GE Hydraulic Connector bolt failure in Lower Marine Riser Package (LMRP)
The upper and lower bodies of a GE Hydraulic (H4) Connector contained in the Lower Marine Riser Package (LMRP) separated. Upon investigation, it has been determined that stress corrosion cracking caused by hydrogen embrittlement was a contributor to that incident.
GE has received information on three H4 Connectors with bolts that were produced from June 2007 to October 2009. GE is investigating the production history of these H4 Connector bolts. Preliminary investigation indicates bolts produced during this time are more susceptible to hydrogen embrittlement.
Part number: H10004-2, including bolt kit numbers H125004-5, H125004-6, H125004-7.
GE requires the inspection of the referenced bolts. A formal inspection procedure will be issued shortly and will include steps summarized in the flow chart on the following page.
Inspection and Data Collection (all bolts)
- Remove coating/paint from bolt heads.
- Use bolt data collection template to record data for each bolt, including location, serial number, and batch.
- If bolts have markings that match any bolt listed on website (see link for bolts affected), please remove these bolts for disposition.
- If bolts have markings not found at website, perform a precautionary ‘torque test’ to ensure the integrity of all installed bolts (see procedure in appendix).
- If bolt does not pass the ‘torque test’, remove the bolt for disposition.
Disposition and Containment(identified bolts)
- Using a properly calibrated torque tool, mark the bolt’s location on the head of the bolt and remove the bolt.
- Record the break-out torque required for each identified bolt, as well as the general appearance of each bolt on the supplied data collection template (see appendix).
- GE will supply new bolts as appropriate.
Corrective and Preventative Actions
GE will update the fleet with pertinent developments.