Notice
to Lessees and Operators (NTL) of Federal Oil, Gas,
and Sulphur Leases in the Outer Continental Shelf
American Petroleum Institute
(API) Specification 6D (SPEC 6D),
Specification for Pipeline Valves (Gate, Plug, Ball, and Check Valves),
21st Edition (March 31, 1994), and Supplements 1 and 2
We are concerned that allowable minimal leakage rates
for metal-to-metal valve seats included in Supplements 1 and 2 might diminish the
operational safety of OCS pipelines. Therefore, we will not adopt these supplements as
documents incorporated by reference under 30 CFR Part 250.
The Minerals Management Service (MMS) regulations published
July 1, 1998, at 30 CFR 250.101, incorporate by reference API SPEC 6D, 21st
Edition, but not the two supplements. The API Subcommittee on Valves and Wellhead
Equipment issued Supplements 1 and 2 to the 21st Edition of API SPEC 6D on
December 1, 1996, and December 1, 1997, respectively. The supplements allow minimal
leakage rates for pipeline valves having metal-to-metal seats in section 5.3 of SPEC 6D
and in section C3 of Appendix C to SPEC 6D. Prior to APIs issuing the supplements,
API SPEC 6D allowed no visible leakage from any valves.
The APIs decision to adopt minimal leakage rates for
metal-to-metal seats appears to be largely based on the information contained in API
Standard 598, "Valve Inspection and Testing"; International Standards
Organization (ISO) Standard 5208, "Industrial Valves--Pressure Testing of
Valves"; and ISO Draft Industry Standard 14313, "Petroleum and natural gas
industries--Ball, check, gate and plug valves--Specification." All of these standards
allow minimal leakage rates for metal-to-metal seats.
It may well be that the "no visible leakage"
standard contained in the 21st and previous editions of API SPEC 6D is an
unreasonably high standard for metal-to-metal seats. Metal-to-metal seats are
non-deforming compared to non-metal-to-metal seats; therefore, it may be reasonable to
expect that some leakage would occur between facing metal surfaces. Nevertheless, there
appears to be no data or agreed-upon formula for predicting an acceptable leakage rate.
Valve leakage within pipelines poses a major safety
concern. Multiple fatalities have occurred offshore when workers attempted either to cut
into a pipeline or open a pig trap when they believed that combustible hydrocarbons or
high pressure had been eliminated from the system. Once a system is bled down and
isolated, there is a danger that the system may become re-pressurized if the pipeline
valves have "allowable leakage rates." Since all pipeline systems eventually are
cut into for repair or modification purposes, "allowable leakage rates" can have
deadly consequences for unsuspecting workers.
![Go to Top Page](https://webarchive.library.unt.edu/eot2008/20080921180657im_/http://www.mms.gov/ntls/Assets/Buttons/top.gif)
We are currently reviewing our pipeline safety regulations
under 30 CFR 250.1000 through 250.1014. If metal-to-metal seats cannot assure a
"leak-proof" seal, we may need to consider allowing only "resilient-seated
valves," as they are described in API Standard 598. We realize that there may be many
valves in OCS pipelines that contain metal-to-metal seats. We anticipate that any change
in our regulations affecting pipeline valves with metal-to-metal seats would likely only
affect newly installed valves and old valves being replaced due to normal wear or
corrosion. We would not want to require wholesale replacement of metal-to-metal seated
valves and thereby increase worker exposure to the potential hazards described in the
preceding paragraph.
Our regulations under 30 CFR 250.101 allow you to use a
later edition of a document incorporated by reference provided (1) that the lessee
demonstrates that compliance with the later edition provides a degree of protection,
safety, or performance equal to or better than that which would be achieved by compliance
with the listed edition, and (2) that the lessee obtains prior written approval of the
authorized MMS official. We do not believe that the allowable leakage rates for
metal-to-metal valve seats cited in supplements 1 and 2 to the 21st Edition of
API SPEC 6D provide a degree of protection, safety, or performance equal to or better than
that provided in the original document. Therefore, we will not incorporate by reference
these supplements in our regulations and will not approve requests for their use under 30
CFR 250.101.
Paperwork Reduction Act of 1995 Statement: This
Notice to Lessees and Operators (NTL) refers to information collection requirements in 30
CFR Part 250, Subpart A. The Office of Management and Budget has approved the collection
of information in these regulations and has assigned OMB Control Number 1010-0030. This
NTL does not impose additional information collection requirements subject to the
Paperwork Reduction Act of 1995.
If you have any questions about this notice, please contact
Mr. Joseph R. Levine on (703) 787-1033.
[signed] Carolita U. Kallaur,
Associate Director for Offshore Energy and Minerals Management
| Privacy |
Disclaimers |
Accessibility |
Topic Index | FOIA |
Last Updated:
08/14/2008,
10:27 AM
![Top of Page](https://webarchive.library.unt.edu/eot2008/20080921180657im_/http://www.mms.gov/ntls/Assets/Icons/top.gif)
|