For very heavy pipes and fittings, tackle is required for lifting and holding them. Chains, steel cable, heavy-duty C-clamps, chain hoists, and cranes are used, if available. Hammers of various sizes, crowbars, and pinch bars are needed occasionally to bend the pipe joints in order to align them. These tools should always be used carefully so that they will not damage the pipe or the pipe joint.

Steel rules, steel tapes, spirit levels, protractors, and rafter squares are indispensable tools for fitting-up pipe. Careless usage of these tools must be avoided as it may impair their accuracy. A level that does not read correctly or a square that is “out-of-square” can cause serious errors. For this reason, levels and squares should be checked occasionally.

A level is checked by placing it on a plane surface that is horizontal, or nearly so. In Fig. 14-1, this is called POSITION І and the encircled numbers identify the ends of the level. When in POSITION I, carefully read the position of the bubble in the glass. Then turn the level around to POSITION 2, Fig. 14-1. If the level is

POSITION i

Pig. 14-1. Method of checking a level. The bubble should read the same when the level is in either position shown.

reading correctly, the bubble will be in the same place but on the opposite side of the glass in relation to the ends of the level. The vertical and 45-degree glasses can only be checked by placing the level on surfaces that are known to be vertical or 45 degrees. Most levels have provision for adjusting the glass so that it will read correctly.

The best method of checking a square is to hold it against a square that is known to be true. Both squares should be placed on a perfectly flat surface, as shown in Fig. 14-2A. Another method, shown in Fig. 14-2B, is to set the square on a flat surface and against another, smooth surface on which a line can be scribed. Scribe a line using the square and then turn it around and scribe another line in ttye same place. If the two scribed lines coincide, the square is true.

A square that is not true can only be corrected in a precision machine shop. Usually it is less expensive to purchase a new square.

Pipe Fittings. A wide variety of standard pipe fittings is shown in Fig, І4-3. These fittings are produced especially for welded pipe and they are purchased with the ends beveled correctly in preparation for welding.