Iron Cement Joint

Iron Cement Joint is one stopped with iron cement. This composition is prepared as follows : - Two parts of flower of sulphur, three parts of muriate of ammonia, and 16 parts of wrought iron filings, quite free from rust, are mixed thoroughly together and kept quite dry until required for use. When the cement is about to be used, one part of this compound is added to twelve parts of clean iron filings, turnings, or borings, in which those from wrought iron should preponderate, and the whole mixed with sufficient water (in which a few drops of sulphuric acid have been let fall) to bring it to a pasty consistency. In caulking sockets with this material it is necessary to exercise care, lest they are inadvertently fractured with the caulking tool, which should be selected of the proper size and cranked to enter the socket more readily. Further particulars connected with the use of this cement are given under the alternative title of Rust Joint.

Joggle Joint

Joggle Joint is one between cast iron pieces, having jogs or notches to prevent sliding. Large screw piles, for instance, with internal flanges bolted together, are strengthened against the strain of torsion at the joint by joggling the flanges.

Jump Joint occurs when the edges of plates forming a butt joint are squarely and smoothly planed so that the contact between them being perfect throughout, the cover plates and rivets are relieved of part of the compressive stress passing along the main plates, and are, therefore, respectively shorter and less numerous than with the ordinary butt.

Key Joint

In screw-piling, a coupling joint consisting of a square or polygonal head fitting into a corresponding socket by which the whole can be revolved with capstan bars, etc. In some descriptions of work it is necessary to lash the outer extremities of the bars together to keep them in their holes in case of the capstan taking charge.

Lap Or Lapped Joint

In girder work, etc, this is the simplest form of riveted joint, and is made by overlapping the plates and uniting them by either a single, double, or triple riveted joint, under which terms further explanation will be found. Hoop-iron bond is lapped and riveted at angles. Sheets of galvanised iron are laid to form roof coverings with a lap of about 2 in. at the fluted and about 4 in. at the straight edges, and are secured with nails or screws to wooden bearers, or with bolts to iron ones.

Lead Or Leaded Joint

In bedding an iron column upon a post stone, bed stone, etc, a plate of sheet lead is now and again laid between the stone and iron base, which, by its yielding to the irregularities of surface, enables the column to remain vertical after it has been truly adjusted in that position. In the same way bed plates lie upon a piece of lead spread out upon the foundation slab. Other allusions to this practice will be found under Bed Joint. The operation of stopping joints with molten lead is described in the Plumbers' Section under Run Joint.