L00035 Examination of the Properties of Quench and Tempered Fitting

The properties of a pipe fitting reported by the manufacturer normally are measured using test specimens prepared from trim material that is removed from the fitting after forming and that, subsequently, is welded to the fitting for heat treatment with the fitting.

The goals of this investigation were to determine the uniformity of properties in a representative fitting and to determine how well properties measured on test specimens cut from the fitting match the manufacturer's test report. A quenched and tempered 30 x 30 x 30 inch straight tee fitting was used in this study. The yield strength and ultimate tensile strength only varied a few ksi at the various locations examined. Total elongation was slightly lower in specimens with the major axis transverse to the plate rolling direction. Energy-absorption values from longitudinal Charpy V-notch tests at 20 F showed significant variation, ranging from 37 to 86 ft-lbs. The measured tensile yield strength was about 15 ksi lower than that reported by the manufacturer. Finally, limited studies to determine the effects of stress-relief treatments showed that stress relieving for 1 hour at 1100 F reduced energy adsorption values by about 25 ft-lbs. A similar treatment for 5 hours at 950 F had little effect on the tensile or impact properties.