[53]“When we have to deal with comparatively thin boiler plates, there is no difficulty in obtaining a sufficiently high percentage of strength in the joints, by using the ordinary double riveted joint, but when we have to deal with thick plates, as in the case of large marine boilers, as 1 inch or upwards, a more costly form of joint must be employed, in order to obtain the required percentage of strength at the joint; hence the ordinary double riveted joint is replaced by various other forms as follows:
[53] From “Steam Boilers.”
Fig. 3248.
“First, a triple zigzag riveted lap joint, such as shown in [Fig. 3248], or a chain riveted joint as in [Fig. 3249], in both of which the third row of rivets enables the rivet pitch to be increased, thus increasing the plate percentage, while the third row of rivets also increases the rivet percentage.
Fig. 3249.
“Second, by employing butt joints with butt straps, either double or treble riveted.