discharge of drilling mud into the gulf of mexico from defective
equipment. Lower Marine Riser Package
(LMRP) Connector Failure
There have been quite a few incidents where drilling mud has
been discharged to the Gulf of Mexico from defective drilling equipment. On January 24, 2013, BSEE personnel met with
industry to discuss initial findings associated with a pollution incident
involving the discharge of synthetic base mud (SBM) into the Gulf of Mexico
(GOM) due to a loss of integrity of a LMRP H-4 connector. During this meeting, a qualified third-party
presented preliminary evidence that the stress corrosion cracking caused by
hydrogen embrittlement was a contributor to the incident. It was introduced that zinc electroplating
without proper baking, as per ASTM B633, was a possible cause of hydrogen
embrittlement. During this meeting, BSEE
was informed of two other rigs as having H-4 connector bolt failures.
On January 25, 2013, BSEE received information from the
connector vendor which identified rigs as having blowout preventer (BOP) stack
connectors that may contain bolts that may no longer be fit for purpose. BSEE issued emails to the associated operators
of the subset of rigs with current well operations in the Gulf of Mexico. The content of the emails notified these
operators of the initial findings and gave specific instructions on securing
the current well operations in order to retrieve the LMRP and/or BOP to the
surface, if not already on the surface. These
operators were directed to then suspend operations until the existing bolts on
the LMRP connector/wellhead connector could be changed out with bolts that have
been certified by an independent third-party to be in compliance with
recommended heat treatment practices or the existing bolts have been examined
and certified by an independent third-party that they are fit for purpose.
In order to ensure all of these affected bolts are identified
and proper corrective action is taken, BSEE recommends the following:
Operators are hereby urged to make an inventory of your
contracted rigs [currently involved in well operations in the Gulf of Mexico
Outer Continental Shelf (GOM) or planned to conduct well operations in the GOM]
and investigate the bolts of the LMRP and Wellhead connectors. For detailed instructions on identifying
affected bolts please refer to the Safety Notice issued by GE Oil and Gas on
January 25, 2013, titled, “H4 Connector Bolt Inspection Required(P/N H10004-2)”
at the following: http://www.ge-energy.com/connector-update.jsp
If you have H-4 connectors, as identified in GE’s safety
notice, and have verified through documentation that the connector contains any
affected bolts, you should immediately notify BSEE. You should also consult
with your contractors and subcontractors to determine the appropriate
inspection, disposition and/or corrective actions. BSEE will require an
independent third-party certification that confirms proper inspection and
refurbishment processes were completed prior to reinstallation of any affected
bolts.
Operators should review the QA/QC programs for all equipment
vendors (contracted and sub-contracted) to ensure that all equipment is being
manufactured to the required specifications. Special attention should be given
to ensure proper heat treating has taken place in accordance with the
specifications.
AUGUST 2014 – SUMMARY OF
FINDINGS
On December 18, 2012, while the Transocean Discoverer India was
performing drilling operations at the Keathley Canyon (KC) KC-736 lease block
in the Gulf of Mexico, the rig’s lower marine riser package (LMRP) separated
from the blowout preventer (BOP) stack resulting in the release of
approximately 432 barrels of synthetic-based drilling fluids into the Gulf of
Mexico. Chevron, the designated operator, reported to the Bureau of Safety and
Environmental Enforcement (BSEE) that the incident was the result of the
failure of H4 connector bolts manufactured by GE Oil and Gas (formerly
Vetco-Gray), on the LMRP.
Based on the initial analysis of the failure performed by
Transocean, Chevron, and GE, GE sent replacement bolts for all known H4
connectors to customers worldwide. After learning of the December 18th
incident, BSEE worked with GE to ensure that the company replaced any faulty
bolts that were in use in equipment deployed on the Outer Continental Shelf
(OCS), in a timely manner. This process resulted in the replacement of more
than 10,000 bolts over a relatively short time frame and short-term disruption
of related deepwater activities.
Verification of the structural integrity of a critical
component like H4 connector bolts, which are currently deployed on the OCS and
globally, is essential for both worker safety and the protection of the
environment. Accordingly, in January 2013, BSEE tasked the Quality
Control-Failure Incident Team (QC-FIT) to evaluate the possibility of
additional bolt failures and make recommendations to mitigate potential risks
of future failures, either domestically or internationally. BSEE charged the
team, comprised of BSEE engineers and other technical personnel, with
evaluating the currently available information including: (1) the
Chevron/Transocean/GE root-cause analysis, (2) GE ’s connection design,
manufacturing, and quality control processes, and (3) other information related
to the performance of this equipment. During its inquiry, the QC-FIT was made
aware of other offshore oil and gas failures related to bolts, studs, inserts
and connectors, appearing to share similar contributing factors. BSEE management
requested the QC-FIT to evaluate whether the causes of these other failures
were related and whether evidence existed of an industry-wide issue.
The QC-FIT conducted visits with drilling contractors,
equipment manufacturers, and a classification society; contacted BSEE’s
counterparts in the International Regulators’ Forum (IRF); met with three
operators- BP, Shell, and Chevron in the Gulf of Mexico; reviewed reports of
similar incidents of bolt and connector failures in subsea environments; and
researched technical documents and standards. These activities provided
significant information on the material properties used in subsea applications,
corrosion behaviors, manufacturing processes and protective coatings of bolts
in environments similar to those of this application.
This report is based on the review of available data and input
from various sources and was reviewed by an independent technical consultant.
KEY FINDINGS
The failure of the GE H4 connector bolts was
primarily caused by hydrogen induced stress corrosion cracking (SCC) due to
hydrogen embrittlement, which led to the fracturing of the installed bolts.
This finding is consistent with the conclusions of the Transocean/Chevron/GE
root cause analysis.
A GE subcontractor relied on an older 1998
version of the American Society for Testing and Materials (ASTM) B633 standard
and therefore, the bolts did not receive the required post electroplating
treatment. This finding is consistent with the Transocean/Chevron/GE submitted
root cause analysis report.
The GE quality management system (QMS) in place
at the time, which met the industry standards and certification programs,
qualified and audited only first-tier level suppliers (GE’s contractors) and
not others in the supply chain. In this incident, since a third-tier level
supplier (subcontractor) performed the electroplating coating of the bolts,
GE’s QMS was unable to detect the issue. Neither Transocean nor Chevron in
their management system assessment of contractor qualification, nor the programs
that ensure the mechanical integrity of critical equipment detected this
sub-tier supplier issue.
An inadequate coat of paint on the portion of
the bolt heads was determined to be a potential contributory factor. The GE
inspection procedures, in place at the time, did not adequately address this
potential issue.
In 2003, a drilling riser bolt insert failure
occurred in which the hardness of the inserts and cathodic protection systems
were identified as areas of concern. Although the OEM and the Minerals
Management Service (MMS) issued general cathodic protection guidelines in 2005
and several operators changed their internal specifications for the maximum
hardness of bolts, there is no evidence of a successfully coordinated effort by
industry to address the potential safety concerns associated with the issue. A
more comprehensive incident and data sharing effort by industry over the past
10 years could possibly have flagged this issue earlier and resulted in the
setting of consistent standards on the hardness of bolts/inserts or on the
optimal applied voltage for cathodic protection on drillships.1
Existing industry standards do not adequately
address bolting/connector performance in subsea marine applications. For
example, although API Specification 16A provides requirements for BOP
connectors, it does not contain material property requirements for the
connection bolting used for subsea applications. Furthermore, other industry
standards that apply to subsea equipment have different maximum hardness limit
requirements for bolts.
OPEN ISSUES
Areas of inquiry where the QC-FIT was unable to make conclusive
findings:
The QC-FIT noted that a number of incidents
appeared to have occurred on Transocean owned rigs. The data set is too small
to determine if this percentage is a statistical significant result that
supports a conclusion that Transocean’s operating or maintenance practices may
be increasing the likelihood of a failure. However, there are some potential
factors that could have played a role in these failures. The QC-FIT noted that
either the lack of adequate cathode protection or the use of dissimilar metals
near the H4 bolts could have caused accelerated corrosion of the bolts. QC-FIT
also concluded that the information and issues regarding cathodic protection,
operation, and maintenance need to be explored further.
It remains unclear whether the material
selection plating requirements for service class (SC) SC2 bolts are appropriate
for the marine environment when these bolts are used per ASTM B633. GE
maintains that this material selection is appropriate. GE also contends that
API thickness restrictions would make a coating thickness beyond a SC2
specified thickness untenable. Further assessment of the appropriateness of
this plating material needs to be performed and clarified in future editions of
ASTM B633 as needed. BSEE suggests developing a joint industry technical forum
to evaluate these issues.
KEY RECOMMENDATIONS
The QC-FIT formulated recommendations that BSEE should take (detailed
in the body of this report) to mitigate the likelihood of future failures that
could impact safety and/or the environment. These are:
1. Improve industry standards.
BSEE should encourage industry to develop a
consistent set of standards for connections and connection fasteners used in
all offshore subsea systems, including a requirement that allows tracking
connection components during their service life. This should include clear and
consistent guidance on material hardness, yield strength and ultimate tensile
strength requirements. (The release of API Spec 20E; First Edition, August 2012
"Alloy and Carbon Steel Bolting for use in the Petroleum and Natural Gas
Industries" should address some of the concerns regarding manufacture of bolts,
studs, etc.)
BSEE should request that ASTM further revise its
relevant standards to provide additional clarity related to the design and use
of coatings for marine service.
BSEE should request that industry develop an
improved quality management standard that addresses the use of subcontractors
by manufacturers through multiple tiers in the manufacturing chain. The
industry and BSEE should also review API RP75 (SEMS) and the BSEE SEMS
regulation (Subpart S) to ensure that the sections on mechanical integrity and
contractor qualification are sufficiently robust.
BSEE should request that industry issue guidance
or a standard on the optimal applied voltage limits for cathodic protection
systems for use on drillships/modus.
2. Initiate joint industry research initiatives. BSEE should
facilitate, support, and encourage specific studies that compare and contrast
the connection and connection fastener design, material, maintenance, and
quality specifications to identify potential requirement gaps and
inconsistencies across the industry. The impact of cathodic protection systems
on the performance of connectors should also be evaluated.
3. Promote Failure Reporting. BSEE should encourage industry to
adopt a failure reporting system that allows data on failures and potential
failures involving critical equipment to be collected, analyzed, and reported
to the industry and BSEE. This information will better allow the industry and BSEE
to identify trends and take corrective action before any injuries or impact to
the environment occurs.
4. Develop regulations that ensure specific design standards
are met. If necessary, BSEE should develop proposed regulations and/or notices
to lessees to implement improved standards for connections and connection
fasteners and cathodic protection systems.
BSEE remains interested in GE’s and any others ongoing tests
and may take further steps to address potential safety risks as indicated.
