Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURER'S MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS. THESE CONTAIN INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

1. SUBTASK 70-31-02-220-003 Inspection Limits of Orbital Torch Welds.

   1. Weld bead shape. See Figure.

      1. The weld crown and the underbead must have a smooth contour with the parent metal. There must be no sharp changes of section.

      2. The weld must be visible and fully penetrate its complete length. The maximum height of the crown or the underbead must not be more than 1t. The maximum thickness of the weld must not be more than 2.25t of the tube material thickness.

      3. The weld bead width must be between 2.5 and 5t.

   2. Defects in the weld that are not permitted.

      1. Cracks in the weld or heat affected zone.

      2. Lack of side fusion with the parent metal.

      3. Lack of penetration.

      4. Chain porosity (porosity in a continuous line).

      5. Oxidation of the crown or underbead.

      6. Incorrect weld bead geometry.

      7. Ballooning of the weld bead because internal argon pressure is too high.

      8. Unfused tack welds.

      9. Arc damage anywhere on the tube.

   3. Permitted defects in the weld.

      1. Undercut and sinkage is permitted to a maximum 0.1t, if there is no sharp change of section or sharp edges.

      2. Stop craters at the weld run out, if they are not more than 1t diameter and 0.25t deep.

      3. Subsurface porosity.

         1. 0.5t in the weld bead.

         2. 0.25t in the blend of the bead to the parent metal.

         3. For general porosity limits, refer to the SPM TASK 70-31-02-310-501-001, SUBTASK 70-31-02-260-001.

      4. Two tungsten inclusions, if they are not more than 0.75t in diameter and are fully in the weld bead. They must have a minimum distance of 0.2 in. (5 mm) between them.

      5. Misalignment of the tube and end fitting up to 0.15t or 0.005 inch (0.13 mm) whichever is greater.

      6. Smooth flaring up to 0.15t without loss of wall thickness.

2. SUBTASK 70-31-02-220-004 Visual Inspection of Orbital Torch Welds.

   1. All welds must be visually examined as specified in Step. The weld crown must be examined visually without magnification aids and where possible examine the underbead with an intrascope.

   2. Where the geometry of the tube permits, the tube must be visually examined to make sure it is not blocked. If this is not possible a ball check must be done. To do this check, a sphere of applicable diameter is passed along the bore of the tube. Alternatively do a flow check with CoMat 01-277 KEROSINE.

3. SUBTASK 70-31-02-230-002 Penetrant Inspection of Orbital Torch Welds.

   1. Subsequent to a visual inspection it is important that all welds are examined with an approved penetrant procedure. Refer to the SPM TASK 70-23-00-230-501.

   2. Inspect to the standard given in Step.

4. SUBTASK 70-31-02-260-003 Radiographic Inspection of Oribital Torch Welds.

   1. Radiographic inspection of welds shows defects which cannot be found with visual or penetrant procedures. All tube assemblies must be radiographically examined. Refer to the SPM TASK 70-26-01-260-501.

      Inspect to the standard given in Step.

   2. Do as follows for a radiographic inspection of tubes with an internal diameter of less than 1.50 in. (38.1 mm). It is necessary to use a double-wall double image procedure with two exposures at right angles to each other. Refer to Figure this shows the beam angle for different tube diameters.

   3. Refer to the SPM TASK 70-26-01-260-501 for methods and control of Radiographic inspection.

5. SUBTASK 70-31-02-780-001 Do a Pressure Test

   1. All tube assemblies must have a pressure test done after repair. The instructions will be given in the applicable Repair.

6. SUBTASK 70-31-02-320-001 Cut Back the Weld Bead

   1. The weld bead can be cut back mechanically to make its geometry better and to remove small surface defects within the limitations of Step.Cutting back of the parent material is acceptable up to a maximum depth of 0.1t.

7. SUBTASK 70-31-02-350-001 Ream the Weld Underbead

   1. Where the geometry of the tube permits, it is permitted to ream the underbead to the limits given in Step. The location of the reamer is important to make sure the underbead is reamed concentric with the tube wall. All swarf must be removed.

      Sharp edges remaining after the underbead is reamed must be removed. Make sure the weld bead geometry is in the specified limits.

      .

8. SUBTASK 70-31-02-350-002 Rework

   1. With the exception of oxidised underbeads hand or automatic re-welding may be carried out but shall be limited to two rewlds only.

Figure: Weld bead dimensions

Weld bead dimensions



Figure: Radiographic inspection of butt welded tubes

Radiographic inspection of butt welded tubes