This procedure covers the welding of stabbing guides and shims onto Vulcan Offshore Pipe Caps. This procedure does not cover other types of repair welding on Vulcan parts; there are other Vulcan “RWP” procedures to cover these types of welds. This procedure is not valid on parts not of Vulcan manufacture; such procedures should be obtained from the manufacturer of the part.
2.0 DEFECT INSPECTION
It is imperative that the area to be welded be completely sound metal, free from cracks, shrinkage and porosity. The use of magnetic-particle or dye-penetrant inspection of the weld area is strongly recommended.
3.0 PREHEAT TEMPERATURE
The minimum preheat temperature is 212° F (100°C). Localized heating is permissible.
4.0 INTERPASS TEMPERATURE
The interpass temperature for this procedure is 212° F (100°C).
5.0 WELDING PARAMETERS
The “shielded metal arc welding” process (SMAW) should be used for all welding.
(A) Welding Current
Direct-Current, reverse-polarity (DCRP) is required for the electrodes recommended. The voltage and amperage settings should be based upon the recommendations of the electrode manufacturer. In the absence of specific instructions, the following guide may be used:
Electrode Amperage Voltage Diameter Flat Position Flat Position 1/8″ (3mm) 100-120 25/27
A suitable electrode is the TECH Rod E600.
No special technique is required. The weld bead should be the stringer type. The slag should be removed from the weld deposit between each pass.
7.0 POST-WELDING HEAT TREATMENT AND INSPECTION
Post-welding heat treatment is generally not necessary for areas of carbon steel which are less than 3″ (8cm) thick. For those which are, after welding, reheat the weld area to 150° C. When necessary, cover the weld area with an insulating material such as a thermal cloth. This will retard the cooling rate and reduce the welding stresses induced into the component. In either case, after the procedure is complete, 100% magnetic particle inspection should be performed on the welds. Any cracks discovered must be repaired according to the procedure before the part is used.
The following precautions should be observed:
- This procedure should not be used if excessive weld failures are experienced in service.
- Welds should be inspected after use and repairs effected if these are found.