GB2144085A - Steel pontoon - Google Patents

Abstract

The pontoon for floating bridges, ferries and rafts comprises a top plate (1), a bottom plate (2) and side plates (3) and is characterised in that the side plates (3) are secured, preferably by welding (w), to folded margins of the top plate (1) and bottom plate (2). Flanges are welded to the end margins of the top and bottom plates. End plates are welded to the flanges. For transport, the side and end plates are packaged between abutting margins of the top and bottom plates. <IMAGE>

Description

SPECIFICATION Improved steel pontoon This invention relates to steel pontoons for floating bridges, ferries and rafts.

Steel pontoons are essentially watertight steel boxes usually of flat elongated rectangular shape as illustrated in perspective view in Fig. 1 of the accompanying drawings. Around the periphery of such a pontoon there are provided at positions A, B .... L, M sets of couplings by which the pontoons can be interconnected to form various sizes and shapes of floating rafts.

Traditionally these pontoons have had a fabricated framework of rolled steel sections, which carry and distribute all the loads, and onto which steel skin plates are applied. This last operation requires a large amount of continuous welding around all the edges of each skin plate. Furthermore all these welds have to be checked for watertightness. As an example, a typical transverse cross-section is shown in Fig. 2, where it will be seen that eight continuous welds, marked 'w', between top and bottom plates 1, 2 and side plates 3 must be laid down and checked for watertightness.

The present design seeks'to provide a more efficient and more economical pontoon, firstly by applying the principle of stressed skin design, whereby the skin plates carry and distribute the loads, reducing the amount of framework required, and secondly by folding the skin plates to reduce the amount of welding required.

This is illustrated in Fig. 3, again being a typical transverse cross-section, where the top and bottom plates 1,2 have been folded over and the side plates 3 are welded at the four points marked 'w'. Comparison with Fig. 2 shows that the amount of watertight welding between top, bottom and side plates has been halved. End plates (not shown) are secured by welding to flanges (not shown) which are welded to the end margins of the top and bottom plates 1, 2 and extend in planes perpendicular thereto.

A further improvement is concerned with reducing transport cost for pontoons required for overseas. Here, the top and bottom plates 1, 2 are jig-fabricated complete with side and end couplings, and the remaining parts to form the ends and sides are stowed between them to form a "knocked-down" parcel as illustrated in Fig. 4. Comparing this with Fig.

1 shows the considerable saving in shipping volume achieved, the knocked-down" parcel being approximately one tenth of the voiume of the finished pontoon. This more than offsets the cost of completing the fabrication of the pontoons on site.

1. A steel pontoon comprising a top plate, a bottom plate and side plates wherein the side plates are secured to folded margins of the top plate and the bottom plate.

2. A steel pontoon as claimed in claim 1 wherein the folded margins are perpendicular to the planes of the top and bottom plates and the side plates are secured to the folded margins by welding.

3. A steel pontoon as claimed in claim 1 or claim 2 and including end plates which are secured to flanges welded to the end margins of the top and bottom plates.

4. A dismantled steel pontoon adapted to be assembled as claimed in any of claims 1 to 3 and of which side plates and end plates are contained in the enclosure defined between aligned abutting top and bottom plates.

CLAIMS (Filed on 10.11.83) 1. A steel pontoon comprising a top plate, a bottom plate and side plates wherein the side plates are secured to folded margins of the top plate and the bottom plate, the folded margins being perpendicular to the planes of the top and bottom plates and the side plates being secured to the folded margins by welding.

2. A steel pontoon as claimed in claim 1 and including end plates which are secured to flanges welded to the end margins of the top and bottom plates.

3. A dismantled steel pontoon adapted to be assembled as claimed in claim 1 or claim 2 and of which side plates and end plates are contained in the enclosure defined between aligned abutting top and bottom plates.

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

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved steel pontoon This invention relates to steel pontoons for floating bridges, ferries and rafts. Steel pontoons are essentially watertight steel boxes usually of flat elongated rectangular shape as illustrated in perspective view in Fig. 1 of the accompanying drawings. Around the periphery of such a pontoon there are provided at positions A, B .... L, M sets of couplings by which the pontoons can be interconnected to form various sizes and shapes of floating rafts. Traditionally these pontoons have had a fabricated framework of rolled steel sections, which carry and distribute all the loads, and onto which steel skin plates are applied. This last operation requires a large amount of continuous welding around all the edges of each skin plate. Furthermore all these welds have to be checked for watertightness. As an example, a typical transverse cross-section is shown in Fig. 2, where it will be seen that eight continuous welds, marked 'w', between top and bottom plates 1, 2 and side plates 3 must be laid down and checked for watertightness. The present design seeks'to provide a more efficient and more economical pontoon, firstly by applying the principle of stressed skin design, whereby the skin plates carry and distribute the loads, reducing the amount of framework required, and secondly by folding the skin plates to reduce the amount of welding required. This is illustrated in Fig. 3, again being a typical transverse cross-section, where the top and bottom plates 1,2 have been folded over and the side plates 3 are welded at the four points marked 'w'. Comparison with Fig. 2 shows that the amount of watertight welding between top, bottom and side plates has been halved. End plates (not shown) are secured by welding to flanges (not shown) which are welded to the end margins of the top and bottom plates 1, 2 and extend in planes perpendicular thereto. A further improvement is concerned with reducing transport cost for pontoons required for overseas. Here, the top and bottom plates 1, 2 are jig-fabricated complete with side and end couplings, and the remaining parts to form the ends and sides are stowed between them to form a "knocked-down" parcel as illustrated in Fig. 4. Comparing this with Fig. 1 shows the considerable saving in shipping volume achieved, the knocked-down" parcel being approximately one tenth of the voiume of the finished pontoon. This more than offsets the cost of completing the fabrication of the pontoons on site. CLAIMS

1. A steel pontoon comprising a top plate, a bottom plate and side plates wherein the side plates are secured to folded margins of the top plate and the bottom plate.

2. A steel pontoon as claimed in claim 1 wherein the folded margins are perpendicular to the planes of the top and bottom plates and the side plates are secured to the folded margins by welding.

3. A dismantled steel pontoon adapted to be assembled as claimed in claim 1 or claim 2 and of which side plates and end plates are contained in the enclosure defined between aligned abutting top and bottom plates.

3. A steel pontoon as claimed in claim 1 or claim 2 and including end plates which are secured to flanges welded to the end margins of the top and bottom plates.

4. A dismantled steel pontoon adapted to be assembled as claimed in any of claims 1 to 3 and of which side plates and end plates are contained in the enclosure defined between aligned abutting top and bottom plates.

CLAIMS (Filed on 10.11.83) 1. A steel pontoon comprising a top plate, a bottom plate and side plates wherein the side plates are secured to folded margins of the top plate and the bottom plate, the folded margins being perpendicular to the planes of the top and bottom plates and the side plates being secured to the folded margins by welding.

2. A steel pontoon as claimed in claim 1 and including end plates which are secured to flanges welded to the end margins of the top and bottom plates.