Page 113 - Ship Construction.DJ Eyres 6Ed

Ch10-H8070.fm Page 102 Wednesday, October 18, 2006 7:37 AM
102 Ship Construction
BACKSTEP METHOD OF WELDING
Direction of weld Direction of weld

6 5 4 3 2 1 1 2 3 4 5 6

Progression of welder Progression of welder
--- ใช้เพื่อการศึกษาเท่านั้น---
Direction of weld Direction of weld
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
6 4 2 5 3 1 1 3 5 2 4 6

Progression of welder Progression of welder
WANDERING METHOD OF WELDING

WELD DISTORTION

ึ

Shrinkage
stresses

Weld direction

FIGURE 10.3 Backstep and wandering methods of welding

the hull structure would tend to be shortened causing the hull to rise from the
blocks at the ends. Where in modern construction the side shell and deck
plating are erected in blocks and a suitable welding sequence is employed
this problem does not arise.
In repair work correct welding sequences are also important, particularly
where new material is fitted into the existing relatively rigid structure.
Again the procedure follows the general pattern for butts and seams in
plate panels. If a new shell plate is to be welded in place the seams and
butts in the surrounding structure are cut back 300 to 375 mm from the
opening; likewise the connection of the stiffening in way of the opening.