| Industry: |
Oil & Gas |
| Specimen Description: |
Offshore Platform Drilling Riser Bolt Insert |
| Material: |
AISI 4340 Quenched and Tempered Low Alloy Steel |
| Environment: |
Seawater |
| Background: |
|
| Time in Service: |
Unknown |
| Findings: |
Visual examination of the as-received insert showed
circumferantial cracking at the body to flange radius. The fracture
face was brittle appearing with a single cracking
initiation site. SEM imaging
of the fracture revealed a deposit high in calcium obscuring the fracture
features. After removing the deposit with inhibited hydrochloric acid,
the true, intergranular fracture could be observed. The integranular
fracture and knowledge of the service environment suggested failure from
hydrogen embrittlemnt. |
