Swivel joint blanks for fracturing manifolds should be manufactured from qualified alloy steel with traceable heat numbers and verified mechanical properties. The forging process must ensure dense internal structure and sufficient machining allowance for pressure-bearing features.
Heating temperature, holding time, forging ratio, and deformation sequence should be controlled to avoid overheating, coarse grain, folds, cracks, and decarburization. After forging, controlled cooling and preliminary inspection are required before heat treatment.
Heat treatment is selected to achieve the specified tensile strength, yield strength, hardness, and impact toughness. Excessive hardness should be avoided for pressure-containing components, especially where sour-service requirements may apply.
Machining allowance should consider final wall thickness, seal grooves, ball races, threads, and connection shoulders. Ultrasonic testing, magnetic-particle testing, dimensional inspection, and hydrostatic testing are used to verify the finished component.
