This invention relates to flange shields and in particular relates to shields for flanged joints on pipe lines carrying corrosive or dangerous fluids.

Where pipe lines carrying corrosive or dangerous fluids are joined a flange joint is commonly used. In this, flanges surrounding the ends of each pipe to be joined are bolted together to effect the join, usually with a gasket placed between the two to prevent leakage of the fluid to be carried. Many pipe lines carry dangerous fluids such as alkalis or acids, often under pressure. Should a flange gasket fail then a high pressure spray of corrosive material may ensue with consequent danger to personnel and machinery in the vicinity. To prevent such an occurence there has been proposed to provide flange shields, which fall into two main categories. One is a strip of inert material, e.g. plastics material, which is bent around the flange joint and affixed into a circular shape by clips, rivets, studs or the like. Another proposal uses a flexible plastics material coated cloth which is wrapped round the joint and affixed with draw-strings.

While both of the above proposals are reasonably effective they are expensive and can be difficult to affix. The invention seeks to provide a form of flange shield improved in these respects.

According to the present invention there is provided a flange shield dimensioned so as to cover a desired flange joint characterised in that it is formed in two halves

hingedly attached to one another in one area and adapted to be fixed together at an opposite area.

The flange shield of the invention may have the general appearance of a wide wheel and axle and we can therefore define axial, radial and circumferential directions. Preferably, the flange shield will be split in a radial plane passing through the axis, and the hinge will be located at one of the points where the split plane passes through the circumference, the parts adapted to be fixed together being located at the opposite position where the ^" radial plane passes through the circumference. In this way the shield can be hinged open, brought to a flange joint, closed about the joint, and secured very simply and easily. Moreover, since the product can be moulded from a plastics material it can be produced less expensively than with conventional materials.

Preferably, the device is vaccuum formed in moulds, and it can be formed from a variety of plastics materials. Such materials include pvc, polyolefins, nylon, PTFE, and the like. However, for a combination of chemical inertness, economy and good hinging characteristics it is preferred to form the flange shield from polypropylene.

The invention will be described further, by way of example, with reference to the accompanying drawings in which,

Figure 1 there is an elevational view of a shield in accordance with the invention in place on a flange joint;

Figure 2 is a side view of the joint when split; and

Figure 3 is a plan view of the shield corresponding to Figure 2.

Referring to the drawings, a flange shield generally designated 10 having a generally wheel-shaped profile is formed in two halves 12, 14 hingedly attached together at 16. The two halves 12, 14 may be produced by vaccuum forming in moulds from a suitable material such as polypropylene. The hinge may be produced at the same time and indeed the shield is preferably produced integrally.

The two portions 12, 14 when joined together (Figure 1) define a central disc shaped portion 18 which surrounds the flanges 20 of a flange joint 22 on a pipeline 24 in use. In order that the shield 10 will fit a variety of pipe diameters it is constructed with "axle" portions 26 which are stepped. Each axle portion 26 may be cut (usually by means of a hacksaw) at any of the points A, B, C or D to give four available diameters of opening for the pipeline 24. As illustrated in Figure 1 the cut would be made at position D but for a pipeline of smaller diameter one of the other points would be selected.

As illustrated, the shield is formed in two halves split about a radial plane passing through the longitudinal axis of the device 28. The hinge 16 is formed at one portion where the split crosses the circumference of the disc portion 18. At the opposite portion where the split crosses the circumference means 30 is provided to enable the opposite edges to be affixed together. Preferably the means 30 comprises a tongue and detent arrangement whereby the two opposite edges are a "snap fit". Alternatively clips, bolts or the like may be employed.

Use of the flange shield invention is simple. For a given diameter of pipeline all the flange shields can be cut at the relevant point A, B, C, or D to provide an opening of the correct diameter. The operative then takes one shield to each flange joint 22 places it round the joint and snap fits the two halves 12, 14, together by means of the fixing arrangement 30. The joint is then surrounded and a failure of the gasket (not shown in the drawings) would not allow corrosive fluid to spray beyond the flange shield 10. The shield 10 is not meant to be a complete protection against escaping fluid, but merely to prevent fluid spraying from the joint. Seepage of the fluid from the flange shield can be observed by a maintenance check and the problem rectified.

If desired part or all of the shield of the invention can be made transparent to aid inspection of the joint.

The flange shield of the invention provides a simple, economical and easy to use way of preventing spray from leaking flange joints.