information regarding the PEB, you should refer to the current  Steelworker  TRAMAN. STRUCTURAL  STEEL  CONNECTORS There are four basic connectors used in making structural steel connections. They are bolts, welds, pins, and rivets.  Bolts  and  welds  are  the  most  common connectors used in military construction. Pins are used for connections at the ends of bracing rods and various support  members  that  require  freedom  of  rotation. Commercial  prefabricated  steel  assemblies  may  be received  in  the  field  with  riveted  conectors.  Types  and uses of the four basic connectors are discussed in the following  text. Bolts Bolts  are  used  more  than  any  other  type  of connectors. They are easy to use and, in contrast to all other  types  of  connectors,  require  little  special equipment.  The  development  of  higher  strength  steels and  improved  manufacturing  processes  have  resulted  in the  production  of  bolts  that  will  produce  strong structural steel connections. Specifications for most bolted structural joints call for the use of high-strength steel bolts tightened to a high tension. The bolts are used in holes slightly larger than the nominal bolt size. Joints that are required to resist shear  between  connected  parts  are  designated  as  either friction-type or bearing-type connectors. Bolted  parts  should  fit  solidly  together  when  they are assembled and should NOT be separated by gaskets or any other type of compressible material. Holes should be a nominal diameter, not more that 1/16 inch in excess of the nominal bolt diameter. When the bolted parts are assembled, all joint surfaces should be free of scale, burrs, dirt, and other foreign material. Contact surfaces with friction-type joints must be free of oil, paint, or other  coatings. Welds Welding  is  a  highly  specialized  skill,  and  welding of load-bearing parts of a structure should be performed only by properly qualified personnel. As an EA, you will not   be   expected   to   perform   welding   operations. However, you should have a general knowledge of the principal  welding  processes  and  the  different  types  of welds  and  their  applications,  and  you  should  know  how welding  symbols  are  used  to  identify  welded connections shown in working drawings. The  two  principal  welding  processes  used  in structural work are  electric arc welding and  oxy-MAPP gas welding. In the electric arc welding process, welding heat, sufficient to fuse the metal together, is developed by an electric arc formed between a suitable electrode (welding rod) and the base metal (the metal of the parts being  welded).  In  the  oxy-MAPP  gas  welding  process, heat is obtained by burning a mixture of MAPP gas and oxygen as it is discharged from a torch designed for this purpose. While electric arc welding is normally used for metals  that  are  1/8  inch  or  larger  in  thickness, oxy-MAPP gas welding is usually restricted to thinner metals. The  principal  types  of  welds  and  welded  joints  that are suitable for structural work are shown in figures 1-48 and  1-49. On drawings, special symbols are used to show the kinds of welds to be used for welded connections. These symbols  have  been  standardized  by  the  American Welding Society (AWS). You should become familiar with the basic welding symbols and with the standard location of all elements of a welding symbol. The distinction between a  weld  symbol  and a welding symbol should be noted. A weld symbol is a basic symbol used to indicate the type of weld. Basic weld symbols are shown at the top of figure 1-50. The supplementary  symbols  shown  in  the  figure  are  used when  necessary  in  connection  with  the  basic  weld symbols. A welding symbol consists of the following eight elements, or as many of these elements as are required: (1) reference line, (2) arrow, (3) basic weld symbol, (4)  dimensions  and  other  data,  (5)  supplementary symbols,  (6)  finish  symbols,  (7)  tail,  and  (8)  specifica- tion, process, or other reference. These elements of the welding  symbol  have  specific  standard  locations  with respect to each other, as shown in figure 1-50. When a finish symbol is used in a welding symbol, it indicates the  method  of  finish,  not  the  degree  of  finish.  For example, a C is used to indicate finish by chipping, an M indicates machining, and a  G indicates  grinding. 1-24