Each bar or tube used to manufacture
HWDP tool joints or integral
HWDP shall be examined for both surface and internal defects in
accordance with Clause *1 of ISO ******1/API Spec
**1.
? Stress relief features are optional. When
specified in the purchase agreement, stress relief features
complying with the dimensions specified in API Spec 7 shall be
provided. The surfaces of stress relief features shall
be free of stress risers such as tool marks and steel stencil
impressions. Laboratory fatigue tests and tests under actual
service conditions have demonstrated the beneficial effects of
stress relief contours at the pin shoulder and at the base of the
box thread. It is recommended that, where fatigue failures at
points of high stress are a problem, stress relief features be
provided. The bareback design is the recommended relief
feature for box connections. However, the box relief groove design
has been shown to also provide beneficial effects. It may be used
as an alternate to the bareback design. Stress relief features will cause a slight
reduction in the tensile strength of the pin and the section
modulus of the connection. However, under most conditions this
reduction in cross-sectional area is more than offset by the
reduction in fatigue failures. If unusually high tensile loads are
expected, calculations of the effect should be
made.
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