 of support 4 and is secured to the hook 11 of spraying unit 2. Readily-thinned paint is first prepared and a full container of the paint is attached to the spraying unit 2. Then, the operator 13 hoists the spraying unit 2 up the guide ropes 3 by means of the rope 6 to the top of the apparatus, that is, to the support 4. He then switches on the electric sprayer 8 and slowly and evenly begins to lower the spraying unit 2 by means of the rope 6, so that paint is evenly deposited in a vertical strip on the tank surface 32.

When the spraying unit 2 reaches the bottom of the tank, that is to say, the weight 5, the operator 13 switches off the electric sprayer 8 and another person (not shown) at the top of the tank 33 shifts the support 4 along for another vertical strip of paint to be applied. The operator 13 then hoists the spraying unit 2 again to the top of the apparatus, switches it on and again starts lowering it slowly and evenly towards the ground to paint another strip. Obviously, it is not necessary for successively painted strips to overlap. Successively painted strips may be spaced apart, for the space between them to be filled in by subsequently painted strips.

Conveniently, in addition to the operator 13 who hoists and lowers the spraying unit 2 and switches the electric sprayer 8 on and off, and the person (not shown) on the top of the tank 33 who positions the support 4, a third person may be employed to mix the paint in containers for recharging the spraying unit 22 from time to time.

Even so, only three persons are required for painting the entire tank surface 32. The two persons on the ground can readily exchange duties if desired.

Claims

1. A method of spraying a surface with fluid by means of a spraying unit, comprising the steps of spraying the surface with the fluid in a series of strips one after another by means of said unit, the unit being moved in a controlled manner along an elongate guide during the spraying of each strip, the guide being held substantially stationary during the spraying and being moved from one position to another in intervals between the spraying of successive strips.

2. A method as claimed in claim 1 wherein all the strips and the guide are substantially vertical.

3. A method as claimed in claim 2 wherein the guide is suspended from a support which is held stationary during the spraying of each strip and is moved from position to position in the intervals between the spraying of successive strips.

4. A method as claimed in claim 3 wherein the bottom end of the guide is weighted down.

5. A method as claimed in claim 3 or 4 wherein the support is moved on roller means in said intervals.

6. A method as claimed in any preceding claim wherein the fluid is paint.

7. Apparatus for spraying a surface with fluid, comprising a spraying unit, an elongate guide along which said unit can be guidedly moved, means for holding the guide substantially stationary during spraying and for enabling the guide to be moved from position to position in intervals between spraying, and means for controlling the movement of said unit along said guide.

8. Apparatus as claimed in claim 7 wherein the guide-holding means comprises a support for suspending the guide substantially vertically.

9. Apparatus as claimed in claim 8 wherein the guide-holding means comprises a weight for weighting down the bottom end of the guide.

10. Apparatus as claimed in claim 8 or 9 wherein the support has roller means for movement of the support from position to position in said intervals between spraying.

11. Apparatus as claimed in claim 8, 9 or 10 wherein the guide is formed by one or more ropes.

12. Apparatus as claimed in any one of claims 8 to 11 wherein the unit movement controlling means comprises a rope attached to said unit and extending over a pulley of said support.