10.3.3 Cold forming is not permitted above 250°C and beyond a strain limit of
12 per cent, i.e. mean radius of 4,2 times plate thickness.
10.3.4 All welding is to be performed using the heat input within the range
qualified.
10.3.5 Where welding procedures for High Strength Steel – Special Application 2 are to be
approved for undermatched welding, the design should take into account the minimum
yield strength of the consumable in predicting the joint or structural properties.
To ensure that design intent is maintained for any structure containing undermatched
welds, the design should also account for any design tolerances, e.g. for weld
misalignment, joint gap, repair of plate or weld defects. These limits are to be
rigorously applied in production with any deviations or concessions being authorised
by the project authority.
10.3.7 As a minimum, visual inspection is to be carried out on the
following:
- All weld preparations, including excavations for the repair
of defects, surfaces to be clad, etc., prior to welding.
- Root passes before any subsequent passes are made.
- After back gouging.
- On completion of the weld on all exposed surfaces of the
weld, at the weld toes for evidence of cracking and adjacent to the welds for
evidence of damage by stray arcing.
- All stops and starts to ensure they are clear of porosity
and/or crater cracks.
- Any other project specific requirements.
10.3.8 The application of pre-heat is required for all weld joints and is to be in
accordance with the qualified welding procedure, with consideration of the
restraints of the intended application. The recommended pre-heat temperatures for
each Material Class (Special application 1 and 2) are shown in
Table 13.10.3 Recommended pre-heat temperature requirements for applicable Material
Class Special Applications 1 and 2 .
Table 13.10.3 Recommended pre-heat temperature requirements for applicable Material
Class Special Applications 1 and 2
| Weld
Type
|
Material thickness
|
Root
Run
(°C minimum)
|
Filling
Run
(°C minimum)
|
| High
strength steel – Special Application 1
High strength steel –
Special Application 2 (undermatched welds)
|
All
thicknesses
|
120
|
70
|
| High
strength steel – Special Application 2 (matched welds)
|
All
thicknesses
|
120
|
120
|
10.3.9 The application of pre-heat shall be of a uniform soaking type, e.g.
using resistance or induction electric heaters. The use of torches to provide
preheat is limited to tack or temporary welding locations or to those applications
involving welding within a localised area.
10.3.10 The interpass temperature for all multi-pass welds is not to exceed
150°C.
10.3.11 Where stress relieving is considered necessary for a particular
application, details of the welding procedure and heat treatment cycle to be applied
are to be submitted for special consideration and approval.
10.3.12 Welding of temporary attachments (including lugs, bolts, studs etc.) to
pressure hulls and frames is to be kept to a minimum.
10.3.13 Stud welding is to be in accordance with an approved drawing and welding
procedure. It is prohibited for shock-mounted equipment, equipment whose failure may
result in injury to personnel, or for any equipment inside reactor compartments
(where applicable).
10.3.14 For weld joints between High Strength Steel – Special Application 1 or 2,
to other approved structural steels, the welding consumable is to be selected to
match the strength of High Strength Steel – Special Application 1 or 2
10.3.15 Welding conditions and techniques to be employed for production welding
is to be in accordance with a welding procedure qualified specifically for joining
High Strength Steel – Special Application 1 or 2 to the other approved structural
steels.
10.3.16 The extent of NDE for all welds will be stated in the project
requirements. This is to be considered to be the minimum requirement and the extent
is to be increased when warranted by the analysis of previous results.
10.3.17 Final NDE of weld joints is to be carried out 48 hours after welding for High
Strength Steel – Special Application 1 and High Strength Steel – Special Application
2 undermatched welds. For High Strength Steel – Special Application 2 matched welds,
final NDE of the weld joint is to be carried out 72 hours after welding.
10.3.18 The results of all NDE is to be evaluated in accordance with these Rules
and the project specific requirements.