GB2359777A

GB2359777A - Lining a structure

Info

Publication number: GB2359777A
Application number: GB0004899A
Authority: GB
Inventors: David Swinnerton Smith; David Terence Bell; John Owen Fowler
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2000-03-02
Filing date: 2000-03-02
Publication date: 2001-09-05
Also published as: GB0004899D0

Description

1 LINING OF STRUCTURES 2359777 This invention relates to the lining of

structures and in particular to the lining of steel structures with a 5 protective layer of lead.

Lead is extremely resistant to attack by a wide range of compounds. This makes its use attractive in applications where such resistance is necessary, for instance in the manufacture of reaction vessels that operationally contain corrosive liquids such as sulphuric acid. However, the cost and weight of lead are such that it is often impractical to manufacture the full vessel from lead. One way in which this problem has been solved in the past is to make use of a vessel that is made from relatively cheap and light steel that has been provided with a lead lining on those of its portions exposed to the corrosive liquid.

While such lead-lined vessels are effective for containing corrosive liquids, they can often be difficult to manufacture. One way in which manufacture can be carried out is by a process in which molten lead is manually applied to the surface to be protected. Such a technique is, however, potentially hazardous due to the toxic nature of the fumes generated by the molten lead. It is also very time consuming and hence expensive to carry out. 25 It is an object of the present invention to provide a method of providing a lead lining on a structure in which such potentially hazardous and expensive techniques are substantially avoided. According to the present invention, method of providing a metallic structure with a metallic lining comprises the steps of coating at least one of said lining material in sheet form and said structure with an interfacial medium capable of generating a transient liquid phase at elevated temperature and/or pressure, overlying at least part of said structure with said sheet of lining material so that said interfacial medium is interposed therebetween, and applying 2 sufficient cause said phase and structure. Said thereof. Said Said Said 10 of 3.85 x Said The heat and/or pressure to the resultant assembly to interfacial medium to form a transient liquid subsequently bond said lining material to said metallic lining material may be lead or an alloy metallic structure may be formed from steel. interfacial medium is preferably a solder paint. resultant assembly may be subjected to a pressure 10-7 NM-2 at a temperature of 150 degrees Celsius.

lining in sheet form may be 8mm thick.

present invention will now be described, by way of example, with reference to the accompanying drawing which is a section side view of a portion of a structure in the process of being provided with a lead lining in accordance with the method of the present invention.

Referring to the drawing, a vessel 10, part of which can be seen in the drawing, is formed by conventional techniques from steel into a shape which makes it suitable as a reaction vessel for containing corrosive liquids such as sulphuric acid. In order to protect the steel vessel from attack by the corrosive liquid, it is provided with a lining of lead 11. Although in this particular case, lead alone has been utilised, it will be appreciated that in other applications, it may be desirable to employ an alloy of lead.

Prior to the application of the lead lining 11 to the vessel 10 part, the portions of the steel vessel 10 surface to be lined are roughened by shot blasting. Similarly, the surf ace of a sheet of lead of about 8mm thickness to be used for lining the vessel is roughened by wire brushing. To either or both of the roughened surfaces is then applied a solder paint. A typical solder paint suitable for this purpose is manufactured by Fry's Metals Limited. It has the product code EX3995 and contains by weight 1-5% Antimony, 20- 50% Lead, 20-50% Tin and 10-20% Zinc Chloride. The metallic 3 constituents of the paint are present as a suspension of particles in the Zinc Chloride carrier.

The lead lining 11 is then placed over the steel vessel 10 portion so that the roughened surfaces thereof are adjacent each other and the solder paint is interposed between them. The temperature of the lining 11 and vessel 10 portion is then raised to 150 degrees Celsius. This temperature is sufficiently high to melt the metallic constituents of the solder paint but not melt the lead lining lo 11 or the steel vessel 10 portion. Indeed, if necessary, the temperature could be raised as high as 250 degrees Celsius. Pressure of the order of 3.85 x 107 Nm -2 is then exerted upon the lining 11 by means of a platen 12 for a period of 2 minutes. The combination of elevated temperature and pressure results in the metallic constituents of the solder paint melting to form a transient liquid phase between the lining 11 and the vessel 10 portion. This conditions the interface between the lining 11 and vessel 10 portion, leading in turn to the creation of a bond that is essentially mechanical in nature between the lead lining 11 and the vessel 10 portion. This process is then repeated over the whole of the surface of the vessel 10 that it is desired to line.

Although in this particular case, specific pressure temperature and time parameters are employed, it is possible that other combinations of such parameters could be employed as long as they bring about the desired effect of the creation of a transient fluid phase between the lining 11 and the vessel portion 10 and the subsequent bonding of the lining 11 to the vessel portion 10. However, there are limits which must be observed in individual case to ensure that there is no undesirable thinning, or indeed melting, of the lead lining 11. Such limits will be clearly apparent to those skilled in the art carrying out specific applications of the present invention.

The method of the present invention thus results in the provision of a lead lining 11 on the vessel 10 that is of 4 generally constant thickness. The method is also less labour intensive than existing techniques employing the melting of lead and does not result in the generation of significant quantities of toxic fumes.

Although in the case of the embodiment of the present invention described above, lead sheet 10 is used to line the relevant portions of the vessel 10, other suitable metallic materials, such as copper, could be employed depending upon the eventual use to which the reaction vessel 10 is to be put. However, in all cases, the same general technique of interface conditioning is employed in which a material capable creating a transient liquid phase in interposed between the metallic structure and the metallic sheet prior to the application of heat and/or pressure.

Claims

1. A method of providing a metallic structure with a metallic lining comprising the steps of coating at least one of said lining material in sheet form and said structure with an interfacial medium capable of generating a transient liquid phase at elevated temperature and/or pressure, overlying at least part of said structure with said sheet of lining material so that said interfacial medium is interposed therebetween, and applying sufficient heat and/or pressure to the resultant assembly to cause said interfacial medium to form a transient lining material to

2. A method of liquid phase and subsequently bond said said structure.

providing a metallic structure with a 15 metallic lining as claimed in claim 1 wherein said metallic lining material is lead or an alloy thereof.

3. A method of providing a metallic structure with a metallic lining as claimed in claim 1 or claim 2 wherein said metallic structure is formed from steel.

4. A method of providing a metallic structure with a metallic lining as claimed in any one preceding claim wherein said interfacial medium is a solder paint.

5. A method of providing a metallic structure with a metallic lining as claimed in any one preceding claim wherein said resultant assembly is subjected to a pressure of 3.85 x 107 NM-2 at a temperature of 150 degrees Celsius.

6. A method of providing a metallic structure with a metallic lining as claimed in any one preceding claim wherein said lining in sheet form is 8mm thick prior to the application of said heat and pressure.

7. A metallic structure lined in accordance with the method of any one preceding claim.

8. A method of providing a metallic structure with a metallic lining substantially as hereinbefore described with reference to and as shown in the accompanying drawing.