WPS QW-402 Joints
ASME Section IX WPS : QW-402 Weld Joint Design Example
ASME Section IX Welding Variables for a WPS : QW-402 Joints
Joint or Groove Design QW-402.1
General description of the types of joints that apply to this WPS.
Examples: Groove, Fillets, Single Vee Groove, Double Vee Groove, Lap Joints, etc.
All variables associated to QW-402 are defined as “Non-Essential”
Within ASME work scopes it is common to include an exception statement in the QW-402 section.
As per ASME Section IX paragraph QW-402.1, groove design is a non-essential variable. Non-essential variables can be editorially changed without requalification of the procedure. As such, the joint design depicted on the WPS can be substituted with those specified on engineering specifications, drawings, or other details which are approved for the project scope the WPS applies to.
Backing QW-402.4, QW-402.5
Establish by each weld process if backing is required or optional
Sometimes the mistake is made for only specifying the root process in combination procedures
Retainers QW-402.11
Retainers are a non-consumable form of backing used to contain/retain and shape the molten weld puddle, and do not become part of the weld.
Retainers are typically only used in ESW Electroslag Welding, or EGW Electrogas Welding
Retainers are a moveable, and re-moveable backing often water cooled, and built in a way that it can move along the joint as the weld is being made.
Retainers can also be referred to as a “Retaining Shoe”
Backing Material
Backing material typically consists of one or more of the following
Base Metal : often in the form of a backing strip, needs to comply with that specified in QW-403
Weld Metal : often this will be the weld metal of the root, as the second weld process will be welded with this as backing
Non-Fusing Metal : An example of this would be a copper block, to which the weld does not fuse
Non-Metallic : An example of this would be ceramic backing
Root Spacing QW-402.10
Root spacing is one of the joint configurations variables that is specifically called out, so it must be addressed on the WPS
Joint Configuration QW-402.1
Misalignment : Misalignment can often be overlooked, B31.3 specifies that permitted misalignment is to be per the WPS; so for B31.3 applications misalignment should be included
Joint Angle : The included angle of the groove should be stated, including tolerances
Face or Land : The face or the land of the joint can affect the root process and should be specified
Groove Radius : For joint configurations such as a U or J bevel, the radius of the groove should be specified
Essential Variable: Variables for which a change is considered to affect the mechanical properties (other than notch toughness) of the joint. Essential variable changes that fall outside their qualified range requires re-qualification.
Supplementary Essential Variable: Variables for which a change is considered to affect the toughness properties of the joint, heat-affected zone (HAZ), or base material.
Supplementary essential variables become additional essential variables in situations where toughness testing is required. When toughness testing is not required supplementary essential variables are not applicable.
Non-Essential Variable: Variables for which a change is considered to not affect the mechanical properties of the joint. This allows for editorial revisions to procedures within that permitted by Section IX without the need to requalify the procedure. Nonessential variables shall be documented on the procedure.