Drill pipe fracture. Part 2. Fracture-mechanics concept offers models to help calculate fatigue life in drill pipe

Journal Article · Mon Aug 13 00:00:00 EDT 1984 · Oil Gas J.; (United States)

OSTI ID:6018127

Kral, E; Sengupta, P K; Newlin, L; Quan, S S

This second of 2 articles on drill pipe fatigue analysis discusses the problem of calculating fatigue life of drill pipe under known operating conditions. Focusing attention on surface cracks, an attempt is made to characterize the most severe of these in terms of their dimensions and location by non-destructive examination. Keeping in mind the current threshold levels for crack detectability in routine nondestructive techniques like ultrasonic testing, it is assumed that a surface crack ca 0.03 to 0.04 in. deep may remain undetected in a length of unused pipe that has passed pre-service inspection. The stress intensity factors at the front of a surface crack and the attendant crack propagation rates into the wall of the cylinder are calculated on the basis of the behavior of the crack in the corresponding flat plate under the same uniform tensile stress at that experienced by the cylinder. The tensile stresses acting on the plate are calculated from the combined action of the axial load and the bending loads imposed on the pipe.

• OSTI ID: 6018127
• Journal Information: Oil Gas J.; (United States), Vol. 82:33
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
42 ENGINEERING
DRILL PIPES
FRACTURE MECHANICS
SERVICE LIFE
CALCULATION METHODS
CRACK PROPAGATION
FATIGUE
FRACTURES
STRESS ANALYSIS
STRESS INTENSITY FACTORS
STRESSES
DRILLING EQUIPMENT
EQUIPMENT
FAILURES
MECHANICAL PROPERTIES
MECHANICS
PIPES
020300* - Petroleum- Drilling & Production
420206 - Engineering- Mining & Drilling Equipment & Facilities- (1980-1989)