According to suppliers in the oil and gas industry, stabbing guides help workers align two sections of tubing, drill pipe, or casing for male-to-female connections. The foundry that produced this 47-lb. ductile iron casting—Phenix Foundry, Phenix City, Alabama—summarized its end use function: “To guide drill pipe into the top drive unit.”

Converted from a seven-piece weldment, the single-piece casting reduced lead time by 12 weeks by eliminating cutting and forging. Phenix Foundry also achieved an eight-hour reduction in machining time and provided a cost reduction to their customer of 15%.
Casting consistently offers tremendous reduction in lead time and overall cost savings compared to a multi-piece fabrication assembly consisting of various operations of cutting, forming, welding, and machining.  Additionally, castings offer dimensional tolerances with smooth transitions with fillet and radii for better fatigue life and performance.

Following is a breakdown of this casting’s key design features: 

1. Parting and orientation

• Body core at center with prints to make as-cast windows opening

• The drag (bottom half) of the casting typically is an ideal location for lettering, such as the part or serial number. The decision about parting and orientation is the first important step in the design—ultimately the casting quality will depend on it. 

  2. As-cast cored pockets 

• Stiffeners for structural rigidity to achieve the same or better stiffness of the structure in casting, webs and cross ribs are typically used. Computer modeling and simulation of the casting process is very effective tool to predict the porosities, micro-structure and properties, and to validate the rigging and process parameters … all before releasing the final design and building an expensive tool.

• As-cast cored pockets are required for the form, fit, and functionality of the part. This largely depends on their location with reference to the casting parting plane. 

  3. Fillets and radii for smooth transitions to reduce stress concentration.

• Generous fillets and radii are very important, especially at all the junctions—L, T, X, and Y—for smoother transitions.
• The overall effect is much reduced stress concentration associative with sharp changes in the cross sections with weldments and better fatigue performance of the structural component.